LCOV - code coverage report
Current view: top level - contrib/pgstattuple - pgstatindex.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17beta1 Lines: 160 235 68.1 %
Date: 2024-06-17 23:11:01 Functions: 21 26 80.8 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*
       2             :  * contrib/pgstattuple/pgstatindex.c
       3             :  *
       4             :  *
       5             :  * pgstatindex
       6             :  *
       7             :  * Copyright (c) 2006 Satoshi Nagayasu <nagayasus@nttdata.co.jp>
       8             :  *
       9             :  * Permission to use, copy, modify, and distribute this software and
      10             :  * its documentation for any purpose, without fee, and without a
      11             :  * written agreement is hereby granted, provided that the above
      12             :  * copyright notice and this paragraph and the following two
      13             :  * paragraphs appear in all copies.
      14             :  *
      15             :  * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
      16             :  * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
      17             :  * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
      18             :  * DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
      19             :  * OF THE POSSIBILITY OF SUCH DAMAGE.
      20             :  *
      21             :  * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
      22             :  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
      23             :  * A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
      24             :  * IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
      25             :  * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
      26             :  */
      27             : 
      28             : #include "postgres.h"
      29             : 
      30             : #include "access/gin_private.h"
      31             : #include "access/hash.h"
      32             : #include "access/htup_details.h"
      33             : #include "access/nbtree.h"
      34             : #include "access/relation.h"
      35             : #include "access/table.h"
      36             : #include "catalog/namespace.h"
      37             : #include "catalog/pg_am.h"
      38             : #include "funcapi.h"
      39             : #include "miscadmin.h"
      40             : #include "storage/bufmgr.h"
      41             : #include "storage/lmgr.h"
      42             : #include "utils/builtins.h"
      43             : #include "utils/rel.h"
      44             : #include "utils/varlena.h"
      45             : 
      46             : 
      47             : /*
      48             :  * Because of backward-compatibility issue, we have decided to have
      49             :  * two types of interfaces, with regclass-type input arg and text-type
      50             :  * input arg, for each function.
      51             :  *
      52             :  * Those functions which have text-type input arg will be deprecated
      53             :  * in the future release.
      54             :  */
      55           2 : PG_FUNCTION_INFO_V1(pgstatindex);
      56           2 : PG_FUNCTION_INFO_V1(pgstatindexbyid);
      57           2 : PG_FUNCTION_INFO_V1(pg_relpages);
      58           2 : PG_FUNCTION_INFO_V1(pg_relpagesbyid);
      59           2 : PG_FUNCTION_INFO_V1(pgstatginindex);
      60           4 : PG_FUNCTION_INFO_V1(pgstathashindex);
      61             : 
      62           4 : PG_FUNCTION_INFO_V1(pgstatindex_v1_5);
      63           4 : PG_FUNCTION_INFO_V1(pgstatindexbyid_v1_5);
      64           4 : PG_FUNCTION_INFO_V1(pg_relpages_v1_5);
      65           4 : PG_FUNCTION_INFO_V1(pg_relpagesbyid_v1_5);
      66           4 : PG_FUNCTION_INFO_V1(pgstatginindex_v1_5);
      67             : 
      68             : Datum       pgstatginindex_internal(Oid relid, FunctionCallInfo fcinfo);
      69             : 
      70             : #define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
      71             : #define IS_BTREE(r) ((r)->rd_rel->relam == BTREE_AM_OID)
      72             : #define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
      73             : #define IS_HASH(r) ((r)->rd_rel->relam == HASH_AM_OID)
      74             : 
      75             : /* ------------------------------------------------
      76             :  * A structure for a whole btree index statistics
      77             :  * used by pgstatindex().
      78             :  * ------------------------------------------------
      79             :  */
      80             : typedef struct BTIndexStat
      81             : {
      82             :     uint32      version;
      83             :     uint32      level;
      84             :     BlockNumber root_blkno;
      85             : 
      86             :     uint64      internal_pages;
      87             :     uint64      leaf_pages;
      88             :     uint64      empty_pages;
      89             :     uint64      deleted_pages;
      90             : 
      91             :     uint64      max_avail;
      92             :     uint64      free_space;
      93             : 
      94             :     uint64      fragments;
      95             : } BTIndexStat;
      96             : 
      97             : /* ------------------------------------------------
      98             :  * A structure for a whole GIN index statistics
      99             :  * used by pgstatginindex().
