diff options
| -rw-r--r-- | contrib/pgstattuple/README.pgstattuple | 4 | ||||
| -rw-r--r-- | contrib/pgstattuple/pgstattuple.c | 54 |
2 files changed, 38 insertions, 20 deletions
diff --git a/contrib/pgstattuple/README.pgstattuple b/contrib/pgstattuple/README.pgstattuple index c54f97e82f5..6a191e9cced 100644 --- a/contrib/pgstattuple/README.pgstattuple +++ b/contrib/pgstattuple/README.pgstattuple @@ -15,7 +15,7 @@ NOTICE: physical length: 0.08MB live tuples: 20 (0.00MB, 1.17%) dead tuples: 32 18.75 (1 row) - Above example shows tellers tables includes 18.75% dead tuples. + Above example shows tellers table includes 18.75% dead tuples. physical length physical size of the table in MB live tuples information on the live tuples @@ -40,7 +40,7 @@ NOTICE: physical length: 0.08MB live tuples: 20 (0.00MB, 1.17%) dead tuples: 32 4. Notes - pgstattuple does not lock the target table at all. So concurrent + pgstattuple acquires only a read lock on the table. So concurrent update may affect the result. pgstattuple judges a tuple is "dead" if HeapTupleSatisfiesNow() diff --git a/contrib/pgstattuple/pgstattuple.c b/contrib/pgstattuple/pgstattuple.c index 45e92298100..b5afab80de1 100644 --- a/contrib/pgstattuple/pgstattuple.c +++ b/contrib/pgstattuple/pgstattuple.c @@ -1,5 +1,5 @@ /* - * $Header: /cvsroot/pgsql/contrib/pgstattuple/pgstattuple.c,v 1.2 2001/10/25 05:49:20 momjian Exp $ + * $Header: /cvsroot/pgsql/contrib/pgstattuple/pgstattuple.c,v 1.3 2001/12/19 20:28:41 tgl Exp $ * * Copyright (c) 2001 Tatsuo Ishii * @@ -23,6 +23,7 @@ */ #include "postgres.h" + #include "fmgr.h" #include "access/heapam.h" #include "access/transam.h" @@ -48,20 +49,21 @@ pgstattuple(PG_FUNCTION_ARGS) HeapScanDesc scan; HeapTuple tuple; BlockNumber nblocks; - BlockNumber block = InvalidBlockNumber; + BlockNumber block = 0; /* next block to count free space in */ + BlockNumber tupblock; + Buffer buffer; double table_len; uint64 tuple_len = 0; uint64 dead_tuple_len = 0; - uint32 tuple_count = 0; - uint32 dead_tuple_count = 0; + uint64 tuple_count = 0; + uint64 dead_tuple_count = 0; double tuple_percent; double dead_tuple_percent; - Buffer buffer = InvalidBuffer; uint64 free_space = 0; /* free/reusable space in bytes */ double free_percent; /* free/reusable space in % */ - rel = heap_openr(NameStr(*p), NoLock); + rel = heap_openr(NameStr(*p), AccessShareLock); nblocks = RelationGetNumberOfBlocks(rel); scan = heap_beginscan(rel, false, SnapshotAny, 0, NULL); @@ -78,17 +80,33 @@ pgstattuple(PG_FUNCTION_ARGS) dead_tuple_count++; } - if (!BlockNumberIsValid(block) || - block != BlockIdGetBlockNumber(&tuple->t_self.ip_blkid)) + /* + * 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) { - block = BlockIdGetBlockNumber(&tuple->t_self.ip_blkid); buffer = ReadBuffer(rel, block); free_space += PageGetFreeSpace((Page) BufferGetPage(buffer)); ReleaseBuffer(buffer); + block++; } } heap_endscan(scan); - heap_close(rel, NoLock); + + while (block < nblocks) + { + buffer = ReadBuffer(rel, block); + free_space += PageGetFreeSpace((Page) BufferGetPage(buffer)); + ReleaseBuffer(buffer); + block++; + } + + heap_close(rel, AccessShareLock); table_len = (double) nblocks *BLCKSZ; @@ -105,20 +123,20 @@ pgstattuple(PG_FUNCTION_ARGS) free_percent = (double) free_space *100.0 / table_len; } - elog(NOTICE, "physical length: %.2fMB live tuples: %u (%.2fMB, %.2f%%) dead tuples: %u (%.2fMB, %.2f%%) free/reusable space: %.2fMB (%.2f%%) overhead: %.2f%%", + elog(NOTICE, "physical length: %.2fMB live tuples: %.0f (%.2fMB, %.2f%%) dead tuples: %.0f (%.2fMB, %.2f%%) free/reusable space: %.2fMB (%.2f%%) overhead: %.2f%%", - table_len / 1024 / 1024, /* phsical length in MB */ + table_len / (1024 * 1024), /* physical length in MB */ - tuple_count, /* number of live tuples */ - (double) tuple_len / 1024 / 1024, /* live tuples in MB */ + (double) tuple_count, /* number of live tuples */ + (double) tuple_len / (1024 * 1024), /* live tuples in MB */ tuple_percent, /* live tuples in % */ - dead_tuple_count, /* number of dead tuples */ - (double) dead_tuple_len / 1024 / 1024, /* dead tuples in MB */ + (double) dead_tuple_count, /* number of dead tuples */ + (double) dead_tuple_len / (1024 * 1024), /* dead tuples in MB */ dead_tuple_percent, /* dead tuples in % */ - (double) free_space / 1024 / 1024, /* free/available space in - * MB */ + (double) free_space / (1024 * 1024), /* free/available space in + * MB */ free_percent, /* free/available space in % */ |