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https://issues.apache.org/jira/browse/PHOENIX-1278?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Anoop Sam John updated PHOENIX-1278:
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Description:
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.
was: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.
> 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
>
> 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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