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From: ekoifman@apache.org
To: commits@hive.apache.org
Date: Fri, 22 Jul 2016 16:56:51 -0000
Message-Id: <b99c72d4137548ddb739d7b0ac9d77c2@git.apache.org>
Subject: [1/2] hive git commit: HIVE-14292 ACID table creation fails on mysql
 with MySQLIntegrityConstraintViolationException(Eugene Koifman,
 reviewed by Wei Zheng)
archived-at: Fri, 22 Jul 2016 16:56:55 -0000

Repository: hive
Updated Branches:
  refs/heads/branch-2.1 e96994b10 -> 0efafc0df


http://git-wip-us.apache.org/repos/asf/hive/blob/0efafc0d/metastore/src/java/org/apache/hadoop/hive/metastore/txn/TxnHandler.java.orig
----------------------------------------------------------------------
diff --git a/metastore/src/java/org/apache/hadoop/hive/metastore/txn/TxnHandler.java.orig b/metastore/src/java/org/apache/hadoop/hive/metastore/txn/TxnHandler.java.orig
deleted file mode 100644
index bc818e0..0000000
--- a/metastore/src/java/org/apache/hadoop/hive/metastore/txn/TxnHandler.java.orig
+++ /dev/null
@@ -1,3233 +0,0 @@
-/**
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.apache.hadoop.hive.metastore.txn;
-
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.util.concurrent.Service;
-import com.jolbox.bonecp.BoneCPConfig;
-import com.jolbox.bonecp.BoneCPDataSource;
-import org.apache.commons.dbcp.ConnectionFactory;
-import org.apache.commons.dbcp.DriverManagerConnectionFactory;
-import org.apache.commons.dbcp.PoolableConnectionFactory;
-import org.apache.commons.lang.NotImplementedException;
-import org.apache.hadoop.hive.common.ServerUtils;
-import org.apache.hadoop.hive.common.classification.InterfaceAudience;
-import org.apache.hadoop.hive.common.classification.InterfaceStability;
-import org.apache.hadoop.hive.metastore.Warehouse;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.apache.commons.dbcp.PoolingDataSource;
-
-import org.apache.commons.pool.ObjectPool;
-import org.apache.commons.pool.impl.GenericObjectPool;
-import org.apache.hadoop.hive.common.JavaUtils;
-import org.apache.hadoop.hive.conf.HiveConf;
-import org.apache.hadoop.hive.metastore.api.*;
-import org.apache.hadoop.hive.shims.ShimLoader;
-import org.apache.hadoop.util.StringUtils;
-
-import javax.sql.DataSource;
-
-import java.io.IOException;
-import java.sql.*;
-import java.util.*;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.Semaphore;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.locks.ReentrantLock;
-import java.util.regex.Pattern;
-
-/**
- * A handler to answer transaction related calls that come into the metastore
- * server.
- *
- * Note on log messages:  Please include txnid:X and lockid info using
- * {@link org.apache.hadoop.hive.common.JavaUtils#txnIdToString(long)}
- * and {@link org.apache.hadoop.hive.common.JavaUtils#lockIdToString(long)} in all messages.
- * The txnid:X and lockid:Y matches how Thrift object toString() methods are generated,
- * so keeping the format consistent makes grep'ing the logs much easier.
- *
- * Note on HIVE_LOCKS.hl_last_heartbeat.
- * For locks that are part of transaction, we set this 0 (would rather set it to NULL but
- * Currently the DB schema has this NOT NULL) and only update/read heartbeat from corresponding
- * transaction in TXNS.
- *
- * In general there can be multiple metastores where this logic can execute, thus the DB is
- * used to ensure proper mutexing of operations.
- * Select ... For Update (or equivalent: either MsSql with(updlock) or actual Update stmt) is
- * used to properly sequence operations.  Most notably:
- * 1. various sequence IDs are generated with aid of this mutex
- * 2. ensuring that each (Hive) Transaction state is transitioned atomically.  Transaction state
- *  includes its actual state (Open, Aborted) as well as it's lock list/component list.  Thus all
- *  per transaction ops, either start by update/delete of the relevant TXNS row or do S4U on that row.
- *  This allows almost all operations to run at READ_COMMITTED and minimizes DB deadlocks.
- * 3. checkLock() - this is mutexted entirely since we must ensure that while we check if some lock
- *  can be granted, no other (strictly speaking "earlier") lock can change state.
- *
- * The exception to his is Derby which doesn't support proper S4U.  Derby is always running embedded
- * (this is the only supported configuration for Derby)
- * in the same JVM as HiveMetaStoreHandler thus we use JVM wide lock to properly sequnce the operations.
- *
- * {@link #derbyLock}
-
- * If we ever decide to run remote Derby server, according to
- * https://db.apache.org/derby/docs/10.0/manuals/develop/develop78.html all transactions will be
- * seriazlied, so that would also work though has not been tested.
- *
- * General design note:
- * It's imperative that any operation on a txn (e.g. commit), ensure (atomically) that this txn is
- * still valid and active.  In the code this is usually achieved at the same time the txn record
- * is locked for some operation.
- */
-@InterfaceAudience.Private
-@InterfaceStability.Evolving
-abstract class TxnHandler implements TxnStore, TxnStore.MutexAPI {
-
-  static final protected char INITIATED_STATE = 'i';
-  static final protected char WORKING_STATE = 'w';
-  static final protected char READY_FOR_CLEANING = 'r';
-  static final char FAILED_STATE = 'f';
-  static final char SUCCEEDED_STATE = 's';
-  static final char ATTEMPTED_STATE = 'a';
-
-  // Compactor types
-  static final protected char MAJOR_TYPE = 'a';
-  static final protected char MINOR_TYPE = 'i';
-
-  // Transaction states
-  static final protected char TXN_ABORTED = 'a';
-  static final protected char TXN_OPEN = 'o';
-
-  // Lock states
-  static final protected char LOCK_ACQUIRED = 'a';
-  static final protected char LOCK_WAITING = 'w';
-
-  // Lock types
-  static final protected char LOCK_EXCLUSIVE = 'e';
-  static final protected char LOCK_SHARED = 'r';
-  static final protected char LOCK_SEMI_SHARED = 'w';
-
-  static final private int ALLOWED_REPEATED_DEADLOCKS = 10;
-  static final private Logger LOG = LoggerFactory.getLogger(TxnHandler.class.getName());
-
-  static private DataSource connPool;
-  static private boolean doRetryOnConnPool = false;
-  
-  private enum OpertaionType {
-    INSERT('i'), UPDATE('u'), DELETE('d');
-    private final char sqlConst;
-    OpertaionType(char sqlConst) {
-      this.sqlConst = sqlConst;
-    }
-    public String toString() {
-      return Character.toString(sqlConst);
-    }
-    public static OpertaionType fromString(char sqlConst) {
-      switch (sqlConst) {
-        case 'i':
-          return INSERT;
-        case 'u':
-          return UPDATE;
-        case 'd':
-          return DELETE;
-        default:
-          throw new IllegalArgumentException(quoteChar(sqlConst));
-      }
-    }
-    //we should instead just pass in OpertaionType from client (HIVE-13622)
-    @Deprecated
-    public static OpertaionType fromLockType(LockType lockType) {
-      switch (lockType) {
-        case SHARED_READ:
-          return INSERT;
-        case SHARED_WRITE:
-          return UPDATE;
-        default:
-          throw new IllegalArgumentException("Unexpected lock type: " + lockType);
-      }
-    }
-  }
-
-  /**
-   * Number of consecutive deadlocks we have seen
-   */
-  private int deadlockCnt;
-  private long deadlockRetryInterval;
-  protected HiveConf conf;
-  protected DatabaseProduct dbProduct;
-
-  // (End user) Transaction timeout, in milliseconds.
-  private long timeout;
-
-  private String identifierQuoteString; // quotes to use for quoting tables, where necessary
-  private long retryInterval;
-  private int retryLimit;
-  private int retryNum;
-  /**
-   * Derby specific concurrency control
-   */
-  private static final ReentrantLock derbyLock = new ReentrantLock(true);
-  /**
-   * must be static since even in UT there may be > 1 instance of TxnHandler
-   * (e.g. via Compactor services)
-   */
-  private final static ConcurrentHashMap<String, Semaphore> derbyKey2Lock = new ConcurrentHashMap<>();
-  private static final String hostname = ServerUtils.hostname();
-
-  // Private methods should never catch SQLException and then throw MetaException.  The public
-  // methods depend on SQLException coming back so they can detect and handle deadlocks.  Private
-  // methods should only throw MetaException when they explicitly know there's a logic error and
-  // they want to throw past the public methods.
-  //
-  // All public methods that write to the database have to check for deadlocks when a SQLException
-  // comes back and handle it if they see one.  This has to be done with the connection pooling
-  // in mind.  To do this they should call checkRetryable() AFTER rolling back the db transaction,
-  // and then they should catch RetryException and call themselves recursively. See commitTxn for an example.
-
-  public TxnHandler() {
-  }
-
-  /**
-   * This is logically part of c'tor and must be called prior to any other method.
-   * Not physically part of c'tor due to use of relfection
-   */
-  public void setConf(HiveConf conf) {
-    this.conf = conf;
-
-    checkQFileTestHack();
-
-    Connection dbConn = null;
-    // Set up the JDBC connection pool
-    try {
-      setupJdbcConnectionPool(conf);
-      dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-      determineDatabaseProduct(dbConn);
-    } catch (SQLException e) {
-      String msg = "Unable to instantiate JDBC connection pooling, " + e.getMessage();
-      LOG.error(msg);
-      throw new RuntimeException(e);
-    }
-    finally {
-      closeDbConn(dbConn);
-    }
-
-    timeout = HiveConf.getTimeVar(conf, HiveConf.ConfVars.HIVE_TXN_TIMEOUT, TimeUnit.MILLISECONDS);
-    buildJumpTable();
-    retryInterval = HiveConf.getTimeVar(conf, HiveConf.ConfVars.HMSHANDLERINTERVAL,
-        TimeUnit.MILLISECONDS);
-    retryLimit = HiveConf.getIntVar(conf, HiveConf.ConfVars.HMSHANDLERATTEMPTS);
-    deadlockRetryInterval = retryInterval / 10;
-  }
-
-  public GetOpenTxnsInfoResponse getOpenTxnsInfo() throws MetaException {
-    try {
-      // We need to figure out the current transaction number and the list of
-      // open transactions.  To avoid needing a transaction on the underlying
-      // database we'll look at the current transaction number first.  If it
-      // subsequently shows up in the open list that's ok.