     100             :  * ------------------------------------------------
     101             :  */
     102             : typedef struct GinIndexStat
     103             : {
     104             :     int32       version;
     105             : 
     106             :     BlockNumber pending_pages;
     107             :     int64       pending_tuples;
     108             : } GinIndexStat;
     109             : 
     110             : /* ------------------------------------------------
     111             :  * A structure for a whole HASH index statistics
     112             :  * used by pgstathashindex().
     113             :  * ------------------------------------------------
     114             :  */
     115             : typedef struct HashIndexStat
     116             : {
     117             :     int32       version;
     118             :     int32       space_per_page;
     119             : 
     120             :     BlockNumber bucket_pages;
     121             :     BlockNumber overflow_pages;
     122             :     BlockNumber bitmap_pages;
     123             :     BlockNumber unused_pages;
     124             : 
     125             :     int64       live_items;
     126             :     int64       dead_items;
     127             :     uint64      free_space;
     128             : } HashIndexStat;
     129             : 
     130             : static Datum pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo);
     131             : static int64 pg_relpages_impl(Relation rel);
     132             : static void GetHashPageStats(Page page, HashIndexStat *stats);
     133             : 
     134             : /* ------------------------------------------------------
     135             :  * pgstatindex()
     136             :  *
     137             :  * Usage: SELECT * FROM pgstatindex('t1_pkey');
     138             :  *
     139             :  * The superuser() check here must be kept as the library might be upgraded
     140             :  * without the extension being upgraded, meaning that in pre-1.5 installations
     141             :  * these functions could be called by any user.
     142             :  * ------------------------------------------------------
     143             :  */
     144             : Datum
     145           0 : pgstatindex(PG_FUNCTION_ARGS)
     146             : {
     147           0 :     text       *relname = PG_GETARG_TEXT_PP(0);
     148             :     Relation    rel;
     149             :     RangeVar   *relrv;
     150             : 
     151           0 :     if (!superuser())
     152           0 :         ereport(ERROR,
     153             :                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
     154             :                  errmsg("must be superuser to use pgstattuple functions")));
     155             : 
     156           0 :     relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
     157           0 :     rel = relation_openrv(relrv, AccessShareLock);
     158             : 
     159           0 :     PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
     160             : }
     161             : 
     162             : /*
     163             :  * As of pgstattuple version 1.5, we no longer need to check if the user
     164             :  * is a superuser because we REVOKE EXECUTE on the function from PUBLIC.
     165             :  * Users can then grant access to it based on their policies.
     166             :  *
     167             :  * Otherwise identical to pgstatindex (above).
     168             :  */
     169             : Datum
     170          20 : pgstatindex_v1_5(PG_FUNCTION_ARGS)
     171             : {
     172          20 :     text       *relname = PG_GETARG_TEXT_PP(0);
     173             :     Relation    rel;
     174             :     RangeVar   *relrv;
     175             : 
     176          20 :     relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
     177          20 :     rel = relation_openrv(relrv, AccessShareLock);
     178             : 
     179          20 :     PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
     180             : }
     181             : 
     182             : /*
     183             :  * The superuser() check here must be kept as the library might be upgraded
     184             :  * without the extension being upgraded, meaning that in pre-1.5 installations
     185             :  * these functions could be called by any user.
