pg_statistic, lack of documentation

Hi,

http://www.postgresql.org/docs/9.1/interactive/catalog-pg-statistic.html

It specifies that entries are created by ANALYZE, but does not mention
that if a table is empty the entry for it is not created. Probably it
is worth to add to the docs. The test case is below.

grayhemp(at)[local]:5432 test=#create table t1 (i integer);CREATE
TABLEgrayhemp(at)[local]:5432 test=#select stanullfrac, stawidth from
pg_statistic where starelid = 't1'::regclass; stanullfrac | stawidth
-------------+----------(0 rows)
grayhemp(at)[local]:5432 test=#analyze t1;ANALYZEgrayhemp(at)[local]:5432
test=#select stanullfrac, stawidth from pg_statistic where starelid =
't1'::regclass; stanullfrac | stawidth -------------+----------(0
rows)
grayhemp(at)[local]:5432 test=#insert into t1 values (1);INSERT 0
1grayhemp(at)[local]:5432 test=#select stanullfrac, stawidth from
pg_statistic where starelid = 't1'::regclass; stanullfrac | stawidth
-------------+----------(0 rows)
grayhemp(at)[local]:5432 test=#analyze t1;ANALYZEgrayhemp(at)[local]:5432
test=#select stanullfrac, stawidth from pg_statistic where starelid =
't1'::regclass; stanullfrac | stawidth -------------+----------
   0 |        4(1 row)

--
Sergey Konoplev

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