Re: pgstattuple extension for indexes

Patch applied. Thanks.

I updated the README documentation for the new functions, attached. I
could not update the Japanese version of the README.

---------------------------------------------------------------------------

Satoshi Nagayasu wrote:
> Bruce,
>
> Attached patch has been cleaned up,
> and modified to be able to work with CVS HEAD.
>
> Thanks.
>
> Satoshi Nagayasu wrote:
> > Alvaro,
> >
> > Alvaro Herrera wrote:
> >> Huh, I bet it works with 8.1.4, but it doesn't work on CVS HEAD:
> >>
> >> /pgsql/source/00orig/contrib/pgstattuple/pgstatindex.c: In function 'GetBTPageStatistics':
> >> /pgsql/source/00orig/contrib/pgstattuple/pgstatindex.c:182: error: 'BTItem' undeclared (first use in this function)
> >>
> >>
> >> While you're at it, please consider removing C++ style comments and
> >> unused code.
> >>
> >> Formatting is way off as well, but I guess that is easily fixed with
> >> pgindent.
> >
> > Thanks for comments. I'm going to fix my patch from now.
> >
> >> Regarding the pg_relpages function, why do you think it's necessary?
> >> (It returns the true number of blocks of a given relation). It may
> >> belong into core given a reasonable use case, but otherwise it doesn't
> >> seem to belong into pgstatindex (or pgstattuple for that matter).
> >
> > I wanted to sample some pages from the table/index, and get their statistics
> > to know table/index conditions. I know pgstattuple() reports table
> > statistics, however, pgstattuple() generates heavy CPU and I/O load.
> >
> > When we need to sample some pages from table/index, we need to know
> > true number of blocks.
> >
> > I have another function, called pgstatpage(), to get information inside
> > a single block/page statistics of the table. pg_relpages() will be used
> > with this.
> >
> > Sorry for not mentioned in previous post about pgstatpage(),
> > but I've remembered about it just now.
> >
> > Many memories in my brain have already `paged-out` (too busy in last few months),
> > and some of them got `out-of-memory`. :^)
> >
> > Thanks.
>
>
> --
> NAGAYASU Satoshi <nagayasus(at)nttdata(dot)co(dot)jp>
> Phone: +81-3-3523-8122

> diff -ruN pgstattuple.orig/Makefile pgstattuple/Makefile
> --- pgstattuple.orig/Makefile 2006-02-27 21:54:40.000000000 +0900
> +++ pgstattuple/Makefile 2006-08-14 09:28:58.000000000 +0900
> @@ -6,7 +6,7 @@
> #
> #-------------------------------------------------------------------------
>
> -SRCS = pgstattuple.c
> +SRCS = pgstattuple.c pgstatindex.c
>
> MODULE_big = pgstattuple
> OBJS = $(SRCS:.c=.o)
> diff -ruN pgstattuple.orig/pgstatindex.c pgstattuple/pgstatindex.c
> --- pgstattuple.orig/pgstatindex.c 1970-01-01 09:00:00.000000000 +0900
> +++ pgstattuple/pgstatindex.c 2006-08-14 11:24:23.000000000 +0900
> @@ -0,0 +1,706 @@
> +/*
> + * pgstatindex
> + *
> + * Copyright (c) 2006 Satoshi Nagayasu <nagayasus(at)nttdata(dot)co(dot)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 "fmgr.h"
> +#include "funcapi.h"
> +#include "access/heapam.h"
> +#include "access/itup.h"
> +#include "access/nbtree.h"
> +#include "access/transam.h"
> +#include "catalog/namespace.h"
> +#include "catalog/pg_type.h"
> +#include "utils/builtins.h"
> +#include "utils/inval.h"
> +
> +PG_FUNCTION_INFO_V1(pgstatindex);
> +PG_FUNCTION_INFO_V1(bt_metap);
> +PG_FUNCTION_INFO_V1(bt_page_items);
> +PG_FUNCTION_INFO_V1(bt_page_stats);
> +PG_FUNCTION_INFO_V1(pg_relpages);
> +
> +extern Datum pgstatindex(PG_FUNCTION_ARGS);
> +extern Datum bt_metap(PG_FUNCTION_ARGS);
> +extern Datum bt_page_items(PG_FUNCTION_ARGS);
> +extern Datum bt_page_stats(PG_FUNCTION_ARGS);
> +extern Datum pg_relpages(PG_FUNCTION_ARGS);
> +