-      Connection dbConn = null;
-      Statement stmt = null;
-      ResultSet rs = null;
-      try {
-        /**
-         * This method can run at READ_COMMITTED as long as long as
-         * {@link #openTxns(org.apache.hadoop.hive.metastore.api.OpenTxnRequest)} is atomic.
-         * More specifically, as long as advancing TransactionID in NEXT_TXN_ID is atomic with
-         * adding corresponding entries into TXNS.  The reason is that any txnid below HWM
-         * is either in TXNS and thus considered open (Open/Aborted) or it's considered Committed.
-         */
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        stmt = dbConn.createStatement();
-        String s = "select ntxn_next - 1 from NEXT_TXN_ID";
-        LOG.debug("Going to execute query <" + s + ">");
-        rs = stmt.executeQuery(s);
-        if (!rs.next()) {
-          throw new MetaException("Transaction tables not properly " +
-            "initialized, no record found in next_txn_id");
-        }
-        long hwm = rs.getLong(1);
-        if (rs.wasNull()) {
-          throw new MetaException("Transaction tables not properly " +
-            "initialized, null record found in next_txn_id");
-        }
-        close(rs);
-        List<TxnInfo> txnInfo = new ArrayList<TxnInfo>();
-        //need the WHERE clause below to ensure consistent results with READ_COMMITTED
-        s = "select txn_id, txn_state, txn_user, txn_host from TXNS where txn_id <= " + hwm;
-        LOG.debug("Going to execute query<" + s + ">");
-        rs = stmt.executeQuery(s);
-        while (rs.next()) {
-          char c = rs.getString(2).charAt(0);
-          TxnState state;
-          switch (c) {
-            case TXN_ABORTED:
-              state = TxnState.ABORTED;
-              break;
-
-            case TXN_OPEN:
-              state = TxnState.OPEN;
-              break;
-
-            default:
-              throw new MetaException("Unexpected transaction state " + c +
-                " found in txns table");
-          }
-          txnInfo.add(new TxnInfo(rs.getLong(1), state, rs.getString(3), rs.getString(4)));
-        }
-        LOG.debug("Going to rollback");
-        dbConn.rollback();
-        return new GetOpenTxnsInfoResponse(hwm, txnInfo);
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "getOpenTxnsInfo");
-        throw new MetaException("Unable to select from transaction database: " + getMessage(e)
-          + StringUtils.stringifyException(e));
-      } finally {
-        close(rs, stmt, dbConn);
-      }
-    } catch (RetryException e) {
-      return getOpenTxnsInfo();
-    }
-  }
-
-  public GetOpenTxnsResponse getOpenTxns() throws MetaException {
-    try {
-      // We need to figure out the current transaction number and the list of
-      // open transactions.  To avoid needing a transaction on the underlying
-      // database we'll look at the current transaction number first.  If it
-      // subsequently shows up in the open list that's ok.
-      Connection dbConn = null;
-      Statement stmt = null;
-      ResultSet rs = null;
-      try {
-        /**
-         * This runs at READ_COMMITTED for exactly the same reason as {@link #getOpenTxnsInfo()}
-\         */
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        stmt = dbConn.createStatement();
-        String s = "select ntxn_next - 1 from NEXT_TXN_ID";
-        LOG.debug("Going to execute query <" + s + ">");
-        rs = stmt.executeQuery(s);
-        if (!rs.next()) {
-          throw new MetaException("Transaction tables not properly " +
-            "initialized, no record found in next_txn_id");
-        }
-        long hwm = rs.getLong(1);
-        if (rs.wasNull()) {
-          throw new MetaException("Transaction tables not properly " +
-            "initialized, null record found in next_txn_id");
-        }
-        close(rs);
-        Set<Long> openList = new HashSet<Long>();
-        //need the WHERE clause below to ensure consistent results with READ_COMMITTED
-        s = "select txn_id from TXNS where txn_id <= " + hwm;
-        LOG.debug("Going to execute query<" + s + ">");
-        rs = stmt.executeQuery(s);
-        while (rs.next()) {
-          openList.add(rs.getLong(1));
-        }
-        LOG.debug("Going to rollback");
-        dbConn.rollback();
-        return new GetOpenTxnsResponse(hwm, openList);
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "getOpenTxns");
-        throw new MetaException("Unable to select from transaction database, "
-          + StringUtils.stringifyException(e));
-      } finally {
-        close(rs, stmt, dbConn);
-      }
-    } catch (RetryException e) {
-      return getOpenTxns();
-    }
-  }
-  public OpenTxnsResponse openTxns(OpenTxnRequest rqst) throws MetaException {
-    int numTxns = rqst.getNum_txns();
-    try {
-      Connection dbConn = null;
-      Statement stmt = null;
-      ResultSet rs = null;
-      try {
-        lockInternal();
-        /**
-         * To make {@link #getOpenTxns()}/{@link #getOpenTxnsInfo()} work correctly, this operation must ensure
-         * that advancing the counter in NEXT_TXN_ID and adding appropriate entries to TXNS is atomic.
-         * Also, advancing the counter must work when multiple metastores are running.
-         * SELECT ... FOR UPDATE is used to prevent
-         * concurrent DB transactions being rolled back due to Write-Write conflict on NEXT_TXN_ID.
-         *
-         * In the current design, there can be several metastore instances running in a given Warehouse.
-         * This makes ideas like reserving a range of IDs to save trips to DB impossible.  For example,
-         * a client may go to MS1 and start a transaction with ID 500 to update a particular row.
-         * Now the same client will start another transaction, except it ends up on MS2 and may get
-         * transaction ID 400 and update the same row.  Now the merge that happens to materialize the snapshot
-         * on read will thing the version of the row from transaction ID 500 is the latest one.
-         *
-         * Longer term we can consider running Active-Passive MS (at least wrt to ACID operations).  This
-         * set could support a write-through cache for added performance.
-         */
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        // Make sure the user has not requested an insane amount of txns.
-        int maxTxns = HiveConf.getIntVar(conf,
-          HiveConf.ConfVars.HIVE_TXN_MAX_OPEN_BATCH);
-        if (numTxns > maxTxns) numTxns = maxTxns;
-
-        stmt = dbConn.createStatement();
-        String s = addForUpdateClause("select ntxn_next from NEXT_TXN_ID");
-        LOG.debug("Going to execute query <" + s + ">");
-        rs = stmt.executeQuery(s);
-        if (!rs.next()) {
-          throw new MetaException("Transaction database not properly " +
-            "configured, can't find next transaction id.");
-        }
-        long first = rs.getLong(1);
-        s = "update NEXT_TXN_ID set ntxn_next = " + (first + numTxns);
-        LOG.debug("Going to execute update <" + s + ">");
-        stmt.executeUpdate(s);
-
-        long now = getDbTime(dbConn);
-        List<Long> txnIds = new ArrayList<Long>(numTxns);
-        ArrayList<String> queries = new ArrayList<String>();
-        String query;
-        String insertClause = "insert into TXNS (txn_id, txn_state, txn_started, txn_last_heartbeat, txn_user, txn_host) values ";
-        StringBuilder valuesClause = new StringBuilder();
-
-        for (long i = first; i < first + numTxns; i++) {
-          txnIds.add(i);
-
-          if (i > first &&
-              (i - first) % conf.getIntVar(HiveConf.ConfVars.METASTORE_DIRECT_SQL_MAX_ELEMENTS_VALUES_CLAUSE) == 0) {
-            // wrap up the current query, and start a new one
-            query = insertClause + valuesClause.toString();
-            queries.add(query);
-
-            valuesClause.setLength(0);
-            valuesClause.append("(").append(i).append(", 'o', ").append(now).append(", ").append(now)
-                .append(", '").append(rqst.getUser()).append("', '").append(rqst.getHostname())
-                .append("')");
-
-            continue;
-          }
-
-          if (i > first) {
-            valuesClause.append(", ");
-          }
-
-          valuesClause.append("(").append(i).append(", 'o', ").append(now).append(", ").append(now)
-              .append(", '").append(rqst.getUser()).append("', '").append(rqst.getHostname())
-              .append("')");
-        }
-
-        query = insertClause + valuesClause.toString();
-        queries.add(query);
-
-        for (String q : queries) {
-          LOG.debug("Going to execute update <" + q + ">");
-          stmt.execute(q);
-        }
-        LOG.debug("Going to commit");
-        dbConn.commit();
-        return new OpenTxnsResponse(txnIds);
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "openTxns(" + rqst + ")");
-        throw new MetaException("Unable to select from transaction database "
-          + StringUtils.stringifyException(e));
-      } finally {
-        close(rs, stmt, dbConn);
-        unlockInternal();
-      }
-    } catch (RetryException e) {
-      return openTxns(rqst);
-    }
-  }
-
-  public void abortTxn(AbortTxnRequest rqst) throws NoSuchTxnException, MetaException {
-    long txnid = rqst.getTxnid();
-    try {
-      Connection dbConn = null;
-      try {
-        lockInternal();
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        if (abortTxns(dbConn, Collections.singletonList(txnid), true) != 1) {
-          LOG.debug("Going to rollback");
-          dbConn.rollback();
-          throw new NoSuchTxnException("No such transaction " + JavaUtils.txnIdToString(txnid));
-        }
-
-        LOG.debug("Going to commit");
-        dbConn.commit();
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "abortTxn(" + rqst + ")");
-        throw new MetaException("Unable to update transaction database "
-          + StringUtils.stringifyException(e));
-      } finally {
-        closeDbConn(dbConn);
-        unlockInternal();
-      }
-    } catch (RetryException e) {
-      abortTxn(rqst);
-    }
-  }
-
-  public void abortTxns(AbortTxnsRequest rqst) throws NoSuchTxnException, MetaException {
-    List<Long> txnids = rqst.getTxn_ids();
-    try {
-      Connection dbConn = null;
-      try {
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        int numAborted = abortTxns(dbConn, txnids, false);
-        if (numAborted != txnids.size()) {
-          LOG.warn("Abort Transactions command only abort " + numAborted + " out of " +
-              txnids.size() + " transactions. It's possible that the other " +
-              (txnids.size() - numAborted) +
-              " transactions have been aborted or committed, or the transaction ids are invalid.");
-        }
-        LOG.debug("Going to commit");
-        dbConn.commit();
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "abortTxns(" + rqst + ")");
-        throw new MetaException("Unable to update transaction database "
-            + StringUtils.stringifyException(e));
-      } finally {
-        closeDbConn(dbConn);
-      }
-    } catch (RetryException e) {
-      abortTxns(rqst);
-    }
-  }
-
-  /**
-   * Concurrency/isolation notes:
-   * This is mutexed with {@link #openTxns(OpenTxnRequest)} and other {@link #commitTxn(CommitTxnRequest)}
-   * operations using select4update on NEXT_TXN_ID.  Also, mutexes on TXNX table for specific txnid:X
-   * see more notes below.
