Use table scan API in compression code

Refactor the compression code to only use the table scan API when
scanning relations instead of a mix of the table and heap scan
APIs. The table scan API is a higher-level API and recommended as it
works for any type of relation and uses table slots directly, which
means that in some cases a full heap tuple need not be materialized.

tsl/src/compression/api.c

@@ -8,6 +8,7 @@
  *  compress and decompress chunks
  */
 #include <postgres.h>
+#include <access/tableam.h>
 #include <access/xact.h>
 #include <catalog/dependency.h>
 #include <commands/tablecmds.h>
@@ -36,6 +37,7 @@
 #include "hypercube.h"
 #include "hypertable.h"
 #include "hypertable_cache.h"
+#include "ts_catalog/catalog.h"
 #include "ts_catalog/continuous_agg.h"
 #include "ts_catalog/hypertable_compression.h"
 #include "ts_catalog/compression_chunk_size.h"
@@ -934,6 +936,7 @@ bool
 tsl_recompress_chunk_wrapper(Chunk *uncompressed_chunk)
 {
 	Oid uncompressed_chunk_relid = uncompressed_chunk->table_id;
+
 	if (ts_chunk_is_unordered(uncompressed_chunk))
 	{
 		if (!decompress_chunk_impl(uncompressed_chunk->hypertable_relid,
@@ -1129,28 +1132,23 @@ fetch_unmatched_uncompressed_chunk_into_tuplesort(Tuplesortstate *segment_tuples
 												  Relation uncompressed_chunk_rel,
 												  bool *unmatched_rows_exist)
 {
-	TableScanDesc heapScan;
-	HeapTuple uncompressed_tuple;
-	TupleDesc uncompressed_rel_tupdesc = RelationGetDescr(uncompressed_chunk_rel);
+	TableScanDesc scan;
+	TupleTableSlot *slot = table_slot_create(uncompressed_chunk_rel, NULL);
+	Snapshot snapshot = GetLatestSnapshot();
 
-	heapScan = table_beginscan(uncompressed_chunk_rel, GetLatestSnapshot(), 0, NULL);
-	TupleTableSlot *heap_tuple_slot =
-		MakeTupleTableSlot(uncompressed_rel_tupdesc, &TTSOpsHeapTuple);
+	scan = table_beginscan(uncompressed_chunk_rel, snapshot, 0, NULL);
 
-	while ((uncompressed_tuple = heap_getnext(heapScan, ForwardScanDirection)) != NULL)
+	while (table_scan_getnextslot(scan, ForwardScanDirection, slot))
 	{
 		if (!(*unmatched_rows_exist))
 			*unmatched_rows_exist = true;
 
-		ExecStoreHeapTuple(uncompressed_tuple, heap_tuple_slot, false);
-		slot_getallattrs(heap_tuple_slot);
-
-		tuplesort_puttupleslot(segment_tuplesortstate, heap_tuple_slot);
-
-		simple_heap_delete(uncompressed_chunk_rel, &uncompressed_tuple->t_self);
+		slot_getallattrs(slot);
+		tuplesort_puttupleslot(segment_tuplesortstate, slot);
+		simple_table_tuple_delete(uncompressed_chunk_rel, &slot->tts_tid, snapshot);
 	}
-	ExecDropSingleTupleTableSlot(heap_tuple_slot);
-	table_endscan(heapScan);
+	ExecDropSingleTupleTableSlot(slot);
+	table_endscan(scan);
 }
 
 static bool
@@ -1159,9 +1157,8 @@ fetch_matching_uncompressed_chunk_into_tuplesort(Tuplesortstate *segment_tupleso
 												 Relation uncompressed_chunk_rel,
 												 CompressedSegmentInfo **current_segment)
 {
-	TableScanDesc heapScan;
-	HeapTuple uncompressed_tuple;
-	TupleDesc uncompressed_rel_tupdesc = RelationGetDescr(uncompressed_chunk_rel);
+	TableScanDesc scan;
+	Snapshot snapshot;
 	int index = 0;
 	int nsegbycols_nonnull = 0;
 	Bitmapset *null_segbycols = NULL;
@@ -1202,21 +1199,18 @@ fetch_matching_uncompressed_chunk_into_tuplesort(Tuplesortstate *segment_tupleso
 		index++;
 	}
 
-	heapScan =
-		table_beginscan(uncompressed_chunk_rel, GetLatestSnapshot(), nsegbycols_nonnull, scankey);
-	TupleTableSlot *heap_tuple_slot =
-		MakeTupleTableSlot(uncompressed_rel_tupdesc, &TTSOpsHeapTuple);
+	snapshot = GetLatestSnapshot();
+	scan = table_beginscan(uncompressed_chunk_rel, snapshot, nsegbycols_nonnull, scankey);
+	TupleTableSlot *slot = table_slot_create(uncompressed_chunk_rel, NULL);
 
-	while ((uncompressed_tuple = heap_getnext(heapScan, ForwardScanDirection)) != NULL)
+	while (table_scan_getnextslot(scan, ForwardScanDirection, slot))
 	{
 		bool valid = true;
 		/* check for NULL values in this segment manually */
 		for (int attno = bms_next_member(null_segbycols, -1); attno >= 0;
 			 attno = bms_next_member(null_segbycols, attno))
 		{
-			if (!heap_attisnull(uncompressed_tuple,
-								attno,
-								RelationGetDescr(uncompressed_chunk_rel)))
+			if (!slot_attisnull(slot, attno))
 			{
 				valid = false;
 				break;
@@ -1225,16 +1219,15 @@ fetch_matching_uncompressed_chunk_into_tuplesort(Tuplesortstate *segment_tupleso
 		if (valid)
 		{
 			matching_exist = true;
-			ExecStoreHeapTuple(uncompressed_tuple, heap_tuple_slot, false);
-			slot_getallattrs(heap_tuple_slot);
-			tuplesort_puttupleslot(segment_tuplesortstate, heap_tuple_slot);
-			/* simple_heap_delete since we don't expect concurrent updates, have exclusive lock on
-			 * the relation */
-			simple_heap_delete(uncompressed_chunk_rel, &uncompressed_tuple->t_self);
+			slot_getallattrs(slot);
+			tuplesort_puttupleslot(segment_tuplesortstate, slot);
+			/* simple_table_tuple_delete since we don't expect concurrent
+			 * updates, have exclusive lock on the relation */
+			simple_table_tuple_delete(uncompressed_chunk_rel, &slot->tts_tid, snapshot);
 		}
 	}
-	ExecDropSingleTupleTableSlot(heap_tuple_slot);
-	table_endscan(heapScan);
+	ExecDropSingleTupleTableSlot(slot);
+	table_endscan(scan);
 
 	if (null_segbycols != NULL)
 		pfree(null_segbycols);