diff options
Diffstat (limited to 'contrib/pgstattuple/pgstatindex.c')
| -rw-r--r-- | contrib/pgstattuple/pgstatindex.c | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/contrib/pgstattuple/pgstatindex.c b/contrib/pgstattuple/pgstatindex.c index b40669250ad..17a53e3bb7d 100644 --- a/contrib/pgstattuple/pgstatindex.c +++ b/contrib/pgstattuple/pgstatindex.c @@ -29,6 +29,7 @@ #include "access/gin_private.h" #include "access/heapam.h" +#include "access/hash.h" #include "access/htup_details.h" #include "access/nbtree.h" #include "catalog/namespace.h" @@ -36,6 +37,7 @@ #include "funcapi.h" #include "miscadmin.h" #include "storage/bufmgr.h" +#include "storage/lmgr.h" #include "utils/builtins.h" #include "utils/rel.h" #include "utils/varlena.h" @@ -54,6 +56,7 @@ PG_FUNCTION_INFO_V1(pgstatindexbyid); PG_FUNCTION_INFO_V1(pg_relpages); PG_FUNCTION_INFO_V1(pg_relpagesbyid); PG_FUNCTION_INFO_V1(pgstatginindex); +PG_FUNCTION_INFO_V1(pgstathashindex); PG_FUNCTION_INFO_V1(pgstatindex_v1_5); PG_FUNCTION_INFO_V1(pgstatindexbyid_v1_5); @@ -66,6 +69,7 @@ Datum pgstatginindex_internal(Oid relid, FunctionCallInfo fcinfo); #define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX) #define IS_BTREE(r) ((r)->rd_rel->relam == BTREE_AM_OID) #define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID) +#define IS_HASH(r) ((r)->rd_rel->relam == HASH_AM_OID) /* ------------------------------------------------ * A structure for a whole btree index statistics @@ -102,7 +106,29 @@ typedef struct GinIndexStat int64 pending_tuples; } GinIndexStat; +/* ------------------------------------------------ + * A structure for a whole HASH index statistics + * used by pgstathashindex(). + * ------------------------------------------------ + */ +typedef struct HashIndexStat +{ + int32 version; + int32 space_per_page; + + BlockNumber bucket_pages; + BlockNumber overflow_pages; + BlockNumber bitmap_pages; + BlockNumber zero_pages; + + int64 live_items; + int64 dead_items; + uint64 free_space; +} HashIndexStat; + static Datum pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo); +static void GetHashPageStats(Page page, HashIndexStat *stats); + /* ------------------------------------------------------ * pgstatindex() @@ -528,3 +554,172 @@ pgstatginindex_internal(Oid relid, FunctionCallInfo fcinfo) return (result); } + +/* ------------------------------------------------------ + * pgstathashindex() + * + * Usage: SELECT * FROM pgstathashindex('hashindex'); + * ------------------------------------------------------ + */ +Datum +pgstathashindex(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + BlockNumber nblocks; + BlockNumber blkno; + Relation rel; + HashIndexStat stats; + BufferAccessStrategy bstrategy; + HeapTuple tuple; + TupleDesc tupleDesc; + Datum values[8]; + bool nulls[8]; + Buffer metabuf; + HashMetaPage metap; + float8 free_percent; + uint64 total_space; + + rel = index_open(relid, AccessShareLock); + + if (!IS_HASH(rel)) + elog(ERROR, "relation \"%s\" is not a HASH index", + RelationGetRelationName(rel)); + + /* + * Reject attempts to read non-local temporary relations; we would be + * likely to get wrong data since we have no visibility into the owning + * session's local buffers. + */ + if (RELATION_IS_OTHER_TEMP(rel)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot access temporary indexes of other sessions"))); + + /* Get the information we need from the metapage. */ + memset(&stats, 0, sizeof(stats)); + metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE); + metap = HashPageGetMeta(BufferGetPage(metabuf)); + stats.version = metap->hashm_version; + stats.space_per_page = metap->hashm_bsize; + _hash_relbuf(rel, metabuf); + + /* Get the current relation length */ + nblocks = RelationGetNumberOfBlocks(rel); + + /* prepare access strategy for this index */ + bstrategy = GetAccessStrategy(BAS_BULKREAD); + + /* Start from blkno 1 as 0th block is metapage */ + for (blkno = 1; blkno < nblocks; blkno++) + { + Buffer buf; + Page page; + HashPageOpaque opaque; + + CHECK_FOR_INTERRUPTS(); + + buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, + bstrategy); + LockBuffer(buf, BUFFER_LOCK_SHARE); + page = (Page) BufferGetPage(buf); + + if (PageIsNew(page)) + stats.zero_pages++; + else if (PageGetSpecialSize(page) != + MAXALIGN(sizeof(HashPageOpaqueData))) + ereport(ERROR, + (errcode(ERRCODE_INDEX_CORRUPTED), + errmsg("index \"%s\" contains corrupted page at block %u", + RelationGetRelationName(rel), + BufferGetBlockNumber(buf)))); + else + { + opaque = (HashPageOpaque) PageGetSpecialPointer(page); + if (opaque->hasho_flag & LH_BUCKET_PAGE) + { + stats.bucket_pages++; + GetHashPageStats(page, &stats); + } + else if (opaque->hasho_flag & LH_OVERFLOW_PAGE) + { + stats.overflow_pages++; + GetHashPageStats(page, &stats); + } + else if (opaque->hasho_flag & LH_BITMAP_PAGE) + stats.bitmap_pages++; + else + ereport(ERROR, + (errcode(ERRCODE_INDEX_CORRUPTED), + errmsg("unexpected page type 0x%04X in HASH index \"%s\" block %u", + opaque->hasho_flag, RelationGetRelationName(rel), + BufferGetBlockNumber(buf)))); + } + UnlockReleaseBuffer(buf); + } + + /* Done accessing the index */ + index_close(rel, AccessShareLock); + + /* Count zero pages as free space. */ + stats.free_space += stats.zero_pages * stats.space_per_page; + + /* + * Total space available for tuples excludes the metapage and the bitmap + * pages. + */ + total_space = (nblocks - (stats.bitmap_pages + 1)) * stats.space_per_page; + + if (total_space == 0) + free_percent = 0.0; + else + free_percent = 100.0 * stats.free_space / total_space; + + /* + * Build a tuple descriptor for our result type + */ + if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE) + elog(ERROR, "return type must be a row type"); + + tupleDesc = BlessTupleDesc(tupleDesc); + + /* + * Build and return the tuple + */ + MemSet(nulls, 0, sizeof(nulls)); + values[0] = Int32GetDatum(stats.version); + values[1] = Int64GetDatum((int64) stats.bucket_pages); + values[2] = Int64GetDatum((int64) stats.overflow_pages); + values[3] = Int64GetDatum((int64) stats.bitmap_pages); + values[4] = Int64GetDatum((int64) stats.zero_pages); + values[5] = Int64GetDatum(stats.live_items); + values[6] = Int64GetDatum(stats.dead_items); + values[7] = Float8GetDatum(free_percent); + tuple = heap_form_tuple(tupleDesc, values, nulls); + + PG_RETURN_DATUM(HeapTupleGetDatum(tuple)); +} + +/* ------------------------------------------------- + * GetHashPageStatis() + * + * Collect statistics of single hash page + * ------------------------------------------------- + */ +static void +GetHashPageStats(Page page, HashIndexStat *stats) +{ + OffsetNumber maxoff = PageGetMaxOffsetNumber(page); + int off; + + /* count live and dead tuples, and free space */ + for (off = FirstOffsetNumber; off <= maxoff; off++) + { + ItemId id = PageGetItemId(page, off); + + if (!ItemIdIsDead(id)) + stats->live_items++; + else + stats->dead_items++; + } + stats->free_space += PageGetExactFreeSpace(page); +} |