-   * In order to prevent lost updates, we need to determine if any 2 transactions overlap.  Each txn
-   * is viewed as an interval [M,N]. M is the txnid and N is taken from the same NEXT_TXN_ID sequence
-   * so that we can compare commit time of txn T with start time of txn S.  This sequence can be thought of
-   * as a logical time counter.  If S.commitTime < T.startTime, T and S do NOT overlap.
-   *
-   * Motivating example:
-   * Suppose we have multi-statment transactions T and S both of which are attempting x = x + 1
-   * In order to prevent lost update problem, the the non-overlapping txns must lock in the snapshot
-   * that they read appropriately.  In particular, if txns do not overlap, then one follows the other
-   * (assumig they write the same entity), and thus the 2nd must see changes of the 1st.  We ensure
-   * this by locking in snapshot after 
-   * {@link #openTxns(OpenTxnRequest)} call is made (see {@link org.apache.hadoop.hive.ql.Driver#acquireLocksAndOpenTxn()})
-   * and mutexing openTxn() with commit().  In other words, once a S.commit() starts we must ensure
-   * that txn T which will be considered a later txn, locks in a snapshot that includes the result
-   * of S's commit (assuming no other txns).
-   * As a counter example, suppose we have S[3,3] and T[4,4] (commitId=txnid means no other transactions
-   * were running in parallel).  If T and S both locked in the same snapshot (for example commit of
-   * txnid:2, which is possible if commitTxn() and openTxnx() is not mutexed)
-   * 'x' would be updated to the same value by both, i.e. lost update. 
-   */
-  public void commitTxn(CommitTxnRequest rqst)
-    throws NoSuchTxnException, TxnAbortedException,  MetaException {
-    long txnid = rqst.getTxnid();
-    try {
-      Connection dbConn = null;
-      Statement stmt = null;
-      ResultSet lockHandle = null;
-      ResultSet commitIdRs = null, rs;
-      try {
-        lockInternal();
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        stmt = dbConn.createStatement();
-        /**
-         * This S4U will mutex with other commitTxn() and openTxns(). 
-         * -1 below makes txn intervals look like [3,3] [4,4] if all txns are serial
-         * Note: it's possible to have several txns have the same commit id.  Suppose 3 txns start
-         * at the same time and no new txns start until all 3 commit.
-         * We could've incremented the sequence for commitId is well but it doesn't add anything functionally.
-         */
-        commitIdRs = stmt.executeQuery(addForUpdateClause("select ntxn_next - 1 from NEXT_TXN_ID"));
-        if(!commitIdRs.next()) {
-          throw new IllegalStateException("No rows found in NEXT_TXN_ID");
-        }
-        long commitId = commitIdRs.getLong(1);
-        /**
-         * Runs at READ_COMMITTED with S4U on TXNS row for "txnid".  S4U ensures that no other
-         * operation can change this txn (such acquiring locks). While lock() and commitTxn()
-         * should not normally run concurrently (for same txn) but could due to bugs in the client
-         * which could then corrupt internal transaction manager state.  Also competes with abortTxn().
-         */
-        lockHandle = lockTransactionRecord(stmt, txnid, TXN_OPEN);
-        if(lockHandle == null) {
-          //this also ensures that txn is still there and in expected state (hasn't been timed out)
-          ensureValidTxn(dbConn, txnid, stmt);
-          shouldNeverHappen(txnid);
-        }
-        Savepoint undoWriteSetForCurrentTxn = dbConn.setSavepoint();
-        int numCompsWritten = stmt.executeUpdate("insert into WRITE_SET (ws_database, ws_table, ws_partition, ws_txnid, ws_commit_id, ws_operation_type)" +
-          " select tc_database, tc_table, tc_partition, tc_txnid, " + commitId + ", tc_operation_type " +
-          "from TXN_COMPONENTS where tc_txnid=" + txnid + " and tc_operation_type IN(" + quoteChar(OpertaionType.UPDATE.sqlConst) + "," + quoteChar(OpertaionType.DELETE.sqlConst) + ")");
-        if(numCompsWritten == 0) {
-          /**
-           * current txn didn't update/delete anything (may have inserted), so just proceed with commit
-           * 
-           * We only care about commit id for write txns, so for RO (when supported) txns we don't
-           * have to mutex on NEXT_TXN_ID.
-           * Consider: if RO txn is after a W txn, then RO's openTxns() will be mutexed with W's
-           * commitTxn() because both do S4U on NEXT_TXN_ID and thus RO will see result of W txn.
-           * If RO < W, then there is no reads-from relationship.
-           */
-        }
-        else {
-          /**
-           * see if there are any overlapping txns wrote the same element, i.e. have a conflict
-           * Since entire commit operation is mutexed wrt other start/commit ops,
-           * committed.ws_commit_id <= current.ws_commit_id for all txns
-           * thus if committed.ws_commit_id < current.ws_txnid, transactions do NOT overlap
-           * For example, [17,20] is committed, [6,80] is being committed right now - these overlap
-           * [17,20] committed and [21,21] committing now - these do not overlap.
-           * [17,18] committed and [18,19] committing now - these overlap  (here 18 started while 17 was still running)
-           */
-          rs = stmt.executeQuery
-            (addLimitClause(1, "committed.ws_txnid, committed.ws_commit_id, committed.ws_database," +
-              "committed.ws_table, committed.ws_partition, cur.ws_commit_id " + 
-              "from WRITE_SET committed INNER JOIN WRITE_SET cur " +
-            "ON committed.ws_database=cur.ws_database and committed.ws_table=cur.ws_table " +
-              //For partitioned table we always track writes at partition level (never at table)
-              //and for non partitioned - always at table level, thus the same table should never
-              //have entries with partition key and w/o
-            "and (committed.ws_partition=cur.ws_partition or (committed.ws_partition is null and cur.ws_partition is null)) " +
-            "where cur.ws_txnid <= committed.ws_commit_id" + //txns overlap; could replace ws_txnid
-              // with txnid, though any decent DB should infer this
-            " and cur.ws_txnid=" + txnid + //make sure RHS of join only has rows we just inserted as
-              // part of this commitTxn() op
-            " and committed.ws_txnid <> " + txnid + //and LHS only has committed txns
-              //U+U and U+D is a conflict but D+D is not and we don't currently track I in WRITE_SET at all
-              " and (committed.ws_operation_type=" + quoteChar(OpertaionType.UPDATE.sqlConst) +  
-                    " OR cur.ws_operation_type=" + quoteChar(OpertaionType.UPDATE.sqlConst) + ")"));
-          if(rs.next()) {
-            //found a conflict
-            String committedTxn = "[" + JavaUtils.txnIdToString(rs.getLong(1)) + "," + rs.getLong(2) + "]";
-            StringBuilder resource = new StringBuilder(rs.getString(3)).append("/").append(rs.getString(4));
-            String partitionName = rs.getString(5);
-            if(partitionName != null) {
-              resource.append('/').append(partitionName);
-            }
-            String msg = "Aborting [" + JavaUtils.txnIdToString(txnid) + "," + rs.getLong(6) + "]" + " due to a write conflict on " + resource +
-              " committed by " + committedTxn;
-            close(rs);
-            //remove WRITE_SET info for current txn since it's about to abort
-            dbConn.rollback(undoWriteSetForCurrentTxn);
-            LOG.info(msg);
-            //todo: should make abortTxns() write something into TXNS.TXN_META_INFO about this
-            if(abortTxns(dbConn, Collections.singletonList(txnid), true) != 1) {
-              throw new IllegalStateException(msg + " FAILED!");
-            }
-            dbConn.commit();
-            close(null, stmt, dbConn);
-            throw new TxnAbortedException(msg);
-          }
-          else {
-            //no conflicting operations, proceed with the rest of commit sequence
-          }
-        }
-        // Move the record from txn_components into completed_txn_components so that the compactor
-        // knows where to look to compact.
-        String s = "insert into COMPLETED_TXN_COMPONENTS select tc_txnid, tc_database, tc_table, " +
-          "tc_partition from TXN_COMPONENTS where tc_txnid = " + txnid;
-        LOG.debug("Going to execute insert <" + s + ">");
-        if (stmt.executeUpdate(s) < 1) {
-          //this can be reasonable for an empty txn START/COMMIT or read-only txn
-          LOG.info("Expected to move at least one record from txn_components to " +
-            "completed_txn_components when committing txn! " + JavaUtils.txnIdToString(txnid));
-        }
-        s = "delete from TXN_COMPONENTS where tc_txnid = " + txnid;
-        LOG.debug("Going to execute update <" + s + ">");
-        stmt.executeUpdate(s);
-        s = "delete from HIVE_LOCKS where hl_txnid = " + txnid;
-        LOG.debug("Going to execute update <" + s + ">");
-        stmt.executeUpdate(s);
-        s = "delete from TXNS where txn_id = " + txnid;
-        LOG.debug("Going to execute update <" + s + ">");
-        stmt.executeUpdate(s);
-        LOG.debug("Going to commit");
-        dbConn.commit();
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "commitTxn(" + rqst + ")");
-        throw new MetaException("Unable to update transaction database "
-          + StringUtils.stringifyException(e));
-      } finally {
-        close(commitIdRs);
-        close(lockHandle, stmt, dbConn);
-        unlockInternal();
-      }
-    } catch (RetryException e) {
-      commitTxn(rqst);
-    }
-  }
-  @Override
-  public void performWriteSetGC() {
-    Connection dbConn = null;
-    Statement stmt = null;
-    ResultSet rs = null;
-    try {
-      dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-      stmt = dbConn.createStatement();
-      rs = stmt.executeQuery("select ntxn_next - 1 from NEXT_TXN_ID");
-      if(!rs.next()) {
-        throw new IllegalStateException("NEXT_TXN_ID is empty: DB is corrupted");
-      }
-      long highestAllocatedTxnId = rs.getLong(1);
-      close(rs);
-      rs = stmt.executeQuery("select min(txn_id) from TXNS where txn_state=" + quoteChar(TXN_OPEN));
-      if(!rs.next()) {
-        throw new IllegalStateException("Scalar query returned no rows?!?!!");
-      }
-      long commitHighWaterMark;//all currently open txns (if any) have txnid >= than commitHighWaterMark
-      long lowestOpenTxnId = rs.getLong(1);
-      if(rs.wasNull()) {
-        //if here then there are no Open txns and  highestAllocatedTxnId must be
-        //resolved (i.e. committed or aborted), either way
-        //there are no open txns with id <= highestAllocatedTxnId
-        //the +1 is there because "delete ..." below has < (which is correct for the case when
-        //there is an open txn
-        //Concurrency: even if new txn starts (or starts + commits) it is still true that
-        //there are no currently open txns that overlap with any committed txn with 
-        //commitId <= commitHighWaterMark (as set on next line).  So plain READ_COMMITTED is enough.
