PostgreSQL Weekly News - April 24 2005
- There's been a lot of discussion of patents and the PostgreSQL community's public stance on them should be. We've taken that public stance by making our software patent-free in every instance we have found. Let's take the discussion off the -www list and continue it on -advocacy where it belongs. Tom Lane added bitmapping of regular indexes in memory, hereafter known as a "bitmapscan". The purpose of this innovation is to allow bitmap operations joining several different indexes, or even several OR conditions on the same INDEX. It is expected to dramatically improve performance on queries with complex WHERE conditions on servers with fast CPU and lots of RAM. However, we have not yet set the planner cost estimates for using bitmapscans, so users are encouraged to download the current snapshot, test with enable_bitmapscan turned on or off, and report results. Please note that this is a different feature than Victor Y. Yegorov's on-disk bitmap indexes, which are a new index type intended to allow indexing low-cardinality attributes on large tables. The two features together should greatly improve performance of descision support / business intelligence workloads. Josh Berkus brought up the fact that PostgreSQL's estimates of index cardinality are very far off. Andrew Dunstan proposed a solution from a paper from 2000.
- You can help by deciphering arithmetic for the estimator and turning
it into a patch.
PostgreSQL Product News
OpenRPT is a graphical SQL report writer, designer and rendering engine, optimized for PostgreSQL. WYSIWYG display, GUI built with Qt, runs on Linux, Windows, Mac OS X. Server-side rendering engine. Reports can be saved as XML, either as files or in a database.
PostgreSQL in the News
- Neil Conway gave a talk on the optimizer at linux.conf.au.
Source: PostgreSQL Announcements Mailing List (pgsql-announce) - http://archives.postgresql.org/pgsql-announce/