> +#define PGSTATINDEX_TYPE "public.pgstatindex_type"
> +#define PGSTATINDEX_NCOLUMNS 10
> +
> +#define BTMETAP_TYPE "public.bt_metap_type"
> +#define BTMETAP_NCOLUMNS 6
> +
> +#define BTPAGEITEMS_TYPE "public.bt_page_items_type"
> +#define BTPAGEITEMS_NCOLUMNS 6
> +
> +#define BTPAGESTATS_TYPE "public.bt_page_stats_type"
> +#define BTPAGESTATS_NCOLUMNS 11
> +
> +
> +#define IS_INDEX(r) ((r)->rd_rel->relkind == 'i')
> +#define IS_BTREE(r) ((r)->rd_rel->relam == BTREE_AM_OID)
> +
> +#define CHECK_PAGE_OFFSET_RANGE(page, offset) { \
> + if ( !(FirstOffsetNumber<=(offset) && \
> + (offset)<=PageGetMaxOffsetNumber(page)) ) \
> + elog(ERROR, "Page offset number out of range."); }
> +
> +#define CHECK_RELATION_BLOCK_RANGE(rel, blkno) { \
> + if ( (blkno)<0 && RelationGetNumberOfBlocks((rel))<=(blkno) ) \
> + elog(ERROR, "Block number out of range."); }
> +
> +/* ------------------------------------------------
> + * structure for single btree page statistics
> + * ------------------------------------------------
> + */
> +typedef struct BTPageStat
> +{
> + uint32 blkno;
> + uint32 live_items;
> + uint32 dead_items;
> + uint32 page_size;
> + uint32 max_avail;
> + uint32 free_size;
> + uint32 avg_item_size;
> + uint32 fragments;
> + char type;
> +
> + /* opaque data */
> + BlockNumber btpo_prev;
> + BlockNumber btpo_next;
> + union
> + {
> + uint32 level;
> + TransactionId xact;
> + } btpo;
> + uint16 btpo_flags;
> + BTCycleId btpo_cycleid;
> +} BTPageStat;
> +
> +/* ------------------------------------------------
> + * A structure for a whole btree index statistics
> + * used by pgstatindex().
> + * ------------------------------------------------
> + */
> +typedef struct BTIndexStat
> +{
> + uint32 magic;
> + uint32 version;
> + BlockNumber root_blkno;
> + uint32 level;
> +
> + BlockNumber fastroot;
> + uint32 fastlevel;
> +
> + uint32 live_items;
> + uint32 dead_items;
> +
> + uint32 root_pages;
> + uint32 internal_pages;
> + uint32 leaf_pages;
> + uint32 empty_pages;
> + uint32 deleted_pages;
> +
> + uint32 page_size;
> + uint32 avg_item_size;
> +
> + uint32 max_avail;
> + uint32 free_space;
> +
> + uint32 fragments;
> +} BTIndexStat;
> +
> +/* -------------------------------------------------
> + * GetBTPageStatistics()
> + *
> + * Collect statistics of single b-tree leaf page
> + * -------------------------------------------------
> + */
> +static bool
> +GetBTPageStatistics(BlockNumber blkno, Buffer buffer, BTPageStat * stat)
> +{
> + Page page = BufferGetPage(buffer);
> + PageHeader phdr = (PageHeader) page;
> + OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
> + BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
> + int item_size = 0;
> + int off;
> +
> + stat->blkno = blkno;
> +
> + stat->max_avail = BLCKSZ - (BLCKSZ - phdr->pd_special + SizeOfPageHeaderData);
> +
> + stat->dead_items = stat->live_items = 0;
> +
> + stat->page_size = PageGetPageSize(page);
> +
> + /* page type (flags) */
> + if (P_ISDELETED(opaque))
> + {
> + stat->type = 'd';
> + return true;
> + }
> + else if (P_IGNORE(opaque))
> + stat->type = 'e';
> + else if (P_ISLEAF(opaque))
> + stat->type = 'l';
> + else if (P_ISROOT(opaque))
> + stat->type = 'r';
> + else
> + stat->type = 'i';
> +
> + /* btpage opaque data */
> + stat->btpo_prev = opaque->btpo_prev;
> + stat->btpo_next = opaque->btpo_next;
> + if (P_ISDELETED(opaque))
> + stat->btpo.xact = opaque->btpo.xact;
> + else
> + stat->btpo.level = opaque->btpo.level;
> + stat->btpo_flags = opaque->btpo_flags;
> + stat->btpo_cycleid = opaque->btpo_cycleid;
> +
> + /*----------------------------------------------
> + * If a next leaf is on the previous block,
> + * it means a fragmentation.