     186             :  */
     187             : Datum
     188           0 : pgstatindexbyid(PG_FUNCTION_ARGS)
     189             : {
     190           0 :     Oid         relid = PG_GETARG_OID(0);
     191             :     Relation    rel;
     192             : 
     193           0 :     if (!superuser())
     194           0 :         ereport(ERROR,
     195             :                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
     196             :                  errmsg("must be superuser to use pgstattuple functions")));
     197             : 
     198           0 :     rel = relation_open(relid, AccessShareLock);
     199             : 
     200           0 :     PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
     201             : }
     202             : 
     203             : /* No need for superuser checks in v1.5, see above */
     204             : Datum
     205           2 : pgstatindexbyid_v1_5(PG_FUNCTION_ARGS)
     206             : {
     207           2 :     Oid         relid = PG_GETARG_OID(0);
     208             :     Relation    rel;
     209             : 
     210           2 :     rel = relation_open(relid, AccessShareLock);
     211             : 
     212           2 :     PG_RETURN_DATUM(pgstatindex_impl(rel, fcinfo));
     213             : }
     214             : 
     215             : static Datum
     216          22 : pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
     217             : {
     218             :     Datum       result;
     219             :     BlockNumber nblocks;
     220             :     BlockNumber blkno;
     221             :     BTIndexStat indexStat;
     222          22 :     BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
     223             : 
     224          22 :     if (!IS_INDEX(rel) || !IS_BTREE(rel))
     225          12 :         ereport(ERROR,
     226             :                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
     227             :                  errmsg("relation \"%s\" is not a btree index",
     228             :                         RelationGetRelationName(rel))));
     229             : 
     230             :     /*
     231             :      * Reject attempts to read non-local temporary relations; we would be
     232             :      * likely to get wrong data since we have no visibility into the owning
     233             :      * session's local buffers.
     234             :      */
     235          10 :     if (RELATION_IS_OTHER_TEMP(rel))
     236           0 :         ereport(ERROR,
     237             :                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     238             :                  errmsg("cannot access temporary tables of other sessions")));
     239             : 
     240             :     /*
     241             :      * A !indisready index could lead to ERRCODE_DATA_CORRUPTED later, so exit
     242             :      * early.  We're capable of assessing an indisready&&!indisvalid index,
     243             :      * but the results could be confusing.  For example, the index's size
     244             :      * could be too low for a valid index of the table.
     245             :      */
     246          10 :     if (!rel->rd_index->indisvalid)
     247           0 :         ereport(ERROR,
     248             :                 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
     249             :                  errmsg("index \"%s\" is not valid",
     250             :                         RelationGetRelationName(rel))));
     251             : 
     252             :     /*
     253             :      * Read metapage
     254             :      */
     255             :     {
     256          10 :         Buffer      buffer = ReadBufferExtended(rel, MAIN_FORKNUM, 0, RBM_NORMAL, bstrategy);
     257          10 :         Page        page = BufferGetPage(buffer);
     258          10 :         BTMetaPageData *metad = BTPageGetMeta(page);
     259             : 
     260          10 :         indexStat.version = metad->btm_version;
     261          10 :         indexStat.level = metad->btm_level;
     262          10 :         indexStat.root_blkno = metad->btm_root;
     263             : 
     264          10 :         ReleaseBuffer(buffer);
     265             :     }
     266             : 
     267             :     /* -- init counters -- */
     268          10 :     indexStat.internal_pages = 0;
     269          10 :     indexStat.leaf_pages = 0;
     270          10 :     indexStat.empty_pages = 0;
     271          10 :     indexStat.deleted_pages = 0;
     272             : 
     273          10 :     indexStat.max_avail = 0;
     274          10 :     indexStat.free_space = 0;
     275             : 
     276          10 :     indexStat.fragments = 0;
     277             : 
     278             :     /*
     279             :      * Scan all blocks except the metapage
     280             :      */
     281          10 :     nblocks = RelationGetNumberOfBlocks(rel);
     282             : 
     283          10 :     for (blkno = 1; blkno < nblocks; blkno++)
     284             :     {
     285             :         Buffer      buffer;
     286             :         Page        page;
     287             :         BTPageOpaque opaque;
     288             : 
     289           0 :         CHECK_FOR_INTERRUPTS();
     290             : 
     291             :         /* Read and lock buffer */
     292           0 :         buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
     293           0 :         LockBuffer(buffer, BUFFER_LOCK_SHARE);
     294             : 
     295           0 :         page = BufferGetPage(buffer);
     296           0 :         opaque = BTPageGetOpaque(page);
     297             : 
     298             :         /*
     299             :          * Determine page type, and update totals.
