PostgreSQL TODO List
====================
Current maintainer: Bruce Momjian (bruce@momjian.us)
-Last updated: Wed Jun 18 21:15:40 EDT 2008
+Last updated: Mon Jun 23 16:20:35 EDT 2008
The most recent version of this document can be viewed at
http://www.postgresql.org/docs/faqs.TODO.html.
o Allow multi-column hash indexes
o -During index creation, pre-sort the tuples to improve build speed
+Sorting
+=======
+* Consider using hash buckets to do DISTINCT, rather than sorting
+
+ This would be beneficial when there are few distinct values. This is
+ already used by GROUP BY.
+
+* Consider whether duplicate keys should be sorted by block/offset
+
+ http://archives.postgresql.org/pgsql-hackers/2008-03/msg00558.php
+
+* -Avoid tuple some tuple copying in sort routines
+* Consider being smarter about memory and external files used during
+ sorts
+
+ http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php
+ http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php
+
+* Consider detoasting keys before sorting
Fsync
http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php
-* Consider using hash buckets to do DISTINCT, rather than sorting
-
- This would be beneficial when there are few distinct values. This is
- already used by GROUP BY.
-
* Log statements where the optimizer row estimates were dramatically
different from the number of rows actually found?
* Consider compressed annealing to search for query plans
http://archives.postgresql.org/pgsql-hackers/2008-01/msg01119.php
-* -Avoid tuple some tuple copying in sort routines
* SMP scalability improvements
http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php
http://archives.postgresql.org/pgsql-hackers/2007-09/msg00895.php
-* Consider being smarter about memory and external files used during
- sorts
-
- http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php
- http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php
-
* Allow one transaction to see tuples using the snapshot of another
transaction
http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php
http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php
-* Consider detoasting keys before sorting
* Consider GnuTLS if OpenSSL license becomes a problem
http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php
<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:bruce@momjian.us">bruce@momjian.us</a>)<br/>
-Last updated: Wed Jun 18 21:15:40 EDT 2008
+Last updated: Mon Jun 23 16:20:35 EDT 2008
</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>.
</li><li>Allow multi-column hash indexes
</li><li>-<em>During index creation, pre-sort the tuples to improve build speed</em>
</li></ul>
-<h1><a name="section_13">Fsync</a></h1>
+<h1><a name="section_13">Sorting</a></h1>
+<ul>
+ <li>Consider using hash buckets to do DISTINCT, rather than sorting
+<p> This would be beneficial when there are few distinct values. This is
+ already used by GROUP BY.
+</p>
+ </li><li>Consider whether duplicate keys should be sorted by block/offset
+<p> <a href="http://archives.postgresql.org/pgsql-hackers/2008-03/msg00558.php">http://archives.postgresql.org/pgsql-hackers/2008-03/msg00558.php</a>
+</p>
+ </li><li>-<em>Avoid tuple some tuple copying in sort routines</em>
+ </li><li>Consider being smarter about memory and external files used during
+ sorts
+<p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php">http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php</a>
+ <a href="http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php">http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php</a>
+</p>
+ </li><li>Consider detoasting keys before sorting
+</li></ul>
+<h1><a name="section_14">Fsync</a></h1>
<ul>
<li>Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-06/msg00541.php">http://archives.postgresql.org/pgsql-hackers/2007-06/msg00541.php</a>
</p>
</li></ul>
-<h1><a name="section_14">Cache Usage</a></h1>
+<h1><a name="section_15">Cache Usage</a></h1>
<ul>
<li>Speed up COUNT(*)
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-11/msg00562.php">http://archives.postgresql.org/pgsql-hackers/2007-11/msg00562.php</a>
</p>
</li></ul>
-<h1><a name="section_15">Vacuum</a></h1>
+<h1><a name="section_16">Vacuum</a></h1>
<ul>
<li>Improve speed with indexes
</p>
</li></ul>
</li></ul>
-<h1><a name="section_16">Locking</a></h1>
+<h1><a name="section_17">Locking</a></h1>
<ul>
<li>Fix priority ordering of read and write light-weight locks (Neil)
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php">http://archives.postgresql.org/pgsql-hackers/2008-01/msg00873.php</a>
</p>
</li></ul>
-<h1><a name="section_17">Startup Time Improvements</a></h1>
+<h1><a name="section_18">Startup Time Improvements</a></h1>
<ul>
<li>Experiment with multi-threaded backend for backend creation
a single session using multiple threads to execute a statement faster.
