PostgreSQL TODO List

====================

Current maintainer:Bruce Momjian (pgman@candle.pha.pa.us)

Last updated:Tue Aug 30 19:25:23 EDT 2005

Last updated:Thu Sep 1 20:49:44 EDT 2005

The most recent version of this document can be viewed at

http://www.postgresql.org/docs/faqs.TODO.html.

write lock. However, the read lock promotion to write lock could lead

to deadlock situations.

* Maintain a map of recently-expired rows

This allows vacuum to target specific pages for possible free space

without requiring a sequential scan.

* Auto-fill the free space map by scanning the buffer cache or by

checking pages written by the background writer

* Create a bitmap of pages that need vacuuming

writer or some other process record pages that have expired rows, then

VACUUM can look at just those pages rather than the entire table. In

the event of a system crash, the bitmap would probably be invalidated.

One complexity is that index entries still have to be vacuumed, and

doing this without an index scan (by using the heap values to find the

index entry) might be slow and unreliable, especially for user-defined

index functions.

* %Add system view to show free space map contents

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<h1><aname="section_1">PostgreSQL TODO List</a></h1>

<p>Current maintainer: Bruce Momjian (<ahref="mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</a>)<br/>

Last updated:Tue Aug 30 19:25:23 EDT 2005

Last updated:Thu Sep 1 20:49:44 EDT 2005

<p>The most recent version of this document can be viewed at<br/>

<ahref="http://www.postgresql.org/docs/faqs.TODO.html">http://www.postgresql.org/docs/faqs.TODO.html</a>.

<p> Moved tuples are invisible to other backends so they don't require a

write lock. However, the read lock promotion to write lock could lead

to deadlock situations.

</li><li>Maintain a map of recently-expired rows

<p> This allows vacuum to target specific pages for possible free space

without requiring a sequential scan.

</li><li>Auto-fill the free space map by scanning the buffer cache or by

checking pages written by the background writer

writer or some other process record pages that have expired rows, then

VACUUM can look at just those pages rather than the entire table. In

the event of a system crash, the bitmap would probably be invalidated.

One complexity is that index entries still have to be vacuumed, and

doing this without an index scan (by using the heap values to find the

index entry) might be slow and unreliable, especially for user-defined

index functions.

</li><li>%Add system view to show free space map contents

</li><li>Auto-vacuum