TODO list for PostgreSQL

========================

Current maintainer:Bruce Momjian (pgman@candle.pha.pa.us)

Last updated:Wed Jan19 09:17:41 EST 2005

Last updated:Sat Jan22 15:05:08 EST 2005

The most recent version of this document can be viewed at the PostgreSQL web

site, http://www.PostgreSQL.org.

* Use indexes for MIN() and MAX()

MIN/MAX queries can already be rewritten as SELECT col FROM tab ORDER

BY col {DESC} LIMIT 1. Completing this item involvesmaking this

BY col {DESC} LIMIT 1. Completing this item involvesdoing this

transformation automatically.

* Use index to restrict rows returned by multi-key index when used with

We could use a fixed row count and a +/- count to follow MVCC

visibility rules, or a single cached value could be used and

invalidated if anyone modifies the table.

invalidated if anyone modifies the table. Another idea is to

get a count directly from a unique index, but for this to be

faster than a sequential scan it must avoid access to the heap

to obtain tuple visibility information.

* Allow data to be pulled directly from indexes

Currently indexes do not have enough tuple tuple visibility

information to allow data to be pulled from the index without

also accessing the heap. One way to allow this is to set a bit

to index tuples to indicate if a tuple is currently visible to

all transactions when the first valid heap lookup happens. This

bit would have to be cleared when a heap tuple is expired.

* Consider automatic caching of queries at various levels:

o Parsed query tree

o Query execute plan