ANALYZE command

This patch is a follow-up to the split of the vacuum and analyze (done by Bruce Momjian last year).

It adds a separate SQL extension command ANALYZE that will only perform the analyze part and thus only use shared locks.

I will submit the doc and test changes in a separate patch, if you decide that we are really going ahead with the ANALYZE command.

This version still does not update pg_class. Those statistics are still tied in the vacuum part (num. of pages, tuples and indication if the relation has an index). The patch allows for analyze_rel() to work differently if run as part of a VACUUM or as an standalone ANALYZE, so the missing bits can be added without changes to the current behavior of VACUUM ANALYZE.

Possible future improvements:

1) Add the pg_class update to ANALYZE;

2) Add a VERBOSE option that prints information to gives the DBA a hint if it is worth of running VACUUM or not.

Thanks.

--
Fernando Nasser
Red Hat Inc. E-Mail: fnasser(at)redhat(dot)com