     300             :          *
     301             :          * Note that we arbitrarily bucket deleted pages together without
     302             :          * considering if they're leaf pages or internal pages.
     303             :          */
     304           0 :         if (P_ISDELETED(opaque))
     305           0 :             indexStat.deleted_pages++;
     306           0 :         else if (P_IGNORE(opaque))
     307           0 :             indexStat.empty_pages++;    /* this is the "half dead" state */
     308           0 :         else if (P_ISLEAF(opaque))
     309             :         {
     310             :             int         max_avail;
     311             : 
     312           0 :             max_avail = BLCKSZ - (BLCKSZ - ((PageHeader) page)->pd_special + SizeOfPageHeaderData);
     313           0 :             indexStat.max_avail += max_avail;
     314           0 :             indexStat.free_space += PageGetFreeSpace(page);
     315             : 
     316           0 :             indexStat.leaf_pages++;
     317             : 
     318             :             /*
     319             :              * If the next leaf is on an earlier block, it means a
     320             :              * fragmentation.
     321             :              */
     322           0 :             if (opaque->btpo_next != P_NONE && opaque->btpo_next < blkno)
     323           0 :                 indexStat.fragments++;
     324             :         }
     325             :         else
     326           0 :             indexStat.internal_pages++;
     327             : 
     328             :         /* Unlock and release buffer */
     329           0 :         LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
     330           0 :         ReleaseBuffer(buffer);
     331             :     }
     332             : 
     333          10 :     relation_close(rel, AccessShareLock);
     334             : 
     335             :     /*----------------------------
     336             :      * Build a result tuple
     337             :      *----------------------------
     338             :      */
     339             :     {
     340             :         TupleDesc   tupleDesc;
     341             :         int         j;
     342             :         char       *values[10];
     343             :         HeapTuple   tuple;
     344             : 
     345             :         /* Build a tuple descriptor for our result type */
     346          10 :         if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
     347           0 :             elog(ERROR, "return type must be a row type");
     348             : 
     349          10 :         j = 0;
     350          10 :         values[j++] = psprintf("%d", indexStat.version);
     351          10 :         values[j++] = psprintf("%d", indexStat.level);
     352          20 :         values[j++] = psprintf(INT64_FORMAT,
     353             :                                (1 + /* include the metapage in index_size */
     354          10 :                                 indexStat.leaf_pages +
     355          10 :                                 indexStat.internal_pages +
     356          10 :                                 indexStat.deleted_pages +
     357          10 :                                 indexStat.empty_pages) * BLCKSZ);
     358          10 :         values[j++] = psprintf("%u", indexStat.root_blkno);
     359          10 :         values[j++] = psprintf(INT64_FORMAT, indexStat.internal_pages);
     360          10 :         values[j++] = psprintf(INT64_FORMAT, indexStat.leaf_pages);
     361          10 :         values[j++] = psprintf(INT64_FORMAT, indexStat.empty_pages);
     362          10 :         values[j++] = psprintf(INT64_FORMAT, indexStat.deleted_pages);
     363          10 :         if (indexStat.max_avail > 0)
     364           0 :             values[j++] = psprintf("%.2f",
     365           0 :                                    100.0 - (double) indexStat.free_space / (double) indexStat.max_avail * 100.0);
     366             :         else
     367          10 :             values[j++] = pstrdup("NaN");
     368          10 :         if (indexStat.leaf_pages > 0)
     369           0 :             values[j++] = psprintf("%.2f",
     370           0 :                                    (double) indexStat.fragments / (double) indexStat.leaf_pages * 100.0);
     371             :         else
     372          10 :             values[j++] = pstrdup("NaN");
     373             : 
     374          10 :         tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
     375             :                                        values);
     376             : 
     377          10 :         result = HeapTupleGetDatum(tuple);
     378             :     }
     379             : 
     380          10 :     return result;
     381             : }
     382             : 
     383             : /* --------------------------------------------------------
     384             :  * pg_relpages()
     385             :  *
     386             :  * Get the number of pages of the table/index.
