Hi,

Currently, btree indexes cannot used for ILIKE (~~*) operator if the pattern
has case-varying characters although LIKE (~~) expression can be converted
to indexable clauses by the planner support function (if the collation
is "C" or operator class 'text_pattern_ops' is used).

For example, "t ~~ '123foo%'" is converted to "(t >= '123foo' AND t < 
'123fop')" 
and index scan can be used for this condition. On the other hand, "t ~~* 
'123foo'"
cannot be converted and sequential scan is used. 

Even in this case, we can use a bitmap index scan for the condition 
"(t >= '123f' AND t < '123g') OR "(t >= '123F' AND t < '123G')" followed by
recheck by the original condition "t ~~* '123foo'", and this could be faster
than seqscan. 

However, even if the support function would return OR clauses, the current
planner implementation cannot not build bitmap scan paths using them. 


The attached patches allow to ILIKE (~~*) forward matching to use btree index. 

The patch 0001 enables get_index_clause_from_support to receive OR clauses
from support functions and use them to build bitmap index scan later. OR clauses
returned by support functions are collected in the new argument 'orclauses" of
match_restriction_clauses_to_index(), and they are passed to
generate_bitmap_or_paths() later to build bitmap scan paths.

The patch 0002 modifies the support function to return OR clauses as an example
above when ILIKE's pattern has case-varying characters in forward matching. The
OR clauses contains two index conditions for the upper and the lower letter of
the first case-varying character in the pattern respectively. Although the
subsequent characters are not considered in the index scans, it could enough be
faster then sequent scan.

Here is an example. 

1. Create a table with random text records

=# CREATE TABLE tbl (t text);
=# INSERT INTO tbl SELECT CASE WHEN i%2=1 THEN upper(x) ELSE x END
                  FROM (SELECT i, md5(i::text) x FROM 
generate_series(1,5000000) i);

2. Create an index
=# CREATE INDEX ON tbl (t text_pattern_ops);

3. Before applying patch: Seq Scan was selected. It takes about 4 sec.

=# EXPLIN ANALYZE SELECT * FROM tbl WHERE t ILIKE '12ab%';

                                                       QUERY PLAN               
                                         
-------------------------------------------------------------------------------------------------------------------------
 Gather  (cost=1000.00..58712.97 rows=500 width=33) (actual 
time=101.096..4110.979 rows=64 loops=1)
   Workers Planned: 4
   Workers Launched: 4
   Buffers: shared hit=10778 read=31260
   ->  Parallel Seq Scan on tbl  (cost=0.00..57662.97 rows=125 width=33) 
(actual time=440.232..4101.023 rows=13 loops=5)
         Filter: (t ~~* '12ab%'::text)
         Rows Removed by Filter: 999987
         Buffers: shared hit=10778 read=31260
 Planning Time: 0.415 ms
 Execution Time: 4111.051 ms
(10 rows)

4. After applying patch: Bitmap Index Scan was selected. It takes only 10 ms.

=# EXPLIN ANALYZE SELECT * FROM tbl WHERE t ILIKE '12ab%';
                                                                               
QUERY PLAN                                                                      
       
  
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
--
 Bitmap Heap Scan on tbl  (cost=9.38..13.40 rows=500 width=33) (actual 
time=3.720..9.660 rows=64 loops=1)
   Recheck Cond: (((t ~>=~ '12A'::text) AND (t ~<~ '12B'::text) AND (t ~~* 
'12ab%'::text)) OR ((t ~>=~ '12a'::text) AND (t ~<~ '12b'::text) AND (t ~~* 
'12ab%'::text))
)
   Filter: (t ~~* '12ab%'::text)
   Rows Removed by Filter: 1205
   Heap Blocks: exact=1254
   Buffers: shared hit=1271
   ->  BitmapOr  (cost=9.38..9.38 rows=1 width=0) (actual time=2.370..2.372 
rows=0 loops=1)
         Buffers: shared hit=17
         ->  Bitmap Index Scan on tbl_t_idx  (cost=0.00..4.57 rows=1 width=0) 
(actual time=1.192..1.193 rows=604 loops=1)
               Index Cond: ((t ~>=~ '12A'::text) AND (t ~<~ '12B'::text))
               Buffers: shared hit=8
         ->  Bitmap Index Scan on tbl_t_idx  (cost=0.00..4.57 rows=1 width=0) 
(actual time=1.174..1.174 rows=675 loops=1)
               Index Cond: ((t ~>=~ '12a'::text) AND (t ~<~ '12b'::text))
               Buffers: shared hit=9
 Planning Time: 1.144 ms
 Execution Time: 9.785 ms
(16 rows)

What do you think about it?

