Horton

Re: PoC/WIP: Extended statistics on expressions

Dean Rasheed <dean.a.rasheed@gmail.com>

View thread View on postgr.es
From: Dean Rasheed <dean.a.rasheed@gmail.com>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2021-03-25T13:33:34Z
Lists: pgsql-hackers 
On Thu, 25 Mar 2021 at 00:05, Tomas Vondra
<tomas.vondra@enterprisedb.com> wrote:
>
> here's an updated patch. 0001

The change to the way that CreateStatistics() records dependencies
isn't quite right -- recordDependencyOnSingleRelExpr() will not create
any dependencies if the expression uses only a whole-row Var. However,
pull_varattnos() will include whole-row Vars, and so nattnums_exprs
will be non-zero, and CreateStatistics() will not create a whole-table
dependency when it should.

I suppose that could be fixed up by inspecting the bitmapset returned
by pull_varattnos() in more detail, but I think it's probably safer to
revert to the previous code, which matched what index_create() did.

Regards,
Dean

Commits

  1. Disallow extended statistics on system columns

  2. Identify simple column references in extended statistics

  3. Don't print extra parens around expressions in extended stats

  4. Change position of field "transformed" in struct CreateStatsStmt.

  5. Add transformed flag to nodes/*funcs.c for CREATE STATISTICS

  6. Stabilize stats_ext test with other collations

  7. Extended statistics on expressions

  8. Reduce duration of stats_ext regression tests

  9. Allow composite types in catalog bootstrap

  10. Convert Typ from array to list in bootstrap

  11. Disallow CREATE STATISTICS on system catalogs