sql: bring back resultRowBuffer in updateRun and deleteRun

For some reason, updateRun and deleteRun differ from insertRun in that
they were creating result slices for RETURNING in processSourceRow,
instead of creating a resultRowBuffer in startExec. This commit does a
small refactor to move allocation of resultRowBuffer to startExec.

This refactor will make it easier for the new UPDATE and DELETE fast
path planNodes to share updateRun and deleteRun with the existing
updateNode and deleteNode.

Epic: None

Release note: None

Author: michae2

pkg/sql/delete.go

@@ -41,6 +41,10 @@ type deleteRun struct {
 	// to BatchedNext() has completed the work already.
 	done bool
 
+	// resultRowBuffer is used to prepare a result row for accumulation
+	// into the row container above, when rowsNeeded is set.
+	resultRowBuffer tree.Datums
+
 	// traceKV caches the current KV tracing flag.
 	traceKV bool
 
@@ -67,6 +71,10 @@ func (d *deleteNode) startExec(params runParams) error {
 		d.run.td.rows = rowcontainer.NewRowContainer(
 			params.p.Mon().MakeBoundAccount(),
 			colinfo.ColTypeInfoFromResCols(d.columns))
+		d.run.resultRowBuffer = make([]tree.Datum, len(d.columns))
+		for i := range d.run.resultRowBuffer {
+			d.run.resultRowBuffer[i] = tree.DNull
+		}
 	}
 	return d.run.td.init(params.ctx, params.p.txn, params.EvalContext())
 }
@@ -185,15 +193,14 @@ func (d *deleteNode) processSourceRow(params runParams, sourceVals tree.Datums)
 		//
 		// d.run.rows.NumCols() is guaranteed to only contain the requested
 		// public columns.
-		resultValues := make(tree.Datums, d.run.td.rows.NumCols())
 		largestRetIdx := -1
 		for i := range d.run.rowIdxToRetIdx {
 			retIdx := d.run.rowIdxToRetIdx[i]
 			if retIdx >= 0 {
 				if retIdx >= largestRetIdx {
 					largestRetIdx = retIdx
 				}
-				resultValues[retIdx] = deleteVals[i]
+				d.run.resultRowBuffer[retIdx] = deleteVals[i]
 			}
 		}
 
@@ -207,12 +214,12 @@ func (d *deleteNode) processSourceRow(params runParams, sourceVals tree.Datums)
 
 			for i := 0; i < d.run.numPassthrough; i++ {
 				largestRetIdx++
-				resultValues[largestRetIdx] = passthroughValues[i]
+				d.run.resultRowBuffer[largestRetIdx] = passthroughValues[i]
 			}
 
 		}
 
-		if _, err := d.run.td.rows.AddRow(params.ctx, resultValues); err != nil {
+		if _, err := d.run.td.rows.AddRow(params.ctx, d.run.resultRowBuffer); err != nil {
 			return err
 		}
 	}

pkg/sql/update.go

@@ -48,6 +48,10 @@ type updateRun struct {
 	// BatchedNext() has completed the work already.
 	done bool
 
+	// resultRowBuffer is used to prepare a result row for accumulation
+	// into the row container above, when rowsNeeded is set.
+	resultRowBuffer tree.Datums
+
 	// traceKV caches the current KV tracing flag.
 	traceKV bool
 
@@ -77,6 +81,10 @@ func (u *updateNode) startExec(params runParams) error {
 			params.p.Mon().MakeBoundAccount(),
 			colinfo.ColTypeInfoFromResCols(u.columns),
 		)
+		u.run.resultRowBuffer = make([]tree.Datum, len(u.columns))
+		for i := range u.run.resultRowBuffer {
+			u.run.resultRowBuffer[i] = tree.DNull
+		}
 	}
 	return u.run.tu.init(params.ctx, params.p.txn, params.EvalContext())
 }
@@ -240,15 +248,14 @@ func (u *updateNode) processSourceRow(params runParams, sourceVals tree.Datums)
 		//
 		// MakeUpdater guarantees that the first columns of the new values
 		// are those specified u.columns.
-		resultValues := make([]tree.Datum, len(u.columns))
 		largestRetIdx := -1
 		for i := range u.run.rowIdxToRetIdx {
 			retIdx := u.run.rowIdxToRetIdx[i]
 			if retIdx >= 0 {
 				if retIdx >= largestRetIdx {
 					largestRetIdx = retIdx
 				}
-				resultValues[retIdx] = newValues[i]
+				u.run.resultRowBuffer[retIdx] = newValues[i]
 			}
 		}
 
@@ -257,10 +264,10 @@ func (u *updateNode) processSourceRow(params runParams, sourceVals tree.Datums)
 		// clause that refer to other tables (from the FROM clause of the update).
 		for i := 0; i < u.run.numPassthrough; i++ {
 			largestRetIdx++
-			resultValues[largestRetIdx] = passthroughValues[i]
+			u.run.resultRowBuffer[largestRetIdx] = passthroughValues[i]
 		}
 
-		if _, err := u.run.tu.rows.AddRow(params.ctx, resultValues); err != nil {
+		if _, err := u.run.tu.rows.AddRow(params.ctx, u.run.resultRowBuffer); err != nil {
 			return err
 		}
 	}