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https://issues.apache.org/jira/browse/DERBY-6211?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rick Hillegas updated DERBY-6211:
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Attachment: derby-6211-10-aa-makingCostEstimateObject.diff
Attaching derby-6211-10-aa-makingCostEstimateObject.diff. This patch simplifies
the construction of CostEstimate objects and fixes an NPE when running
XML-based optimizer tracing against an outer join query. Tests passed cleanly
for me on this patch.
While investigating the optimizer's handling of outer joins, I tripped across 2
problems:
1) The xml-based optimizer tracer dies on an NPE in trying to assign a table
name to the ProjectRestrictNode which sits on top of the outer join node. The
fix, for the moment, is to give the ProjectRestrictNode a generic name.
2) During outer join optimization, other optimizers are created for the sole
purpose of asking them to manufacture empty CostEstimate objects. This is wrong
for several reasons:
a) It violates the principle that an optimizer instance corresponds to a query
block.
b) It's inefficient.
c) It's unnecessary because there is already a method on OptimizerFactory for
creating an empty CostEstimate object.
The fix to (2) is to make Optimizer.newCostEstimate() private, remove the
pointless instantiations of new optimizers, and call
OptimizerFactory.getCostEstimate() to make empty CostEstimates.
Touches the following files:
--------------------
M java/engine/org/apache/derby/impl/sql/compile/XMLOptTrace.java
Changes for (1).
--------------------
M java/engine/org/apache/derby/iapi/sql/compile/OptimizerFactory.java
M java/engine/org/apache/derby/iapi/sql/compile/Optimizer.java
M java/engine/org/apache/derby/impl/sql/compile/FromTable.java
M
java/engine/org/apache/derby/impl/sql/compile/SingleChildResultSetNode.java
M java/engine/org/apache/derby/impl/sql/compile/DistinctNode.java
M java/engine/org/apache/derby/impl/sql/compile/ProjectRestrictNode.java
M java/engine/org/apache/derby/impl/sql/compile/GroupByNode.java
M java/engine/org/apache/derby/impl/sql/compile/OptimizerFactoryImpl.java
M java/engine/org/apache/derby/impl/sql/compile/RowResultSetNode.java
M java/engine/org/apache/derby/impl/sql/compile/CurrentOfNode.java
M java/engine/org/apache/derby/impl/sql/compile/OptimizerImpl.java
M java/engine/org/apache/derby/impl/sql/compile/TableOperatorNode.java
Changes for (2).
> Make Optimizer trace logic pluggable.
> -------------------------------------
>
> Key: DERBY-6211
> URL: https://issues.apache.org/jira/browse/DERBY-6211
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 10.11.0.0
> Reporter: Rick Hillegas
> Assignee: Rick Hillegas
> Labels: derby_triage10_11
> Attachments: derby-6211-01-aa-createPlugin.diff,
> derby-6211-02-aa-cleanup.diff, derby-6211-02-ab-cleanup.diff,
> derby-6211-03-aa-customTracer.diff,
> derby-6211-04-aa-moveOptimizerTracerToEngineJar.diff,
> derby-6211-05-aa-xmlOptimizerTracer.diff,
> derby-6211-06-ab-packageProtect-XMLOptTrace.diff,
> derby-6211-07-aa-useSchemaQualifiedNamesInSummaries.diff,
> derby-6211-07-ab-useSchemaQualifiedNamesInSummaries.diff,
> derby-6211-08-aa-fixNPE.diff, derby-6211-09-aa-addTests.diff,
> derby-6211-10-aa-makingCostEstimateObject.diff
>
>
> Right now the trace logic in the optimizer is hard-coded to produce a stream
> of diagnostics. It would be good to be able to plug alternative trace logic
> into the optimizer. This would make the following possible:
> 1) Plug in trace logic which produces formats which are easier to study and
> which can be analyzed mechanically. E.g., xml formatted output.
> 2) Plug in trace logic which can be used during unit testing to verify that
> the optimizer has picked the right plan. Over time this might make it easier
> to migrate canon-based tests to assertion-based tests.
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