Support for custom slots in the custom executor nodes

akorotkov · akorotkov · commit cee120951427 · 2022-11-24T00:36:11.000+03:00
Some custom table access method may have their tuple format and use custom executor nodes for their custom scan types. The ability to set a custom slot would save them from tuple format conversion. Other users of custom executor nodes may also benefit. Discussion: https://postgr.es/m/CAPpHfduJUU6ToecvTyRE_yjxTS80FyPpct4OHaLFk3OEheMTNA@mail.gmail.com Author: Alexander Korotkov Reviewed-by: Pavel Borisov
diff --git a/src/backend/executor/nodeCustom.c b/src/backend/executor/nodeCustom.c
@@ -29,6 +29,7 @@ CustomScanState *
 ExecInitCustomScan(CustomScan *cscan, EState *estate, int eflags)
 {
 	CustomScanState *css;
+	const TupleTableSlotOps *slotOps;
 	Relation	scan_rel = NULL;
 	Index		scanrelid = cscan->scan.scanrelid;
 	int			tlistvarno;
@@ -63,6 +64,14 @@ ExecInitCustomScan(CustomScan *cscan, EState *estate, int eflags)
 		css->ss.ss_currentRelation = scan_rel;
 	}
 
+	/*
+	 * Use a custom slot if specified in CustomScanState or use virtual slot
+	 * otherwise.
+	 */
+	slotOps = css->slotOps;
+	if (!slotOps)
+		slotOps = &TTSOpsVirtual;
+
 	/*
 	 * Determine the scan tuple type.  If the custom scan provider provided a
 	 * targetlist describing the scan tuples, use that; else use base
@@ -73,14 +82,14 @@ ExecInitCustomScan(CustomScan *cscan, EState *estate, int eflags)
 		TupleDesc	scan_tupdesc;
 
 		scan_tupdesc = ExecTypeFromTL(cscan->custom_scan_tlist);
-		ExecInitScanTupleSlot(estate, &css->ss, scan_tupdesc, &TTSOpsVirtual);
+		ExecInitScanTupleSlot(estate, &css->ss, scan_tupdesc, slotOps);
 		/* Node's targetlist will contain Vars with varno = INDEX_VAR */
 		tlistvarno = INDEX_VAR;
 	}
 	else
 	{
 		ExecInitScanTupleSlot(estate, &css->ss, RelationGetDescr(scan_rel),
-							  &TTSOpsVirtual);
+							  slotOps);
 		/* Node's targetlist will contain Vars with varno = scanrelid */
 		tlistvarno = scanrelid;
 	}
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
@@ -1949,6 +1949,7 @@ typedef struct CustomScanState
 	List	   *custom_ps;		/* list of child PlanState nodes, if any */
 	Size		pscan_len;		/* size of parallel coordination information */
 	const struct CustomExecMethods *methods;
+	const struct TupleTableSlotOps *slotOps;
 } CustomScanState;
 
 /* ----------------------------------------------------------------
