Re: Removing unneeded self joins

Andrei Lepikhov <lepihov@gmail.com>

From: Andrei Lepikhov <lepihov@gmail.com>

To: Alexander Korotkov <aekorotkov@gmail.com>, Dean Rasheed <dean.a.rasheed@gmail.com>

Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, Richard Guo <guofenglinux@gmail.com>, Alexander Lakhin <exclusion@gmail.com>, "Gregory Stark (as CFM)" <stark.cfm@gmail.com>, Michał Kłeczek <michal@kleczek.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2024-07-22T02:13:49Z

Lists: pgsql-hackers

Commits

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Remove GUC_NOT_IN_SAMPLE from enable_self_join_elimination
- 717d0e8dd945 18.0 landed
Put enable_self_join_elimination into postgresql.conf.sample
- c2d329260cd8 18.0 landed
Get rid of ojrelid local variable in remove_rel_from_query()
- e167191dc146 18.0 landed
Implement Self-Join Elimination
- fc069a3a6319 18.0 cited
Revert: Remove useless self-joins
- d1d286d83c0e 17.0 landed
Replace lateral references to removed rels in subqueries
- 466979ef031a 17.0 landed
Replace relids in lateral subquery parse tree during SJE
- 489072ab7a9e 17.0 landed
Forbid SJE with result relation
- 8c441c082797 17.0 landed
Fix misuse of RelOptInfo.unique_for_rels cache by SJE
- 30b4955a4668 17.0 landed
Replace the relid in some missing fields during SJE
- a7928a57b9f0 17.0 landed
Revert 56-bit relfilenode change and follow-up commits.
- a448e49bcbe4 16.0 cited
Stabilize timetz test across DST transitions.
- 4a071afbd056 14.0 cited
Speed up finding EquivalenceClasses for a given set of rels
- 3373c7155350 13.0 cited
Fix mark-and-restore-skipping test case to not be a self-join.
- 24d08f3c0a1f 12.0 landed

On 20/7/2024 18:38, Alexander Korotkov wrote:
> On Fri, Jul 19, 2024 at 11:30 AM Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
>> On Wed, 17 Jul 2024 at 01:45, Alexander Korotkov <aekorotkov@gmail.com> wrote:
> We initially didn't use ChangeVarNodes() in SJE at all.  See the last
> patch version without it [1].  We're trying to address Tom Lane's
> proposal to re-use more of existing tree-manipulation infrastructure
> [2].  I agree with you that the case with ChangeVarNodes() looks
> questionable.  Do you have other ideas how we can re-use some more of
> existing tree-manipulation infrastructure in SJE?
As I can see, ChangeVarNodes is dedicated to working with the query tree 
before the planning phase. SJE works right in the middle of the planning 
process. So, it may be more practical to keep it separate as a walker, 
as Dean has proposed. If the optimisation stuff changes, the walker code 
will be changed, too.

-- 
regards, Andrei Lepikhov