diff options
| author | Bruce Momjian <bruce@momjian.us> | 2005-12-17 16:43:11 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2005-12-17 16:43:11 +0000 |
| commit | 9e9a844f551249d4594894f683a5f0a1d9b73431 (patch) | |
| tree | b03f4c5d0003929b83f5a11012e638ae53e96e1b /doc/src | |
| parent | 927f57687ffb4afba0b394580d314dedefbdbee6 (diff) | |
Add:
* Allow star join optimizations
While our bitmap scan allows multiple indexes to be joined to get
to heap rows, a star joins allows multiple dimension _tables_ to
be joined to index into a larger main fact table. The join is
usually performed by either creating a cartesian product of all
the dimmension tables and doing a single join on that product or
using subselects to create bitmaps of each dimmension table match
and merge the bitmaps to perform the join on the fact table.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/FAQ/TODO.html | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/doc/src/FAQ/TODO.html b/doc/src/FAQ/TODO.html index 3768d5e9d52..ef8a024fb11 100644 --- a/doc/src/FAQ/TODO.html +++ b/doc/src/FAQ/TODO.html @@ -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: Sat Dec 17 09:18:30 EST 2005 +Last updated: Sat Dec 17 11:43:02 EST 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>. @@ -933,6 +933,15 @@ first. </p> </li><li>Log statements where the optimizer row estimates were dramatically different from the number of rows actually found? + </li><li>Allow star join optimizations +<p> While our bitmap scan allows multiple indexes to be joined to get + to heap rows, a star joins allows multiple dimension _tables_ to + be joined to index into a larger main fact table. The join is + usually performed by either creating a cartesian product of all + the dimmension tables and doing a single join on that product or + using subselects to create bitmaps of each dimmension table match + and merge the bitmaps to perform the join on the fact table. +</p> </li></ul> <h1><a name="section_21">Miscellaneous Performance</a></h1> |