Merge #39294

39294: exec: fix output batches of LEFT SEMI for hash and merge joiners r=yuzefovich a=yuzefovich

Previously, the merge joiner's output batch would always have the
columns corresponding to both the left and the right sides (even
with LEFT SEMI and LEFT ANTI join types although the right side
output would not be used). This is incorrect, and now the merge
joiner outputs batches with the correct number of columns.

A similar issue was present with LEFT SEMI hash joiner and is now
fixed.

Release note: None

Co-authored-by: Yahor Yuzefovich <[email protected]>

pkg/sql/exec/hashjoiner.go

@@ -750,10 +750,21 @@ func makeHashJoinProber(
 	var outColTypes []coltypes.T
 	var buildColOffset, probeColOffset uint32
 	if buildRightSide {
-		outColTypes = append(probe.sourceTypes, build.sourceTypes...)
+		if len(build.outCols) == 0 {
+			// We do not have output columns from the right side in case of LEFT SEMI
+			// and LEFT ANTI joins, and we should not have the corresponding columns
+			// in the output batch, so we only have the types from the left side in
+			// outColTypes.
+			outColTypes = probe.sourceTypes
+		} else {
+			outColTypes = append(probe.sourceTypes, build.sourceTypes...)
+		}
 		buildColOffset = uint32(len(probe.sourceTypes))
 		probeColOffset = 0
 	} else {
+		// Note that we don't need to check whether probe.outCols is non-empty
+		// before populating outColTypes because LEFT SEMI and LEFT ANTI joins will
+		// always build the right side.
 		outColTypes = append(build.sourceTypes, probe.sourceTypes...)
 		buildColOffset = 0
 		probeColOffset = nBuildCols

pkg/sql/exec/mergejoiner.go

@@ -330,7 +330,15 @@ func (o *mergeJoinBase) Init() {
 func (o *mergeJoinBase) initWithBatchSize(outBatchSize uint16) {
 	outColTypes := make([]coltypes.T, len(o.left.sourceTypes)+len(o.right.sourceTypes))
 	copy(outColTypes, o.left.sourceTypes)
-	copy(outColTypes[len(o.left.sourceTypes):], o.right.sourceTypes)
+	if len(o.right.outCols) == 0 {
+		// We do not have output columns from the right input in case of LEFT SEMI
+		// and LEFT ANTI joins, and we should not have the corresponding columns in
+		// the output batch, so we only have the types from the left input in
+		// outColTypes.
+		outColTypes = outColTypes[:len(o.left.sourceTypes)]
+	} else {
+		copy(outColTypes[len(o.left.sourceTypes):], o.right.sourceTypes)
+	}
 
 	o.output = coldata.NewMemBatchWithSize(outColTypes, int(outBatchSize))
 	o.left.source.Init()

pkg/sql/logictest/testdata/logic_test/exec_hash_join_dist

@@ -0,0 +1,30 @@
+# LogicTest: 5node-dist-vec
+
+statement ok
+CREATE TABLE t (k INT, v INT)
+
+statement ok
+INSERT INTO t VALUES (1, 10), (2, 20), (3, 30)
+
+statement ok
+ALTER TABLE t EXPERIMENTAL_RELOCATE VALUES (ARRAY[3], 1)
+
+statement ok
+CREATE TABLE xy (x INT PRIMARY KEY, y INT)
+
+statement ok
+INSERT INTO xy VALUES (2, 200), (3, 300), (4, 400)
+
+statement ok
+ALTER TABLE t SPLIT AT VALUES (3), (4)
+
+statement ok
+ALTER TABLE t EXPERIMENTAL_RELOCATE VALUES (ARRAY[1], 2), (ARRAY[2], 3), (ARRAY[3], 4)
+
+# Test that LEFT SEMI hash join outputs batches only with the columns from the
+# left side.
+query II rowsort
+SELECT * FROM t WHERE EXISTS(SELECT * FROM xy WHERE x=t.k)
+----
+2  20
+3  30

pkg/sql/logictest/testdata/logic_test/exec_merge_join_dist

@@ -3,50 +3,59 @@
 # Regression test for #39317.
 
 statement ok
-CREATE TABLE l (a INT PRIMARY KEY)
+CREATE TABLE l (a INT PRIMARY KEY, b INT)
 
 statement ok
-CREATE TABLE r (a INT PRIMARY KEY)
+CREATE TABLE r (a INT PRIMARY KEY, b INT)
 
 statement ok
-INSERT INTO l VALUES (1), (2)
+INSERT INTO l VALUES (1, 10), (2, 20), (3, 30)
 
 statement ok
-INSERT INTO r VALUES (2), (3)
+INSERT INTO r VALUES (2, 200), (3, 300), (4, 400)
 
 statement ok
-ALTER TABLE l SPLIT AT VALUES (2)
+ALTER TABLE l SPLIT AT VALUES (2), (3)
 
