feature: Use amflags to support Column-oriented scanning of custom tableam (#407)

For custom tableam, maybe it support column-oriented scanning, the postgres
planner can no longer use whether am_handler is aocs handler to decide
whether only to add the columns required by the operator to the targetlist,
but use amflags to determine

If table am supports column-oriented scanning, the flags returned by set_flags
will set the SCAN_SUPPORT_COLUMN_ORIENTED_SCAN bit.

Co-authored-by: GongXun <gongxun@hashdata.cn>

Author: gongxun0928

src/backend/access/aocs/aocsam_handler.c

@@ -760,7 +760,7 @@ aoco_getnextslot(TableScanDesc scan, ScanDirection direction, TupleTableSlot *sl
 static uint32
 aoco_scan_flags(Relation rel)
 {
-	return 0;
+	return SCAN_SUPPORT_COLUMN_ORIENTED_SCAN;
 }
 
 static Size

src/backend/optimizer/plan/createplan.c

@@ -974,7 +974,7 @@ use_physical_tlist(PlannerInfo *root, Path *path, int flags)
 	 * Using physical target list with column store will result in scanning all
 	 * column files, which will cause a significant performance degradation.
 	 */
-	if (AMHandlerIsAoCols(rel->amhandler))
+	if (rel->amflags & AMFLAG_HAS_COLUMN_ORIENTED_SCAN)
 		return false;
 
 	/*

src/backend/optimizer/util/plancat.c

@@ -491,6 +491,12 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 		relation->rd_tableam->scan_getnextslot_tidrange != NULL)
 		rel->amflags |= AMFLAG_HAS_TID_RANGE;
 
+	/* Collect info about relation's store information, if it support column-oriented scan  */
+	if (relation->rd_tableam && relation->rd_tableam->scan_flags && 
+		(relation->rd_tableam->scan_flags(relation) & SCAN_SUPPORT_COLUMN_ORIENTED_SCAN)) {
+		rel->amflags |= AMFLAG_HAS_COLUMN_ORIENTED_SCAN;
+	}
+
 	/*
 	 * Collect info about relation's partitioning scheme, if any. Only
 	 * inheritance parents may be partitioned.

src/include/access/tableam.h

@@ -41,6 +41,18 @@ struct TBMIterateResult;
 struct VacuumParams;
 struct ValidateIndexState;
 
+/**
+ * Flags represented the supported features of scan.
+ * 
+ * The first 8 bits are reserved for kernel expansion of some attributes,
+ * and the remaining 24 bits are reserved for custom tableam.
+ * 
+ * If you add a new flag, make sure the flag's bit is consecutive with
+ * the previous one.
+ * 
+*/
+#define SCAN_SUPPORT_COLUMN_ORIENTED_SCAN (1 << 0)  /* support column-oriented scanning*/
+
 /*
  * Bitmask values for the flags argument to the scan_begin callback.
  */

src/include/nodes/pathnodes.h

@@ -823,6 +823,8 @@ static inline void planner_subplan_put_plan(struct PlannerInfo *root, SubPlan *s
 
 /* Bitmask of flags supported by table AMs */
 #define AMFLAG_HAS_TID_RANGE (1 << 0)
+/* Column-oriented scanning of flags supported by table AMs */
+#define AMFLAG_HAS_COLUMN_ORIENTED_SCAN (1 << 1)
 
 typedef enum RelOptKind
 {