     387             :  *
     388             :  * Usage: SELECT pg_relpages('t1');
     389             :  *        SELECT pg_relpages('t1_pkey');
     390             :  *
     391             :  * Must keep superuser() check, see above.
     392             :  * --------------------------------------------------------
     393             :  */
     394             : Datum
     395           0 : pg_relpages(PG_FUNCTION_ARGS)
     396             : {
     397           0 :     text       *relname = PG_GETARG_TEXT_PP(0);
     398             :     Relation    rel;
     399             :     RangeVar   *relrv;
     400             : 
     401           0 :     if (!superuser())
     402           0 :         ereport(ERROR,
     403             :                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
     404             :                  errmsg("must be superuser to use pgstattuple functions")));
     405             : 
     406           0 :     relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
     407           0 :     rel = relation_openrv(relrv, AccessShareLock);
     408             : 
     409           0 :     PG_RETURN_INT64(pg_relpages_impl(rel));
     410             : }
     411             : 
     412             : /* No need for superuser checks in v1.5, see above */
     413             : Datum
     414          18 : pg_relpages_v1_5(PG_FUNCTION_ARGS)
     415             : {
     416          18 :     text       *relname = PG_GETARG_TEXT_PP(0);
     417             :     Relation    rel;
     418             :     RangeVar   *relrv;
     419             : 
     420          18 :     relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
     421          18 :     rel = relation_openrv(relrv, AccessShareLock);
     422             : 
     423          18 :     PG_RETURN_INT64(pg_relpages_impl(rel));
     424             : }
     425             : 
     426             : /* Must keep superuser() check, see above. */
     427             : Datum
     428           0 : pg_relpagesbyid(PG_FUNCTION_ARGS)
     429             : {
     430           0 :     Oid         relid = PG_GETARG_OID(0);
     431             :     Relation    rel;
     432             : 
     433           0 :     if (!superuser())
     434           0 :         ereport(ERROR,
     435             :                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
     436             :                  errmsg("must be superuser to use pgstattuple functions")));
     437             : 
     438           0 :     rel = relation_open(relid, AccessShareLock);
     439             : 
     440           0 :     PG_RETURN_INT64(pg_relpages_impl(rel));
     441             : }
     442             : 
     443             : /* No need for superuser checks in v1.5, see above */
     444             : Datum
     445           6 : pg_relpagesbyid_v1_5(PG_FUNCTION_ARGS)
     446             : {
     447           6 :     Oid         relid = PG_GETARG_OID(0);
     448             :     Relation    rel;
     449             : 
     450           6 :     rel = relation_open(relid, AccessShareLock);
     451             : 
     452           6 :     PG_RETURN_INT64(pg_relpages_impl(rel));
     453             : }
     454             : 
     455             : static int64
     456          24 : pg_relpages_impl(Relation rel)
     457             : {
     458             :     int64       relpages;
     459             : 
     460          24 :     if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
     461           6 :         ereport(ERROR,
     462             :                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
     463             :                  errmsg("cannot get page count of relation \"%s\"",
     464             :                         RelationGetRelationName(rel)),
     465             :                  errdetail_relkind_not_supported(rel->rd_rel->relkind)));
     466             : 
     467             :     /* note: this will work OK on non-local temp tables */
     468             : 
     469          18 :     relpages = RelationGetNumberOfBlocks(rel);
     470             : 
     471          18 :     relation_close(rel, AccessShareLock);
     472             : 
     473          18 :     return relpages;
     474             : }
     475             : 
     476             : /* ------------------------------------------------------
     477             :  * pgstatginindex()
     478             :  *
     479             :  * Usage: SELECT * FROM pgstatginindex('ginindex');
     480             :  *
     481             :  * Must keep superuser() check, see above.
