From: Tomas Vondra Date: Mon, 19 Aug 2024 11:31:51 +0000 (+0200) Subject: Explain dropdb can't use syscache because of TOAST X-Git-Tag: REL_18_BETA1~2092 X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=5cb902e9d5a99a0e1a2c9098555447e097102e39;p=postgresql.git Explain dropdb can't use syscache because of TOAST Add a comment explaining dropdb() can't rely on syscache. The issue with flattened rows was fixed by commit 0f92b230f88b, but better to have a clear explanation why the systable scan is necessary. The other places doing in-place updates on pg_database have the same comment. Suggestion and patch by Yugo Nagata. Backpatch to 12, same as the fix. Author: Yugo Nagata Backpatch-through: 12 Discussion: https://postgr.es/m/CAJTYsWWNkCt+-UnMhg=BiCD3Mh8c2JdHLofPxsW3m2dkDFw8RA@mail.gmail.com --- diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c index 7a7e2c6e3ef..d00ae40e192 100644 --- a/src/backend/commands/dbcommands.c +++ b/src/backend/commands/dbcommands.c @@ -1790,7 +1790,9 @@ dropdb(const char *dbname, bool missing_ok, bool force) pgstat_drop_database(db_id); /* - * Update the database's pg_database tuple + * Get the pg_database tuple to scribble on. Note that this does not + * directly rely on the syscache to avoid issues with flattened toast + * values for the in-place update. */ ScanKeyInit(&scankey, Anum_pg_database_datname,