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Duplicate: 

< * Maintain a map of recently-expired rows
<
<   This allows vacuum to target specific pages for possible free space
<   without requiring a sequential scan.
<
Update entry:

>   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.
This commit is contained in:
Bruce Momjian 2005-09-02 00:49:57 +00:00
parent ce128c01a6
commit 55af2a4337
2 changed files with 10 additions and 11 deletions
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11
doc/TODO
View File

@ -2,7 +2,7 @@
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.
@ -810,11 +810,6 @@ Vacuum
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
@ -823,6 +818,10 @@ Vacuum
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

10
doc/src/FAQ/TODO.html
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@ -8,7 +8,7 @@
<body bgcolor="#FFFFFF" text="#000000" link="#FF0000" vlink="#A00000" alink="#0000FF">
<h1><a name="section_1">PostgreSQL TODO List</a></h1>
<p>Current maintainer: Bruce Momjian (<a href="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>
<p>The most recent version of this document can be viewed at<br/>
<a href="http://www.postgresql.org/docs/faqs.TODO.html">http://www.postgresql.org/docs/faqs.TODO.html</a>.
@ -730,10 +730,6 @@ first.
<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.
</p>
</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.
</p>
</li><li>Auto-fill the free space map by scanning the buffer cache or by
checking pages written by the background writer
@ -742,6 +738,10 @@ first.
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.
</p>
</li><li>%Add system view to show free space map contents
</li><li>Auto-vacuum