opt: do not generate unnecessary cross-joins on lookup join input

This commit fixes a bug that caused unnecessary cross-joins on the input
of lookup joins, causing both suboptimal query plans and incorrect query
results. The bug only affected lookup joins with lookup expressions.

Fixes #79384

Release note (bug fix): A bug has been fixed that caused the optimizer
to generate query plans with logically incorrect lookup joins. The bug
can only occur in queries with an inner join, e.g., `t1 JOIN t2`, if all
of the following are true:
  1. The join contains an equality condition between columns of both
     tables, e.g., `t1.a = t2.a`.
  2. A query filter or `CHECK` constraint constrains a column to a set
     of specific values, e.g., `t2.b IN (1, 2, 3)`. In the case of a
     `CHECK` constraint, the column must be `NOT NULL`.
  3. A query filter or `CHECK` constraint constrains a column to a
     range, e.g., `t2.c > 0`. In the case of a `CHECK` constraint, the
     column must be `NOT NULL`.
  4. An index contains a column from each of the criteria above, e.g.,
     `INDEX t2(a, b, c)`.
This bug has been present since version 21.2.0.

pkg/sql/logictest/testdata/logic_test/lookup_join

@@ -665,3 +665,31 @@ SELECT * FROM (VALUES (1, 10), (2, 20), (3, NULL)) AS u(w, x) WHERE NOT EXISTS (
 )
 ----
 3  NULL
+
+# Regression test for #79384. Do not generate unnecessary cross-joins on a
+# lookup join's input when the lookup join uses a lookup expression.
+statement ok
+CREATE TABLE t79384a (
+  k INT NOT NULL
+)
+
+statement ok
+CREATE TABLE t79384b (
+  a INT,
+  b INT,
+  c INT,
+  INDEX (a, b, c)
+)
+
+statement ok
+INSERT INTO t79384a VALUES (1)
+
+statement ok
+INSERT INTO t79384b VALUES (1, 1, 1)
+
+# The joined tables have a single row each, so this query should never return
+# more than one row.
+query I
+SELECT k FROM t79384a INNER LOOKUP JOIN t79384b ON k = a AND b IN (1, 2, 3) AND c > 0
+----
+1

pkg/sql/opt/exec/execbuilder/testdata/inner-join

@@ -248,4 +248,3 @@ vectorized: true
               missing stats
               table: def@def_pkey
               spans: FULL SCAN
-

pkg/sql/opt/exec/execbuilder/testdata/lookup_join_spans

@@ -837,16 +837,14 @@ vectorized: true
         │ equality cols are key
         │
         └── • lookup join
+            │ estimated row count: 0
             │ table: metric_values@secondary
             │ lookup condition: ((metric_id = id) AND (nullable = 1)) AND ("time" < '2020-01-01 00:00:10+00:00')
             │
-            └── • render
-                │ estimated row count: 1
-                │
-                └── • scan
-                      estimated row count: 1 (10% of the table; stats collected <hidden> ago)
-                      table: metrics@name_index
-                      spans: [/'cpu' - /'cpu']
+            └── • scan
+                  estimated row count: 1 (10% of the table; stats collected <hidden> ago)
+                  table: metrics@name_index
+                  spans: [/'cpu' - /'cpu']
 
 
 # Regression test for issue #68200.  This ensures that we properly construct the

pkg/sql/opt/xform/join_funcs.go

@@ -534,6 +534,9 @@ func (c *CustomFuncs) generateLookupJoinsImpl(
 
 			// Reset KeyCols since we're not using it anymore.
 			lookupJoin.KeyCols = opt.ColList{}
+			// Reset input since we don't need any constant values that may have
+			// been joined on the input above.
+			lookupJoin.Input = input
 		}
 