I think another application of OR-clause returning support function might be
allowing to use an index for NOT LIKE (!~~) expression  because, for example, 
"t !~~ '123foo%'" could be converted to "(t < '123foo' OR t >= '123fooz')". 
(The second condition is a bit loose but this would be safe and not problem
since tuples are filtered by the original condition after the index scan.) 
However, it would not very useful unless the distribution is much skew so that
NOT LIKE expression's selectivity is enough small.

Regards,
Yugo Nagata

-- 
Yugo Nagata <nag...@sraoss.co.jp>
>From 89912ca337d16ab44823f98dcabb3466557ac8ac Mon Sep 17 00:00:00 2001
From: Yugo Nagata <nag...@sraoss.co.jp>
Date: Thu, 19 Dec 2024 23:41:07 +0900
Subject: [PATCH 2/2] Allow ILIKE forward matching to use btree index

Previously, ILIKE could not use btree index if the pattern
has case-varying characters. To enable it, the planner
support function converts an ILINK operator expression to OR
clause that contains two index clauses for the upper letter and
the lower letter respectively.

For example, "t ILIKE '123foo%'" can be converted to
"(t <= '123F'AND t > '123G') OR (t <= '123f' AND t < '123g')",
and bitmap index scan plan could be used for this.
---
 src/backend/utils/adt/like_support.c          | 141 ++++++++++++++----
 src/test/regress/expected/btree_index.out     |  15 +-
 .../regress/expected/collate.icu.utf8.out     |  22 ++-
 src/test/regress/sql/collate.icu.utf8.sql     |   4 +-
 4 files changed, 137 insertions(+), 45 deletions(-)

diff --git a/src/backend/utils/adt/like_support.c b/src/backend/utils/adt/like_support.c
index ee71ca89ff..06cf4eb8d2 100644
--- a/src/backend/utils/adt/like_support.c
+++ b/src/backend/utils/adt/like_support.c
@@ -66,7 +66,10 @@ typedef enum
 
 typedef enum
 {
-	Pattern_Prefix_None, Pattern_Prefix_Partial, Pattern_Prefix_Exact,
+	Pattern_Prefix_None,
+	Pattern_Prefix_Partial,
+	Pattern_Prefix_Partial_IC,
+	Pattern_Prefix_Exact,
 } Pattern_Prefix_Status;
 
 static Node *like_regex_support(Node *rawreq, Pattern_Type ptype);
@@ -245,7 +248,7 @@ match_pattern_prefix(Node *leftop,
 					 Oid opfamily,
 					 Oid indexcollation)
 {
-	List	   *result;
+	List	   *result = NIL;
 	Const	   *patt;
 	Const	   *prefix;
 	Pattern_Prefix_Status pstatus;
@@ -259,6 +262,8 @@ match_pattern_prefix(Node *leftop,
 	Expr	   *expr;
 	FmgrInfo	ltproc;
 	Const	   *greaterstr;
+	List	   *prefixes;
+	ListCell   *lc;
 
 	/*
 	 * Can't do anything with a non-constant or NULL pattern argument.
@@ -434,35 +439,112 @@ match_pattern_prefix(Node *leftop,
 		return NIL;
 
