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o -Support a smaller header for short variable-length fields
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Bruce Momjian 2007-04-07 02:48:16 +00:00
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2 changed files with 4 additions and 19 deletions
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12
doc/TODO
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@ -2,7 +2,7 @@
PostgreSQL TODO List PostgreSQL TODO List
==================== ====================
Current maintainer: Bruce Momjian (bruce@momjian.us) Current maintainer: Bruce Momjian (bruce@momjian.us)
Last updated: Wed Apr 4 22:08:46 EDT 2007 Last updated: Fri Apr 6 22:48:08 EDT 2007
The most recent version of this document can be viewed at The most recent version of this document can be viewed at
http://www.postgresql.org/docs/faqs.TODO.html. http://www.postgresql.org/docs/faqs.TODO.html.
@ -1436,15 +1436,7 @@ Miscellaneous Performance
* -Merge xmin/xmax/cmin/cmax back into three header fields * -Merge xmin/xmax/cmin/cmax back into three header fields
* Consider ways of storing rows more compactly on disk * Consider ways of storing rows more compactly on disk
o Support a smaller header for short variable-length fields? o -Support a smaller header for short variable-length fields
One idea is to create zero-or-one-byte-header versions
of varlena data types. In involves setting the high-bit and
0-127 length in the single-byte header, or clear the high bit
and store the 7-bit ASCII value in the rest of the byte.
The small-header versions have no alignment requirements.
http://archives.postgresql.org/pgsql-hackers/2006-09/msg01372.php
o Reduce the row header size? o Reduce the row header size?
o Consider reducing on-disk varlena length from four to two o Consider reducing on-disk varlena length from four to two
because a heap row cannot be more than 64k in length because a heap row cannot be more than 64k in length

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doc/src/FAQ/TODO.html
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<body bgcolor="#FFFFFF" text="#000000" link="#FF0000" vlink="#A00000" alink="#0000FF"> <body bgcolor="#FFFFFF" text="#000000" link="#FF0000" vlink="#A00000" alink="#0000FF">
<h1><a name="section_1">PostgreSQL TODO List</a></h1> <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/> <p>Current maintainer: Bruce Momjian (<a href="mailto:bruce@momjian.us">bruce@momjian.us</a>)<br/>
Last updated: Wed Apr 4 22:08:46 EDT 2007 Last updated: Fri Apr 6 22:48:08 EDT 2007
</p> </p>
<p>The most recent version of this document can be viewed at<br/> <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>. <a href="http://www.postgresql.org/docs/faqs.TODO.html">http://www.postgresql.org/docs/faqs.TODO.html</a>.
@ -1273,14 +1273,7 @@ first. There is also a developer's wiki at<br/>
</li><li>-<em>Merge xmin/xmax/cmin/cmax back into three header fields</em> </li><li>-<em>Merge xmin/xmax/cmin/cmax back into three header fields</em>
</li><li>Consider ways of storing rows more compactly on disk </li><li>Consider ways of storing rows more compactly on disk
<ul> <ul>
<li>Support a smaller header for short variable-length fields? <li>-<em>Support a smaller header for short variable-length fields</em>
<p> One idea is to create zero-or-one-byte-header versions
of varlena data types. In involves setting the high-bit and
0-127 length in the single-byte header, or clear the high bit
and store the 7-bit ASCII value in the rest of the byte.
The small-header versions have no alignment requirements.
<a href="http://archives.postgresql.org/pgsql-hackers/2006-09/msg01372.php">http://archives.postgresql.org/pgsql-hackers/2006-09/msg01372.php</a>
</p>
</li><li>Reduce the row header size? </li><li>Reduce the row header size?
</li><li>Consider reducing on-disk varlena length from four to two </li><li>Consider reducing on-disk varlena length from four to two
because a heap row cannot be more than 64k in length because a heap row cannot be more than 64k in length