     482             :  * ------------------------------------------------------
     483             :  */
     484             : Datum
     485           0 : pgstatginindex(PG_FUNCTION_ARGS)
     486             : {
     487           0 :     Oid         relid = PG_GETARG_OID(0);
     488             : 
     489           0 :     if (!superuser())
     490           0 :         ereport(ERROR,
     491             :                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
     492             :                  errmsg("must be superuser to use pgstattuple functions")));
     493             : 
     494           0 :     PG_RETURN_DATUM(pgstatginindex_internal(relid, fcinfo));
     495             : }
     496             : 
     497             : /* No need for superuser checks in v1.5, see above */
     498             : Datum
     499          14 : pgstatginindex_v1_5(PG_FUNCTION_ARGS)
     500             : {
     501          14 :     Oid         relid = PG_GETARG_OID(0);
     502             : 
     503          14 :     PG_RETURN_DATUM(pgstatginindex_internal(relid, fcinfo));
     504             : }
     505             : 
     506             : Datum
     507          14 : pgstatginindex_internal(Oid relid, FunctionCallInfo fcinfo)
     508             : {
     509             :     Relation    rel;
     510             :     Buffer      buffer;
     511             :     Page        page;
     512             :     GinMetaPageData *metadata;
     513             :     GinIndexStat stats;
     514             :     HeapTuple   tuple;
     515             :     TupleDesc   tupleDesc;
     516             :     Datum       values[3];
     517          14 :     bool        nulls[3] = {false, false, false};
     518             :     Datum       result;
     519             : 
     520          14 :     rel = relation_open(relid, AccessShareLock);
     521             : 
     522          14 :     if (!IS_INDEX(rel) || !IS_GIN(rel))
     523          12 :         ereport(ERROR,
     524             :                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
     525             :                  errmsg("relation \"%s\" is not a GIN index",
     526             :                         RelationGetRelationName(rel))));
     527             : 
     528             :     /*
     529             :      * Reject attempts to read non-local temporary relations; we would be
     530             :      * likely to get wrong data since we have no visibility into the owning
     531             :      * session's local buffers.
     532             :      */
     533           2 :     if (RELATION_IS_OTHER_TEMP(rel))
     534           0 :         ereport(ERROR,
     535             :                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     536             :                  errmsg("cannot access temporary indexes of other sessions")));
     537             : 
     538             :     /* see pgstatindex_impl */
     539           2 :     if (!rel->rd_index->indisvalid)
     540           0 :         ereport(ERROR,
     541             :                 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
     542             :                  errmsg("index \"%s\" is not valid",
     543             :                         RelationGetRelationName(rel))));
     544             : 
     545             :     /*
     546             :      * Read metapage
     547             :      */
     548           2 :     buffer = ReadBuffer(rel, GIN_METAPAGE_BLKNO);
     549           2 :     LockBuffer(buffer, GIN_SHARE);
     550           2 :     page = BufferGetPage(buffer);
     551           2 :     metadata = GinPageGetMeta(page);
     552             : 
     553           2 :     stats.version = metadata->ginVersion;
     554           2 :     stats.pending_pages = metadata->nPendingPages;
     555           2 :     stats.pending_tuples = metadata->nPendingHeapTuples;
     556             : 
     557           2 :     UnlockReleaseBuffer(buffer);
     558           2 :     relation_close(rel, AccessShareLock);
     559             : 
     560             :     /*
     561             :      * Build a tuple descriptor for our result type
     562             :      */
     563           2 :     if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
     564           0 :         elog(ERROR, "return type must be a row type");
     565             : 
     566           2 :     values[0] = Int32GetDatum(stats.version);
     567           2 :     values[1] = UInt32GetDatum(stats.pending_pages);
     568           2 :     values[2] = Int64GetDatum(stats.pending_tuples);
     569             : 
     570             :     /*
     571             :      * Build and return the tuple
     572             :      */
     573           2 :     tuple = heap_form_tuple(tupleDesc, values, nulls);
     574           2 :     result = HeapTupleGetDatum(tuple);
     575             : 
     576           2 :     return result;
     577             : }
     578             : 
     579             : /* ------------------------------------------------------