 	/*
-	 * We can always say "x >= prefix".
+	 * If the pattern for case-insensiive matching has a case-varying
+	 * character, make two prefixes including the upper letter and the
+	 * lower letter respectively. For example, if the pattern is
+	 * '123foo%', we get '123F' and '123f' as prefixes.
 	 */
-	if (!op_in_opfamily(geopr, opfamily))
-		return NIL;
-	expr = make_opclause(geopr, BOOLOID, false,
-						 (Expr *) leftop, (Expr *) prefix,
-						 InvalidOid, indexcollation);
-	result = list_make1(expr);
-
-	/*-------
-	 * If we can create a string larger than the prefix, we can say
-	 * "x < greaterstr".  NB: we rely on make_greater_string() to generate
-	 * a guaranteed-greater string, not just a probably-greater string.
-	 * In general this is only guaranteed in C locale, so we'd better be
-	 * using a C-locale index collation.
-	 *-------
-	 */
-	if (!op_in_opfamily(ltopr, opfamily))
-		return result;
-	fmgr_info(get_opcode(ltopr), &ltproc);
-	greaterstr = make_greater_string(prefix, &ltproc, indexcollation);
-	if (greaterstr)
+	if (pstatus == Pattern_Prefix_Partial_IC)
+	{
+		int			prefix_len;
+		Datum		first_letter;
+		Datum		upper_letter;
+		Datum		lower_letter;
+		const char *prefix_l;
+		const char *prefix_u;
+
+		Assert(ptype == Pattern_Type_Like_IC);
+
+		/* get the first case-varying characketer in the pattern */
+		prefix_len = DatumGetInt32(DirectFunctionCall1Coll(textlen,
+														   indexcollation,
+														   prefix->constvalue));
+		first_letter = DirectFunctionCall3Coll(text_substr, indexcollation,
+											   patt->constvalue,
+											   Int32GetDatum(prefix_len + 1),
+											   Int32GetDatum(1));
+
+
+		/* prefix followed by the upper letter */
+		upper_letter = DirectFunctionCall1Coll(upper, indexcollation,
+											   first_letter);
+		prefix_u = TextDatumGetCString(DirectFunctionCall2Coll(textcat,
+															   indexcollation,
+															   prefix->constvalue,
+															   upper_letter));
+		prefixes = list_make1(string_to_const(prefix_u, prefix->consttype));
+
+		/* prefix followed by the lower letter */
+		lower_letter = DirectFunctionCall1Coll(lower, indexcollation,
+											   first_letter);
+		prefix_l = TextDatumGetCString(DirectFunctionCall2Coll(textcat,
+															   indexcollation,
+															   prefix->constvalue,
+															   lower_letter));
+		if (!DatumGetBool(DirectFunctionCall2Coll(texteq,
+										   indexcollation,
+										   CStringGetTextDatum(prefix_u),
+										   CStringGetTextDatum(prefix_l))))
+			prefixes = lappend(prefixes, string_to_const(prefix_l, prefix->consttype));
+	}
+	else
+		prefixes = list_make1(prefix);
+
+	foreach (lc, prefixes)
 	{
-		expr = make_opclause(ltopr, BOOLOID, false,
-							 (Expr *) leftop, (Expr *) greaterstr,
+		List  *clauses;
+
+		prefix = (Const *) lfirst(lc);
+
+		/*
+		 * We can always say "x >= prefix".
+		 */
+		if (!op_in_opfamily(geopr, opfamily))
+			return NIL;
+		expr = make_opclause(geopr, BOOLOID, false,
+							 (Expr *) leftop, (Expr *) prefix,
 							 InvalidOid, indexcollation);
-		result = lappend(result, expr);
+		clauses = list_make1(expr);
+
+		/*-------
+		 * If we can create a string larger than the prefix, we can say
+		 * "x < greaterstr".  NB: we rely on make_greater_string() to generate
+		 * a guaranteed-greater string, not just a probably-greater string.
+		 * In general this is only guaranteed in C locale, so we'd better be
+		 * using a C-locale index collation.
+		 *-------
+		 */
+		if (op_in_opfamily(ltopr, opfamily))
+		{
+			fmgr_info(get_opcode(ltopr), &ltproc);
+			greaterstr = make_greater_string(prefix, &ltproc, indexcollation);
+			if (greaterstr)
+			{
+				expr = make_opclause(ltopr, BOOLOID, false,
+									 (Expr *) leftop, (Expr *) greaterstr,
+									 InvalidOid, indexcollation);
+				clauses = lappend(clauses, expr);
+			}
+		}
+
+		/*
+		 * If case-insensitive pattern matching generated two clauses for
+		 * uppder and lower letters, convert them to explicit AND because
+		 * they will be under OR later.
+		 */
+		if (pstatus == Pattern_Prefix_Partial_IC && list_length(prefixes) > 1)
+			result = lappend(result, make_ands_explicit(clauses));
+		else
+			result = clauses;
 	}
 
+	/*
+	 * If case-insensitive pattern matching generated two clauses for upper and
+	 * lower letters, OR them.
+	 */
+	if (pstatus == Pattern_Prefix_Partial_IC && list_length(prefixes) > 1)
+		result = list_make1(make_orclause(result));
+
 	return result;
 }
 