-        commitHighWaterMark = highestAllocatedTxnId + 1;
-      }
-      else {
-        commitHighWaterMark = lowestOpenTxnId;
-      }
-      int delCnt = stmt.executeUpdate("delete from WRITE_SET where ws_commit_id < " + commitHighWaterMark);
-      LOG.info("Deleted " + delCnt + " obsolete rows from WRTIE_SET");
-      dbConn.commit();
-    } catch (SQLException ex) {
-      LOG.warn("WriteSet GC failed due to " + getMessage(ex), ex);
-    }
-    finally {
-      close(rs, stmt, dbConn);
-    }
-  }
-  /**
-   * As much as possible (i.e. in absence of retries) we want both operations to be done on the same
-   * connection (but separate transactions).  This avoid some flakiness in BONECP where if you
-   * perform an operation on 1 connection and immediately get another fron the pool, the 2nd one
-   * doesn't see results of the first.
-   */
-  public LockResponse lock(LockRequest rqst) throws NoSuchTxnException, TxnAbortedException, MetaException {
-    ConnectionLockIdPair connAndLockId = enqueueLockWithRetry(rqst);
-    try {
-      return checkLockWithRetry(connAndLockId.dbConn, connAndLockId.extLockId, rqst.getTxnid());
-    }
-    catch(NoSuchLockException e) {
-      // This should never happen, as we just added the lock id
-      throw new MetaException("Couldn't find a lock we just created! " + e.getMessage());
-    }
-  }
-  private static final class ConnectionLockIdPair {
-    private final Connection dbConn;
-    private final long extLockId;
-    private ConnectionLockIdPair(Connection dbConn, long extLockId) {
-      this.dbConn = dbConn;
-      this.extLockId = extLockId;
-    }
-  }
-
-  /**
-   * Note that by definition select for update is divorced from update, i.e. you executeQuery() to read
-   * and then executeUpdate().  One other alternative would be to actually update the row in TXNS but
-   * to the same value as before thus forcing db to acquire write lock for duration of the transaction.
-   *
-   * There is no real reason to return the ResultSet here other than to make sure the reference to it
-   * is retained for duration of intended lock scope and is not GC'd thus (unlikely) causing lock
-   * to be released.
-   * @param txnState the state this txn is expected to be in.  may be null
-   * @return null if no row was found
-   * @throws SQLException
-   * @throws MetaException
-   */
-  private ResultSet lockTransactionRecord(Statement stmt, long txnId, Character txnState) throws SQLException, MetaException {
-    String query = "select TXN_STATE from TXNS where TXN_ID = " + txnId + (txnState != null ? " AND TXN_STATE=" + quoteChar(txnState) : "");
-    ResultSet rs = stmt.executeQuery(addForUpdateClause(query));
-    if(rs.next()) {
-      return rs;
-    }
-    close(rs);
-    return null;
-  }
-
-  /**
-   * This enters locks into the queue in {@link #LOCK_WAITING} mode.
-   *
-   * Isolation Level Notes:
-   * 1. We use S4U (withe read_committed) to generate the next (ext) lock id.  This serializes
-   * any 2 {@code enqueueLockWithRetry()} calls.
-   * 2. We use S4U on the relevant TXNS row to block any concurrent abort/commit/etc operations
-   * @see #checkLockWithRetry(Connection, long, long)
-   */
-  private ConnectionLockIdPair enqueueLockWithRetry(LockRequest rqst) throws NoSuchTxnException, TxnAbortedException, MetaException {
-    boolean success = false;
-    Connection dbConn = null;
-    try {
-      Statement stmt = null;
-      ResultSet rs = null;
-      ResultSet lockHandle = null;
-      try {
-        lockInternal();
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        long txnid = rqst.getTxnid();
-        stmt = dbConn.createStatement();
-        if (isValidTxn(txnid)) {
-          //this also ensures that txn is still there in expected state
-          lockHandle = lockTransactionRecord(stmt, txnid, TXN_OPEN);
-          if(lockHandle == null) {
-            ensureValidTxn(dbConn, txnid, stmt);
-            shouldNeverHappen(txnid);
-          }
-        }
-        /** Get the next lock id.
-         * This has to be atomic with adding entries to HIVE_LOCK entries (1st add in W state) to prevent a race.
-         * Suppose ID gen is a separate txn and 2 concurrent lock() methods are running.  1st one generates nl_next=7,
-         * 2nd nl_next=8.  Then 8 goes first to insert into HIVE_LOCKS and aquires the locks.  Then 7 unblocks,
-         * and add it's W locks but it won't see locks from 8 since to be 'fair' {@link #checkLock(java.sql.Connection, long)}
-         * doesn't block on locks acquired later than one it's checking*/
-        String s = addForUpdateClause("select nl_next from NEXT_LOCK_ID");
-        LOG.debug("Going to execute query <" + s + ">");
-        rs = stmt.executeQuery(s);
-        if (!rs.next()) {
-          LOG.debug("Going to rollback");
-          dbConn.rollback();
-          throw new MetaException("Transaction tables not properly " +
-            "initialized, no record found in next_lock_id");
-        }
-        long extLockId = rs.getLong(1);
-        s = "update NEXT_LOCK_ID set nl_next = " + (extLockId + 1);
-        LOG.debug("Going to execute update <" + s + ">");
-        stmt.executeUpdate(s);
-
-        if (txnid > 0) {
-          /**DBTxnManager#acquireLocks() knows if it's I/U/D (that's how it decides what lock to get)
-           * So if we add that to LockRequest we'll know that here 
-           * Should probably add it to LockComponent so that if in the future we decide wo allow 1 LockRequest
-           * to contain LockComponent for multiple operations.
-           * Deriving it from lock info doesn't distinguish between Update and Delete
-           * 
-           * QueryPlan has BaseSemanticAnalyzer which has acidFileSinks list of FileSinkDesc
-           * FileSinkDesc.table is ql.metadata.Table
-           * Table.tableSpec which is TableSpec, which has specType which is SpecType
-           * So maybe this can work to know that this is part of dynamic partition insert in which case
-           * we'll get addDynamicPartitions() call and should not write TXN_COMPONENTS here.
-           * In any case, that's an optimization for now;  will be required when adding multi-stmt txns
-           */
-          // For each component in this lock request,
-          // add an entry to the txn_components table
-          // This must be done before HIVE_LOCKS is accessed
-          for (LockComponent lc : rqst.getComponent()) {
-            String dbName = lc.getDbname();
-            String tblName = lc.getTablename();
-            String partName = lc.getPartitionname();
-            s = "insert into TXN_COMPONENTS " +
-              "(tc_txnid, tc_database, tc_table, tc_partition, tc_operation_type) " +
-              "values (" + txnid + ", '" + dbName + "', " +
-              (tblName == null ? "null" : "'" + tblName + "'") + ", " +
-              (partName == null ? "null" : "'" + partName + "'")+ "," +
-              quoteString(OpertaionType.fromLockType(lc.getType()).toString()) + ")";
-            LOG.debug("Going to execute update <" + s + ">");
-            stmt.executeUpdate(s);
-          }
-        }
-
-        long intLockId = 0;
-        for (LockComponent lc : rqst.getComponent()) {
-          intLockId++;
-          String dbName = lc.getDbname();
-          String tblName = lc.getTablename();
-          String partName = lc.getPartitionname();
-          LockType lockType = lc.getType();
-          char lockChar = 'z';
-          switch (lockType) {
-            case EXCLUSIVE:
-              lockChar = LOCK_EXCLUSIVE;
-              break;
-            case SHARED_READ:
-              lockChar = LOCK_SHARED;
-              break;
-            case SHARED_WRITE:
-              lockChar = LOCK_SEMI_SHARED;
-              break;
-          }
-          long now = getDbTime(dbConn);
-          s = "insert into HIVE_LOCKS " +
-            " (hl_lock_ext_id, hl_lock_int_id, hl_txnid, hl_db, hl_table, " +
-            "hl_partition, hl_lock_state, hl_lock_type, hl_last_heartbeat, hl_user, hl_host)" +
-            " values (" + extLockId + ", " +
-            +intLockId + "," + txnid + ", '" +
-            dbName + "', " + (tblName == null ? "null" : "'" + tblName + "'")
-            + ", " + (partName == null ? "null" : "'" + partName + "'") +
-            ", '" + LOCK_WAITING + "', " + "'" + lockChar + "', " +
-            //for locks associated with a txn, we always heartbeat txn and timeout based on that
-            (isValidTxn(txnid) ? 0 : now) + ", '" +
-            rqst.getUser() + "', '" + rqst.getHostname() + "')";
-          LOG.debug("Going to execute update <" + s + ">");
-          stmt.executeUpdate(s);
-        }
-        dbConn.commit();
-        success = true;
-        return new ConnectionLockIdPair(dbConn, extLockId);
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "enqueueLockWithRetry(" + rqst + ")");
-        throw new MetaException("Unable to update transaction database " +
-          StringUtils.stringifyException(e));
-      } finally {
-        close(lockHandle);
-        close(rs, stmt, null);
-        if (!success) {
-          /* This needs to return a "live" connection to be used by operation that follows it.
-          Thus it only closes Connection on failure/retry. */
-          closeDbConn(dbConn);
-        }
-        unlockInternal();
-      }
-    }
-    catch(RetryException e) {
-      return enqueueLockWithRetry(rqst);
-    }
-  }
-  private LockResponse checkLockWithRetry(Connection dbConn, long extLockId, long txnId)
-    throws NoSuchLockException, NoSuchTxnException, TxnAbortedException, MetaException {
-    try {
-      try {
-        lockInternal();
-        if(dbConn.isClosed()) {
-          //should only get here if retrying this op
-          dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        }
-        return checkLock(dbConn, extLockId);
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "checkLockWithRetry(" + extLockId + "," + txnId + ")");
-        throw new MetaException("Unable to update transaction database " +
-          StringUtils.stringifyException(e));
-      } finally {
-        unlockInternal();
-        closeDbConn(dbConn);
-      }
-    }
-    catch(RetryException e) {
-      return checkLockWithRetry(dbConn, extLockId, txnId);
-    }
-  }
-  /**
-   * Why doesn't this get a txnid as parameter?  The caller should either know the txnid or know there isn't one.
-   * Either way getTxnIdFromLockId() will not be needed.  This would be a Thrift change.
