Re: empty table explain... - Mailing list pgsql-general

From Tom Lane
Subject Re: empty table explain...
Date
Msg-id 23680.1225137709@sss.pgh.pa.us
Whole thread Raw
In response to empty table explain...  (Luca Ferrari <fluca1978@infinito.it>)
List pgsql-general
Luca Ferrari <fluca1978@infinito.it> writes:
> I'm curious to know why, if a table is empty, it seems that an ANALYZE
> of the table does not insert any stats in the pg_stats table,

Uh ... because there are no stats to insert.  The only available
information is that the table is empty, which is something we track in
pg_class not pg_stats.

> Second, if I execute an EXPLAIN
> on an empty table, even after an ANALYZE of the table, I got an explain that
> proposes me a row numbers and size that I cannot understand (since it seems to
> be different depending on the table definition).

That's the planner not wanting to bet on an empty table staying empty.

            regards, tom lane

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