C++ (Cpp) build_pgstattuple_type Examples

Example #1

File: pgstattuple.c Project: gencer/postgres

/*
 * pgstat_index -- returns live/dead tuples info in a generic index
 */
static Datum
pgstat_index(Relation rel, BlockNumber start, pgstat_page pagefn,
			 FunctionCallInfo fcinfo)
{
	BlockNumber nblocks;
	BlockNumber blkno;
	BufferAccessStrategy bstrategy;
	pgstattuple_type stat = {0};

	/* prepare access strategy for this index */
	bstrategy = GetAccessStrategy(BAS_BULKREAD);

	blkno = start;
	for (;;)
	{
		/* Get the current relation length */
		LockRelationForExtension(rel, ExclusiveLock);
		nblocks = RelationGetNumberOfBlocks(rel);
		UnlockRelationForExtension(rel, ExclusiveLock);

		/* Quit if we've scanned the whole relation */
		if (blkno >= nblocks)
		{
			stat.table_len = (uint64) nblocks *BLCKSZ;

			break;
		}

		for (; blkno < nblocks; blkno++)
		{
			CHECK_FOR_INTERRUPTS();

			pagefn(&stat, rel, blkno, bstrategy);
		}
	}

	relation_close(rel, AccessShareLock);

	return build_pgstattuple_type(&stat, fcinfo);
}

Example #2

File: pgstattuple.c Project: markwkm/postgres

/*
 * pgstat_heap -- returns live/dead tuples info in a heap
 */
static Datum
pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
{
	HeapScanDesc scan;
	HeapTuple	tuple;
	BlockNumber nblocks;
	BlockNumber block = 0;		/* next block to count free space in */
	BlockNumber tupblock;
	Buffer		buffer;
	pgstattuple_type stat = {0};

	/* Disable syncscan because we assume we scan from block zero upwards */
	scan = heap_beginscan_strat(rel, SnapshotAny, 0, NULL, true, false);

	nblocks = scan->rs_nblocks; /* # blocks to be scanned */

	/* scan the relation */
	while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
	{
		CHECK_FOR_INTERRUPTS();

		/* must hold a buffer lock to call HeapTupleSatisfiesVisibility */
		LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);

		if (HeapTupleSatisfiesVisibility(tuple, SnapshotNow, scan->rs_cbuf))
		{
			stat.tuple_len += tuple->t_len;
			stat.tuple_count++;
		}
		else
		{
			stat.dead_tuple_len += tuple->t_len;
			stat.dead_tuple_count++;
		}

		LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);

		/*
		 * To avoid physically reading the table twice, try to do the
		 * free-space scan in parallel with the heap scan.	However,
		 * heap_getnext may find no tuples on a given page, so we cannot
		 * simply examine the pages returned by the heap scan.
		 */
		tupblock = BlockIdGetBlockNumber(&tuple->t_self.ip_blkid);

		while (block <= tupblock)
		{
			CHECK_FOR_INTERRUPTS();

			buffer = ReadBuffer(rel, block);
			LockBuffer(buffer, BUFFER_LOCK_SHARE);
			stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
			UnlockReleaseBuffer(buffer);
			block++;
		}
	}
	heap_endscan(scan);

	while (block < nblocks)
	{
		CHECK_FOR_INTERRUPTS();

		buffer = ReadBuffer(rel, block);
		LockBuffer(buffer, BUFFER_LOCK_SHARE);
		stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
		UnlockReleaseBuffer(buffer);
		block++;
	}

	relation_close(rel, AccessShareLock);

	stat.table_len = (uint64) nblocks *BLCKSZ;

	return build_pgstattuple_type(&stat, fcinfo);
}