> + *----------------------------------------------
> + */
> + stat->fragments = 0;
> + if (stat->type == 'l')
> + {
> + if (opaque->btpo_next != P_NONE && opaque->btpo_next < blkno)
> + stat->fragments++;
> + }
> +
> + /* count live and dead tuples, and free space */
> + for (off = FirstOffsetNumber; off <= maxoff; off++)
> + {
> + IndexTuple itup;
> +
> + ItemId id = PageGetItemId(page, off);
> +
> + itup = (IndexTuple) PageGetItem(page, id);
> +
> + item_size += IndexTupleSize(itup);
> +
> + if (!ItemIdDeleted(id))
> + stat->live_items++;
> + else
> + stat->dead_items++;
> + }
> + stat->free_size = PageGetFreeSpace(page);
> +
> + if ((stat->live_items + stat->dead_items) > 0)
> + stat->avg_item_size = item_size / (stat->live_items + stat->dead_items);
> + else
> + stat->avg_item_size = 0;
> +
> + return true;
> +}
> +
> +
> +/* ------------------------------------------------------
> + * pgstatindex()
> + *
> + * Usage: SELECT * FROM pgstatindex('t1_pkey');
> + * ------------------------------------------------------
> + */
> +Datum
> +pgstatindex(PG_FUNCTION_ARGS)
> +{
> + text *relname = PG_GETARG_TEXT_P(0);
> + Relation rel;
> + RangeVar *relrv;
> + Datum result;
> + uint32 nblocks;
> + uint32 blkno;
> + BTIndexStat indexStat;
> +
> + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
> + rel = relation_openrv(relrv, AccessShareLock);
> +
> + if (!IS_INDEX(rel) || !IS_BTREE(rel))
> + elog(ERROR, "pgstatindex() can be used only on b-tree index.");
> +
> + /*-------------------
> + * Read a metapage
> + *-------------------
> + */
> + {
> + Buffer buffer = ReadBuffer(rel, 0);
> + Page page = BufferGetPage(buffer);
> + BTMetaPageData *metad = BTPageGetMeta(page);
> +
> + indexStat.magic = metad->btm_magic;
> + indexStat.version = metad->btm_version;
> + indexStat.root_blkno = metad->btm_root;
> + indexStat.level = metad->btm_level;
> + indexStat.fastroot = metad->btm_fastroot;
> + indexStat.fastlevel = metad->btm_fastlevel;
> +
> + ReleaseBuffer(buffer);
> + }
> +
> + nblocks = RelationGetNumberOfBlocks(rel);
> +
> + /* -- init stat -- */
> + indexStat.fragments = 0;
> +
> + indexStat.root_pages = 0;
> + indexStat.leaf_pages = 0;
> + indexStat.internal_pages = 0;
> + indexStat.empty_pages = 0;
> + indexStat.deleted_pages = 0;
> +
> + indexStat.max_avail = 0;
> + indexStat.free_space = 0;
> +
> + /*-----------------------
> + * Scan all blocks
> + *-----------------------
> + */
> + for (blkno = 1; blkno < nblocks; blkno++)
> + {
> + Buffer buffer = ReadBuffer(rel, blkno);
> + BTPageStat stat;
> +
> + /* scan one page */
> + stat.blkno = blkno;
> + GetBTPageStatistics(blkno, buffer, &stat);
> +
> + /*---------------------
> + * page status (type)
> + *---------------------
> + */
> + switch (stat.type)
> + {
> + case 'd':
> + indexStat.deleted_pages++;
> + break;
> + case 'l':
> + indexStat.leaf_pages++;
> + break;
> + case 'i':
> + indexStat.internal_pages++;
> + break;
> + case 'e':
> + indexStat.empty_pages++;
> + break;
> + case 'r':
> + indexStat.root_pages++;
> + break;
> + default:
> + elog(ERROR, "unknown page status.");
> + }
> +
> + /* -- leaf fragmentation -- */
> + indexStat.fragments += stat.fragments;
> +
> + if (stat.type == 'l')
> + {
> + indexStat.max_avail += stat.max_avail;
> + indexStat.free_space += stat.free_size;
> + }
> +
> + ReleaseBuffer(buffer);
> + }
