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-rw-r--r--src/backend/commands/statscmds.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
index cf406f6f96..34d11c2a98 100644
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -485,6 +485,10 @@ RemoveStatisticsById(Oid statsOid)
*
* For MCV lists that's not the case, as those statistics store the datums
* internally. In this case we simply reset the statistics value to NULL.
+ *
+ * Note that "type change" includes collation change, which means we can rely
+ * on the MCV list being consistent with the collation info in pg_attribute
+ * during estimation.
*/
void
UpdateStatisticsForTypeChange(Oid statsOid, Oid relationOid, int attnum,