@@ -997,6 +1079,7 @@ like_fixed_prefix(Const *patt_const, bool case_insensitive, Oid collation,
 				match_pos;
 	bool		is_multibyte = (pg_database_encoding_max_length() > 1);
 	pg_locale_t locale = 0;
+	bool		has_case_varying = false;
 
 	/* the right-hand const is type text or bytea */
 	Assert(typeid == BYTEAOID || typeid == TEXTOID);
@@ -1058,7 +1141,10 @@ like_fixed_prefix(Const *patt_const, bool case_insensitive, Oid collation,
 		/* Stop if case-varying character (it's sort of a wildcard) */
 		if (case_insensitive &&
 			pattern_char_isalpha(patt[pos], is_multibyte, locale))
+		{
+			has_case_varying = true;
 			break;
+		}
 
 		match[match_pos++] = patt[pos];
 	}
@@ -1077,6 +1163,9 @@ like_fixed_prefix(Const *patt_const, bool case_insensitive, Oid collation,
 	pfree(patt);
 	pfree(match);
 
+	if (case_insensitive && has_case_varying)
+		return Pattern_Prefix_Partial_IC;
+
 	/* in LIKE, an empty pattern is an exact match! */
 	if (pos == pattlen)
 		return Pattern_Prefix_Exact;	/* reached end of pattern, so exact */
diff --git a/src/test/regress/expected/btree_index.out b/src/test/regress/expected/btree_index.out
index def78ef858..244d6d999e 100644
--- a/src/test/regress/expected/btree_index.out
+++ b/src/test/regress/expected/btree_index.out
@@ -332,14 +332,19 @@ select proname from pg_proc where proname ilike '00%foo' order by 1;
 
 explain (costs off)
 select proname from pg_proc where proname ilike 'ri%foo' order by 1;
-                  QUERY PLAN                  
-----------------------------------------------
+                                                                                             QUERY PLAN                                                                                             
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Sort
    Sort Key: proname
-   ->  Seq Scan on pg_proc
-         Disabled: true
+   ->  Bitmap Heap Scan on pg_proc
+         Recheck Cond: (((proname >= 'R'::text) AND (proname < 'S'::text) AND (proname ~~* 'ri%foo'::text)) OR ((proname >= 'r'::text) AND (proname < 's'::text) AND (proname ~~* 'ri%foo'::text)))
          Filter: (proname ~~* 'ri%foo'::text)
-(5 rows)
+         ->  BitmapOr
+               ->  Bitmap Index Scan on pg_proc_proname_args_nsp_index
+                     Index Cond: ((proname >= 'R'::text) AND (proname < 'S'::text))
+               ->  Bitmap Index Scan on pg_proc_proname_args_nsp_index
+                     Index Cond: ((proname >= 'r'::text) AND (proname < 's'::text))
+(10 rows)
 
 reset enable_seqscan;
 reset enable_indexscan;
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index d4f327636f..f13f9e1245 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -988,14 +988,13 @@ SELECT relname, pg_get_indexdef(oid) FROM pg_class WHERE relname LIKE 'collate_t
 set enable_seqscan = off;
 explain (costs off)
 select * from collate_test1 where b ilike 'abc';
-          QUERY PLAN           
--------------------------------
- Seq Scan on collate_test1
-   Disabled: true
+                      QUERY PLAN                      
+------------------------------------------------------
+ Index Scan using collate_test1_idx3 on collate_test1
    Filter: (b ~~* 'abc'::text)
-(3 rows)
+(2 rows)
 
-select * from collate_test1 where b ilike 'abc';
+select * from collate_test1 where b ilike 'abc' order by 1;
  a |  b  
 ---+-----
  1 | abc
@@ -1004,14 +1003,13 @@ select * from collate_test1 where b ilike 'abc';
 
 explain (costs off)
 select * from collate_test1 where b ilike 'ABC';
-          QUERY PLAN           
--------------------------------
- Seq Scan on collate_test1
-   Disabled: true
+                      QUERY PLAN                      
+------------------------------------------------------
+ Index Scan using collate_test1_idx3 on collate_test1
    Filter: (b ~~* 'ABC'::text)
-(3 rows)
+(2 rows)
 
