Re: Making Vars outer-join aware

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: Zhihong Yu <zyu@yugabyte.com>

Cc: PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>, Richard Guo <guofenglinux@gmail.com>, "Finnerty, Jim" <jfinnert@amazon.com>

Date: 2022-08-01T20:26:30Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Re-allow INDEX_VAR as rt_index in ChangeVarNodes().
- fbf80421ead5 16.0 landed
Fix thinkos in have_unsafe_outer_join_ref; reduce to Assert check.
- f50f029c497d 16.0 landed
Invent "join domains" to replace the below_outer_join hack.
- 3bef56e11650 16.0 landed
Do assorted mop-up in the planner.
- b448f1c8d83f 16.0 landed
Make Vars be outer-join-aware.
- 2489d76c4906 16.0 landed
Invent "multibitmapsets", and use them to speed up antijoin detection.
- e9e26b5e7166 16.0 landed
Add basic regression tests for semi/antijoin recognition.
- 0043aa6b8597 16.0 landed
Improve performance of adjust_appendrel_attrs_multilevel.
- 2f17b57017e5 16.0 landed
Refactor addition of PlaceHolderVars to joinrel targetlists.
- afa0ec30bfd1 16.0 landed
Use an explicit state flag to control PlaceHolderInfo creation.
- b3ff6c742f6c 16.0 landed
Make PlaceHolderInfo lookup O(1).
- 6569ca43973b 16.0 landed

Zhihong Yu <zyu@yugabyte.com> writes:
> For v3-0003-label-Var-nullability-in-parser.patch :

> +   if (rtindex > 0 && rtindex <= list_length(pstate->p_nullingrels))
> +       relids = (Bitmapset *) list_nth(pstate->p_nullingrels, rtindex - 1);
> +   else
> +       relids = NULL;
> +
> +   /*
> +    * Merge with any already-declared nulling rels.  (Typically there won't
> +    * be any, but let's get it right if there are.)
> +    */
> +   if (relids != NULL)

> It seems the last if block can be merged into the previous if block. That
> way `relids = NULL` can be omitted.

No, because the list entry we fetch could be NULL.

			regards, tom lane