 		if len(lookupJoin.KeyCols) == 0 && len(lookupJoin.LookupExpr) == 0 {

pkg/sql/opt/xform/testdata/external/tpce

@@ -4029,34 +4029,31 @@ project
  │    │    ├── fd: ()-->(1,8,27,30,31,45-47), (48)-->(49,50), (31)==(47), (47)==(31), (8)==(45), (45)==(8)
  │    │    ├── limit hint: 1.00
  │    │    ├── inner-join (lookup commission_rate)
- │    │    │    ├── columns: c_id:1!null c_tier:8!null cr_c_tier:45!null cr_tt_id:46!null cr_ex_id:47!null cr_from_qty:48!null cr_to_qty:49!null commission_rate.cr_rate:50!null
- │    │    │    ├── key columns: [8 57] = [45 46]
- │    │    │    ├── key: (47,48)
- │    │    │    ├── fd: ()-->(1,8,45,46), (47,48)-->(49,50), (8)==(45), (45)==(8)
- │    │    │    ├── project
- │    │    │    │    ├── columns: "lookup_join_const_col_@46":57!null c_id:1!null c_tier:8!null
+ │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null cr_c_tier:45!null cr_tt_id:46!null cr_ex_id:47!null cr_from_qty:48!null cr_to_qty:49!null commission_rate.cr_rate:50!null
+ │    │    │    ├── lookup expression
+ │    │    │    │    └── filters
+ │    │    │    │         ├── cr_ex_id:47 = s_ex_id:31 [outer=(31,47), constraints=(/31: (/NULL - ]; /47: (/NULL - ]), fd=(31)==(47), (47)==(31)]
+ │    │    │    │         ├── cr_c_tier:45 IN (1, 2, 3) [outer=(45), constraints=(/45: [/1 - /1] [/2 - /2] [/3 - /3]; tight)]
+ │    │    │    │         ├── cr_tt_id:46 = 'TLS' [outer=(46), constraints=(/46: [/'TLS' - /'TLS']; tight), fd=()-->(46)]
+ │    │    │    │         └── cr_from_qty:48 <= 100 [outer=(48), constraints=(/48: (/NULL - /100]; tight)]
+ │    │    │    ├── key: (45,48)
+ │    │    │    ├── fd: ()-->(27,30,31,46,47), (45,48)-->(49,50), (31)==(47), (47)==(31)
+ │    │    │    ├── scan security
+ │    │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null
+ │    │    │    │    ├── constraint: /27: [/'ROACH' - /'ROACH']
  │    │    │    │    ├── cardinality: [0 - 1]
  │    │    │    │    ├── key: ()
- │    │    │    │    ├── fd: ()-->(1,8,57)
- │    │    │    │    ├── scan customer
- │    │    │    │    │    ├── columns: c_id:1!null c_tier:8!null
- │    │    │    │    │    ├── constraint: /1: [/0 - /0]
- │    │    │    │    │    ├── cardinality: [0 - 1]
- │    │    │    │    │    ├── key: ()
- │    │    │    │    │    └── fd: ()-->(1,8)
- │    │    │    │    └── projections
- │    │    │    │         └── 'TLS' [as="lookup_join_const_col_@46":57]
+ │    │    │    │    └── fd: ()-->(27,30,31)
  │    │    │    └── filters
- │    │    │         ├── cr_from_qty:48 <= 100 [outer=(48), constraints=(/48: (/NULL - /100]; tight)]
  │    │    │         └── cr_to_qty:49 >= 200 [outer=(49), constraints=(/49: [/200 - ]; tight)]
- │    │    ├── scan security
- │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null
- │    │    │    ├── constraint: /27: [/'ROACH' - /'ROACH']
+ │    │    ├── scan customer
+ │    │    │    ├── columns: c_id:1!null c_tier:8!null
+ │    │    │    ├── constraint: /1: [/0 - /0]
  │    │    │    ├── cardinality: [0 - 1]
  │    │    │    ├── key: ()
- │    │    │    └── fd: ()-->(27,30,31)
