Merge #84366

84366: opt: fix internal error due to node with MaxCost added to memo r=rytaft a=rytaft

This commit fixes an internal error caused by calculating the
selectivity of a join as NaN. The solution is to avoid dividing by
0 when calculating the selectivity.

Fixes #84236

Release note (bug fix): Fixed an internal error "node ... with
MaxCost added to the memo" that could occur during planning when
calculating the cardinality of an outer join when one of the inputs
had 0 rows.

Co-authored-by: Rebecca Taft <[email protected]>

pkg/sql/opt/memo/statistics_builder.go

@@ -4080,7 +4080,7 @@ func (sb *statisticsBuilder) predicateSelectivity(
 	nonNullSelectivity, nullSelectivity props.Selectivity, inputNullCount, inputRowCount float64,
 ) props.Selectivity {
 	outRowCount := nonNullSelectivity.AsFloat()*(inputRowCount-inputNullCount) + nullSelectivity.AsFloat()*inputNullCount
-	sel := props.MakeSelectivity(outRowCount / inputRowCount)
+	sel := props.MakeSelectivityFromFraction(outRowCount, inputRowCount)
 
 	return sel
 }

pkg/sql/opt/memo/testdata/stats/join

@@ -1975,3 +1975,68 @@ anti-join (cross)
  │    └── stats: [rows=1000, distinct(7)=500, null(7)=0, avgsize(7)=4, distinct(8)=50, null(8)=0, avgsize(8)=4]
  └── filters
       └── (firstchoiceclassid:7 = classid:1) OR (secondchoiceclassid:8 = classid:1) [type=bool, outer=(1,7,8), constraints=(/1: (/NULL - ])]
+
+# Regression test for #84236. Don't calculate selectivity as NaN.
+exec-ddl
+CREATE TABLE t84236_1 (
+  col1_0 DATE NOT NULL,
+  col1_1 FLOAT4 NOT NULL,
+  col1_2 INT NOT NULL,
+  col1_4 INT NOT NULL,
+  col1_5 BOOL,
+  col1_6 STRING NOT NULL,
+  PRIMARY KEY (col1_4 ASC, col1_1, col1_6, col1_2 ASC)
+);
+----
+
+exec-ddl
+CREATE TABLE t84236_2 (col2_0 BIT(27), col2_2 TIMETZ NOT NULL);
+----
+
+norm
+SELECT
+        t2.col2_0, '1971-10-24':::DATE
+FROM
+        t84236_2 AS t2
+        FULL JOIN t84236_2 AS t2_2
+                INNER JOIN t84236_1 AS t1 ON NULL ON t1.col1_5
+ORDER BY
+        t2.col2_2 DESC
+LIMIT
+        82;
+----
+project
+ ├── columns: col2_0:1(bit) date:19(date!null)  [hidden: t2.col2_2:2(timetz)]
+ ├── cardinality: [0 - 82]
+ ├── stats: [rows=82]
+ ├── fd: ()-->(19)
+ ├── ordering: -2 opt(19) [actual: -2]
+ ├── limit
+ │    ├── columns: t2.col2_0:1(bit) t2.col2_2:2(timetz) col1_5:15(bool)
+ │    ├── internal-ordering: -2
+ │    ├── cardinality: [0 - 82]
+ │    ├── stats: [rows=82]
+ │    ├── ordering: -2
+ │    ├── sort
+ │    │    ├── columns: t2.col2_0:1(bit) t2.col2_2:2(timetz) col1_5:15(bool)
+ │    │    ├── stats: [rows=1000]
+ │    │    ├── ordering: -2
+ │    │    ├── limit hint: 82.00
+ │    │    └── full-join (cross)
+ │    │         ├── columns: t2.col2_0:1(bit) t2.col2_2:2(timetz) col1_5:15(bool)
+ │    │         ├── multiplicity: left-rows(exactly-one), right-rows(one-or-more)
+ │    │         ├── stats: [rows=1000]
+ │    │         ├── scan t84236_2 [as=t2]
+ │    │         │    ├── columns: t2.col2_0:1(bit) t2.col2_2:2(timetz!null)
+ │    │         │    └── stats: [rows=1000]
+ │    │         ├── values
+ │    │         │    ├── columns: col1_5:15(bool!null)
+ │    │         │    ├── cardinality: [0 - 0]
+ │    │         │    ├── stats: [rows=0, distinct(15)=0, null(15)=0, avgsize(15)=0]
+ │    │         │    ├── key: ()
+ │    │         │    └── fd: ()-->(15)
+ │    │         └── filters
+ │    │              └── col1_5:15 [type=bool, outer=(15), constraints=(/15: [/true - /true]; tight), fd=()-->(15)]
+ │    └── 82 [type=int]
+ └── projections
+      └── '1971-10-24' [as=date:19, type=date]