-select * from collate_test1 where b ilike 'ABC';
+select * from collate_test1 where b ilike 'ABC' order by 1;
  a |  b  
 ---+-----
  1 | abc
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 5ee2da4e0e..948201c3e1 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -344,10 +344,10 @@ SELECT relname, pg_get_indexdef(oid) FROM pg_class WHERE relname LIKE 'collate_t
 set enable_seqscan = off;
 explain (costs off)
 select * from collate_test1 where b ilike 'abc';
-select * from collate_test1 where b ilike 'abc';
+select * from collate_test1 where b ilike 'abc' order by 1;
 explain (costs off)
 select * from collate_test1 where b ilike 'ABC';
-select * from collate_test1 where b ilike 'ABC';
+select * from collate_test1 where b ilike 'ABC' order by 1;
 reset enable_seqscan;
 
 
-- 
2.34.1

>From 1732b4fce53cb72445dd19bf61cb97c0c12b417c Mon Sep 17 00:00:00 2001
From: Yugo Nagata <nag...@sraoss.co.jp>
Date: Wed, 18 Dec 2024 12:04:55 +0900
Subject: [PATCH 1/2] Allow planner support function to return index conditions
 in OR clause

Previously,  as a response to SupportRequestIndexCondition, planner
support functions could return only directly indexable condition but
not multiple index conditions formed in OR clause. To increase the
opportunity to use index in support function uses, this commit enables
get_index_clause_from_support receive OR clauses from support functions,
and use them to build bitmap index scan later
---
 src/backend/optimizer/path/indxpath.c | 118 ++++++++++++++++++--------
 1 file changed, 83 insertions(+), 35 deletions(-)

diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
index 5d102a0d37..cc27f678ab 100644
--- a/src/backend/optimizer/path/indxpath.c
+++ b/src/backend/optimizer/path/indxpath.c
@@ -134,7 +134,8 @@ static double adjust_rowcount_for_semijoins(PlannerInfo *root,
 static double approximate_joinrel_size(PlannerInfo *root, Relids relids);
 static void match_restriction_clauses_to_index(PlannerInfo *root,
 											   IndexOptInfo *index,
-											   IndexClauseSet *clauseset);
+											   IndexClauseSet *clauseset,
+											   List **orclauses);
 static void match_join_clauses_to_index(PlannerInfo *root,
 										RelOptInfo *rel, IndexOptInfo *index,
 										IndexClauseSet *clauseset,
@@ -145,15 +146,18 @@ static void match_eclass_clauses_to_index(PlannerInfo *root,
 static void match_clauses_to_index(PlannerInfo *root,
 								   List *clauses,
 								   IndexOptInfo *index,
-								   IndexClauseSet *clauseset);
+								   IndexClauseSet *clauseset,
+								   List **orclauses);
 static void match_clause_to_index(PlannerInfo *root,
 								  RestrictInfo *rinfo,
 								  IndexOptInfo *index,
-								  IndexClauseSet *clauseset);
+								  IndexClauseSet *clauseset,
+								  List **orclauses);
 static IndexClause *match_clause_to_indexcol(PlannerInfo *root,
 											 RestrictInfo *rinfo,
 											 int indexcol,
-											 IndexOptInfo *index);
+											 IndexOptInfo *index,
+											 List **orclauses);
 static bool IsBooleanOpfamily(Oid opfamily);
 static IndexClause *match_boolean_index_clause(PlannerInfo *root,
 											   RestrictInfo *rinfo,
@@ -161,17 +165,20 @@ static IndexClause *match_boolean_index_clause(PlannerInfo *root,
 static IndexClause *match_opclause_to_indexcol(PlannerInfo *root,
 											   RestrictInfo *rinfo,
 											   int indexcol,
-											   IndexOptInfo *index);
+											   IndexOptInfo *index,
+											   List **orclauses);
 static IndexClause *match_funcclause_to_indexcol(PlannerInfo *root,
 												 RestrictInfo *rinfo,
 												 int indexcol,
-												 IndexOptInfo *index);
+												 IndexOptInfo *index,
+												 List **orclauses);
 static IndexClause *get_index_clause_from_support(PlannerInfo *root,
 												  RestrictInfo *rinfo,
 												  Oid funcid,
 												  int indexarg,
 												  int indexcol,
-												  IndexOptInfo *index);
+												  IndexOptInfo *index,
+												  List* *orclauses);
 static IndexClause *match_saopclause_to_indexcol(PlannerInfo *root,
 												 RestrictInfo *rinfo,
 												 int indexcol,
@@ -244,6 +251,7 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
 	List	   *bitindexpaths;
 	List	   *bitjoinpaths;
 	List	   *joinorclauses;
+	List	   *orclauses;
 	IndexClauseSet rclauseset;
 	IndexClauseSet jclauseset;
 	IndexClauseSet eclauseset;
@@ -254,7 +262,7 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
 		return;
 