-   *
-   * Also, when lock acquisition returns WAITING, it's retried every 15 seconds (best case, see DbLockManager.backoff(),
-   * in practice more often)
-   * which means this is heartbeating way more often than hive.txn.timeout and creating extra load on DB.
-   *
-   * The clients that operate in blocking mode, can't heartbeat a lock until the lock is acquired.
-   * We should make CheckLockRequest include timestamp or last request to skip unnecessary heartbeats. Thrift change.
-   *
-   * {@link #checkLock(java.sql.Connection, long)}  must run at SERIALIZABLE (make sure some lock we are checking
-   * against doesn't move from W to A in another txn) but this method can heartbeat in
-   * separate txn at READ_COMMITTED.
-   */
-  public LockResponse checkLock(CheckLockRequest rqst)
-    throws NoSuchTxnException, NoSuchLockException, TxnAbortedException, MetaException {
-    try {
-      Connection dbConn = null;
-      long extLockId = rqst.getLockid();
-      try {
-        lockInternal();
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        // Heartbeat on the lockid first, to assure that our lock is still valid.
-        // Then look up the lock info (hopefully in the cache).  If these locks
-        // are associated with a transaction then heartbeat on that as well.
-        LockInfo info = getTxnIdFromLockId(dbConn, extLockId);
-        if(info == null) {
-          throw new NoSuchLockException("No such lock " + JavaUtils.lockIdToString(extLockId));
-        }
-        if (info.txnId > 0) {
-          heartbeatTxn(dbConn, info.txnId);
-        }
-        else {
-          heartbeatLock(dbConn, extLockId);
-        }
-        //todo: strictly speaking there is a bug here.  heartbeat*() commits but both heartbeat and
-        //checkLock() are in the same retry block, so if checkLock() throws, heartbeat is also retired
-        //extra heartbeat is logically harmless, but ...
-        return checkLock(dbConn, extLockId);
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "checkLock(" + rqst + " )");
-        throw new MetaException("Unable to update transaction database " +
-          JavaUtils.lockIdToString(extLockId) + " " + StringUtils.stringifyException(e));
-      } finally {
-        closeDbConn(dbConn);
-        unlockInternal();
-      }
-    } catch (RetryException e) {
-      return checkLock(rqst);
-    }
-
-  }
-
-  /**
-   * This would have been made simpler if all locks were associated with a txn.  Then only txn needs to
-   * be heartbeated, committed, etc.  no need for client to track individual locks.
-   * When removing locks not associated with txn this potentially conflicts with
-   * heartbeat/performTimeout which are update/delete of HIVE_LOCKS thus will be locked as needed by db.
-   * since this only removes from HIVE_LOCKS at worst some lock acquire is delayed
-   */
-  public void unlock(UnlockRequest rqst)
-    throws NoSuchLockException, TxnOpenException, MetaException {
-    try {
-      Connection dbConn = null;
-      Statement stmt = null;
-      long extLockId = rqst.getLockid();
-      try {
-        /**
-         * This method is logically like commit for read-only auto commit queries.
-         * READ_COMMITTED since this only has 1 delete statement and no new entries with the
-         * same hl_lock_ext_id can be added, i.e. all rows with a given hl_lock_ext_id are
-         * created in a single atomic operation.
-         * Theoretically, this competes with {@link #lock(org.apache.hadoop.hive.metastore.api.LockRequest)}
-         * but hl_lock_ext_id is not known until that method returns.
-         * Also competes with {@link #checkLock(org.apache.hadoop.hive.metastore.api.CheckLockRequest)}
-         * but using SERIALIZABLE doesn't materially change the interaction.
-         * If "delete" stmt misses, additional logic is best effort to produce meaningful error msg.
-         */
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        stmt = dbConn.createStatement();
-        //hl_txnid <> 0 means it's associated with a transaction
-        String s = "delete from HIVE_LOCKS where hl_lock_ext_id = " + extLockId + " AND (hl_txnid = 0 OR" +
-          " (hl_txnid <> 0 AND hl_lock_state = '" + LOCK_WAITING + "'))";
-        //(hl_txnid <> 0 AND hl_lock_state = '" + LOCK_WAITING + "') is for multi-statement txns where
-        //some query attempted to lock (thus LOCK_WAITING state) but is giving up due to timeout for example
-        LOG.debug("Going to execute update <" + s + ">");
-        int rc = stmt.executeUpdate(s);
-        if (rc < 1) {
-          LOG.debug("Going to rollback");
-          dbConn.rollback();
-          LockInfo info = getTxnIdFromLockId(dbConn, extLockId);
-          if(info == null) {
-            //didn't find any lock with extLockId but at ReadCommitted there is a possibility that
-            //it existed when above delete ran but it didn't have the expected state.
-            LOG.error("No lock in " + LOCK_WAITING + " mode found for unlock(" + rqst + ")");
-            throw new NoSuchLockException("No such lock " + JavaUtils.lockIdToString(extLockId));
-          }
-          if(info.txnId != 0) {
-            String msg = "Unlocking locks associated with transaction not permitted.  " + info;
-            LOG.error(msg);
-            throw new TxnOpenException(msg);
-          }
-          if(info.txnId == 0) {
-            //we didn't see this lock when running DELETE stmt above but now it showed up
-            //so should "should never happen" happened...
-            String msg = "Found lock in unexpected state " + info;
-            LOG.error(msg);
-            throw new MetaException(msg);
-          }
-        }
-        LOG.debug("Going to commit");
-        dbConn.commit();
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "unlock(" + rqst + ")");
-        throw new MetaException("Unable to update transaction database " +
-          JavaUtils.lockIdToString(extLockId) + " " + StringUtils.stringifyException(e));
-      } finally {
-        closeStmt(stmt);
-        closeDbConn(dbConn);
-      }
-    } catch (RetryException e) {
-      unlock(rqst);
-    }
-  }
-
-  /**
-   * used to sort entries in {@link org.apache.hadoop.hive.metastore.api.ShowLocksResponse}
-   */
-  private static class LockInfoExt extends LockInfo {
-    private final ShowLocksResponseElement e;
-    LockInfoExt(ShowLocksResponseElement e) {
-      super(e);
-      this.e = e;
-    }
-  }
-  public ShowLocksResponse showLocks(ShowLocksRequest rqst) throws MetaException {
-    try {
-      Connection dbConn = null;
-      ShowLocksResponse rsp = new ShowLocksResponse();
-      List<ShowLocksResponseElement> elems = new ArrayList<ShowLocksResponseElement>();
-      List<LockInfoExt> sortedList = new ArrayList<LockInfoExt>();
-      Statement stmt = null;
-      try {
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        stmt = dbConn.createStatement();
-
-        String s = "select hl_lock_ext_id, hl_txnid, hl_db, hl_table, hl_partition, hl_lock_state, " +
-          "hl_lock_type, hl_last_heartbeat, hl_acquired_at, hl_user, hl_host, hl_lock_int_id," +
-          "hl_blockedby_ext_id, hl_blockedby_int_id from HIVE_LOCKS";
-
-        // Some filters may have been specified in the SHOW LOCKS statement. Add them to the query.
-        String dbName = rqst.getDbname();
-        String tableName = rqst.getTablename();
-        String partName = rqst.getPartname();
-
-        StringBuilder filter = new StringBuilder();
-        if (dbName != null && !dbName.isEmpty()) {
-          filter.append("hl_db=").append(quoteString(dbName));
-        }
-        if (tableName != null && !tableName.isEmpty()) {
-          if (filter.length() > 0) {
-            filter.append(" and ");
-          }
-          filter.append("hl_table=").append(quoteString(tableName));
-        }
-        if (partName != null && !partName.isEmpty()) {
-          if (filter.length() > 0) {
-            filter.append(" and ");
-          }
-          filter.append("hl_partition=").append(quoteString(partName));
-        }
-        String whereClause = filter.toString();
-
-        if (!whereClause.isEmpty()) {
-          s = s + " where " + whereClause;
-        }
-
-        LOG.debug("Doing to execute query <" + s + ">");
-        ResultSet rs = stmt.executeQuery(s);
-        while (rs.next()) {
-          ShowLocksResponseElement e = new ShowLocksResponseElement();
-          e.setLockid(rs.getLong(1));
-          long txnid = rs.getLong(2);
-          if (!rs.wasNull()) e.setTxnid(txnid);
-          e.setDbname(rs.getString(3));
-          e.setTablename(rs.getString(4));
-          String partition = rs.getString(5);
-          if (partition != null) e.setPartname(partition);
-          switch (rs.getString(6).charAt(0)) {
-            case LOCK_ACQUIRED: e.setState(LockState.ACQUIRED); break;
-            case LOCK_WAITING: e.setState(LockState.WAITING); break;
-            default: throw new MetaException("Unknown lock state " + rs.getString(6).charAt(0));
-          }
-          switch (rs.getString(7).charAt(0)) {
-            case LOCK_SEMI_SHARED: e.setType(LockType.SHARED_WRITE); break;
-            case LOCK_EXCLUSIVE: e.setType(LockType.EXCLUSIVE); break;
-            case LOCK_SHARED: e.setType(LockType.SHARED_READ); break;
-            default: throw new MetaException("Unknown lock type " + rs.getString(6).charAt(0));
-          }
-          e.setLastheartbeat(rs.getLong(8));
-          long acquiredAt = rs.getLong(9);
-          if (!rs.wasNull()) e.setAcquiredat(acquiredAt);
-          e.setUser(rs.getString(10));
-          e.setHostname(rs.getString(11));
-          e.setLockIdInternal(rs.getLong(12));
-          long id = rs.getLong(13);
-          if(!rs.wasNull()) {
-            e.setBlockedByExtId(id);
-          }
-          id = rs.getLong(14);
-          if(!rs.wasNull()) {
-            e.setBlockedByIntId(id);
-          }
-          sortedList.add(new LockInfoExt(e));
-        }
-        LOG.debug("Going to rollback");
-        dbConn.rollback();
-      } catch (SQLException e) {
-        checkRetryable(dbConn, e, "showLocks(" + rqst + ")");
-        throw new MetaException("Unable to select from transaction database " +
-          StringUtils.stringifyException(e));
-      } finally {
-        closeStmt(stmt);
-        closeDbConn(dbConn);
-      }
-      //this ensures that "SHOW LOCKS" prints the locks in the same order as they are examined
-      //by checkLock() - makes diagnostics easier.
-      Collections.sort(sortedList, new LockInfoComparator());
-      for(LockInfoExt lockInfoExt : sortedList) {
-        elems.add(lockInfoExt.e);
-      }
-      rsp.setLocks(elems);
-      return rsp;
-    } catch (RetryException e) {
-      return showLocks(rqst);
-    }
-  }
-
-  /**
-   * {@code ids} should only have txnid or lockid but not both, ideally.