> +
> + relation_close(rel, AccessShareLock);
> +
> + /*----------------------------
> + * Build a result tuple
> + *----------------------------
> + */
> + {
> + TupleDesc tupleDesc;
> + int j;
> + char *values[PGSTATINDEX_NCOLUMNS];
> +
> + HeapTupleData tupleData;
> + HeapTuple tuple = &tupleData;
> +
> + tupleDesc = RelationNameGetTupleDesc(PGSTATINDEX_TYPE);
> +
> + j = 0;
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", indexStat.version);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", indexStat.level);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", (indexStat.root_pages +
> + indexStat.leaf_pages +
> + indexStat.internal_pages +
> + indexStat.deleted_pages +
> + indexStat.empty_pages) * BLCKSZ);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", indexStat.root_blkno);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", indexStat.internal_pages);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", indexStat.leaf_pages);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", indexStat.empty_pages);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", indexStat.deleted_pages);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%.2f", 100.0 - (float) indexStat.free_space / (float) indexStat.max_avail * 100.0);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%.2f", (float) indexStat.fragments / (float) indexStat.leaf_pages * 100.0);
> +
> + tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
> + values);
> +
> + result = TupleGetDatum(TupleDescGetSlot(tupleDesc), tuple);
> + }
> +
> + PG_RETURN_DATUM(result);
> +}
> +
> +/* -----------------------------------------------
> + * bt_page()
> + *
> + * Usage: SELECT * FROM bt_page('t1_pkey', 0);
> + * -----------------------------------------------
> + */
> +Datum
> +bt_page_stats(PG_FUNCTION_ARGS)
> +{
> + text *relname = PG_GETARG_TEXT_P(0);
> + uint32 blkno = PG_GETARG_UINT32(1);
> + Buffer buffer;
> +
> + Relation rel;
> + RangeVar *relrv;
> + Datum result;
> +
> + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
> + rel = relation_openrv(relrv, AccessShareLock);
> +
> + CHECK_RELATION_BLOCK_RANGE(rel, blkno);
> +
> + buffer = ReadBuffer(rel, blkno);
> +
> + if (!IS_INDEX(rel) || !IS_BTREE(rel))
> + elog(ERROR, "bt_page_stats() can be used only on b-tree index.");
> +
> + if (blkno == 0)
> + elog(ERROR, "Block 0 is a meta page.");
> +
> + {
> + HeapTuple tuple;
> + TupleDesc tupleDesc;
> + int j;
> + char *values[BTPAGESTATS_NCOLUMNS];
> +
> + BTPageStat stat;
> +
> + GetBTPageStatistics(blkno, buffer, &stat);
> +
> + tupleDesc = RelationNameGetTupleDesc(BTPAGESTATS_TYPE);
> +
> + j = 0;
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", stat.blkno);
> +
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%c", stat.type);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", stat.live_items);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", stat.dead_items);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", stat.avg_item_size);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", stat.page_size);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", stat.free_size);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", stat.btpo_prev);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", stat.btpo_next);
> +
> + values[j] = palloc(32);
> + if (stat.type == 'd')
