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CK Tan wrote:
> Hi,
>
> I am submitting a patch for review that:
>
> 1. for small relation (smaller than 60% of bufferpool), use the
> current logic
> 2. for big relation:
> - use a ring buffer in heap scan
> - pin first 12 pages when scan starts
> - on consumption of every 4-page, read and pin the next 4-page
> - invalidate used pages of in the scan so they do not force out
> other useful pages
>
> 4 files changed:
> bufmgr.c, bufmgr.h, heapam.c, relscan.h
>
> If there are interests, I can submit another scan patch that returns
> N tuples at a time, instead of current one-at-a-time interface. This
> improves code locality and further improve performance by another
> 10-20%.
>
> For TPCH 1G tables, we are seeing more than 20% improvement in scans
> on the same hardware.
>
> ------------------------------------------------------------------------
> -
> ----- PATCHED VERSION
> ------------------------------------------------------------------------
> -
> gptest=# select count(*) from lineitem;
> count
> ---------
> 6001215
> (1 row)
>
> Time: 2117.025 ms
>
> ------------------------------------------------------------------------
> -
> ----- ORIGINAL CVS HEAD VERSION
> ------------------------------------------------------------------------
> -
> gptest=# select count(*) from lineitem;
> count
> ---------
> 6001215
> (1 row)
>
> Time: 2722.441 ms
>
>
> Suggestions for improvement are welcome.
>
> Regards,
> -cktan
> Greenplum, Inc.
>
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>
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--
Bruce Momjian <bruce@momjian.us>
http://momjian.us
EnterpriseDB
http://www.enterprisedb.com
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match