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https://issues.apache.org/jira/browse/HIVE-924?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12784699#action_12784699
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Ning Zhang commented on HIVE-924:
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I like the idea of refactoring the LogicalPlan and PhysicalPlan in general, but
since it is too large, can you separate it into several small JIRAs. e.g., 1
JIRA for PhysicalPlan and PhysicalPlan generator and 1 JIRA for LogicalPlan and
its generator, and 1 for the rest of misc changes. It is more managable to
review and have less chance of conflicting with other patches.
Some detailed comments:
1) the transform() function now returns void instead of
ParseContext/LogicalPlan. This may be OK in the current implementation, but in
general if we want to extend the rule-based rewrite system to cost based one,
we probably need transform return a different LogicalPlan (the rewritten one)
and keep the input plan unchanged. Then we can cost them. The optimize()
function is similar, it should return the best plan given an input plan in the
cost-based rewrite framework.
2) I noticed that you removed some code and had a comment like "possible bug".
Can you come up with some unit tests for such cases that the old code cause
bugs? I've seen some diff in the unit test results under this patch, so I'm
wondering whether they are caused by these changes.
> Extract LogicalPlan and PhysicalPlan classes from SemanticAnalysis class
> ------------------------------------------------------------------------
>
> Key: HIVE-924
> URL: https://issues.apache.org/jira/browse/HIVE-924
> Project: Hadoop Hive
> Issue Type: Bug
> Components: Query Processor
> Reporter: Carl Steinbach
> Attachments: HIVE-924.patch
>
>
> Currently the SemanticAnalyzer class handles semantic analysis, as well as
> logical plan generation and physical plan generation. I think it would be
> beneficial to extract distinct LogicalPlan and PhysicalPlan classes from the
> SemanticAnalyzer, and have the query processing phase be coordinated by a
> QueryCompiler class that would be responsible for triggering the parsing,
> semantic analysis, logical plan generation, optimization, and physical plan
> generation phases. This proposed reorganization of components would help to
> isolate the state of each phase, and would also bring the source into closer
> alignment with the description of the query compiler in the Hive design
> document on the wiki.
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