> + snprintf(values[j++], 32, "%d", stat.btpo.xact);
> + else
> + snprintf(values[j++], 32, "%d", stat.btpo.level);
> +
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", stat.btpo_flags);
> +
> + tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
> + values);
> +
> + result = TupleGetDatum(TupleDescGetSlot(tupleDesc), tuple);
> + }
> +
> + ReleaseBuffer(buffer);
> +
> + relation_close(rel, AccessShareLock);
> +
> + PG_RETURN_DATUM(result);
> +}
> +
> +/*-------------------------------------------------------
> + * bt_page_items()
> + *
> + * Get IndexTupleData set in a leaf page
> + *
> + * Usage: SELECT * FROM bt_page_items('t1_pkey', 0);
> + *-------------------------------------------------------
> + */
> +/* ---------------------------------------------------
> + * data structure for SRF to hold a scan information
> + * ---------------------------------------------------
> + */
> +struct user_args
> +{
> + TupleDesc tupd;
> + Relation rel;
> + Buffer buffer;
> + Page page;
> + uint16 offset;
> +};
> +
> +Datum
> +bt_page_items(PG_FUNCTION_ARGS)
> +{
> + text *relname = PG_GETARG_TEXT_P(0);
> + uint32 blkno = PG_GETARG_UINT32(1);
> +
> + RangeVar *relrv;
> + Datum result;
> + char *values[BTPAGEITEMS_NCOLUMNS];
> + BTPageOpaque opaque;
> + HeapTuple tuple;
> + ItemId id;
> +
> + FuncCallContext *fctx;
> + MemoryContext mctx;
> + struct user_args *uargs = NULL;
> +
> + if (blkno == 0)
> + elog(ERROR, "Block 0 is a meta page.");
> +
> + if (SRF_IS_FIRSTCALL())
> + {
> + fctx = SRF_FIRSTCALL_INIT();
> + mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
> +
> + uargs = palloc(sizeof(struct user_args));
> +
> + uargs->tupd = RelationNameGetTupleDesc(BTPAGEITEMS_TYPE);
> + uargs->offset = FirstOffsetNumber;
> +
> + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
> + uargs->rel = relation_openrv(relrv, AccessShareLock);
> +
> + CHECK_RELATION_BLOCK_RANGE(uargs->rel, blkno);
> +
> + uargs->buffer = ReadBuffer(uargs->rel, blkno);
> +
> + if (!IS_INDEX(uargs->rel) || !IS_BTREE(uargs->rel))
> + elog(ERROR, "bt_page_items() can be used only on b-tree index.");
> +
> + uargs->page = BufferGetPage(uargs->buffer);
> +
> + opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page);
> +
> + if (P_ISDELETED(opaque))
> + elog(NOTICE, "bt_page_items(): this page is deleted.");
> +
> + fctx->max_calls = PageGetMaxOffsetNumber(uargs->page);
> + fctx->user_fctx = uargs;
> +
> + MemoryContextSwitchTo(mctx);
> + }
> +
> + fctx = SRF_PERCALL_SETUP();
> + uargs = fctx->user_fctx;
> +
> + if (fctx->call_cntr < fctx->max_calls)
> + {
> + IndexTuple itup;
> +
> + id = PageGetItemId(uargs->page, uargs->offset);
> +
> + if (!ItemIdIsValid(id))
> + elog(ERROR, "Invalid ItemId.");
> +
> + itup = (IndexTuple) PageGetItem(uargs->page, id);
> +
> + {
> + int j = 0;
> +
> + BlockNumber blkno = BlockIdGetBlockNumber(&(itup->t_tid.ip_blkid));
> +
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", uargs->offset);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "(%u,%u)", blkno, itup->t_tid.ip_posid);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", IndexTupleSize(itup));
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%c", IndexTupleHasNulls(itup) ? 't' : 'f');
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%c", IndexTupleHasVarwidths(itup) ? 't' : 'f');
> +
> + {
> + int off;
