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https://issues.apache.org/jira/browse/PHOENIX-1278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14150419#comment-14150419
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James Taylor commented on PHOENIX-1278:
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If we want row key order for salted tables, we need to merge sort the results.
The rows keys among different regions for salted tables are interleaved. If
users don't want row key order, they can set
phoenix.query.rowKeyOrderSaltedTable to false to avoid the merge sort.
> Performance degradation for salted tables with guideposts
> ---------------------------------------------------------
>
> Key: PHOENIX-1278
> URL: https://issues.apache.org/jira/browse/PHOENIX-1278
> Project: Phoenix
> Issue Type: Bug
> Reporter: James Taylor
> Assignee: Anoop Sam John
>
> When a table is salted, we're seeing a degradation in performance using our
> new guidepost-based parallelization. With salted tables, we do a merge sort
> with the results from all the parallel scans. I suspect the cause here is
> that we're doing a merge sort now between more chunks than before (since we
> chunk everything up more now than we used to). We should group the scans
> we're doing for the same bucket together and do a concat with those results
> and then do a merge sort only with the concatenated batches.
> Pls revert PHOENIX-1279 when we implement this.
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