+ │    │    │    └── fd: ()-->(1,8)
  │    │    └── filters
- │    │         └── cr_ex_id:47 = s_ex_id:31 [outer=(31,47), constraints=(/31: (/NULL - ]; /47: (/NULL - ]), fd=(31)==(47), (47)==(31)]
+ │    │         └── cr_c_tier:45 = c_tier:8 [outer=(8,45), constraints=(/8: (/NULL - ]; /45: (/NULL - ]), fd=(8)==(45), (45)==(8)]
  │    └── 1
  └── projections
       └── commission_rate.cr_rate:50::FLOAT8 [as=cr_rate:53, outer=(50), immutable]
@@ -4097,34 +4094,26 @@ project
  │    │    ├── key: (48)
  │    │    ├── fd: ()-->(1,8,27,30,31,45-47), (48)-->(49,50), (8)==(45), (45)==(8), (31)==(47), (47)==(31)
  │    │    ├── limit hint: 1.00
- │    │    ├── project
- │    │    │    ├── columns: "lookup_join_const_col_@46":54!null c_id:1!null c_tier:8!null s_symb:27!null s_name:30!null s_ex_id:31!null
+ │    │    ├── inner-join (cross)
+ │    │    │    ├── columns: c_id:1!null c_tier:8!null s_symb:27!null s_name:30!null s_ex_id:31!null
  │    │    │    ├── cardinality: [0 - 1]
+ │    │    │    ├── multiplicity: left-rows(zero-or-one), right-rows(zero-or-one)
  │    │    │    ├── key: ()
- │    │    │    ├── fd: ()-->(1,8,27,30,31,54)
+ │    │    │    ├── fd: ()-->(1,8,27,30,31)
  │    │    │    ├── limit hint: 1.00
- │    │    │    ├── inner-join (cross)
- │    │    │    │    ├── columns: c_id:1!null c_tier:8!null s_symb:27!null s_name:30!null s_ex_id:31!null
+ │    │    │    ├── scan customer
+ │    │    │    │    ├── columns: c_id:1!null c_tier:8!null
+ │    │    │    │    ├── constraint: /1: [/0 - /0]
  │    │    │    │    ├── cardinality: [0 - 1]
- │    │    │    │    ├── multiplicity: left-rows(zero-or-one), right-rows(zero-or-one)
  │    │    │    │    ├── key: ()
- │    │    │    │    ├── fd: ()-->(1,8,27,30,31)
- │    │    │    │    ├── limit hint: 1.00
- │    │    │    │    ├── scan customer
- │    │    │    │    │    ├── columns: c_id:1!null c_tier:8!null
- │    │    │    │    │    ├── constraint: /1: [/0 - /0]
- │    │    │    │    │    ├── cardinality: [0 - 1]
- │    │    │    │    │    ├── key: ()
- │    │    │    │    │    └── fd: ()-->(1,8)
- │    │    │    │    ├── scan security
- │    │    │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null
- │    │    │    │    │    ├── constraint: /27: [/'ROACH' - /'ROACH']
- │    │    │    │    │    ├── cardinality: [0 - 1]
- │    │    │    │    │    ├── key: ()
- │    │    │    │    │    └── fd: ()-->(27,30,31)
- │    │    │    │    └── filters (true)
- │    │    │    └── projections
- │    │    │         └── 'TLS' [as="lookup_join_const_col_@46":54]
+ │    │    │    │    └── fd: ()-->(1,8)
+ │    │    │    ├── scan security
+ │    │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null
+ │    │    │    │    ├── constraint: /27: [/'ROACH' - /'ROACH']
+ │    │    │    │    ├── cardinality: [0 - 1]
+ │    │    │    │    ├── key: ()
+ │    │    │    │    └── fd: ()-->(27,30,31)
+ │    │    │    └── filters (true)
  │    │    └── filters
  │    │         └── cr_to_qty:49 >= 200 [outer=(49), constraints=(/49: [/200 - ]; tight)]
  │    └── 1

pkg/sql/opt/xform/testdata/external/tpce-no-stats

@@ -4060,34 +4060,31 @@ project
  │    │    ├── fd: ()-->(1,8,27,30,31,45-47), (48)-->(49,50), (31)==(47), (47)==(31), (8)==(45), (45)==(8)
  │    │    ├── limit hint: 1.00
  │    │    ├── inner-join (lookup commission_rate)
- │    │    │    ├── columns: c_id:1!null c_tier:8!null cr_c_tier:45!null cr_tt_id:46!null cr_ex_id:47!null cr_from_qty:48!null cr_to_qty:49!null commission_rate.cr_rate:50!null
- │    │    │    ├── key columns: [8 57] = [45 46]
- │    │    │    ├── key: (47,48)
- │    │    │    ├── fd: ()-->(1,8,45,46), (47,48)-->(49,50), (8)==(45), (45)==(8)
- │    │    │    ├── project
- │    │    │    │    ├── columns: "lookup_join_const_col_@46":57!null c_id:1!null c_tier:8!null
+ │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null cr_c_tier:45!null cr_tt_id:46!null cr_ex_id:47!null cr_from_qty:48!null cr_to_qty:49!null commission_rate.cr_rate:50!null
+ │    │    │    ├── lookup expression
+ │    │    │    │    └── filters
+ │    │    │    │         ├── cr_ex_id:47 = s_ex_id:31 [outer=(31,47), constraints=(/31: (/NULL - ]; /47: (/NULL - ]), fd=(31)==(47), (47)==(31)]
+ │    │    │    │         ├── cr_c_tier:45 IN (1, 2, 3) [outer=(45), constraints=(/45: [/1 - /1] [/2 - /2] [/3 - /3]; tight)]
+ │    │    │    │         ├── cr_tt_id:46 = 'TLS' [outer=(46), constraints=(/46: [/'TLS' - /'TLS']; tight), fd=()-->(46)]
+ │    │    │    │         └── cr_from_qty:48 <= 100 [outer=(48), constraints=(/48: (/NULL - /100]; tight)]
+ │    │    │    ├── key: (45,48)
+ │    │    │    ├── fd: ()-->(27,30,31,46,47), (45,48)-->(49,50), (31)==(47), (47)==(31)
+ │    │    │    ├── scan security
+ │    │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null
+ │    │    │    │    ├── constraint: /27: [/'ROACH' - /'ROACH']
  │    │    │    │    ├── cardinality: [0 - 1]
  │    │    │    │    ├── key: ()
- │    │    │    │    ├── fd: ()-->(1,8,57)
- │    │    │    │    ├── scan customer
- │    │    │    │    │    ├── columns: c_id:1!null c_tier:8!null
- │    │    │    │    │    ├── constraint: /1: [/0 - /0]
- │    │    │    │    │    ├── cardinality: [0 - 1]
- │    │    │    │    │    ├── key: ()
- │    │    │    │    │    └── fd: ()-->(1,8)
- │    │    │    │    └── projections
- │    │    │    │         └── 'TLS' [as="lookup_join_const_col_@46":57]
+ │    │    │    │    └── fd: ()-->(27,30,31)
  │    │    │    └── filters
- │    │    │         ├── cr_from_qty:48 <= 100 [outer=(48), constraints=(/48: (/NULL - /100]; tight)]
  │    │    │         └── cr_to_qty:49 >= 200 [outer=(49), constraints=(/49: [/200 - ]; tight)]
- │    │    ├── scan security
- │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null
- │    │    │    ├── constraint: /27: [/'ROACH' - /'ROACH']
+ │    │    ├── scan customer
+ │    │    │    ├── columns: c_id:1!null c_tier:8!null
+ │    │    │    ├── constraint: /1: [/0 - /0]
  │    │    │    ├── cardinality: [0 - 1]
  │    │    │    ├── key: ()
- │    │    │    └── fd: ()-->(27,30,31)