> + char *dump;
> + char *ptr = (char *) itup + IndexInfoFindDataOffset(itup->t_info);
> +
> + dump = palloc(IndexTupleSize(itup) * 3);
> + memset(dump, 0, IndexTupleSize(itup) * 3);
> +
> + for (off = 0;
> + off < IndexTupleSize(itup) - IndexInfoFindDataOffset(itup->t_info);
> + off++)
> + {
> + if (dump[0] == '\0')
> + sprintf(dump, "%02x", *(ptr + off) & 0xff);
> + else
> + {
> + char buf[4];
> +
> + sprintf(buf, " %02x", *(ptr + off) & 0xff);
> + strcat(dump, buf);
> + }
> + }
> + values[j] = dump;
> + }
> +
> + tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(uargs->tupd), values);
> + result = TupleGetDatum(TupleDescGetSlot(uargs->tupd), tuple);
> + }
> +
> + uargs->offset = uargs->offset + 1;
> +
> + SRF_RETURN_NEXT(fctx, result);
> + }
> + else
> + {
> + ReleaseBuffer(uargs->buffer);
> + relation_close(uargs->rel, AccessShareLock);
> +
> + SRF_RETURN_DONE(fctx);
> + }
> +}
> +
> +
> +/* ------------------------------------------------
> + * bt_metap()
> + *
> + * Get a btree meta-page information
> + *
> + * Usage: SELECT * FROM bt_metap('t1_pkey')
> + * ------------------------------------------------
> + */
> +Datum
> +bt_metap(PG_FUNCTION_ARGS)
> +{
> + text *relname = PG_GETARG_TEXT_P(0);
> + Buffer buffer;
> +
> + Relation rel;
> + RangeVar *relrv;
> + Datum result;
> +
> + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
> + rel = relation_openrv(relrv, AccessShareLock);
> +
> + if (!IS_INDEX(rel) || !IS_BTREE(rel))
> + elog(ERROR, "bt_metap() can be used only on b-tree index.");
> +
> + buffer = ReadBuffer(rel, 0);
> +
> + {
> + BTMetaPageData *metad;
> +
> + TupleDesc tupleDesc;
> + int j;
> + char *values[BTMETAP_NCOLUMNS];
> + HeapTuple tuple;
> +
> + Page page = BufferGetPage(buffer);
> +
> + metad = BTPageGetMeta(page);
> +
> + tupleDesc = RelationNameGetTupleDesc(BTMETAP_TYPE);
> +
> + j = 0;
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", metad->btm_magic);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", metad->btm_version);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", metad->btm_root);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", metad->btm_level);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", metad->btm_fastroot);
> + values[j] = palloc(32);
> + snprintf(values[j++], 32, "%d", metad->btm_fastlevel);
> +
> + tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
> + values);
> +
> + result = TupleGetDatum(TupleDescGetSlot(tupleDesc), tuple);
> + }
> +
> + ReleaseBuffer(buffer);
> +
> + relation_close(rel, AccessShareLock);
> +
> + PG_RETURN_DATUM(result);
> +}
> +
> +/* --------------------------------------------------------
> + * pg_relpages()
> + *
> + * Get a number of pages of the table/index.
> + *
> + * Usage: SELECT pg_relpages('t1');
> + * SELECT pg_relpages('t1_pkey');
> + * --------------------------------------------------------
> + */
> +Datum
> +pg_relpages(PG_FUNCTION_ARGS)
> +{
> + text *relname = PG_GETARG_TEXT_P(0);
> +
> + Relation rel;
> + RangeVar *relrv;
> + int4 relpages;
> +
> + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
> + rel = relation_openrv(relrv, AccessShareLock);
> +
> + relpages = RelationGetNumberOfBlocks(rel);
> +
> + relation_close(rel, AccessShareLock);
> +
> + PG_RETURN_INT32(relpages);
> +}
> diff -ruN pgstattuple.orig/pgstattuple.sql.in pgstattuple/pgstattuple.sql.in
