Simon Riggs wrote:
> 2.
> USING keyword, no brackets
> CREATE STATISTICS s1 USING (dependencies, ndistinct) ON (a, b) FROM t1
> WHERE partial-stuff;
>
> and if there are options, use the WITH for the optional parameters like this
> CREATE STATISTICS s1 USING (dependencies, ndistinct) WITH (options) ON
> (a, b) FROM t1 WHERE partial-stuff;
>
>
> I think I like (2)
OK, sounds sensible.
Note that the USING list is also optional -- if you don't specify it, we
default to creating all stat types. Also note that we currently don't
have any option other than stat types, so the WITH would always be empty
-- in other words we should remove it until we implement some option.
(I can readily see two possible options to implement for pg11, so the
omission of the WITH clause would be temporary:
1. sample size to use instead of the per-column values
2. whether to forcibly collect stats for all column for this stat
object even if the column has gotten a SET STATISTICS 0
Surely there can be others.)
Patch attached that adds the USING clause replacing the WITH clause,
which is also optional and only accepts statistic types (it doesn't
accept "foo = OFF" anymore, as it seems pointless, but I'm open to
accepting it if people care about it.)
(This patch removes WITH, but I verified that bison accepts having both.
The second attached reversed patch is what I used for removal.)
In the meantime, I noticed that pg_dump support for extstats is not
covered, which I'll go fix next.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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