From 344bbad9c752608d55cf9ab83f18336ca7b9aca4 Mon Sep 17 00:00:00 2001 From: Yurii Rashkovskii Date: Fri, 24 Nov 2023 06:32:05 -0800 Subject: [PATCH] Don't copy bytea/text in convert_from/to unless converted. `pg_convert` allocates a new bytea whether actual conversion occurred or not, followed by copying the result which (by definition) is the same as the original value. In the case where conversion has not occurred, it will now simply return the original value, this avoiding unnecessary allocation and copying. --- src/backend/utils/mb/mbutils.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/src/backend/utils/mb/mbutils.c b/src/backend/utils/mb/mbutils.c index 67a1ab2ab2..5a0e49e70b 100644 --- a/src/backend/utils/mb/mbutils.c +++ b/src/backend/utils/mb/mbutils.c @@ -585,19 +585,25 @@ pg_convert(PG_FUNCTION_ARGS) src_encoding, dest_encoding); - /* update len if conversion actually happened */ - if (dest_str != src_str) - len = strlen(dest_str); /* - * build bytea data type structure. + * if no actual conversion happened, return the original string + * (we are checking pointers to strings instead of encodings because + * `pg_do_encoding_conversion` above covers more cases than just + * encoding equality) */ + if (dest_str == src_str) { + PG_RETURN_BYTEA_P(string); + } + + /* if conversion happened, build a new bytea of a correct length */ + len = strlen(dest_str); retval = (bytea *) palloc(len + VARHDRSZ); SET_VARSIZE(retval, len + VARHDRSZ); memcpy(VARDATA(retval), dest_str, len); - if (dest_str != src_str) - pfree(dest_str); + /* free the original result of conversion */ + pfree(dest_str); /* free memory if allocated by the toaster */ PG_FREE_IF_COPY(string, 0); -- 2.33.0