 statement ok
-ALTER TABLE r SPLIT AT VALUES (2)
+ALTER TABLE r SPLIT AT VALUES (2), (3)
 
 statement ok
-ALTER TABLE l EXPERIMENTAL_RELOCATE VALUES (ARRAY[1], 1), (ARRAY[2], 2)
+ALTER TABLE l EXPERIMENTAL_RELOCATE VALUES (ARRAY[1], 1), (ARRAY[2], 2), (ARRAY[3], 3)
 
 statement ok
-ALTER TABLE r EXPERIMENTAL_RELOCATE VALUES (ARRAY[1], 2), (ARRAY[2], 1)
+ALTER TABLE r EXPERIMENTAL_RELOCATE VALUES (ARRAY[1], 2), (ARRAY[2], 3), (ARRAY[3], 1)
 
 query TTTI colnames
-SELECT start_key, end_key, replicas, lease_holder from [SHOW EXPERIMENTAL_RANGES FROM TABLE l]
+SELECT start_key, end_key, replicas, lease_holder from [SHOW EXPERIMENTAL_RANGES FROM TABLE l] ORDER BY lease_holder
 ----
 start_key  end_key  replicas  lease_holder
 NULL       /2       {1}       1
-/2         NULL     {2}       2
+/2         /3       {2}       2
+/3         NULL     {3}       3
 
 query TTTI colnames
-SELECT start_key, end_key, replicas, lease_holder from [SHOW EXPERIMENTAL_RANGES FROM TABLE r]
+SELECT start_key, end_key, replicas, lease_holder from [SHOW EXPERIMENTAL_RANGES FROM TABLE r] ORDER BY lease_holder
 ----
 start_key  end_key  replicas  lease_holder
-/2         NULL     {1}       1
-NULL       /2       {2}       2
+/2         /3       {1}       1
+/3         NULL     {2}       2
+NULL       /2       {3}       3
 
 query T
 SELECT url FROM [EXPLAIN (DISTSQL) SELECT * FROM l LEFT OUTER JOIN r USING(a) WHERE a = 2]
 ----
-https://cockroachdb.github.io/distsqlplan/decode.html#eJzEk09rgzAYxu_7FPLusrEUjXWXwKCXDlq2Ojp3Gh5S884K1kgSYaX43Yc6aHXWtWxsN_Pn97zPkwd3kEmBC75BDewVKBBwISSQKxmh1lJV282lmXgH5hBIsrww1XZIIJIKge3AJCZFYBDwVYpL5AKVXWkJNDxJa-lcJRuuthMFBJ5znmlm2e7Idu1LCEsCsjCfsnu11dZac71u60wohGVIQBseIzC3JEfs7XWKTCqBCkVLKazI7670ZHxEFeNcJhkqe9z2FmxzZNbD9D6w_JdgurTm_mwBBFJ8M1cTenN9p5J43XwCAb8wzKrzHObfZxv_IFuP8YUcydz2uo_QO9prjaant-70t57-buv0qL2_aN39p9Z7bC1R5zLTeFKpThUMRYzNQ2lZqAiflIzqMc3Sr7n6TQVq05x6zWKW1Uf1L3c6TIdh2oWdQ9htwbQLu4PwbQt2uvD4jMxfJg_DdBj2zsoclhcfAQAA___49Nlj
+https://cockroachdb.github.io/distsqlplan/decode.html#eJzEk8Fro0AUxu_7V8jbyy47QWfiXgYWvGQhYTeW1J6Kh4nzagTjyMwIDcH_vaiFVGtsQkt7c2be73vvex8eoVAS12KPBvg9UCDAICZQapWgMUo3113RUj4C9whkRVnZ5jomkCiNwI9gM5sjcIjENscNConabbQkWpHlrXSps73Qh0ADgdtSFIY7Lpu5zP0OcU1AVfZZ9qS2PTg7YXZ9nYBCXMcEjBUpAmc1OTPeSacqlJaoUfaU4oZ8q2TE43_UKa5UVqB25_3ZokOJ3Pm3-Bs54V202DircLkGAjk-2B8B_fXzj87SXfcJBMLKciegJGAk8AdbODmcv8PhyPhrNVOl6w9XMdra77Wml2fvjWeff2z29Ox4n5E9-9LsR4bboClVYfCiaL3GHsoUu3UZVekEb7RK2jbdMWy5drMSje1e_e6wLNqn9ve7HKbTMB3C3kuY9WA6hNkk_LsHe0N4foXnV52nYToN-1d5jutvTwEAAP__eVLb3w==
 
-query I
+query III
 SELECT * FROM l LEFT OUTER JOIN r USING(a) WHERE a = 2
 ----
-2
+2 20 200
 
+# Test that LEFT SEMI merge join outputs batches only with the columns from the
+# left side.
+query II rowsort
+SELECT * FROM l WHERE EXISTS(SELECT * FROM r WHERE r.a=l.a)
+----
+2  20
+3  30