-   * Currently DBTxnManager.heartbeat() enforces this.
-   */
-  public void heartbeat(HeartbeatRequest ids)
-    throws NoSuchTxnException,  NoSuchLockException, TxnAbortedException, MetaException {
-    try {
-      Connection dbConn = null;
-      try {
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        heartbeatLock(dbConn, ids.getLockid());
-        heartbeatTxn(dbConn, ids.getTxnid());
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "heartbeat(" + ids + ")");
-        throw new MetaException("Unable to select from transaction database " +
-          StringUtils.stringifyException(e));
-      } finally {
-        closeDbConn(dbConn);
-      }
-    } catch (RetryException e) {
-      heartbeat(ids);
-    }
-  }
-
-  public HeartbeatTxnRangeResponse heartbeatTxnRange(HeartbeatTxnRangeRequest rqst)
-    throws MetaException {
-    try {
-      Connection dbConn = null;
-      HeartbeatTxnRangeResponse rsp = new HeartbeatTxnRangeResponse();
-      Set<Long> nosuch = new HashSet<Long>();
-      Set<Long> aborted = new HashSet<Long>();
-      rsp.setNosuch(nosuch);
-      rsp.setAborted(aborted);
-      try {
-        /**
-         * READ_COMMITTED is sufficient since {@link #heartbeatTxn(java.sql.Connection, long)}
-         * only has 1 update statement in it and
-         * we only update existing txns, i.e. nothing can add additional txns that this operation
-         * would care about (which would have required SERIALIZABLE)
-         */
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        for (long txn = rqst.getMin(); txn <= rqst.getMax(); txn++) {
-          try {
-            //todo: do all updates in 1 SQL statement and check update count
-            //if update count is less than was requested, go into more expensive checks
-            //for each txn
-            heartbeatTxn(dbConn, txn);
-          } catch (NoSuchTxnException e) {
-            nosuch.add(txn);
-          } catch (TxnAbortedException e) {
-            aborted.add(txn);
-          }
-        }
-        return rsp;
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "heartbeatTxnRange(" + rqst + ")");
-        throw new MetaException("Unable to select from transaction database " +
-          StringUtils.stringifyException(e));
-      } finally {
-        closeDbConn(dbConn);
-      }
-    } catch (RetryException e) {
-      return heartbeatTxnRange(rqst);
-    }
-  }
-
-  long generateCompactionQueueId(Statement stmt) throws SQLException, MetaException {
-    // Get the id for the next entry in the queue
-    String s = addForUpdateClause("select ncq_next from NEXT_COMPACTION_QUEUE_ID");
-    LOG.debug("going to execute query <" + s + ">");
-    ResultSet rs = stmt.executeQuery(s);
-    if (!rs.next()) {
-      throw new IllegalStateException("Transaction tables not properly initiated, " +
-        "no record found in next_compaction_queue_id");
-    }
-    long id = rs.getLong(1);
-    s = "update NEXT_COMPACTION_QUEUE_ID set ncq_next = " + (id + 1);
-    LOG.debug("Going to execute update <" + s + ">");
-    stmt.executeUpdate(s);
-    return id;
-  }
-  public long compact(CompactionRequest rqst) throws MetaException {
-    // Put a compaction request in the queue.
-    try {
-      Connection dbConn = null;
-      Statement stmt = null;
-      try {
-        lockInternal();
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        stmt = dbConn.createStatement();
-        
-        long id = generateCompactionQueueId(stmt);
-
-        StringBuilder buf = new StringBuilder("insert into COMPACTION_QUEUE (cq_id, cq_database, " +
-          "cq_table, ");
-        String partName = rqst.getPartitionname();
-        if (partName != null) buf.append("cq_partition, ");
-        buf.append("cq_state, cq_type");
-        if (rqst.getRunas() != null) buf.append(", cq_run_as");
-        buf.append(") values (");
-        buf.append(id);
-        buf.append(", '");
-        buf.append(rqst.getDbname());
-        buf.append("', '");
-        buf.append(rqst.getTablename());
-        buf.append("', '");
-        if (partName != null) {
-          buf.append(partName);
-          buf.append("', '");
-        }
-        buf.append(INITIATED_STATE);
-        buf.append("', '");
-        switch (rqst.getType()) {
-          case MAJOR:
-            buf.append(MAJOR_TYPE);
-            break;
-
-          case MINOR:
-            buf.append(MINOR_TYPE);
-            break;
-
-          default:
-            LOG.debug("Going to rollback");
-            dbConn.rollback();
-            throw new MetaException("Unexpected compaction type " + rqst.getType().toString());
-        }
-        if (rqst.getRunas() != null) {
-          buf.append("', '");
-          buf.append(rqst.getRunas());
-        }
-        buf.append("')");
-        String s = buf.toString();
-        LOG.debug("Going to execute update <" + s + ">");
-        stmt.executeUpdate(s);
-        LOG.debug("Going to commit");
-        dbConn.commit();
-        return id;
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "compact(" + rqst + ")");
-        throw new MetaException("Unable to select from transaction database " +
-          StringUtils.stringifyException(e));
-      } finally {
-        closeStmt(stmt);
-        closeDbConn(dbConn);
-        unlockInternal();
-      }
-    } catch (RetryException e) {
-      return compact(rqst);
-    }
-  }
-
-  public ShowCompactResponse showCompact(ShowCompactRequest rqst) throws MetaException {
-    ShowCompactResponse response = new ShowCompactResponse(new ArrayList<ShowCompactResponseElement>());
-    Connection dbConn = null;
-    Statement stmt = null;
-    try {
-      try {
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        stmt = dbConn.createStatement();
-        String s = "select cq_database, cq_table, cq_partition, cq_state, cq_type, cq_worker_id, " +
-          "cq_start, -1 cc_end, cq_run_as, cq_hadoop_job_id, cq_id from COMPACTION_QUEUE union all " +
-          "select cc_database, cc_table, cc_partition, cc_state, cc_type, cc_worker_id, " +
-          "cc_start, cc_end, cc_run_as, cc_hadoop_job_id, cc_id from COMPLETED_COMPACTIONS";
-        //what I want is order by cc_end desc, cc_start asc (but derby has a bug https://issues.apache.org/jira/browse/DERBY-6013)
-        //to sort so that currently running jobs are at the end of the list (bottom of screen)
-        //and currently running ones are in sorted by start time
-        //w/o order by likely currently running compactions will be first (LHS of Union)
-        LOG.debug("Going to execute query <" + s + ">");
-        ResultSet rs = stmt.executeQuery(s);
-        while (rs.next()) {
-          ShowCompactResponseElement e = new ShowCompactResponseElement();
-          e.setDbname(rs.getString(1));
-          e.setTablename(rs.getString(2));
-          e.setPartitionname(rs.getString(3));
-          switch (rs.getString(4).charAt(0)) {
-            case INITIATED_STATE: e.setState(INITIATED_RESPONSE); break;
-            case WORKING_STATE: e.setState(WORKING_RESPONSE); break;
-            case READY_FOR_CLEANING: e.setState(CLEANING_RESPONSE); break;
-            case FAILED_STATE: e.setState(FAILED_RESPONSE); break;
-            case SUCCEEDED_STATE: e.setState(SUCCEEDED_RESPONSE); break;
-            case ATTEMPTED_STATE: e.setState(ATTEMPTED_RESPONSE); break;
-            default:
-              //do nothing to handle RU/D if we add another status
-          }
-          switch (rs.getString(5).charAt(0)) {
-            case MAJOR_TYPE: e.setType(CompactionType.MAJOR); break;
-            case MINOR_TYPE: e.setType(CompactionType.MINOR); break;
-            default:
-              //do nothing to handle RU/D if we add another status
-          }
-          e.setWorkerid(rs.getString(6));
-          e.setStart(rs.getLong(7));
-          long endTime = rs.getLong(8);
-          if(endTime != -1) {
-            e.setEndTime(endTime);
-          }
-          e.setRunAs(rs.getString(9));
-          e.setHadoopJobId(rs.getString(10));
-          long id = rs.getLong(11);//for debugging
-          response.addToCompacts(e);
-        }
-        LOG.debug("Going to rollback");
-        dbConn.rollback();
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "showCompact(" + rqst + ")");
-        throw new MetaException("Unable to select from transaction database " +
-          StringUtils.stringifyException(e));
-      } finally {
-        closeStmt(stmt);
-        closeDbConn(dbConn);
-      }
-      return response;
-    } catch (RetryException e) {
-      return showCompact(rqst);
-    }
-  }
-
-  private static void shouldNeverHappen(long txnid) {
-    throw new RuntimeException("This should never happen: " + JavaUtils.txnIdToString(txnid));
-  }
-  private static void shouldNeverHappen(long txnid, long extLockId, long intLockId) {
-    throw new RuntimeException("This should never happen: " + JavaUtils.txnIdToString(txnid) + " "
-      + JavaUtils.lockIdToString(extLockId) + " " + intLockId);
-  }
-
-  public void addDynamicPartitions(AddDynamicPartitions rqst)
-      throws NoSuchTxnException,  TxnAbortedException, MetaException {
-    Connection dbConn = null;
-    Statement stmt = null;
-    ResultSet lockHandle = null;
-    ResultSet rs = null;
-    try {
-      try {
-        lockInternal();
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        stmt = dbConn.createStatement();
-        lockHandle = lockTransactionRecord(stmt, rqst.getTxnid(), TXN_OPEN);
-        if(lockHandle == null) {
-          //ensures txn is still there and in expected state
-          ensureValidTxn(dbConn, rqst.getTxnid(), stmt);
-          shouldNeverHappen(rqst.getTxnid());
-        }
-        //we should be able to get this from AddDynamicPartitions object longer term; in fact we'd have to
-        //for multi stmt txns if same table is written more than once per tx
-        // MoveTask knows if it's I/U/D
-        // MoveTask calls Hive.loadDynamicPartitions() which calls HiveMetaStoreClient.addDynamicPartitions()
-        // which ends up here so we'd need to add a field to AddDynamicPartitions.
