Обсуждение: VACUUM ANALYZE differs under 7.2.3 from 7.2.1

The "VACUUM ANALYZE tablename" command does not have the same effect on
table metadata under 7.2.1 and 7.2.3.  In particular, I've noted that
pg_class.reltuples is not updated by vacuuming after a delete.

Here is a sequence of SQL commands to demonstrate the difference.  Under
7.2.1, the resulting last three displays of the pg_class.reltuples value
will be zero (0), while under 7.2.3 it will be 10.

create table foo (a char(1));

copy foo from stdin;

a

a

a

a

a

a

a

a

a

a

\.

\x

\t

select count(*) from foo;

select reltuples from pg_class where relname = 'foo';

vacuum foo;

select reltuples from pg_class where relname = 'foo';

vacuum analyze foo;

select reltuples from pg_class where relname = 'foo';

analyze foo;

select reltuples from pg_class where relname = 'foo';

delete from foo;

select reltuples from pg_class where relname = 'foo';

select count(*) from foo;

select reltuples from pg_class where relname = 'foo';

vacuum foo;

select reltuples from pg_class where relname = 'foo';

vacuum analyze foo;

select reltuples from pg_class where relname = 'foo';

analyze foo;

select reltuples from pg_class where relname = 'foo';

drop table foo;

Jeff Boes <jboes@nexcerpt.com> writes:
> The "VACUUM ANALYZE tablename" command does not have the same effect on
> table metadata under 7.2.1 and 7.2.3.  In particular, I've noted that
> pg_class.reltuples is not updated by vacuuming after a delete.

Hard to believe ... I see no changes in the 7.2.* CVS logs that might
cause such a problem.

> Here is a sequence of SQL commands to demonstrate the difference.  Under
> 7.2.1, the resulting last three displays of the pg_class.reltuples value
> will be zero (0), while under 7.2.3 it will be 10.

Here I get zeroes, as you expect, with 7.2.3.  Some problem with your
installation perhaps?

            regards, tom lane