     580             :  * pgstathashindex()
     581             :  *
     582             :  * Usage: SELECT * FROM pgstathashindex('hashindex');
     583             :  * ------------------------------------------------------
     584             :  */
     585             : Datum
     586          18 : pgstathashindex(PG_FUNCTION_ARGS)
     587             : {
     588          18 :     Oid         relid = PG_GETARG_OID(0);
     589             :     BlockNumber nblocks;
     590             :     BlockNumber blkno;
     591             :     Relation    rel;
     592             :     HashIndexStat stats;
     593             :     BufferAccessStrategy bstrategy;
     594             :     HeapTuple   tuple;
     595             :     TupleDesc   tupleDesc;
     596             :     Datum       values[8];
     597          18 :     bool        nulls[8] = {0};
     598             :     Buffer      metabuf;
     599             :     HashMetaPage metap;
     600             :     float8      free_percent;
     601             :     uint64      total_space;
     602             : 
     603          18 :     rel = relation_open(relid, AccessShareLock);
     604             : 
     605          18 :     if (!IS_INDEX(rel) || !IS_HASH(rel))
     606          14 :         ereport(ERROR,
     607             :                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
     608             :                  errmsg("relation \"%s\" is not a hash index",
     609             :                         RelationGetRelationName(rel))));
     610             : 
     611             :     /*
     612             :      * Reject attempts to read non-local temporary relations; we would be
     613             :      * likely to get wrong data since we have no visibility into the owning
     614             :      * session's local buffers.
     615             :      */
     616           4 :     if (RELATION_IS_OTHER_TEMP(rel))
     617           0 :         ereport(ERROR,
     618             :                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     619             :                  errmsg("cannot access temporary indexes of other sessions")));
     620             : 
     621             :     /* see pgstatindex_impl */
     622           4 :     if (!rel->rd_index->indisvalid)
     623           0 :         ereport(ERROR,
     624             :                 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
     625             :                  errmsg("index \"%s\" is not valid",
     626             :                         RelationGetRelationName(rel))));
     627             : 
     628             :     /* Get the information we need from the metapage. */
     629           4 :     memset(&stats, 0, sizeof(stats));
     630           4 :     metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE);
     631           4 :     metap = HashPageGetMeta(BufferGetPage(metabuf));
     632           4 :     stats.version = metap->hashm_version;
     633           4 :     stats.space_per_page = metap->hashm_bsize;
     634           4 :     _hash_relbuf(rel, metabuf);
     635             : 
     636             :     /* Get the current relation length */
     637           4 :     nblocks = RelationGetNumberOfBlocks(rel);
     638             : 
     639             :     /* prepare access strategy for this index */
     640           4 :     bstrategy = GetAccessStrategy(BAS_BULKREAD);
     641             : 
     642             :     /* Start from blkno 1 as 0th block is metapage */
     643          32 :     for (blkno = 1; blkno < nblocks; blkno++)
     644             :     {
     645             :         Buffer      buf;
     646             :         Page        page;
     647             : 
     648          28 :         CHECK_FOR_INTERRUPTS();
     649             : 
     650          28 :         buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
     651             :                                  bstrategy);
     652          28 :         LockBuffer(buf, BUFFER_LOCK_SHARE);
     653          28 :         page = (Page) BufferGetPage(buf);
     654             : 
     655          28 :         if (PageIsNew(page))
     656           0 :             stats.unused_pages++;
     657          28 :         else if (PageGetSpecialSize(page) !=
     658             :                  MAXALIGN(sizeof(HashPageOpaqueData)))
     659           0 :             ereport(ERROR,
     660             :                     (errcode(ERRCODE_INDEX_CORRUPTED),
     661             :                      errmsg("index \"%s\" contains corrupted page at block %u",
     662             :                             RelationGetRelationName(rel),
     663             :                             BufferGetBlockNumber(buf))));
     664             :         else
     665             :         {
     666             :             HashPageOpaque opaque;
     667             :             int         pagetype;
     668             : 
     669          28 :             opaque = HashPageGetOpaque(page);