> --- pgstattuple.orig/pgstattuple.sql.in 2006-02-28 01:09:50.000000000 +0900
> +++ pgstattuple/pgstattuple.sql.in 2006-08-14 10:37:32.000000000 +0900
> @@ -22,3 +22,96 @@
> RETURNS pgstattuple_type
> AS 'MODULE_PATHNAME', 'pgstattuplebyid'
> LANGUAGE C STRICT;
> +
> +--
> +-- pgstatindex
> +--
> +DROP TYPE pgstatindex_type CASCADE;
> +CREATE TYPE pgstatindex_type AS (
> + version int4,
> + tree_level int4,
> + index_size int4,
> + root_block_no int4,
> + internal_pages int4,
> + leaf_pages int4,
> + empty_pages int4,
> + deleted_pages int4,
> + avg_leaf_density float8,
> + leaf_fragmentation float8
> +);
> +
> +CREATE OR REPLACE FUNCTION pgstatindex(text)
> +RETURNS pgstatindex_type
> +AS 'MODULE_PATHNAME', 'pgstatindex'
> +LANGUAGE 'C' STRICT;
> +
> +--
> +-- bt_metap()
> +--
> +DROP TYPE bt_metap_type CASCADE;
> +CREATE TYPE bt_metap_type AS (
> + magic int4,
> + version int4,
> + root int4,
> + level int4,
> + fastroot int4,
> + fastlevel int4
> +);
> +
> +CREATE OR REPLACE FUNCTION bt_metap(text)
> +RETURNS bt_metap_type
> +AS 'MODULE_PATHNAME', 'bt_metap'
> +LANGUAGE 'C' STRICT;
> +
> +--
> +-- bt_page_items()
> +--
> +DROP TYPE bt_page_items_type CASCADE;
> +CREATE TYPE bt_page_items_type AS (
> + itemoffset int4,
> + ctid tid,
> + itemlen int4,
> + nulls bool,
> + vars bool,
> + data text
> +);
> +
> +DROP FUNCTION bt_page_items(text, int4);
> +
> +CREATE OR REPLACE FUNCTION bt_page_items(text, int4)
> +RETURNS SETOF bt_page_items_type
> +AS 'MODULE_PATHNAME', 'bt_page_items'
> +LANGUAGE 'C' STRICT;
> +
> +--
> +-- bt_page_stats()
> +--
> +DROP TYPE bt_page_stats_type CASCADE;
> +CREATE TYPE bt_page_stats_type AS (
> + blkno int4,
> + type char,
> + live_items int4,
> + dead_items int4,
> + avg_item_size float,
> + page_size int4,
> + free_size int4,
> + btpo_prev int4,
> + btpo_next int4,
> + btpo int4,
> + btpo_flags int4
> +);
> +
> +DROP FUNCTION bt_page_stats(text, int4);
> +
> +CREATE OR REPLACE FUNCTION bt_page_stats(text, int4)
> +RETURNS bt_page_stats_type
> +AS 'MODULE_PATHNAME', 'bt_page_stats'
> +LANGUAGE 'C' STRICT;
> +
> +--
> +-- pg_relpages()
> +--
> +CREATE OR REPLACE FUNCTION pg_relpages(text)
> +RETURNS int
> +AS 'MODULE_PATHNAME', 'pg_relpages'
> +LANGUAGE 'C' STRICT;
> diff -ruN pgstattuple.orig/test.sh pgstattuple/test.sh
> --- pgstattuple.orig/test.sh 1970-01-01 09:00:00.000000000 +0900
> +++ pgstattuple/test.sh 2006-08-14 10:23:08.000000000 +0900
> @@ -0,0 +1,27 @@
> +#!/bin/sh
> +
> +PGHOME=/home/snaga/pgsql20060814
> +export PATH=${PGHOME}/bin:$PATH
> +
> +psql -p 9999 pgbench<<EOF
> +DROP FUNCTION pgstatindex(text);
> +EOF
> +
> +psql -p 9999 -f ${PGHOME}/share/contrib/pgstattuple.sql pgbench
> +
> +psql -p 9999 pgbench<<EOF
> +SELECT * FROM pg_relpages('accounts_pkey');
> +\x
> +SELECT * FROM pgstatindex('accounts_pkey');
> +SELECT * FROM bt_metap('accounts_pkey');
> +\x
> +SELECT * FROM bt_page_items('accounts_pkey', 0);
> +SELECT * FROM bt_page_items('accounts_pkey', 1) limit 20;
> +
> +SELECT * FROM bt_page_stats('accounts_pkey', 1);
> +\x
> +SELECT * FROM bt_page_stats('accounts_pkey', 1);
> +SELECT * FROM bt_page_stats('accounts_pkey', 361);
> +\x
> +SELECT * FROM bt_page_items('accounts_pkey', 361);
> +EOF
>
--
Bruce Momjian bruce(at)momjian(dot)us
EnterpriseDB http://www.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +