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https://issues.apache.org/jira/browse/FLINK-28247?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rui Li reassigned FLINK-28247:
------------------------------
Assignee: luoyuxia
> Exception will be thrown when over window contains grouping in Hive Dialect
> ---------------------------------------------------------------------------
>
> Key: FLINK-28247
> URL: https://issues.apache.org/jira/browse/FLINK-28247
> Project: Flink
> Issue Type: Sub-task
> Reporter: luoyuxia
> Assignee: luoyuxia
> Priority: Major
> Labels: pull-request-available
>
> The exception will be reprodued by the following sql when using Hive Dialect:
> {code:java}
> create table t(category int, live int, comments int)
> SELECT grouping(category), lag(live) over(partition by grouping(category))
> FROM t GROUP BY category, live; {code}
> The reson is it will first call
> `HiveParserCalcitePlanner#genSelectForWindowing` to generate the window,
> which will then call `HiveParserUtils#rewriteGroupingFunctionAST` to rewrite
> the group function in the over window :
>
> {code:java}
> // rewrite grouping function
> if (current.getType() == HiveASTParser.TOK_FUNCTION
> && current.getChildCount() >= 2) {
> HiveParserASTNode func = (HiveParserASTNode) current.getChild(0);
> if (func.getText().equals("grouping")) {
> visited.setValue(true);
> convertGrouping(
> current, grpByAstExprs, noneSet, legacyGrouping, found);
> }
> }
> {code}
>
> So `grouping(category)` will be converted to `grouping(0, 1)`.
> After `HiveParserCalcitePlanner#genSelectForWindowing`, it will try to
> rewrite it again:
>
> {code:java}
> if (!qbp.getDestToGroupBy().isEmpty()) {
> // Special handling of grouping function
> expr =
> rewriteGroupingFunctionAST(
> getGroupByForClause(qbp, selClauseName),
> expr,
> !cubeRollupGrpSetPresent);
> } {code}
> And it will also fall back to `convertGrouping` again as
> `current.getChildCount() >= 2` will be true. But then, it can't find any
> field
> presented in group by for it's `grouping(0, 1)` now.
>
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