 	/* Bitmap paths are collected and then dealt with at the end */
-	bitindexpaths = bitjoinpaths = joinorclauses = NIL;
+	bitindexpaths = bitjoinpaths = joinorclauses = orclauses = NIL;
 
 	/* Examine each index in turn */
 	foreach(lc, rel->indexlist)
@@ -274,9 +282,11 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
 
 		/*
 		 * Identify the restriction clauses that can match the index.
+		 * Also, collect OR clauses returnd by support functions for later.
 		 */
 		MemSet(&rclauseset, 0, sizeof(rclauseset));
-		match_restriction_clauses_to_index(root, index, &rclauseset);
+		match_restriction_clauses_to_index(root, index,
+										   &rclauseset, &orclauses);
 
 		/*
 		 * Build index paths from the restriction clauses.  These will be
@@ -321,7 +331,7 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
 	 * restriction list.  Add these to bitindexpaths.
 	 */
 	indexpaths = generate_bitmap_or_paths(root, rel,
-										  rel->baserestrictinfo, NIL);
+										  rel->baserestrictinfo, NULL);
 	bitindexpaths = list_concat(bitindexpaths, indexpaths);
 
 	/*
@@ -332,6 +342,14 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
 										  joinorclauses, rel->baserestrictinfo);
 	bitjoinpaths = list_concat(bitjoinpaths, indexpaths);
 
+	/*
+	 * Likewise, generate BitmapOrPaths for any suitable OR-clauses present in
+	 * the orclauses returned by a support function.  Add these to bitjoinpaths.
+	 */
+	indexpaths = generate_bitmap_or_paths(root, rel,
+										  orclauses, rel->baserestrictinfo);
+	bitjoinpaths = list_concat(bitjoinpaths, indexpaths);
+
 	/*
 	 * If we found anything usable, generate a BitmapHeapPath for the most
 	 * promising combination of restriction bitmap index paths.  Note there
@@ -1145,7 +1163,7 @@ build_paths_for_OR(PlannerInfo *root, RelOptInfo *rel,
 		 * Identify the restriction clauses that can match the index.
 		 */
 		MemSet(&clauseset, 0, sizeof(clauseset));
-		match_clauses_to_index(root, clauses, index, &clauseset);
+		match_clauses_to_index(root, clauses, index, &clauseset, NULL);
 
 		/*
 		 * If no matches so far, and the index predicate isn't useful, we
@@ -1157,7 +1175,7 @@ build_paths_for_OR(PlannerInfo *root, RelOptInfo *rel,
 		/*
 		 * Add "other" restriction clauses to the clauseset.
 		 */
-		match_clauses_to_index(root, other_clauses, index, &clauseset);
+		match_clauses_to_index(root, other_clauses, index, &clauseset, NULL);
 
 		/*
 		 * Construct paths if possible.
@@ -2398,15 +2416,18 @@ approximate_joinrel_size(PlannerInfo *root, Relids relids)
 /*
  * match_restriction_clauses_to_index
  *	  Identify restriction clauses for the rel that match the index.
- *	  Matching clauses are added to *clauseset.
+ *	  Matching clauses are added to *clauseset. Also, OR clauses
+ *	  returned by support functions are collected in orclauses.
  */
 static void
 match_restriction_clauses_to_index(PlannerInfo *root,
 								   IndexOptInfo *index,
-								   IndexClauseSet *clauseset)
+								   IndexClauseSet *clauseset,
+								   List **orclauses)
 {
 	/* We can ignore clauses that are implied by the index predicate */
-	match_clauses_to_index(root, index->indrestrictinfo, index, clauseset);
+	match_clauses_to_index(root, index->indrestrictinfo, index,
+						   clauseset, orclauses);
 }
 
