Dead Space Map patch

From: ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>
To: pgsql-patches(at)postgresql(dot)org
Subject: Dead Space Map patch
Date: 2006-12-28 06:14:56
Message-ID: 20061228142827.5FBF.ITAGAKI.TAKAHIRO@oss.ntt.co.jp
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This is a patch for TODO item:
| Create a bitmap of pages that need vacuuming

Dead Space Map allows VACUUM to scan only pages that need vacuuming.
I sent to HACKERS the description of this patch.
Comments, suggestions and evaluation reports are welcome.

Usage of the feature is below:

- VACUUM FREEZE is recommended.
Pages that need vacuuming and freezing are not separated in the patch.
If we do non-FREEZE VACUUM, next VACUUM will also read pages that we
cannot freeze all of tuples in it at the last VACUUM. It's a waste.

- [GUC] dsm_buffers (integer)
The used memory size in dead space map. Default is 16MB,
that can track maximum 1TB of heap tables.

- [GUC] dsm_vacuum (boolean)
This enables the dead space map in VACUUM. Default is on.
Even if it is off, DSM are always recorded and updated.

- contrib/pg_deadspacemap
This shows the contents of dead space map.
See also README.pg_deadspacemap.

Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center

Attachment Content-Type Size
deadspacemap.patch.gz application/octet-stream 25.3 KB

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