Fix up handling of nondeterministic collations with pattern_ops opclasses.

text_pattern_ops and its siblings can't be used with nondeterministic
collations, because they use the text_eq operator which will not behave
as bitwise equality if applied with a nondeterministic collation.  The
initial implementation of that restriction was to insert a run-time test
in the related comparison functions, but that is inefficient, may throw
misleading errors, and will throw errors in some cases that would work.
It seems sufficient to just prevent the combination during CREATE INDEX,
so do that instead.

Lacking any better way to identify the opclasses involved, we need to
hard-wire tests for them, which requires hand-assigned values for their
OIDs, which forces a catversion bump because they previously had OIDs
that would be assigned automatically.  That's slightly annoying in the
v12 branch, but fortunately we're not at rc1 yet, so just do it.

Back-patch to v12 where nondeterministic collations were added.

In passing, run make reformat-dat-files, which found some unrelated
whitespace issues (slightly different ones in HEAD and v12).

Peter Eisentraut, with small corrections by me

Discussion: https://postgr.es/m/22566.1568675619@sss.pgh.pa.us

1 files changed, 6 insertions, 37 deletions

diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index d36156f4e4d..2480074813d 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -2996,34 +2996,12 @@ textgename(PG_FUNCTION_ARGS)
  */
 
 static int
-internal_text_pattern_compare(text *arg1, text *arg2, Oid collid)
+internal_text_pattern_compare(text *arg1, text *arg2)
 {
 	int			result;
 	int			len1,
 				len2;
 
-	check_collation_set(collid);
-
-	/*
-	 * XXX We cannot use a text_pattern_ops index for nondeterministic
-	 * collations, because these operators intentionally ignore the collation.
-	 * However, the planner has no way to know that, so it might choose such
-	 * an index for an "=" clause, which would lead to wrong results.  This
-	 * check here doesn't prevent choosing the index, but it will at least
-	 * error out if the index is chosen.  A text_pattern_ops index on a column
-	 * with nondeterministic collation is pretty useless anyway, since LIKE
-	 * etc. won't work there either.  A future possibility would be to
-	 * annotate the operator class or its members in the catalog to avoid the
-	 * index.  Another alternative is to stay away from the *_pattern_ops
-	 * operator classes and prefer creating LIKE-supporting indexes with
-	 * COLLATE "C".
-	 */
-	if (!get_collation_isdeterministic(collid))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
-						"text_pattern_ops")));
-
 	len1 = VARSIZE_ANY_EXHDR(arg1);
 	len2 = VARSIZE_ANY_EXHDR(arg2);
 
@@ -3046,7 +3024,7 @@ text_pattern_lt(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
+	result = internal_text_pattern_compare(arg1, arg2);
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -3062,7 +3040,7 @@ text_pattern_le(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
+	result = internal_text_pattern_compare(arg1, arg2);
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -3078,7 +3056,7 @@ text_pattern_ge(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
+	result = internal_text_pattern_compare(arg1, arg2);
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -3094,7 +3072,7 @@ text_pattern_gt(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
+	result = internal_text_pattern_compare(arg1, arg2);
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -3110,7 +3088,7 @@ bttext_pattern_cmp(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
+	result = internal_text_pattern_compare(arg1, arg2);
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -3123,17 +3101,8 @@ Datum
 bttext_pattern_sortsupport(PG_FUNCTION_ARGS)
 {
 	SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
-	Oid			collid = ssup->ssup_collation;
 	MemoryContext oldcontext;
 
-	check_collation_set(collid);
-
-	if (!get_collation_isdeterministic(collid))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
-						"text_pattern_ops")));
-
 	oldcontext = MemoryContextSwitchTo(ssup->ssup_cxt);
 
 	/* Use generic string SortSupport, forcing "C" collation */