From e648e77e25708874196326b6e4da30e7717156ab Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Tue, 26 Mar 2024 12:27:41 -0400 Subject: [PATCH] C comment: mention no doc for negative start of substring(text) Also add URL to hackers discussion. Backpatch-through: master --- src/backend/utils/adt/varlena.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c index 8d28dd42ce1..d1b09dedfd4 100644 --- a/src/backend/utils/adt/varlena.c +++ b/src/backend/utils/adt/varlena.c @@ -891,8 +891,9 @@ text_substring(Datum str, int32 start, int32 length, bool length_not_specified) int32 E; /* end position */ /* - * SQL99 says S can be zero or negative, but we still must fetch from the - * start of the string. + * SQL99 says S can be zero or negative (which we don't document), but we + * still must fetch from the start of the string. + * https://www.postgresql.org/message-id/170905442373.643.11536838320909376197%40wrigleys.postgresql.org */ S1 = Max(S, 1);