[PATCHES] Patch for seq scan & scan resistant bufmgr

[CK Tan]

Hi,

I am submitting a patch for review that:


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


4 files changed:
bufmgr.c, bufmgr.h, heapam.c, relscan.h






----- 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.

1. for small relation (smaller than 60% of bufferpool), use the current logic - invalidate used pages of in the scan so they do not force out other useful pages 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. ------------------------------------------------------------------------ - ------------------------------------------------------------------------ - ------------------------------------------------------------------------ - ------------------------------------------------------------------------ -

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