-        String findOperationType = " tc_operation_type from TXN_COMPONENTS where tc_txnid=" + rqst.getTxnid()
-          + " and tc_database=" + quoteString(rqst.getDbname()) + " and tc_table=" + quoteString(rqst.getTablename());
-        //do limit 1 on this; currently they will all have the same operations
-        rs = stmt.executeQuery(addLimitClause(1, findOperationType));
-        if(!rs.next()) {
-          throw new IllegalStateException("Unable to determine tc_operation_type for " + JavaUtils.txnIdToString(rqst.getTxnid()));
-        }
-        OpertaionType ot = OpertaionType.fromString(rs.getString(1).charAt(0));
-        
-        //what if a txn writes the same table > 1 time... let's go with this for now, but really
-        //need to not write this in the first place, i.e. make this delete not needed
-        //see enqueueLockWithRetry() - that's where we write to TXN_COMPONENTS
-        String deleteSql = "delete from TXN_COMPONENTS where tc_txnid=" + rqst.getTxnid() + " and tc_database=" +
-          quoteString(rqst.getDbname()) + " and tc_table=" + quoteString(rqst.getTablename());
-        //we delete the entries made by enqueueLockWithRetry() since those are based on lock information which is
-        //much "wider" than necessary in a lot of cases.  Here on the other hand, we know exactly which
-        //partitions have been written to.  w/o this WRITE_SET would contain entries for partitions not actually
-        //written to
-        stmt.executeUpdate(deleteSql);
-        for (String partName : rqst.getPartitionnames()) {
-          String s =
-            "insert into TXN_COMPONENTS (tc_txnid, tc_database, tc_table, tc_partition, tc_operation_type) values (" +
-              rqst.getTxnid() + "," + quoteString(rqst.getDbname()) + "," + quoteString(rqst.getTablename()) +
-              "," + quoteString(partName) + "," + quoteChar(ot.sqlConst) + ")";
-          LOG.debug("Going to execute update <" + s + ">");
-          stmt.executeUpdate(s);
-        }
-        LOG.debug("Going to commit");
-        dbConn.commit();
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "addDynamicPartitions(" + rqst + ")");
-        throw new MetaException("Unable to insert into from transaction database " +
-          StringUtils.stringifyException(e));
-      } finally {
-        close(lockHandle, stmt, dbConn);
-        unlockInternal();
-      }
-    } catch (RetryException e) {
-      addDynamicPartitions(rqst);
-    }
-  }
-
-  /**
-   * Clean up corresponding records in metastore tables, specifically:
-   * TXN_COMPONENTS, COMPLETED_TXN_COMPONENTS, COMPACTION_QUEUE, COMPLETED_COMPACTIONS
-   */
-  public void cleanupRecords(HiveObjectType type, Database db, Table table,
-                             Iterator<Partition> partitionIterator) throws MetaException {
-    try {
-      Connection dbConn = null;
-      Statement stmt = null;
-
-      try {
-        String dbName;
-        String tblName;
-        dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-        stmt = dbConn.createStatement();
-        List<String> queries = new ArrayList<String>();
-        StringBuilder buff = new StringBuilder();
-
-        switch (type) {
-          case DATABASE:
-            dbName = db.getName();
-
-            buff.append("delete from TXN_COMPONENTS where tc_database='");
-            buff.append(dbName);
-            buff.append("'");
-            queries.add(buff.toString());
-
-            buff.setLength(0);
-            buff.append("delete from COMPLETED_TXN_COMPONENTS where ctc_database='");
-            buff.append(dbName);
-            buff.append("'");
-            queries.add(buff.toString());
-
-            buff.setLength(0);
-            buff.append("delete from COMPACTION_QUEUE where cq_database='");
-            buff.append(dbName);
-            buff.append("'");
-            queries.add(buff.toString());
-
-            buff.setLength(0);
-            buff.append("delete from COMPLETED_COMPACTIONS where cc_database='");
-            buff.append(dbName);
-            buff.append("'");
-            queries.add(buff.toString());
-
-            break;
-          case TABLE:
-            dbName = table.getDbName();
-            tblName = table.getTableName();
-
-            buff.append("delete from TXN_COMPONENTS where tc_database='");
-            buff.append(dbName);
-            buff.append("' and tc_table='");
-            buff.append(tblName);
-            buff.append("'");
-            queries.add(buff.toString());
-
-            buff.setLength(0);
-            buff.append("delete from COMPLETED_TXN_COMPONENTS where ctc_database='");
-            buff.append(dbName);
-            buff.append("' and ctc_table='");
-            buff.append(tblName);
-            buff.append("'");
-            queries.add(buff.toString());
-
-            buff.setLength(0);
-            buff.append("delete from COMPACTION_QUEUE where cq_database='");
-            buff.append(dbName);
-            buff.append("' and cq_table='");
-            buff.append(tblName);
-            buff.append("'");
-            queries.add(buff.toString());
-
-            buff.setLength(0);
-            buff.append("delete from COMPLETED_COMPACTIONS where cc_database='");
-            buff.append(dbName);
-            buff.append("' and cc_table='");
-            buff.append(tblName);
-            buff.append("'");
-            queries.add(buff.toString());
-
-            break;
-          case PARTITION:
-            dbName = table.getDbName();
-            tblName = table.getTableName();
-            List<FieldSchema> partCols = table.getPartitionKeys();  // partition columns
-            List<String> partVals;                                  // partition values
-            String partName;
-
-            while (partitionIterator.hasNext()) {
-              Partition p = partitionIterator.next();
-              partVals = p.getValues();
-              partName = Warehouse.makePartName(partCols, partVals);
-
-              buff.append("delete from TXN_COMPONENTS where tc_database='");
-              buff.append(dbName);
-              buff.append("' and tc_table='");
-              buff.append(tblName);
-              buff.append("' and tc_partition='");
-              buff.append(partName);
-              buff.append("'");
-              queries.add(buff.toString());
-
-              buff.setLength(0);
-              buff.append("delete from COMPLETED_TXN_COMPONENTS where ctc_database='");
-              buff.append(dbName);
-              buff.append("' and ctc_table='");
-              buff.append(tblName);
-              buff.append("' and ctc_partition='");
-              buff.append(partName);
-              buff.append("'");
-              queries.add(buff.toString());
-
-              buff.setLength(0);
-              buff.append("delete from COMPACTION_QUEUE where cq_database='");
-              buff.append(dbName);
-              buff.append("' and cq_table='");
-              buff.append(tblName);
-              buff.append("' and cq_partition='");
-              buff.append(partName);
-              buff.append("'");
-              queries.add(buff.toString());
-
-              buff.setLength(0);
-              buff.append("delete from COMPLETED_COMPACTIONS where cc_database='");
-              buff.append(dbName);
-              buff.append("' and cc_table='");
-              buff.append(tblName);
-              buff.append("' and cc_partition='");
-              buff.append(partName);
-              buff.append("'");
-              queries.add(buff.toString());
-            }
-
-            break;
-          default:
-            throw new MetaException("Invalid object type for cleanup: " + type);
-        }
-
-        for (String query : queries) {
-          LOG.debug("Going to execute update <" + query + ">");
-          stmt.executeUpdate(query);
-        }
-
-        LOG.debug("Going to commit");
-        dbConn.commit();
-      } catch (SQLException e) {
-        LOG.debug("Going to rollback");
-        rollbackDBConn(dbConn);
-        checkRetryable(dbConn, e, "cleanupRecords");
-        if (e.getMessage().contains("does not exist")) {
-          LOG.warn("Cannot perform cleanup since metastore table does not exist");
-        } else {
-          throw new MetaException("Unable to clean up " + StringUtils.stringifyException(e));
-        }
-      } finally {
-        closeStmt(stmt);
-        closeDbConn(dbConn);
-      }
-    } catch (RetryException e) {
-      cleanupRecords(type, db, table, partitionIterator);
-    }
-  }
-
-  /**
-   * For testing only, do not use.
-   */
-  @VisibleForTesting
-  public int numLocksInLockTable() throws SQLException, MetaException {
-    Connection dbConn = null;
-    Statement stmt = null;
-    ResultSet rs = null;
-    try {
-      dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
-      stmt = dbConn.createStatement();
-      String s = "select count(*) from HIVE_LOCKS";
-      LOG.debug("Going to execute query <" + s + ">");
-      rs = stmt.executeQuery(s);
-      rs.next();
-      int rc = rs.getInt(1);
-      // Necessary to clean up the transaction in the db.
-      dbConn.rollback();
-      return rc;
-    } finally {
-      close(rs, stmt, dbConn);
-    }
-  }
-
-  /**
-   * For testing only, do not use.
-   */
-  public long setTimeout(long milliseconds) {
-    long previous_timeout = timeout;
-    timeout = milliseconds;
-    return previous_timeout;
-  }
-
-  protected class RetryException extends Exception {
-
-  }
-
-  protected Connection getDbConn(int isolationLevel) throws SQLException {
-    int rc = doRetryOnConnPool ? 10 : 1;
-    Connection dbConn = null;
-    while (true) {
-      try {
-        dbConn = connPool.getConnection();
-        dbConn.setAutoCommit(false);
-        dbConn.setTransactionIsolation(isolationLevel);
-        return dbConn;
-      } catch (SQLException e){
-        closeDbConn(dbConn);
-        if ((--rc) <= 0) throw e;
-        LOG.error("There is a problem with a connection from the pool, retrying(rc=" + rc + "): " +
-          getMessage(e), e);
-      }
-    }
-  }
-
-  static void rollbackDBConn(Connection dbConn) {
-    try {
-      if (dbConn != null && !dbConn.isClosed()) dbConn.rollback();
-    } catch (SQLException e) {
-      LOG.warn("Failed to rollback db connection " + getMessage(e));
-    }
-  }
-  protected static void closeDbConn(Connection dbConn) {
-    try {
-      if (dbConn != null && !dbConn.isClosed()) {
-        dbConn.close();
-      }
-    } catch (SQLException e) {
-      LOG.warn("Failed to close db connection " + getMessage(e));
-    }
-  }
-
-  /**
-   * Close statement instance.
-   * @param stmt statement instance.
-   */
-  protected static void closeStmt(Statement stmt) {
-    try {
-      if (stmt != null && !stmt.isClosed()) stmt.close();
-    } catch (SQLException e) {
-      LOG.warn("Failed to close statement " + getMessage(e));
-    }
-  }
-
-  /**
-   * Close the ResultSet.
-   * @param rs may be {@code null}
-   */
-  static void close(ResultSet rs) {
-    try {
-      if (rs != null && !rs.isClosed()) {
-        rs.close();
-      }
-    }
-    catch(SQLException ex) {
-      LOG.warn("Failed to close statement " + getMessage(ex));
-    }
-  }
-
-  /**
-   * Close all 3 JDBC artifacts in order: {@code rs stmt dbConn}
-   */
-  static void close(ResultSet rs, Statement stmt, Connection dbConn) {
-    close(rs);
-    closeStmt(stmt);
-    closeDbConn(dbConn);
-  }
-  /**
-   * Determine if an exception was such that it makes sense to retry.  Unfortunately there is no standard way to do
-   * this, so we have to inspect the error messages and catch the telltale signs for each
-   * different database.  This method will throw {@code RetryException}
-   * if the error is retry-able.
-   * @param conn database connection
-   * @param e exception that was thrown.
