Fix compressed DML with constraints of form value OP column

UPDATE/DELETE operations with constraints where the column is on the
right side of the expression and the value on the left side e.g.
'a' > column were not handled correctly when operating on compressed chunks.

.unreleased/pr_6869

@@ -0,0 +1 @@
+Fixes: #6869 Fix compressed DML with constraints of form value OP column

tsl/src/compression/compression.c

@@ -2553,6 +2553,7 @@ fill_predicate_context(Chunk *ch, CompressionSettings *settings, List *predicate
 			case T_OpExpr:
 			{
 				OpExpr *opexpr = (OpExpr *) node;
+				Oid opno = opexpr->opno;
 				RegProcedure opcode = opexpr->opfuncid;
 				Oid collation = opexpr->inputcollid;
 				Expr *leftop, *rightop;
@@ -2575,6 +2576,12 @@ fill_predicate_context(Chunk *ch, CompressionSettings *settings, List *predicate
 				{
 					var = (Var *) rightop;
 					arg_value = (Const *) leftop;
+					opno = get_commutator(opno);
+					if (!OidIsValid(opno))
+						continue;
+					opcode = get_opcode(opno);
+					if (!OidIsValid(opcode))
+						continue;
 				}
 				else
 					continue;
@@ -2584,7 +2591,7 @@ fill_predicate_context(Chunk *ch, CompressionSettings *settings, List *predicate
 					continue;
 				column_name = get_attname(ch->table_id, var->varattno, false);
 				TypeCacheEntry *tce = lookup_type_cache(var->vartype, TYPECACHE_BTREE_OPFAMILY);
-				int op_strategy = get_op_opfamily_strategy(opexpr->opno, tce->btree_opf);
+				int op_strategy = get_op_opfamily_strategy(opno, tce->btree_opf);
 				if (ts_array_is_member(settings->fd.segmentby, column_name))
 				{
 					switch (op_strategy)

tsl/test/expected/compression_update_delete.out

@@ -2944,3 +2944,58 @@ EXPLAIN (analyze, timing off, costs off, summary off) DELETE FROM test_meta_filt
                Rows Removed by Filter: 10
 (8 rows)
 
+-- test commutator handling in compressed dml constraints
+CREATE TABLE test_commutator(time timestamptz NOT NULL, device text);
+SELECT table_name FROM create_hypertable('test_commutator', 'time');
+   table_name    
+-----------------
+ test_commutator
+(1 row)
+
+INSERT INTO test_commutator SELECT '2020-01-01', 'a';
+INSERT INTO test_commutator SELECT '2020-01-01', 'b';
+INSERT INTO test_commutator SELECT '2020-01-01', 'c';
+ALTER TABLE test_commutator SET (timescaledb.compress, timescaledb.compress_segmentby='device');
+NOTICE:  default order by for hypertable "test_commutator" is set to ""time" DESC"
+SELECT compress_chunk(show_chunks('test_commutator'));
+              compress_chunk              
+------------------------------------------
+ _timescaledb_internal._hyper_39_79_chunk
+(1 row)
+
+BEGIN; EXPLAIN (costs off, timing off, summary off, analyze) DELETE FROM test_commutator WHERE 'a' = device; ROLLBACK;
+                                      QUERY PLAN                                      
+--------------------------------------------------------------------------------------
+ Custom Scan (HypertableModify) (actual rows=0 loops=1)
+   Batches decompressed: 1
+   Tuples decompressed: 1
+   ->  Delete on test_commutator (actual rows=0 loops=1)
+         Delete on _hyper_39_79_chunk test_commutator_1
+         ->  Seq Scan on _hyper_39_79_chunk test_commutator_1 (actual rows=1 loops=1)
+               Filter: ('a'::text = device)
+(7 rows)
+
+BEGIN; EXPLAIN (costs off, timing off, summary off, analyze) DELETE FROM test_commutator WHERE 'c' > device; ROLLBACK;
+                                      QUERY PLAN                                      
+--------------------------------------------------------------------------------------
+ Custom Scan (HypertableModify) (actual rows=0 loops=1)
+   Batches decompressed: 2
+   Tuples decompressed: 2
+   ->  Delete on test_commutator (actual rows=0 loops=1)
+         Delete on _hyper_39_79_chunk test_commutator_1
+         ->  Seq Scan on _hyper_39_79_chunk test_commutator_1 (actual rows=2 loops=1)
+               Filter: ('c'::text > device)
+(7 rows)
+
+BEGIN; EXPLAIN (costs off, timing off, summary off, analyze) DELETE FROM test_commutator WHERE 'b' < device; ROLLBACK;
+                                      QUERY PLAN                                      
+--------------------------------------------------------------------------------------
+ Custom Scan (HypertableModify) (actual rows=0 loops=1)
+   Batches decompressed: 1
+   Tuples decompressed: 1
+   ->  Delete on test_commutator (actual rows=0 loops=1)
+         Delete on _hyper_39_79_chunk test_commutator_1
+         ->  Seq Scan on _hyper_39_79_chunk test_commutator_1 (actual rows=1 loops=1)
+               Filter: ('b'::text < device)
+(7 rows)
+

tsl/test/sql/compression_update_delete.sql

@@ -1493,3 +1493,17 @@ SELECT compress_chunk(show_chunks('test_meta_filters'));
 
 EXPLAIN (analyze, timing off, costs off, summary off) DELETE FROM test_meta_filters WHERE device = 'd1' AND metric = 'm1' AND v1 < 100;
 
+-- test commutator handling in compressed dml constraints
+CREATE TABLE test_commutator(time timestamptz NOT NULL, device text);
+SELECT table_name FROM create_hypertable('test_commutator', 'time');
+INSERT INTO test_commutator SELECT '2020-01-01', 'a';
+INSERT INTO test_commutator SELECT '2020-01-01', 'b';
+INSERT INTO test_commutator SELECT '2020-01-01', 'c';
+
+ALTER TABLE test_commutator SET (timescaledb.compress, timescaledb.compress_segmentby='device');
+SELECT compress_chunk(show_chunks('test_commutator'));
+
+BEGIN; EXPLAIN (costs off, timing off, summary off, analyze) DELETE FROM test_commutator WHERE 'a' = device; ROLLBACK;
+BEGIN; EXPLAIN (costs off, timing off, summary off, analyze) DELETE FROM test_commutator WHERE 'c' > device; ROLLBACK;
+BEGIN; EXPLAIN (costs off, timing off, summary off, analyze) DELETE FROM test_commutator WHERE 'b' < device; ROLLBACK;
+