Merge pull request #58197 from nvanbenschoten/backport20.2-58117

release-20.2: sql/rowexec: don't allocate buf per row in sketchInfo.addRow

pkg/sql/rowexec/sampler.go

@@ -500,14 +500,19 @@ func (s *sketchInfo) addRow(
 	}
 
 	if useFastPath {
-		var intbuf [8]byte
 		// Fast path for integers.
 		// TODO(radu): make this more general.
 		val, err := row[col].GetInt()
 		if err != nil {
 			return err
 		}
 
+		if cap(*buf) < 8 {
+			*buf = make([]byte, 8)
+		} else {
+			*buf = (*buf)[:8]
+		}
+
 		// Note: this encoding is not identical with the one in the general path
 		// below, but it achieves the same thing (we want equal integers to
 		// encode to equal []bytes). The only caveat is that all samplers must
@@ -518,8 +523,8 @@ func (s *sketchInfo) addRow(
 		// it must be a very good hash function (HLL expects the hash values to
 		// be uniformly distributed in the 2^64 range). Experiments (on tpcc
 		// order_line) with simplistic functions yielded bad results.
-		binary.LittleEndian.PutUint64(intbuf[:], uint64(val))
-		s.sketch.Insert(intbuf[:])
+		binary.LittleEndian.PutUint64(*buf, uint64(val))
+		s.sketch.Insert(*buf)
 		return nil
 	}
 	isNull := true