WAIT FOR command should do some query jumbling

[pg-hub-mirror]

Read-only mirror. Reply and review on pgsql-hackers; activity here is not sent upstream.

• Original author: Alexander Korotkov <aekorotkov(at)gmail(dot)com>
• Mailing list: pgsql-hackers
• Message-ID: CAPpHfdt1Zasx9AuXgn8w0fqcMHffqWcC4yPrVq-A5Ok+6DWY_A@mail.gmail.com
• Original email

Patch files:

• v3-0001-Jumble-the-WAIT-option-list-by-meaning-not-by-spe.patch

---

Hi!
On Thu, Sep 3, 2026 at 6:38 AM Michael Paquier <michael(at)paquier(dot)xyz> wrote:

Sami has also mentioned to me off-list that we may want something
smarter in terms of the management of the DefElems that include
strings, because we have other commands with contents that we may want
to normalize in some contexts, like an ALTER TABLE with a password as
one example. Perhaps it would be better to not rush that part.
Agreed, so v3 attached drops the generic part and does WAIT only.
Two things today: waits differing only in the timeout get an entry
each, and so does the same wait with its options written in another
order.
1 | WAIT FOR LSN $1 WITH (mode 'primary_flush', timeout '5ms')
1 | WAIT FOR LSN $1 WITH (mode 'primary_flush', timeout '7ms')
1 | WAIT FOR LSN $1 WITH (timeout '5ms', mode 'primary_flush')
With v3 those are one entry:
3 | WAIT FOR LSN $1 WITH (mode 'primary_flush', timeout $2)
while the modes stay apart, as Sirisha asked for:
1 | WAIT FOR LSN $1 WITH (mode 'standby_replay', timeout $2, no_throw)
1 | WAIT FOR LSN $1 WITH (mode 'standby_write', timeout $2, no_throw)
WaitStmt.options gets a custom jumble function that walks the
recognized options in a fixed order instead of the order written,
records TIMEOUT as a constant, and jumbles MODE and NO_THROW as given.
No generic DefElem option normalization: what a value means differs
per option and only the command knows, which is the same problem
VariableSetStmt.jumble_args solves per grammar flavor.
DefElem gains arg_location, since DefElem.location points at the
option name -- recording that one normalizes the wrong token:
WAIT FOR LSN $1 WITH (mode 'primary_flush', $2 '5ms')
and the argument node is a bare String or Integer, which carries no
location at all. Nothing else reads the new field, so no other
statement changes.
One wart left alone: "WITH (no_throw)" and "WITH (no_throw true)" are
still separate entries, as VACUUM (ANALYZE) and VACUUM (ANALYZE true)
are today. Resolving it would mean calling defGetBoolean() while
jumbling, which can throw.
Passwords in pg_stat_statements are untouched by this and can go to
their own thread.

---

Regards,
Alexander Korotkov
Supabase