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Diffstat (limited to 'contrib/pgstattuple/pgstatindex.c')
| -rw-r--r-- | contrib/pgstattuple/pgstatindex.c | 761 |
1 files changed, 761 insertions, 0 deletions
diff --git a/contrib/pgstattuple/pgstatindex.c b/contrib/pgstattuple/pgstatindex.c new file mode 100644 index 0000000..5c06ba6 --- /dev/null +++ b/contrib/pgstattuple/pgstatindex.c @@ -0,0 +1,761 @@ +/* + * contrib/pgstattuple/pgstatindex.c + * + * + * pgstatindex + * + * Copyright (c) 2006 Satoshi Nagayasu <nagayasus@nttdata.co.jp> + * + * Permission to use, copy, modify, and distribute this software and + * its documentation for any purpose, without fee, and without a + * written agreement is hereby granted, provided that the above + * copyright notice and this paragraph and the following two + * paragraphs appear in all copies. + * + * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT, + * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING + * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS + * DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + * + * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS + * IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, + * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. + */ + +#include "postgres.h" + +#include "access/gin_private.h" +#include "access/hash.h" +#include "access/htup_details.h" +#include "access/nbtree.h" +#include "access/relation.h" +#include "access/table.h" +#include "catalog/namespace.h" +#include "catalog/pg_am.h" +#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" + + +/* + * Because of backward-compatibility issue, we have decided to have + * two types of interfaces, with regclass-type input arg and text-type + * input arg, for each function. + * + * Those functions which have text-type input arg will be deprecated + * in the future release. + */ +PG_FUNCTION_INFO_V1(pgstatindex); +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); +PG_FUNCTION_INFO_V1(pg_relpages_v1_5); +PG_FUNCTION_INFO_V1(pg_relpagesbyid_v1_5); +PG_FUNCTION_INFO_V1(pgstatginindex_v1_5); + +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 + * used by pgstatindex(). + * ------------------------------------------------ + */ +typedef struct BTIndexStat +{ + uint32 version; + uint32 level; + BlockNumber root_blkno; + + uint64 internal_pages; + uint64 leaf_pages; + uint64 empty_pages; + uint64 deleted_pages; + + uint64 max_avail; + uint64 free_space; + + uint64 fragments; +} BTIndexStat; + +/* ------------------------------------------------ + * A structure for a whole GIN index statistics + * used by pgstatginindex(). + * ------------------------------------------------ + */ +typedef struct GinIndexStat +{ + int32 version; + + BlockNumber pending_pages; + 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 unused_pages; + + int64 live_items; + int64 dead_items; + uint64 free_space; +} HashIndexStat; + +static Datum pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo); +static int64 pg_relpages_impl(Relation rel); +static void GetHashPageStats(Page page, HashIndexStat *stats); + +/* ------------------------------------------------------ + * pgstatindex() + * + * Usage: SELECT * FROM pgstatindex('t1_pkey'); + * + * The superuser() check here must be kept as the library might be upgraded + * without the extension being upgraded, meaning that in pre-1.5 installations + * these functions could be called by any user. + * ------------------------------------------------------ + */ +Datum +pgstatindex(PG_FUNCTION_ARGS) +{ + text *relname = PG_GETARG_TEXT_PP(0); + Relation rel; + RangeVar *relrv; + + if (!superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("must be superuser to use pgstattuple functions"))); + + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); + rel = relation_openrv(relrv, AccessShareLock); + + PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo)); +} + +/* + * As of pgstattuple version 1.5, we no longer need to check if the user + * is a superuser because we REVOKE EXECUTE on the function from PUBLIC. + * Users can then grant access to it based on their policies. + * + * Otherwise identical to pgstatindex (above). + */ +Datum +pgstatindex_v1_5(PG_FUNCTION_ARGS) +{ + text *relname = PG_GETARG_TEXT_PP(0); + Relation rel; + RangeVar *relrv; + + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); + rel = relation_openrv(relrv, AccessShareLock); + + PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo)); +} + +/* + * The superuser() check here must be kept as the library might be upgraded + * without the extension being upgraded, meaning that in pre-1.5 installations + * these functions could be called by any user. + */ +Datum +pgstatindexbyid(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + Relation rel; + + if (!superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("must be superuser to use pgstattuple functions"))); + + rel = relation_open(relid, AccessShareLock); + + PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo)); +} + +/* No need for superuser checks in v1.5, see above */ +Datum +pgstatindexbyid_v1_5(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + Relation rel; + + rel = relation_open(relid, AccessShareLock); + + PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo)); +} + +static Datum +pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo) +{ + Datum result; + BlockNumber nblocks; + BlockNumber blkno; + BTIndexStat indexStat; + BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD); + + if (!IS_INDEX(rel) || !IS_BTREE(rel)) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("relation \"%s\" is not a btree 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 tables of other sessions"))); + + /* + * A !indisready index could lead to ERRCODE_DATA_CORRUPTED later, so exit + * early. We're capable of assessing an indisready&&!indisvalid index, + * but the results could be confusing. For example, the index's size + * could be too low for a valid index of the table. + */ + if (!rel->rd_index->indisvalid) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("index \"%s\" is not valid", + RelationGetRelationName(rel)))); + + /* + * Read metapage + */ + { + Buffer buffer = ReadBufferExtended(rel, MAIN_FORKNUM, 0, RBM_NORMAL, bstrategy); + Page page = BufferGetPage(buffer); + BTMetaPageData *metad = BTPageGetMeta(page); + + indexStat.version = metad->btm_version; + indexStat.level = metad->btm_level; + indexStat.root_blkno = metad->btm_root; + + ReleaseBuffer(buffer); + } + + /* -- init counters -- */ + indexStat.internal_pages = 0; + indexStat.leaf_pages = 0; + indexStat.empty_pages = 0; + indexStat.deleted_pages = 0; + + indexStat.max_avail = 0; + indexStat.free_space = 0; + + indexStat.fragments = 0; + + /* + * Scan all blocks except the metapage + */ + nblocks = RelationGetNumberOfBlocks(rel); + + for (blkno = 1; blkno < nblocks; blkno++) + { + Buffer buffer; + Page page; + BTPageOpaque opaque; + + CHECK_FOR_INTERRUPTS(); + + /* Read and lock buffer */ + buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy); + LockBuffer(buffer, BUFFER_LOCK_SHARE); + + page = BufferGetPage(buffer); + opaque = BTPageGetOpaque(page); + + /* + * Determine page type, and update totals. + * + * Note that we arbitrarily bucket deleted pages together without + * considering if they're leaf pages or internal pages. + */ + if (P_ISDELETED(opaque)) + indexStat.deleted_pages++; + else if (P_IGNORE(opaque)) + indexStat.empty_pages++; /* this is the "half dead" state */ + else if (P_ISLEAF(opaque)) + { + int max_avail; + + max_avail = BLCKSZ - (BLCKSZ - ((PageHeader) page)->pd_special + SizeOfPageHeaderData); + indexStat.max_avail += max_avail; + indexStat.free_space += PageGetFreeSpace(page); + + indexStat.leaf_pages++; + + /* + * If the next leaf is on an earlier block, it means a + * fragmentation. + */ + if (opaque->btpo_next != P_NONE && opaque->btpo_next < blkno) + indexStat.fragments++; + } + else + indexStat.internal_pages++; + + /* Unlock and release buffer */ + LockBuffer(buffer, BUFFER_LOCK_UNLOCK); + ReleaseBuffer(buffer); + } + + relation_close(rel, AccessShareLock); + + /*---------------------------- + * Build a result tuple + *---------------------------- + */ + { + TupleDesc tupleDesc; + int j; + char *values[10]; + HeapTuple tuple; + + /* 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"); + + j = 0; + values[j++] = psprintf("%d", indexStat.version); + values[j++] = psprintf("%d", indexStat.level); + values[j++] = psprintf(INT64_FORMAT, + (1 + /* include the metapage in index_size */ + indexStat.leaf_pages + + indexStat.internal_pages + + indexStat.deleted_pages + + indexStat.empty_pages) * BLCKSZ); + values[j++] = psprintf("%u", indexStat.root_blkno); + values[j++] = psprintf(INT64_FORMAT, indexStat.internal_pages); + values[j++] = psprintf(INT64_FORMAT, indexStat.leaf_pages); + values[j++] = psprintf(INT64_FORMAT, indexStat.empty_pages); + values[j++] = psprintf(INT64_FORMAT, indexStat.deleted_pages); + if (indexStat.max_avail > 0) + values[j++] = psprintf("%.2f", + 100.0 - (double) indexStat.free_space / (double) indexStat.max_avail * 100.0); + else + values[j++] = pstrdup("NaN"); + if (indexStat.leaf_pages > 0) + values[j++] = psprintf("%.2f", + (double) indexStat.fragments / (double) indexStat.leaf_pages * 100.0); + else + values[j++] = pstrdup("NaN"); + + tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc), + values); + + result = HeapTupleGetDatum(tuple); + } + + return result; +} + +/* -------------------------------------------------------- + * pg_relpages() + * + * Get the number of pages of the table/index. + * + * Usage: SELECT pg_relpages('t1'); + * SELECT pg_relpages('t1_pkey'); + * + * Must keep superuser() check, see above. + * -------------------------------------------------------- + */ +Datum +pg_relpages(PG_FUNCTION_ARGS) +{ + text *relname = PG_GETARG_TEXT_PP(0); + Relation rel; + RangeVar *relrv; + + if (!superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("must be superuser to use pgstattuple functions"))); + + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); + rel = relation_openrv(relrv, AccessShareLock); + + PG_RETURN_INT64(pg_relpages_impl(rel)); +} + +/* No need for superuser checks in v1.5, see above */ +Datum +pg_relpages_v1_5(PG_FUNCTION_ARGS) +{ + text *relname = PG_GETARG_TEXT_PP(0); + Relation