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https://issues.apache.org/jira/browse/IMPALA-7951?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Paul Rogers reassigned IMPALA-7951:
-----------------------------------
Assignee: (was: Paul Rogers)
> Rewrites change meaning when converted to SQL
> ---------------------------------------------
>
> Key: IMPALA-7951
> URL: https://issues.apache.org/jira/browse/IMPALA-7951
> Project: IMPALA
> Issue Type: Bug
> Components: Frontend
> Affects Versions: Impala 3.1.0
> Reporter: Paul Rogers
> Priority: Minor
>
> Consider this query:
> {code:sql}
> SELECT int_col not between 1 and 10 and int_col <> -1
> FROM functional.alltypestiny
> {code}
> Then, render the query using toSql() after rewrites
> {code:sql}
> SELECT int_col < 1 OR int_col > 10 AND int_col != -1
> FROM functional.alltypestiny
> Notice the meaning has changed. Correct grouping:
> {code:sql}
> (int_col < 1 OR int_col > 10) AND int_col != -1
> {code}
> This means to accept all values {{(-infinity, -2), 0 (1, 10)}}.
> Actual grouping based on precedence rules:
> {code:sql}
> int_col < 1 OR (int_col > 10 AND int_col != -1)
> {code}
> This means to accept all values {{(-infinity, 0)}}.
> The rewrites must insert parens if the rewrite would render a tree that is
> incorrect when interpreted using default precedence rules. (That is, if a
> parent node has lower precedence than a child node.)
> The quick fix is to set the “print sql in parens” flag, but this is less than
> idea as it adds parens where they are not required. Better would be to
> compute the parens based on precedence at toSql time, but that is out of
> scope of this fix.
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