</p>
</li></ul>
-<h1><a name="section_18">Write-Ahead Log</a></h1>
+<h1><a name="section_19">Write-Ahead Log</a></h1>
<ul>
<li>Eliminate need to write full pages to WAL before page modification
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-11/msg00035.php">http://archives.postgresql.org/pgsql-hackers/2007-11/msg00035.php</a>
</p>
</li></ul>
-<h1><a name="section_19">Optimizer / Executor</a></h1>
+<h1><a name="section_20">Optimizer / Executor</a></h1>
<ul>
<li>Improve selectivity functions for geometric operators
actual row counts differ by a specified percentage
</li><li>Improve how ANALYZE computes in-doubt tuples
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php">http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php</a>
-</p>
- </li><li>Consider using hash buckets to do DISTINCT, rather than sorting
-<p> This would be beneficial when there are few distinct values. This is
- already used by GROUP BY.
</p>
</li><li>Log statements where the optimizer row estimates were dramatically
different from the number of rows actually found?
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-05/msg00450.php">http://archives.postgresql.org/pgsql-hackers/2007-05/msg00450.php</a>
</p>
</li></ul>
-<h1><a name="section_20">Background Writer</a></h1>
+<h1><a name="section_21">Background Writer</a></h1>
<ul>
<li>Consider having the background writer update the transaction status
<p> <a href="http://archives.postgresql.org/pgsql-patches/2007-06/msg00340.php">http://archives.postgresql.org/pgsql-patches/2007-06/msg00340.php</a>
</p>
</li></ul>
-<h1><a name="section_21">Miscellaneous Performance</a></h1>
+<h1><a name="section_22">Miscellaneous Performance</a></h1>
<ul>
<li>Do async I/O for faster random read-ahead of data
</li><li>Sort large UPDATE/DELETEs so it is done in heap order
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2008-01/msg01119.php">http://archives.postgresql.org/pgsql-hackers/2008-01/msg01119.php</a>
</p>
- </li><li>-<em>Avoid tuple some tuple copying in sort routines</em>
</li><li>SMP scalability improvements
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php">http://archives.postgresql.org/pgsql-hackers/2007-07/msg00439.php</a>
<a href="http://archives.postgresql.org/pgsql-hackers/2007-09/msg00206.php">http://archives.postgresql.org/pgsql-hackers/2007-09/msg00206.php</a>
</p>
</li><li>Research reducing deTOASTing in more places
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-09/msg00895.php">http://archives.postgresql.org/pgsql-hackers/2007-09/msg00895.php</a>
-</p>
- </li><li>Consider being smarter about memory and external files used during
- sorts
-<p> <a href="http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php">http://archives.postgresql.org/pgsql-hackers/2007-11/msg01101.php</a>
- <a href="http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php">http://archives.postgresql.org/pgsql-hackers/2007-12/msg00045.php</a>
</p>
</li><li>Allow one transaction to see tuples using the snapshot of another
transaction
<a href="http://archives.postgresql.org/pgsql-hackers/2008-01/msg00400.php">http://archives.postgresql.org/pgsql-hackers/2008-01/msg00400.php</a>
</p>
</li></ul>
-<h1><a name="section_22">Source Code</a></h1>
+<h1><a name="section_23">Source Code</a></h1>
<ul>
<li>Add use of 'const' for variables in source tree
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php">http://archives.postgresql.org/pgsql-hackers/2006-09/msg02238.php</a>
<a href="http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php">http://archives.postgresql.org/pgsql-patches/2006-10/msg00048.php</a>
</p>
- </li><li>Consider detoasting keys before sorting
</li><li>Consider GnuTLS if OpenSSL license becomes a problem
<p> <a href="http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php">http://archives.postgresql.org/pgsql-patches/2006-05/msg00040.php</a>
<a href="http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php">http://archives.postgresql.org/pgsql-hackers/2006-12/msg01213.php</a>
of result sets using new statement protocol
</li></ul>
</li></ul>
-<h1><a name="section_23">Exotic Features</a></h1>
+<h1><a name="section_24">Exotic Features</a></h1>
<ul>
<li>Add pre-parsing phase that converts non-ISO syntax to supported
<p> <a href="http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.php">http://archives.postgresql.org/pgsql-hackers/2008-01/msg00893.php</a>
</p>
</li></ul>
-<h1><a name="section_24">Features We Do <u>Not</u> Want</a></h1>
+<h1><a name="section_25">Features We Do <u>Not</u> Want</a></h1>
<ul>
<li>All backends running as threads in a single process (not wanted)