     670          28 :             pagetype = opaque->hasho_flag & LH_PAGE_TYPE;
     671             : 
     672          28 :             if (pagetype == LH_BUCKET_PAGE)
     673             :             {
     674          24 :                 stats.bucket_pages++;
     675          24 :                 GetHashPageStats(page, &stats);
     676             :             }
     677           4 :             else if (pagetype == LH_OVERFLOW_PAGE)
     678             :             {
     679           0 :                 stats.overflow_pages++;
     680           0 :                 GetHashPageStats(page, &stats);
     681             :             }
     682           4 :             else if (pagetype == LH_BITMAP_PAGE)
     683           4 :                 stats.bitmap_pages++;
     684           0 :             else if (pagetype == LH_UNUSED_PAGE)
     685           0 :                 stats.unused_pages++;
     686             :             else
     687           0 :                 ereport(ERROR,
     688             :                         (errcode(ERRCODE_INDEX_CORRUPTED),
     689             :                          errmsg("unexpected page type 0x%04X in HASH index \"%s\" block %u",
     690             :                                 opaque->hasho_flag, RelationGetRelationName(rel),
     691             :                                 BufferGetBlockNumber(buf))));
     692             :         }
     693          28 :         UnlockReleaseBuffer(buf);
     694             :     }
     695             : 
     696             :     /* Done accessing the index */
     697           4 :     index_close(rel, AccessShareLock);
     698             : 
     699             :     /* Count unused pages as free space. */
     700           4 :     stats.free_space += (uint64) stats.unused_pages * stats.space_per_page;
     701             : 
     702             :     /*
     703             :      * Total space available for tuples excludes the metapage and the bitmap
     704             :      * pages.
     705             :      */
     706           4 :     total_space = (uint64) (nblocks - (stats.bitmap_pages + 1)) *
     707           4 :         stats.space_per_page;
     708             : 
     709           4 :     if (total_space == 0)
     710           0 :         free_percent = 0.0;
     711             :     else
     712           4 :         free_percent = 100.0 * stats.free_space / total_space;
     713             : 
     714             :     /*
     715             :      * Build a tuple descriptor for our result type
     716             :      */
     717           4 :     if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
     718           0 :         elog(ERROR, "return type must be a row type");
     719             : 
     720           4 :     tupleDesc = BlessTupleDesc(tupleDesc);
     721             : 
     722             :     /*
     723             :      * Build and return the tuple
     724             :      */
     725           4 :     values[0] = Int32GetDatum(stats.version);
     726           4 :     values[1] = Int64GetDatum((int64) stats.bucket_pages);
     727           4 :     values[2] = Int64GetDatum((int64) stats.overflow_pages);
     728           4 :     values[3] = Int64GetDatum((int64) stats.bitmap_pages);
     729           4 :     values[4] = Int64GetDatum((int64) stats.unused_pages);
     730           4 :     values[5] = Int64GetDatum(stats.live_items);
     731           4 :     values[6] = Int64GetDatum(stats.dead_items);
     732           4 :     values[7] = Float8GetDatum(free_percent);
     733           4 :     tuple = heap_form_tuple(tupleDesc, values, nulls);
     734             : 
     735           4 :     PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
     736             : }
     737             : 
     738             : /* -------------------------------------------------
     739             :  * GetHashPageStats()
     740             :  *
     741             :  * Collect statistics of single hash page
     742             :  * -------------------------------------------------
     743             :  */
     744             : static void
     745          24 : GetHashPageStats(Page page, HashIndexStat *stats)
     746             : {
     747          24 :     OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
     748             :     int         off;
     749             : 
     750             :     /* count live and dead tuples, and free space */
     751          24 :     for (off = FirstOffsetNumber; off <= maxoff; off++)
     752             :     {
     753           0 :         ItemId      id = PageGetItemId(page, off);
     754             : 
     755           0 :         if (!ItemIdIsDead(id))
     756           0 :             stats->live_items++;
     757             :         else
     758           0 :             stats->dead_items++;
     759             :     }
     760          24 :     stats->free_space += PageGetExactFreeSpace(page);
     761          24 : }

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