 /*
@@ -2436,7 +2457,7 @@ match_join_clauses_to_index(PlannerInfo *root,
 		if (restriction_is_or_clause(rinfo))
 			*joinorclauses = lappend(*joinorclauses, rinfo);
 		else
-			match_clause_to_index(root, rinfo, index, clauseset);
+			match_clause_to_index(root, rinfo, index, clauseset, NULL);
 	}
 }
 
@@ -2474,20 +2495,21 @@ match_eclass_clauses_to_index(PlannerInfo *root, IndexOptInfo *index,
 		 * since for non-btree indexes the EC's equality operators might not
 		 * be in the index opclass (cf ec_member_matches_indexcol).
 		 */
-		match_clauses_to_index(root, clauses, index, clauseset);
+		match_clauses_to_index(root, clauses, index, clauseset, NULL);
 	}
 }
 
 /*
  * match_clauses_to_index
  *	  Perform match_clause_to_index() for each clause in a list.
- *	  Matching clauses are added to *clauseset.
+ *	  Matching clauses are added to *clauseset. Also, OR clauses
+ *	  returned by support functions are collected in orclauses.
  */
 static void
 match_clauses_to_index(PlannerInfo *root,
 					   List *clauses,
 					   IndexOptInfo *index,
-					   IndexClauseSet *clauseset)
+					   IndexClauseSet *clauseset, List **orclauses)
 {
 	ListCell   *lc;
 
@@ -2495,7 +2517,7 @@ match_clauses_to_index(PlannerInfo *root,
 	{
 		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
 
-		match_clause_to_index(root, rinfo, index, clauseset);
+		match_clause_to_index(root, rinfo, index, clauseset, orclauses);
 	}
 }
 
@@ -2505,7 +2527,8 @@ match_clauses_to_index(PlannerInfo *root,
  *
  * If the clause is usable, add an IndexClause entry for it to the appropriate
  * list in *clauseset.  (*clauseset must be initialized to zeroes before first
- * call.)
+ * call.) Also, OR clauses returned by support functions are collected in
+ * orclauses.
  *
  * Note: in some circumstances we may find the same RestrictInfos coming from
  * multiple places.  Defend against redundant outputs by refusing to add a
@@ -2520,7 +2543,8 @@ static void
 match_clause_to_index(PlannerInfo *root,
 					  RestrictInfo *rinfo,
 					  IndexOptInfo *index,
-					  IndexClauseSet *clauseset)
+					  IndexClauseSet *clauseset,
+					  List **orclauses)
 {
 	int			indexcol;
 
@@ -2559,7 +2583,8 @@ match_clause_to_index(PlannerInfo *root,
 		iclause = match_clause_to_indexcol(root,
 										   rinfo,
 										   indexcol,
-										   index);
+										   index,
+										   orclauses);
 		if (iclause)
 		{
 			/* Success, so record it */
@@ -2635,6 +2660,7 @@ match_clause_to_index(PlannerInfo *root,
  * 'rinfo' is the clause to be tested (as a RestrictInfo node).
  * 'indexcol' is a column number of 'index' (counting from 0).
  * 'index' is the index of interest.
+ * 'orclauses" stores OR clauses returned by planner support functions.
  *
  * Returns an IndexClause if the clause can be used with this index key,
  * or NULL if not.
@@ -2646,7 +2672,8 @@ static IndexClause *
 match_clause_to_indexcol(PlannerInfo *root,
 						 RestrictInfo *rinfo,
 						 int indexcol,
-						 IndexOptInfo *index)
+						 IndexOptInfo *index,
+						 List **orclauses)
 {
 	IndexClause *iclause;
 	Expr	   *clause = rinfo->clause;
@@ -2677,11 +2704,13 @@ match_clause_to_indexcol(PlannerInfo *root,
 	 */
 	if (IsA(clause, OpExpr))
 	{
-		return match_opclause_to_indexcol(root, rinfo, indexcol, index);
+		return match_opclause_to_indexcol(root, rinfo, indexcol, index,
+										  orclauses);
 	}
 	else if (IsA(clause, FuncExpr))
 	{
-		return match_funcclause_to_indexcol(root, rinfo, indexcol, index);
+		return match_funcclause_to_indexcol(root, rinfo, indexcol, index,
+											orclauses);
 	}
 	else if (IsA(clause, ScalarArrayOpExpr))
 	{
@@ -2839,7 +2868,8 @@ static IndexClause *
 match_opclause_to_indexcol(PlannerInfo *root,
 						   RestrictInfo *rinfo,
 						   int indexcol,
-						   IndexOptInfo *index)
+						   IndexOptInfo *index,
+						   List **orclauses)
 {
 	IndexClause *iclause;
 	OpExpr	   *clause = (OpExpr *) rinfo->clause;
@@ -2895,7 +2925,8 @@ match_opclause_to_indexcol(PlannerInfo *root,
 
