Remove table AM callback scan_bitmap_next_block

After pushing the bitmap iterator into table-AM specific code (as part
of making bitmap heap scan use the read stream API in 2b73a8cd33b7),
scan_bitmap_next_block() no longer returns the current block number.
Since scan_bitmap_next_block() isn't returning any relevant information
to bitmap table scan code, it makes more sense to get rid of it.

Now, bitmap table scan code only calls table_scan_bitmap_next_tuple(),
and the heap AM implementation of scan_bitmap_next_block() is a local
helper in heapam_handler.c.

Reviewed-by: Tomas Vondra <tomas@vondra.me>
Discussion: https://postgr.es/m/flat/CAAKRu_ZwCwWFeL_H3ia26bP2e7HiKLWt0ZmGXPVwPO6uXq0vaA%40mail.gmail.com

1 files changed, 24 insertions, 49 deletions

diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c
index 6df34094a13..3e33360c0fc 100644
--- a/src/backend/executor/nodeBitmapHeapscan.c
+++ b/src/backend/executor/nodeBitmapHeapscan.c
@@ -138,69 +138,44 @@ BitmapTableScanSetup(BitmapHeapScanState *node)
 static TupleTableSlot *
 BitmapHeapNext(BitmapHeapScanState *node)
 {
-	ExprContext *econtext;
-	TableScanDesc scan;
-	TupleTableSlot *slot;
-
-	/*
-	 * extract necessary information from index scan node
-	 */
-	econtext = node->ss.ps.ps_ExprContext;
-	slot = node->ss.ss_ScanTupleSlot;
-	scan = node->ss.ss_currentScanDesc;
+	ExprContext *econtext = node->ss.ps.ps_ExprContext;
+	TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
 
 	/*
 	 * If we haven't yet performed the underlying index scan, do it, and begin
 	 * the iteration over the bitmap.
 	 */
 	if (!node->initialized)
-	{
 		BitmapTableScanSetup(node);
-		scan = node->ss.ss_currentScanDesc;
-		goto new_page;
-	}
 
-	for (;;)
+	while (table_scan_bitmap_next_tuple(node->ss.ss_currentScanDesc,
+										slot, &node->recheck,
+										&node->stats.lossy_pages,
+										&node->stats.exact_pages))
 	{
-		while (table_scan_bitmap_next_tuple(scan, slot))
-		{
-			/*
-			 * Continuing in previously obtained page.
-			 */
-
-			CHECK_FOR_INTERRUPTS();
+		/*
+		 * Continuing in previously obtained page.
+		 */
+		CHECK_FOR_INTERRUPTS();
 
-			/*
-			 * If we are using lossy info, we have to recheck the qual
-			 * conditions at every tuple.
-			 */
-			if (node->recheck)
+		/*
+		 * If we are using lossy info, we have to recheck the qual conditions
+		 * at every tuple.
+		 */
+		if (node->recheck)
+		{
+			econtext->ecxt_scantuple = slot;
+			if (!ExecQualAndReset(node->bitmapqualorig, econtext))
 			{
-				econtext->ecxt_scantuple = slot;
-				if (!ExecQualAndReset(node->bitmapqualorig, econtext))
-				{
-					/* Fails recheck, so drop it and loop back for another */
-					InstrCountFiltered2(node, 1);
-					ExecClearTuple(slot);
-					continue;
-				}
+				/* Fails recheck, so drop it and loop back for another */
+				InstrCountFiltered2(node, 1);
+				ExecClearTuple(slot);
+				continue;
 			}
-
-			/* OK to return this tuple */
-			return slot;
 		}
 
-new_page:
-
-		/*
-		 * Returns false if the bitmap is exhausted and there are no further
-		 * blocks we need to scan.
-		 */
-		if (!table_scan_bitmap_next_block(scan,
-										  &node->recheck,
-										  &node->stats.lossy_pages,
-										  &node->stats.exact_pages))
-			break;
+		/* OK to return this tuple */
+		return slot;
 	}
 
 	/*