Get Basic MATCH pattern ready

()-[]->() works, kinda. This is the base that everything after needs
to do MATCH patterns efficiently, or... at least more efficiently than
it was before

Author: JoshInnis

Makefile

@@ -64,6 +64,7 @@ OBJS = src/backend/postgraph.o \
        src/backend/utils/adt/vector.o \
        src/backend/utils/adt/vertex.o \
        src/backend/utils/ag_func.o \
+       src/backend/utils/edge_searching.o \
        src/backend/utils/cache/ag_cache.o \
 
 EXTENSION = postgraph

postgraph--0.1.0.sql

@@ -429,6 +429,26 @@ PARALLEL SAFE
 RETURNS NULL ON NULL INPUT 
 as 'MODULE_PATHNAME';
 
+CREATE TYPE edge_composite AS (id graphid, startid graphid, endid graphid, properties gtype);
+
+CREATE FUNCTION edge_search(graph_oid gtype, id graphid, label gtype, include_props gtype)
+RETURNS TABLE  (id graphid, startid graphid, endid graphid, properties gtype)
+CALLED ON NULL INPUT
+STABLE
+PARALLEL SAFE
+LANGUAGE C
+COST 5000
+AS 'MODULE_PATHNAME';
+
+
+CREATE FUNCTION retrieve_vertex(graph_oid gtype, id graphid)
+RETURNS gtype
+RETURNS NULL ON NULL INPUT
+STABLE
+PARALLEL SAFE
+LANGUAGE C
+COST 5000
+AS 'MODULE_PATHNAME';
 
 --
 -- There are times when the optimizer might eliminate

regress/sql/cypher_create.sql

@@ -48,6 +48,7 @@ CREATE ()-[]->();
 
 EXPLAIN MATCH ()-[]->() RETURN 1;
 
+EXPLAIN ANALYZE MATCH ()-[]->() RETURN 1;
 
 MATCH ()-[]->() RETURN 1;
 
@@ -57,11 +58,13 @@ SELECT * FROM cypher_create._adj__adj__ag_label_vertex;
 SELECT * FROM cypher_create._adj__ag_label_vertex;
 MATCH () RETURN 1;
 
+
 CYPHER WITH 1 as a
 CREATE ();
 
 CREATE () RETURN 1 as a;
 
+
 --
 -- Clean up
 --

src/backend/access/vertex_heap/vertex_hash_search.c

@@ -34,100 +34,6 @@ static void vertex_hash_readnext(TableScanDesc scan, Buffer *bufp,
 						   Page *pagep, HashPageOpaque *opaquep);
 static void vertex_hash_kill_items(TableScanDesc scan);
 
-/*
- *	vertex_hash_next() -- Get the next item in a scan.
- *
- *		On entry, so->currPos describes the current page, which may
- *		be pinned but not locked, and so->currPos.itemIndex identifies
- *		which item was previously returned.
- *
- *		On successful exit, scan->xs_ctup.t_self is set to the TID
- *		of the next heap tuple. so->currPos is updated as needed.
- *
- *		On failure exit (no more tuples), we return false with pin
- *		held on bucket page but no pins or locks held on overflow
- *		page.
- */
-bool
-vertex_hash_next(TableScanDesc scan, ScanDirection dir)
-{
-	Relation	rel = scan->rs_rd;
-	VertexHeapScanDesc so = (VertexHeapScanDesc) scan;
-	HashScanPosItem *currItem;
-	BlockNumber blkno;
-	Buffer		buf;
-	bool		end_of_scan = false;
-
-	/*
-	 * Advance to the next tuple on the current page; or if done, try to read
-	 * data from the next or previous page based on the scan direction. Before
-	 * moving to the next or previous page make sure that we deal with all the
-	 * killed items.
-	 */
-	if (ScanDirectionIsForward(dir))
-	{
-		if (++so->currPos.itemIndex > so->currPos.lastItem)
-		{
-			if (so->numKilled > 0)
-				vertex_hash_kill_items(scan);
-
-			blkno = so->currPos.nextPage;
-			if (BlockNumberIsValid(blkno))
-			{
-				buf = _hash_getbuf(rel, blkno, HASH_READ, LH_OVERFLOW_PAGE);
-				TestForOldSnapshot(scan->rs_snapshot, rel, BufferGetPage(buf));
-				if (!vertex_hash_readpage(scan, &buf, dir))
-					end_of_scan = true;
-			}
-			else
-				end_of_scan = true;
-		}
-	}
-	else
-	{
-		if (--so->currPos.itemIndex < so->currPos.firstItem)
-		{
-			if (so->numKilled > 0)
-				vertex_hash_kill_items(scan);
-
-			blkno = so->currPos.prevPage;
-			if (BlockNumberIsValid(blkno))
-			{
-				buf = _hash_getbuf(rel, blkno, HASH_READ,
-								   LH_BUCKET_PAGE | LH_OVERFLOW_PAGE);
-				TestForOldSnapshot(scan->rs_snapshot, rel, BufferGetPage(buf));
-
-				/*
-				 * We always maintain the pin on bucket page for whole scan
-				 * operation, so releasing the additional pin we have acquired
-				 * here.
-				 */
-				if (buf == so->hashso_bucket_buf ||
-					buf == so->hashso_split_bucket_buf)
-					_hash_dropbuf(rel, buf);
-
-				if (!vertex_hash_readpage(scan, &buf, dir))
-					end_of_scan = true;
-			}
-			else
-				end_of_scan = true;
-		}
-	}
-
-	if (end_of_scan)
-	{
-		//_hash_dropscanbuf(rel,( TableScanDesc)so); TODO
-		HashScanPosInvalidate(so->currPos);
-		return false;
-	}
-
-	/* OK, itemIndex says what to return */
-	currItem = &so->currPos.items[so->currPos.itemIndex];
-	//scan->xs_heaptid = currItem->heapTid;
-
-	return true;
-}
-
 /*
  * Advance to next page in a bucket, if any.  If we are scanning the bucket
  * being populated during split operation then this function advances to the