Horton

Re: BUG #18314: PARALLEL UNSAFE function does not prevent parallel index build

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Tender Wang <tndrwang@gmail.com>
Cc: Alexander Lakhin <exclusion@gmail.com>, pgsql-bugs@lists.postgresql.org
Date: 2024-02-29T09:17:41Z
Lists: pgsql-bugs

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On Thu, Feb 29, 2024 at 3:08 PM Tender Wang <tndrwang@gmail.com> wrote:
>
> Hi jian he,
>   I'm sorry for the delayed response.  Thanks for your reviewing, and the new v2 patch include your advices.
>
> As no others reply to this patch. I would add it to the 2024-03 commitfest.
> --


`
if (heap->rd_rel->relpersistence == RELPERSISTENCE_TEMP ||
!is_parallel_safe(root, (Node *) RelationGetIndexExpressions(index, true)) ||
!is_parallel_safe(root, (Node *) RelationGetIndexPredicate(index, true)))
{
parallel_workers = 0;
goto done;
}
`
I refactored the comments for the code above.
Feel free to change it.

I also toggled {RelationGetIndexExpressions,
RelationGetIndexPredicate}'s second argument
from false to true where it's false,
true to false where it's true.

I guess it's more intuitive to do
`
if (get_raw_expr)
  return result;
`
since at that time, the `result` is a raw expression.

Overall it looks good.

Commits

  1. Revert "Fix parallel-safety check of expressions and predicate for index builds"

  2. Fix parallel-safety check of expressions and predicate for index builds

  3. Ensure we preprocess expressions before checking their volatility.