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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-5089) Skip initializing all enabled storage plugins for every query
Date Sun, 26 Mar 2017 05:46:44 GMT

    [ https://issues.apache.org/jira/browse/DRILL-5089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15942167#comment-15942167
] 

ASF GitHub Bot commented on DRILL-5089:
---------------------------------------

Github user paul-rogers commented on a diff in the pull request:

    https://github.com/apache/drill/pull/795#discussion_r108050520
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/sql/DrillCatalogReader.java
---
    @@ -0,0 +1,180 @@
    +/**
    + * 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
    + * <p>
    + * http://www.apache.org/licenses/LICENSE-2.0
    + * <p>
    + * 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.drill.exec.planner.sql;
    +
    +import com.google.common.base.Joiner;
    +import com.google.common.collect.ImmutableList;
    +import com.google.common.collect.Lists;
    +import com.google.common.collect.Sets;
    +import org.apache.calcite.adapter.java.JavaTypeFactory;
    +import org.apache.calcite.jdbc.CalciteSchema;
    +import org.apache.calcite.jdbc.CalciteSchemaImpl;
    +import org.apache.calcite.jdbc.SimpleCalciteSchema;
    +import org.apache.calcite.prepare.CalciteCatalogReader;
    +import org.apache.calcite.prepare.RelOptTableImpl;
    +import org.apache.calcite.schema.SchemaPlus;
    +import org.apache.drill.common.config.DrillConfig;
    +import org.apache.drill.common.exceptions.UserException;
    +import org.apache.drill.exec.ops.QueryContext;
    +import org.apache.drill.exec.store.SchemaConfig;
    +
    +import java.util.Arrays;
    +import java.util.List;
    +import java.util.Set;
    +
    +/**
    + * Implementation of {@link org.apache.calcite.prepare.Prepare.CatalogReader}
    + * and also {@link org.apache.calcite.sql.SqlOperatorTable} based on tables and
    + * functions defined schemas.
    + *
    + */
    +public class DrillCatalogReader extends CalciteCatalogReader {
    +  private static org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(DrillCatalogReader.class);
    +
    +  final private QueryContext queryContext;
    +  private boolean allowTemporaryTables;
    +  private String temporarySchema;
    +
    +  public DrillCatalogReader(
    +      QueryContext qcontext,
    +      CalciteSchema rootSchema,
    +      boolean caseSensitive,
    +      List<String> defaultSchema,
    +      JavaTypeFactory typeFactory,
    +      String temporarySchema) {
    +    super(rootSchema, caseSensitive, defaultSchema, typeFactory);
    +    assert rootSchema != defaultSchema;
    +    queryContext = qcontext;
    +    this.temporarySchema = temporarySchema;
    +    this.allowTemporaryTables = true;
    +  }
    +
    +  /** Disallow temporary tables presence in sql statement (ex: in view definitions) */
    +  public void disallowTemporaryTables() {
    --- End diff --
    
    Once the constructor gets as complex as this one, and we have secondary methods to set
what should be immutable properties, it may be time to move to a builder pattern:
    
    ```
    public class DrillCatalogReader ...
        static CatalogBuilder builder(QueryContext context) ...
    ...
    class CatalogBuilder {
        CatalogBuider(QueryContext context);
        CatalogBuilder withTemporarySchema(String temporarySchema);
        CatalogBuilder allowsTempTables();
        CatalogBuilder caseSensitive();
        ...
        DrillCatalogReader build();
    }
    ```
    
    Code that uses this class will be easier to follow with named methods for each property.
Reasonable defaults reduces the number of constructor arguments and avoids the need for lots
of code fixups when, inevitably, we add arguments.


> Skip initializing all enabled storage plugins for every query
> -------------------------------------------------------------
>
>                 Key: DRILL-5089
>                 URL: https://issues.apache.org/jira/browse/DRILL-5089
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Query Planning & Optimization
>    Affects Versions: 1.9.0
>            Reporter: Abhishek Girish
>            Assignee: Chunhui Shi
>            Priority: Critical
>
> In a query's lifecycle, at attempt is made to initialize each enabled storage plugin,
while building the schema tree. This is done regardless of the actual plugins involved within
a query. 
> Sometimes, when one or more of the enabled storage plugins have issues - either due to
misconfiguration or the underlying datasource being slow or being down, the overall query
time taken increases drastically. Most likely due the attempt being made to register schemas
from a faulty plugin.
> For example, when a jdbc plugin is configured with SQL Server, and at one point the underlying
SQL Server db goes down, any Drill query starting to execute at that point and beyond begin
to slow down drastically. 
> We must skip registering unrelated schemas (& workspaces) for a query. 



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