+ │    │    │    └── fd: ()-->(1,8)
  │    │    └── filters
- │    │         └── cr_ex_id:47 = s_ex_id:31 [outer=(31,47), constraints=(/31: (/NULL - ]; /47: (/NULL - ]), fd=(31)==(47), (47)==(31)]
+ │    │         └── cr_c_tier:45 = c_tier:8 [outer=(8,45), constraints=(/8: (/NULL - ]; /45: (/NULL - ]), fd=(8)==(45), (45)==(8)]
  │    └── 1
  └── projections
       └── commission_rate.cr_rate:50::FLOAT8 [as=cr_rate:53, outer=(50), immutable]
@@ -4128,32 +4125,25 @@ project
  │    │    ├── key: (48)
  │    │    ├── fd: ()-->(1,8,27,30,31,45-47), (48)-->(49,50), (8)==(45), (45)==(8), (31)==(47), (47)==(31)
  │    │    ├── limit hint: 1.00
- │    │    ├── project
- │    │    │    ├── columns: "lookup_join_const_col_@46":54!null c_id:1!null c_tier:8!null s_symb:27!null s_name:30!null s_ex_id:31!null
+ │    │    ├── inner-join (cross)
+ │    │    │    ├── columns: c_id:1!null c_tier:8!null s_symb:27!null s_name:30!null s_ex_id:31!null
  │    │    │    ├── cardinality: [0 - 1]
+ │    │    │    ├── multiplicity: left-rows(zero-or-one), right-rows(zero-or-one)
  │    │    │    ├── key: ()
- │    │    │    ├── fd: ()-->(1,8,27,30,31,54)
- │    │    │    ├── inner-join (cross)
- │    │    │    │    ├── columns: c_id:1!null c_tier:8!null s_symb:27!null s_name:30!null s_ex_id:31!null
+ │    │    │    ├── fd: ()-->(1,8,27,30,31)
+ │    │    │    ├── scan customer
+ │    │    │    │    ├── columns: c_id:1!null c_tier:8!null
+ │    │    │    │    ├── constraint: /1: [/0 - /0]
  │    │    │    │    ├── cardinality: [0 - 1]
- │    │    │    │    ├── multiplicity: left-rows(zero-or-one), right-rows(zero-or-one)
  │    │    │    │    ├── key: ()
- │    │    │    │    ├── fd: ()-->(1,8,27,30,31)
- │    │    │    │    ├── scan customer
- │    │    │    │    │    ├── columns: c_id:1!null c_tier:8!null
- │    │    │    │    │    ├── constraint: /1: [/0 - /0]
- │    │    │    │    │    ├── cardinality: [0 - 1]
- │    │    │    │    │    ├── key: ()
- │    │    │    │    │    └── fd: ()-->(1,8)
- │    │    │    │    ├── scan security
- │    │    │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null
- │    │    │    │    │    ├── constraint: /27: [/'ROACH' - /'ROACH']
- │    │    │    │    │    ├── cardinality: [0 - 1]
- │    │    │    │    │    ├── key: ()
- │    │    │    │    │    └── fd: ()-->(27,30,31)
- │    │    │    │    └── filters (true)
- │    │    │    └── projections
- │    │    │         └── 'TLS' [as="lookup_join_const_col_@46":54]
+ │    │    │    │    └── fd: ()-->(1,8)
+ │    │    │    ├── scan security
+ │    │    │    │    ├── columns: s_symb:27!null s_name:30!null s_ex_id:31!null
+ │    │    │    │    ├── constraint: /27: [/'ROACH' - /'ROACH']
+ │    │    │    │    ├── cardinality: [0 - 1]
+ │    │    │    │    ├── key: ()
+ │    │    │    │    └── fd: ()-->(27,30,31)
+ │    │    │    └── filters (true)
  │    │    └── filters
  │    │         └── cr_to_qty:49 >= 200 [outer=(49), constraints=(/49: [/200 - ]; tight)]
  │    └── 1