/* * 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); }
/* * 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); }