Support for custom slots in the custom executor nodes

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
index 8f56bd8a23a46c40e60d0134e911e1a38dd72e03..a76ec43b9fe884cb48f09d215ea3393f8641d5de 100644 (file)
--- 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
index 01b1727fc09face14c0eb50554653c4519e39d02..0f10d4432bda7877285f13d4b7f4cd3eb2811755 100644 (file)
--- 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;
 
 /* ----------------------------------------------------------------