rel; + RangeVar *relrv; + + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); + rel = relation_openrv(relrv, AccessShareLock); + + PG_RETURN_INT64(pg_relpages_impl(rel)); +} + +/* Must keep superuser() check, see above. */ +Datum +pg_relpagesbyid(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + Relation rel; + + if (!superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("must be superuser to use pgstattuple functions"))); + + rel = relation_open(relid, AccessShareLock); + + PG_RETURN_INT64(pg_relpages_impl(rel)); +} + +/* No need for superuser checks in v1.5, see above */ +Datum +pg_relpagesbyid_v1_5(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + Relation rel; + + rel = relation_open(relid, AccessShareLock); + + PG_RETURN_INT64(pg_relpages_impl(rel)); +} + +static int64 +pg_relpages_impl(Relation rel) +{ + int64 relpages; + + if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("cannot get page count of relation \"%s\"", + RelationGetRelationName(rel)), + errdetail_relkind_not_supported(rel->rd_rel->relkind))); + + /* note: this will work OK on non-local temp tables */ + + relpages = RelationGetNumberOfBlocks(rel); + + relation_close(rel, AccessShareLock); + + return relpages; +} + +/* ------------------------------------------------------ + * pgstatginindex() + * + * Usage: SELECT * FROM pgstatginindex('ginindex'); + * + * Must keep superuser() check, see above. + * ------------------------------------------------------ + */ +Datum +pgstatginindex(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + + if (!superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("must be superuser to use pgstattuple functions"))); + + PG_RETURN_DATUM(pgstatginindex_internal(relid, fcinfo)); +} + +/* No need for superuser checks in v1.5, see above */ +Datum +pgstatginindex_v1_5(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + + PG_RETURN_DATUM(pgstatginindex_internal(relid, fcinfo)); +} + +Datum +pgstatginindex_internal(Oid relid, FunctionCallInfo fcinfo) +{ + Relation rel; + Buffer buffer; + Page page; + GinMetaPageData *metadata; + GinIndexStat stats; + HeapTuple tuple; + TupleDesc tupleDesc; + Datum values[3]; + bool nulls[3] = {false, false, false}; + Datum result; + + rel = relation_open(relid, AccessShareLock); + + if (!IS_INDEX(rel) || !IS_GIN(rel)) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("relation \"%s\" is not a GIN 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"))); + + /* see pgstatindex_impl */ + if (!rel->rd_index->indisvalid) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("index \"%s\" is not valid", + RelationGetRelationName(rel)))); + + /* + * Read metapage + */ + buffer = ReadBuffer(rel, GIN_METAPAGE_BLKNO); + LockBuffer(buffer, GIN_SHARE); + page = BufferGetPage(buffer); + metadata = GinPageGetMeta(page); + + stats.version = metadata->ginVersion; + stats.pending_pages = metadata->nPendingPages; + stats.pending_tuples = metadata->nPendingHeapTuples; + + UnlockReleaseBuffer(buffer); + relation_close(rel, AccessShareLock); + + /* + * 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"); + + values[0] = Int32GetDatum(stats.version); + values[1] = UInt32GetDatum(stats.pending_pages); + values[2] = Int64GetDatum(stats.pending_tuples); + + /* + * Build and return the tuple + */ + tuple = heap_form_tuple(tupleDesc, values, nulls); + result = HeapTupleGetDatum(tuple); + + 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] = {0}; + Buffer metabuf; + HashMetaPage metap; + float8 free_percent; + uint64 total_space; + + rel = relation_open(relid, AccessShareLock); + + if (!IS_INDEX(rel) || !IS_HASH(rel)) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("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"))); + + /* see pgstatindex_impl */ + if (!rel->rd_index->indisvalid) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("index \"%s\" is not valid", + RelationGetRelationName(rel)))); + + /* 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; + + 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.unused_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 + { + HashPageOpaque opaque; + int pagetype; + + opaque = HashPageGetOpaque(page); + pagetype = opaque->hasho_flag & LH_PAGE_TYPE; + + if (pagetype == LH_BUCKET_PAGE) + { + stats.bucket_pages++; + GetHashPageStats(page, &stats); + } + else if (pagetype == LH_OVERFLOW_PAGE) + { + stats.overflow_pages++; + GetHashPageStats(page, &stats); + } + else if (pagetype == LH_BITMAP_PAGE) + stats.bitmap_pages++; + else if (pagetype == LH_UNUSED_PAGE) + stats.unused_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 unused pages as free space. */ + stats.free_space += (uint64) stats.unused_pages * stats.space_per_page; + + /* + * Total space available for tuples excludes the metapage and the bitmap + * pages. + */ + total_space = (uint64) (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 + */ + 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.unused_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)); +} + +/* ------------------------------------------------- + * GetHashPageStats() + * + * 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); +} |