Check collation when creating partitioned index

petere · petere · commit 5d40b3c4f6ca · 2023-12-01T16:27:18.000+01:00
When creating a partitioned index, the partition key must be a subset of the index's columns. But this currently doesn't check that the collations between the partition key and the index definition match. So you can construct a unique index that fails to enforce uniqueness. (This would most likely involve a nondeterministic collation, so it would have to be crafted explicitly and is not something that would just happen by accident.) This patch adds the required collation check. As a result, any previously allowed unique index that has a collation mismatch would no longer be allowed to be created. Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://www.postgresql.org/message-id/flat/3327cb54-f7f1-413b-8fdb-7a9dceebb938%40eisentraut.org
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
@@ -935,10 +935,13 @@ DefineIndex(Oid relationId,
 			{
 				if (key->partattrs[i] == indexInfo->ii_IndexAttrNumbers[j])
 				{
-					/* Matched the column, now what about the equality op? */
+					/* Matched the column, now what about the collation and equality op? */
 					Oid			idx_opfamily;
 					Oid			idx_opcintype;
 
+					if (key->partcollation[i] != collationObjectId[j])
+						continue;
+
 					if (get_opclass_opfamily_and_input_type(classObjectId[j],
 															&idx_opfamily,
 															&idx_opcintype))

Original file line number	Diff line number	Diff line change
`@@ -935,10 +935,13 @@ DefineIndex(Oid relationId,`
`935`	`935`	`{`
`936`	`936`	`if (key->partattrs[i] == indexInfo->ii_IndexAttrNumbers[j])`
`937`	`937`	`{`
`938`		`- /* Matched the column, now what about the equality op? */`
	`938`	`+ /* Matched the column, now what about the collation and equality op? */`
`939`	`939`	`Oid idx_opfamily;`
`940`	`940`	`Oid idx_opcintype;`
`941`	`941`
	`942`	`+ if (key->partcollation[i] != collationObjectId[j])`
	`943`	`+ continue;`
	`944`	`+`
`942`	`945`	`if (get_opclass_opfamily_and_input_type(classObjectId[j],`
`943`	`946`	`&idx_opfamily,`
`944`	`947`	`&idx_opcintype))`