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Posted to issues@calcite.apache.org by "Julian Hyde (JIRA)" <ji...@apache.org> on 2016/11/22 00:01:58 UTC
[jira] [Updated] (CALCITE-1498) Allow LIMIT with trivial ORDER BY
to be pushed through JOIN
[ https://issues.apache.org/jira/browse/CALCITE-1498?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Julian Hyde updated CALCITE-1498:
---------------------------------
Summary: Allow LIMIT with trivial ORDER BY to be pushed through JOIN (was: RelMdUtil.checkInputForCollationAndLimit() should also consider input collations as a zero-length collation list.)
> Allow LIMIT with trivial ORDER BY to be pushed through JOIN
> -----------------------------------------------------------
>
> Key: CALCITE-1498
> URL: https://issues.apache.org/jira/browse/CALCITE-1498
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.10.0
> Reporter: Maryann Xue
> Assignee: Maryann Xue
> Priority: Minor
>
> {code}
> // Check if the input is already sorted
> boolean alreadySorted = false;
> if (!alreadySorted) {
> for (RelCollation inputCollation : mq.collations(input)) {
> if (inputCollation.satisfies(collation)) {
> alreadySorted = true;
> break;
> }
> }
> }
> {code}
> if {{mq.collations(input)}} returns an empty array, {{alreadySorted}} will always be false even if the required {{collation}} is an empty collation (which indicates there's no need to sort).
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