The following bug has been logged on the website:
Bug reference: 6565
Logged by: Guillaume Cottenceau
Email address: gcottenc@gmail.com
PostgreSQL version: 9.1.3
Operating system: not relevant
Description:=20=20=20=20=20=20=20=20
9.0 release notes contain:
"""
E.8.3.1.4. GEQO
Use the same random seed every time GEQO plans a query (Andres Freund)
While the Genetic Query Optimizer (GEQO) still selects random plans, it now
always selects the same random plans for identical queries, thus giving more
consistent performance. You can modify geqo_seed to experiment with
alternative plans.
"""
However, documentation up to 9.1 (pg website) say:
http://www.postgresql.org/docs/9.1/static/runtime-config-query.html#RUNTIME=
-CONFIG-QUERY-GEQO
"""GEQO's searching is randomized and therefore its plans may vary
nondeterministically."""
I guess this sentence is outdated now?