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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-48) A connection request that has a default schema that is being created by another transaction will fail to connect
Date Thu, 29 May 2008 12:00:45 GMT

    [ https://issues.apache.org/jira/browse/DERBY-48?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12600751#action_12600751
] 

Knut Anders Hatlen commented on DERBY-48:
-----------------------------------------

Hi Dag,

The approach in the latest patch looks elegant. A couple of small comments and questions:

- The try/catch around executeConstantAction() swallows all non-timeout exceptions. I think
we need to move "else throw se" from the inner if to the outer if in the catch block.

- I think the code below is fine, but it would be clearer if the comment also said: "In non-debug
builds, we retry in the parent transaction before giving up."
+							} catch (StandardException e) {
+								if (SanityManager.DEBUG) {
+									// Should not happen
+									throw e;
+								}
+							}

- Not that it makes any difference in practice, but... When we call commit() and destroy()
on the nested transaction in the catch block, wouldn't it be more natural to call abort()+destroy(),
since we don't want any side effects of the work performed by the nested transaction to be
persisted? The javadoc for TransactionController.destroy() says that it will also abort the
transaction, so I guess a call to destroy() would suffice.

- When we check for SQLState.LOCK_TIMEOUT, should we also check for SQLState.LOCK_TIMEOUT_LOG,
which is the message id used when lock tracing is enabled? And should SQLState.DEADLOCK be
handled the same way?

>  A connection request that has a default schema that is being created by another transaction
will fail to connect
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-48
>                 URL: https://issues.apache.org/jira/browse/DERBY-48
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC
>    Affects Versions: 10.0.2.0, 10.0.2.1, 10.0.2.2, 10.1.1.0
>            Reporter: Kathey Marsden
>            Assignee: Dag H. Wanvik
>         Attachments: derby-48-1.diff, derby-48-1.stat, derby-48-2.diff, derby-48-2.stat,
derby-48-3.diff, derby-48-3.stat, LazyDefaultSchemaCreationTest.java
>
>
> A connection request that has a default schema that is being
> created by another transaction will block until that transaction
> completes (or time out). Probably in this situation the connection
> request should be succeed as if the schema does not exist.
> This is a problem in particular for a prepared  XA transaction, where even after restarting
the system, the user cannot reconnect and recover the transaction.
> Here is the reproduction in ij.
> java -Dij.exceptionTrace=true -Dij.protocol=jdbc:derby: -Dij.user=me -Dij.password=pw
org.apache.derby.tools.ij
> ij version 10.0 (C) Copyright IBM Corp. 1997, 2004.
> ij> connect 'testdb;create=true';
> ij> autocommit off;
> ij> create table mytabi(i int);
> 0 rows inserted/updated/deleted
> ij> connect 'testdb';
> ERROR 40XL1: A lock could not be obtained within the time requestedERROR 40XL1: A lock
could not be obtained within the time requested
>         at org.apache.derby.iapi.error.StandardException.newException(StandardException.java:295)
>         at org.apache.derby.impl.services.locks.LockSet.lockObject(LockSet.java:408)
>         at org.apache.derby.impl.services.locks.SinglePool.lockAnObject(SinglePool.java:168)
>         at org.apache.derby.impl.services.locks.SinglePool.lockObject(SinglePool.java:220)
>         at org.apache.derby.impl.store.raw.xact.RowLocking3.lockRecordForRead(RowLocking3.java:181)
>         at org.apache.derby.impl.store.access.heap.HeapController.lockRow(HeapController.java:425)
>         at org.apache.derby.impl.store.access.heap.HeapController.lockRow(HeapController.java:543)
>         at org.apache.derby.impl.store.access.btree.index.B2IRowLocking3.lockRowOnPage(B2IRowLocking3.java:329)
>         at org.apache.derby.impl.store.access.btree.index.B2IRowLocking3._lockScanRow(B2IRowLocking3.java:571)
>         at org.apache.derby.impl.store.access.btree.index.B2IRowLockingRR.lockScanRow(B2IRowLockingRR.java:115)
>         at org.apache.derby.impl.store.access.btree.BTreeForwardScan.fetchRows(BTreeForwardScan.java:374)
>         at org.apache.derby.impl.store.access.btree.BTreeScan.next(BTreeScan.java:1691)
>         at org.apache.derby.impl.sql.catalog.DataDictionaryImpl.getDescriptorViaIndex(DataDictionaryImpl.java:7118)
>         at org.apache.derby.impl.sql.catalog.DataDictionaryImpl.locateSchemaRow(DataDictionaryImpl.java:1381)
>         at org.apache.derby.impl.sql.catalog.DataDictionaryImpl.getSchemaDescriptor(DataDictionaryImpl.java:1291)
>         at org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.initDefaultSchemaDescriptor(GenericLanguageCon
>         at org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.initialize(GenericLanguageConnectionContext.ja
>         at org.apache.derby.impl.db.BasicDatabase.setupConnection(BasicDatabase.java:267)
>         at org.apache.derby.impl.jdbc.TransactionResourceImpl.startTransaction(TransactionResourceImpl.java:182)
>         at org.apache.derby.impl.jdbc.EmbedConnection.<init>(EmbedConnection.java:237)
>         at org.apache.derby.impl.jdbc.EmbedConnection20.<init>(EmbedConnection20.java:49)
>         at org.apache.derby.impl.jdbc.EmbedConnection30.<init>(EmbedConnection30.java:56)
>         at org.apache.derby.jdbc.Driver30.getNewEmbedConnection(Driver30.java:68)
>         at org.apache.derby.jdbc.Driver169.connect(Driver169.java:172)
>         at java.sql.DriverManager.getConnection(DriverManager.java:512)
>         at java.sql.DriverManager.getConnection(DriverManager.java:140)
>         at org.apache.derby.impl.tools.ij.ij.dynamicConnection(ij.java:843)
>         at org.apache.derby.impl.tools.ij.ij.ConnectStatement(ij.java:700)
>         at org.apache.derby.impl.tools.ij.ij.ijStatement(ij.java:528)
>         at org.apache.derby.impl.tools.ij.utilMain.go(utilMain.java:283)
>         at org.apache.derby.impl.tools.ij.Main.go(Main.java:204)
>         at org.apache.derby.impl.tools.ij.Main.mainCore(Main.java:170)
>         at org.apache.derby.impl.tools.ij.Main14.main(Main14.java:50)
>         at org.apache.derby.tools.ij.main(ij.java:54)

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