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https://issues.apache.org/jira/browse/IMPALA-5604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16510435#comment-16510435
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Tim Armstrong commented on IMPALA-5604:
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I saw a user get confused by this:
http://community.cloudera.com/t5/Interactive-Short-cycle-SQL/Very-slow-CodeGen-taking-80-of-runtime/m-p/69016/highlight/false#M4600
I think we can reuse some of the EXEC_SINGLE_NODE_ROWS_THRESHOLD text since the
mechanism is very similar, the differences being:
* It uses a per-backend row count instead of a total row count.
* It disables codegen only (i.e. if it kicks in, it has the same effect as
setting disable_codegen=true)
I can have a go at writing this up if you like [~arodoni_cloudera]
> Document DISABLE_CODEGEN_ROWS_THRESHOLD
> ---------------------------------------
>
> Key: IMPALA-5604
> URL: https://issues.apache.org/jira/browse/IMPALA-5604
> Project: IMPALA
> Issue Type: Task
> Components: Docs
> Affects Versions: Impala 2.10.0
> Reporter: Tim Armstrong
> Assignee: Alex Rodoni
> Priority: Major
>
> We just checking in DISABLE_CODEGEN_ROWS_THRESHOLD to master with default
> value 50,000.
> The option uses the planner's estimates to determine whether to disable
> codegen for a query based on the maximum number of rows flowing through any
> part of the query plan.
> It is similar to EXEC_SINGLE_NODE_ROWS_THRESHOLD in behaviour except the
> threshold is per-node rows instead of total rows.
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