 		/*
 		 * If we didn't find a member of the index's opfamily, try the support
-		 * function for the operator's underlying function.
+		 * function for the operator's underlying function. OR clauses returned
+		 * by the support function are collected in orclauses.
 		 */
 		set_opfuncid(clause);	/* make sure we have opfuncid */
 		return get_index_clause_from_support(root,
@@ -2903,7 +2934,8 @@ match_opclause_to_indexcol(PlannerInfo *root,
 											 clause->opfuncid,
 											 0, /* indexarg on left */
 											 indexcol,
-											 index);
+											 index,
+											 orclauses);
 	}
 
 	if (match_index_to_operand(rightop, indexcol, index) &&
@@ -2935,7 +2967,8 @@ match_opclause_to_indexcol(PlannerInfo *root,
 
 		/*
 		 * If we didn't find a member of the index's opfamily, try the support
-		 * function for the operator's underlying function.
+		 * function for the operator's underlying function. OR clauses returned
+		 * by the support function are collected in orclauses.
 		 */
 		set_opfuncid(clause);	/* make sure we have opfuncid */
 		return get_index_clause_from_support(root,
@@ -2943,7 +2976,8 @@ match_opclause_to_indexcol(PlannerInfo *root,
 											 clause->opfuncid,
 											 1, /* indexarg on right */
 											 indexcol,
-											 index);
+											 index,
+											 orclauses);
 	}
 
 	return NULL;
@@ -2958,7 +2992,8 @@ static IndexClause *
 match_funcclause_to_indexcol(PlannerInfo *root,
 							 RestrictInfo *rinfo,
 							 int indexcol,
-							 IndexOptInfo *index)
+							 IndexOptInfo *index,
+							 List **orclauses)
 {
 	FuncExpr   *clause = (FuncExpr *) rinfo->clause;
 	int			indexarg;
@@ -2968,7 +3003,8 @@ match_funcclause_to_indexcol(PlannerInfo *root,
 	 * We have no built-in intelligence about function clauses, but if there's
 	 * a planner support function, it might be able to do something.  But, to
 	 * cut down on wasted planning cycles, only call the support function if
-	 * at least one argument matches the target index column.
+	 * at least one argument matches the target index column. Also, OR clauses
+	 * returned by the support function are collected in orclauses.
 	 *
 	 * Note that we don't insist on the other arguments being pseudoconstants;
 	 * the support function has to check that.  This is to allow cases where
@@ -2986,7 +3022,8 @@ match_funcclause_to_indexcol(PlannerInfo *root,
 												 clause->funcid,
 												 indexarg,
 												 indexcol,
-												 index);
+												 index,
+												 orclauses);
 		}
 
 		indexarg++;
@@ -2999,6 +3036,8 @@ match_funcclause_to_indexcol(PlannerInfo *root,
  * get_index_clause_from_support()
  *		If the function has a planner support function, try to construct
  *		an IndexClause using indexquals created by the support function.
+ *		If the support function returns OR clauses, collect them into
+ *		orclauses for bitmap scans.
  */
 static IndexClause *
 get_index_clause_from_support(PlannerInfo *root,
@@ -3006,7 +3045,8 @@ get_index_clause_from_support(PlannerInfo *root,
 							  Oid funcid,
 							  int indexarg,
 							  int indexcol,
-							  IndexOptInfo *index)
+							  IndexOptInfo *index,
+							  List **orclauses)
 {
 	Oid			prosupport = get_func_support(funcid);
 	SupportRequestIndexCondition req;
@@ -3045,6 +3085,14 @@ get_index_clause_from_support(PlannerInfo *root,
 		{
 			Expr	   *clause = (Expr *) lfirst(lc);
 
+			if (is_orclause(clause))
+			{
+				if (orclauses)
+					*orclauses = lappend(*orclauses,
+										 make_simple_restrictinfo(root, clause));
+				continue;
+			}
+
 			indexquals = lappend(indexquals,
 								 make_simple_restrictinfo(root, clause));
 		}
-- 
2.34.1

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