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https://issues.apache.org/jira/browse/PHOENIX-1594?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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James Taylor updated PHOENIX-1594:
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Attachment: PHOENIX-1594.patch
[~jeffreyz] - here's a patch that adds FirstKeyOnlyFilter in more situations.
Most of it is just test changes to fix explain plan comparisons where the
FirstKeyOnlyFilter is used now but not before.
Notice for the case you mentioned, only the A column family is projected into
the scan and not all column families. We project families rather than
individual column qualifiers because we've found HBase performance suffers in
this case (~30% if I recall correctly). It's usually faster to just do a next
rather than seek to the next column. We do have a hint to override this
optimization.
> Using KeyOnlyFilter for simple query "select count(1) from <table>"
> -------------------------------------------------------------------
>
> Key: PHOENIX-1594
> URL: https://issues.apache.org/jira/browse/PHOENIX-1594
> Project: Phoenix
> Issue Type: Improvement
> Reporter: Jeffrey Zhong
> Attachments: PHOENIX-1594.patch
>
>
> I found that underlying scan for query "select count(1) or count(*) from
> <table>" still project all columns.
> It should be fast if we use KeyOnlyFilter for this simple query.
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