From 4ea1c48abe3087a38a6260c8e21084de5e1a105b Mon Sep 17 00:00:00 2001 From: Monty Date: Wed, 9 Jun 2021 14:49:58 +0300 Subject: [PATCH] Added a function comment to Field_varstring::mark_unused_memory_as_defined() --- sql/field.cc | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/sql/field.cc b/sql/field.cc index 37d16d33212..d7dbc827ce2 100644 --- a/sql/field.cc +++ b/sql/field.cc @@ -7867,6 +7867,19 @@ bool Field_varstring::send(Protocol *protocol) #ifdef HAVE_MEM_CHECK + +/* + Mark the unused part of the varstring as defined. + + This function is only used be Unique when calculating statistics. + + The marking is needed as we write the whole tree to disk in case of + overflows. For using or comparing values the undefined value part + is never used. We could also use bzero() here, but it would be + slower in production environments. + This function is tested by main.stat_tables-enospc +*/ + void Field_varstring::mark_unused_memory_as_defined() { uint used_length __attribute__((unused)) = get_length();