-   * @param caller name of the method calling this (and other info useful to log)
-   * @throws org.apache.hadoop.hive.metastore.txn.TxnHandler.RetryException when the operation should be retried
-   */
-  protected void checkRetryable(Connection conn,
-                                SQLException e,
-                                String caller) throws RetryException, MetaException {
-
-    // If you change this function, remove the @Ignore from TestTxnHandler.deadlockIsDetected()
-    // to test these changes.
-    // MySQL and MSSQL use 40001 as the state code for rollback.  Postgres uses 40001 and 40P01.
-    // Oracle seems to return different SQLStates and messages each time,
-    // so I've tried to capture the different error messages (there appear to be fewer different
-    // error messages than SQL states).
-    // Derby and newer MySQL driver use the new SQLTransactionRollbackException
-    boolean sendRetrySignal = false;
-    try {
-      if(dbProduct == null) {
-        throw new IllegalStateException("DB Type not determined yet.");
-      }
-      if (e instanceof SQLTransactionRollbackException ||
-        ((dbProduct == DatabaseProduct.MYSQL || dbProduct == DatabaseProduct.POSTGRES ||
-          dbProduct == DatabaseProduct.SQLSERVER) && e.getSQLState().equals("40001")) ||
-        (dbProduct == DatabaseProduct.POSTGRES && e.getSQLState().equals("40P01")) ||
-        (dbProduct == DatabaseProduct.ORACLE && (e.getMessage().contains("deadlock detected")
-          || e.getMessage().contains("can't serialize access for this transaction")))) {
-        if (deadlockCnt++ < ALLOWED_REPEATED_DEADLOCKS) {
-          long waitInterval = deadlockRetryInterval * deadlockCnt;
-          LOG.warn("Deadlock detected in " + caller + ". Will wait " + waitInterval +
-            "ms try again up to " + (ALLOWED_REPEATED_DEADLOCKS - deadlockCnt + 1) + " times.");
-          // Pause for a just a bit for retrying to avoid immediately jumping back into the deadlock.
-          try {
-            Thread.sleep(waitInterval);
-          } catch (InterruptedException ie) {
-            // NOP
-          }
-          sendRetrySignal = true;
-        } else {
-          LOG.error("Too many repeated deadlocks in " + caller + ", giving up.");
-        }
-      } else if (isRetryable(conf, e)) {
-        //in MSSQL this means Communication Link Failure
-        if (retryNum++ < retryLimit) {
-          LOG.warn("Retryable error detected in " + caller + ".  Will wait " + retryInterval +
-            "ms and retry up to " + (retryLimit - retryNum + 1) + " times.  Error: " + getMessage(e));
-          try {
-            Thread.sleep(retryInterval);
-          } catch (InterruptedException ex) {
-            //
-          }
-          sendRetrySignal = true;
-        } else {
-          LOG.error("Fatal error. Retry limit (" + retryLimit + ") reached. Last error: " + getMessage(e));
-        }
-      }
-      else {
-        //make sure we know we saw an error that we don't recognize
-        LOG.info("Non-retryable error: " + getMessage(e));
-      }
-    }
-    finally {
-      /*if this method ends with anything except a retry signal, the caller should fail the operation
-      and propagate the error up to the its caller (Metastore client); thus must reset retry counters*/
-      if(!sendRetrySignal) {
-        deadlockCnt = 0;
-        retryNum = 0;
-      }
-    }
-    if(sendRetrySignal) {
-      throw new RetryException();
-    }
-  }
-
-  /**
-   * Determine the current time, using the RDBMS as a source of truth
-   * @param conn database connection
-   * @return current time in milliseconds
-   * @throws org.apache.hadoop.hive.metastore.api.MetaException if the time cannot be determined
-   */
-  protected long getDbTime(Connection conn) throws MetaException {
-    Statement stmt = null;
-    try {
-      stmt = conn.createStatement();
-      String s;
-      switch (dbProduct) {
-        case DERBY:
-          s = "values current_timestamp";
-          break;
-
-        case MYSQL:
-        case POSTGRES:
-        case SQLSERVER:
-          s = "select current_timestamp";
-          break;
-
-        case ORACLE:
-          s = "select current_timestamp from dual";
-          break;
-
-        default:
-          String msg = "Unknown database product: " + dbProduct.toString();
-          LOG.error(msg);
-          throw new MetaException(msg);
-      }
-      LOG.debug("Going to execute query <" + s + ">");
-      ResultSet rs = stmt.executeQuery(s);
-      if (!rs.next()) throw new MetaException("No results from date query");
-      return rs.getTimestamp(1).getTime();
-    } catch (SQLException e) {
-      String msg = "Unable to determine current time: " + e.getMessage();
-      LOG.error(msg);
-      throw new MetaException(msg);
-    } finally {
-      closeStmt(stmt);
-    }
-  }
-
-  /**
-   * Determine the String that should be used to quote identifiers.
-   * @param conn Active connection
-   * @return quotes
-   * @throws SQLException
-   */
-  protected String getIdentifierQuoteString(Connection conn) throws SQLException {
-    if (identifierQuoteString == null) {
-      identifierQuoteString = conn.getMetaData().getIdentifierQuoteString();
-    }
-    return identifierQuoteString;
-  }
-
-  protected enum DatabaseProduct { DERBY, MYSQL, POSTGRES, ORACLE, SQLSERVER}
-
-  /**
-   * Determine the database product type
-   * @param conn database connection
-   * @return database product type
-   */
-  private DatabaseProduct determineDatabaseProduct(Connection conn) {
-    if (dbProduct == null) {
-      try {
-        String s = conn.getMetaData().getDatabaseProductName();
-        if (s == null) {
-          String msg = "getDatabaseProductName returns null, can't determine database product";
-          LOG.error(msg);
-          throw new IllegalStateException(msg);
-        } else if (s.equals("Apache Derby")) {
-          dbProduct = DatabaseProduct.DERBY;
-        } else if (s.equals("Microsoft SQL Server")) {
-          dbProduct = DatabaseProduct.SQLSERVER;
-        } else if (s.equals("MySQL")) {
-          dbProduct = DatabaseProduct.MYSQL;
-        } else if (s.equals("Oracle")) {
-          dbProduct = DatabaseProduct.ORACLE;
-        } else if (s.equals("PostgreSQL")) {
-          dbProduct = DatabaseProduct.POSTGRES;
-        } else {
-          String msg = "Unrecognized database product name <" + s + ">";
-          LOG.error(msg);
-          throw new IllegalStateException(msg);
-        }
-
-      } catch (SQLException e) {
-        String msg = "Unable to get database product name: " + e.getMessage();
-        LOG.error(msg);
-        throw new IllegalStateException(msg);
-      }
-    }
-    return dbProduct;
-  }
-
-  private static class LockInfo {
-    private final long extLockId;
-    private final long intLockId;
-    //0 means there is no transaction, i.e. it a select statement which is not part of
-    //explicit transaction or a IUD statement that is not writing to ACID table
-    private final long txnId;
-    private final String db;
-    private final String table;
-    private final String partition;
-    private final LockState state;
-    private final LockType type;
-
-    // Assumes the result set is set to a valid row
-    LockInfo(ResultSet rs) throws SQLException, MetaException {
-      extLockId = rs.getLong("hl_lock_ext_id"); // can't be null
-      intLockId = rs.getLong("hl_lock_int_id"); // can't be null
-      db = rs.getString("hl_db"); // can't be null
-      String t = rs.getString("hl_table");
-      table = (rs.wasNull() ? null : t);
-      String p = rs.getString("hl_partition");
-      partition = (rs.wasNull() ? null : p);
-      switch (rs.getString("hl_lock_state").charAt(0)) {
-        case LOCK_WAITING: state = LockState.WAITING; break;
-        case LOCK_ACQUIRED: state = LockState.ACQUIRED; break;
-        default:
-          throw new MetaException("Unknown lock state " + rs.getString("hl_lock_state").charAt(0));
-      }
-      switch (rs.getString("hl_lock_type").charAt(0)) {
-        case LOCK_EXCLUSIVE: type = LockType.EXCLUSIVE; break;
-        case LOCK_SHARED: type = LockType.SHARED_READ; break;
-        case LOCK_SEMI_SHARED: type = LockType.SHARED_WRITE; break;
-        default:
-          throw new MetaException("Unknown lock type " + rs.getString("hl_lock_type").charAt(0));
-      }
-      txnId = rs.getLong("hl_txnid");//returns 0 if value is NULL
-    }
-    LockInfo(ShowLocksResponseElement e) {
-      extLockId = e.getLockid();
-      intLockId = e.getLockIdInternal();
-      txnId = e.getTxnid();
-      db = e.getDbname();
-      table = e.getTablename();
-      partition = e.getPartname();
-      state = e.getState();
-      type = e.getType();
-    }
-
-    public boolean equals(Object other) {
-      if (!(other instanceof LockInfo)) return false;
-      LockInfo o = (LockInfo)other;
-      // Lock ids are unique across the system.
-      return extLockId == o.extLockId && intLockId == o.intLockId;
-    }
-
-    @Override
-    public String toString() {
-      return JavaUtils.lockIdToString(extLockId) + " intLockId:" +
-        intLockId + " " + JavaUtils.txnIdToString(txnId)
-        + " db:" + db + " table:" + table + " partition:" +
-        partition + " state:" + (state == null ? "null" : state.toString())
-        + " type:" + (type == null ? "null" : type.toString());
-    }
-    private boolean isDbLock() {
-      return db != null && table == null && partition == null;
-    }
-    private boolean isTableLock() {
-      return db != null && table != null && partition == null;
-    }
-  }
-
-  private static class LockInfoComparator implements Comparator<LockInfo> {
-    private static final LockTypeComparator lockTypeComparator = new LockTypeComparator();
-    public boolean equals(Object other) {
-      return this == other;
-    }
-
-    public int compare(LockInfo info1, LockInfo info2) {
-      // We sort by state (acquired vs waiting) and then by LockType, they by id
-      if (info1.state == LockState.ACQUIRED &&
-        info2.state != LockState .ACQUIRED) {
-        return -1;
-      }
-      if (info1.state != LockState.ACQUIRED &&
-        info2.state == LockState .ACQUIRED) {
-        return 1;
-      }
-
-      int sortByType = lockTypeComparator.compare(info1.type, info2.type);
-      if(sortByType != 0) {
-        return sortByType;
-      }
-      if (info1.extLockId < info2.extLockId) {
-        return -1;
-      } else if (info1.extLockId > info2.extLockId) {
-        return 1;
-      } else {
-        if (info1.intLockId < info2.intLockId) {
-          return -1;
-        } el

<TRUNCATED>