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Getting from get_raw_page() an all-zero page is considered as a valid case by the buffer manager and it can happen for example when finding a corrupted page with zero_damaged_pages enabled (using zero_damaged_pages to look at corrupted pages happens), or after a crash when a relation file is extended before any WAL for its new data is generated (before a vacuum or autovacuum job comes in to do some cleanup). However, all the functions of pageinspect, as of the index AMs (except hash that has its own idea of new pages), heap, the FSM or the page header have never worked with all-zero pages, causing various crashes when going through the page internals. This commit changes all the pageinspect functions to be compliant with all-zero pages, where the choice is made to return NULL or no rows for SRFs when finding a new page. get_raw_page() still works the same way, returning a batch of zeros in the bytea of the page retrieved. A hard error could be used but NULL, while more invasive, is useful when scanning relation files in full to get a batch of results for a single relation in one query. Tests are added for all the code paths impacted. Reported-by: Daria Lepikhova Author: Michael Paquier Discussion: https://postgr.es/m/561e187b-3549-c8d5-03f5-525c14e65bd0@postgrespro.ru Backpatch-through: 10
608 lines
16 KiB
C
608 lines
16 KiB
C
/*
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* contrib/pageinspect/btreefuncs.c
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*
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*
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* btreefuncs.c
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*
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* Copyright (c) 2006 Satoshi Nagayasu <nagayasus@nttdata.co.jp>
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*
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* Permission to use, copy, modify, and distribute this software and
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* its documentation for any purpose, without fee, and without a
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* written agreement is hereby granted, provided that the above
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* copyright notice and this paragraph and the following two
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* paragraphs appear in all copies.
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*
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
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* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
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* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
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* DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
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* IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
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* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*/
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#include "postgres.h"
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#include "pageinspect.h"
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#include "access/nbtree.h"
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#include "access/relation.h"
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#include "catalog/namespace.h"
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#include "catalog/pg_am.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "utils/builtins.h"
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#include "utils/rel.h"
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#include "utils/varlena.h"
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PG_FUNCTION_INFO_V1(bt_metap);
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PG_FUNCTION_INFO_V1(bt_page_items);
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PG_FUNCTION_INFO_V1(bt_page_items_bytea);
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PG_FUNCTION_INFO_V1(bt_page_stats);
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#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
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#define IS_BTREE(r) ((r)->rd_rel->relam == BTREE_AM_OID)
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/* note: BlockNumber is unsigned, hence can't be negative */
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#define CHECK_RELATION_BLOCK_RANGE(rel, blkno) { \
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if ( RelationGetNumberOfBlocks(rel) <= (BlockNumber) (blkno) ) \
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elog(ERROR, "block number out of range"); }
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/* ------------------------------------------------
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* structure for single btree page statistics
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* ------------------------------------------------
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*/
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typedef struct BTPageStat
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{
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uint32 blkno;
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uint32 live_items;
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uint32 dead_items;
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uint32 page_size;
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uint32 max_avail;
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uint32 free_size;
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uint32 avg_item_size;
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char type;
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/* opaque data */
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BlockNumber btpo_prev;
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BlockNumber btpo_next;
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union
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{
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uint32 level;
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TransactionId xact;
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} btpo;
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uint16 btpo_flags;
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BTCycleId btpo_cycleid;
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} BTPageStat;
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/* -------------------------------------------------
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* GetBTPageStatistics()
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*
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* Collect statistics of single b-tree page
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* -------------------------------------------------
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*/
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static void
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GetBTPageStatistics(BlockNumber blkno, Buffer buffer, BTPageStat *stat)
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{
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Page page = BufferGetPage(buffer);
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PageHeader phdr = (PageHeader) page;
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OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
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BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
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int item_size = 0;
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int off;
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stat->blkno = blkno;
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stat->max_avail = BLCKSZ - (BLCKSZ - phdr->pd_special + SizeOfPageHeaderData);
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stat->dead_items = stat->live_items = 0;
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stat->page_size = PageGetPageSize(page);
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/* page type (flags) */
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if (P_ISDELETED(opaque))
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{
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stat->type = 'd';
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stat->btpo.xact = opaque->btpo.xact;
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return;
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}
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else if (P_IGNORE(opaque))
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stat->type = 'e';
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else if (P_ISLEAF(opaque))
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stat->type = 'l';
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else if (P_ISROOT(opaque))
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stat->type = 'r';
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else
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stat->type = 'i';
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/* btpage opaque data */
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stat->btpo_prev = opaque->btpo_prev;
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stat->btpo_next = opaque->btpo_next;
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stat->btpo.level = opaque->btpo.level;
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stat->btpo_flags = opaque->btpo_flags;
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stat->btpo_cycleid = opaque->btpo_cycleid;
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/* count live and dead tuples, and free space */
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for (off = FirstOffsetNumber; off <= maxoff; off++)
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{
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IndexTuple itup;
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ItemId id = PageGetItemId(page, off);
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itup = (IndexTuple) PageGetItem(page, id);
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item_size += IndexTupleSize(itup);
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if (!ItemIdIsDead(id))
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stat->live_items++;
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else
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stat->dead_items++;
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}
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stat->free_size = PageGetFreeSpace(page);
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if ((stat->live_items + stat->dead_items) > 0)
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stat->avg_item_size = item_size / (stat->live_items + stat->dead_items);
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else
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stat->avg_item_size = 0;
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}
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/* -----------------------------------------------
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* bt_page_stats()
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*
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* Usage: SELECT * FROM bt_page_stats('t1_pkey', 1);
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* -----------------------------------------------
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*/
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Datum
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bt_page_stats(PG_FUNCTION_ARGS)
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{
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text *relname = PG_GETARG_TEXT_PP(0);
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uint32 blkno = PG_GETARG_UINT32(1);
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Buffer buffer;
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Relation rel;
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RangeVar *relrv;
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Datum result;
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HeapTuple tuple;
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TupleDesc tupleDesc;
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int j;
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char *values[11];
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BTPageStat stat;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use pageinspect functions"))));
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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
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rel = relation_openrv(relrv, AccessShareLock);
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if (!IS_INDEX(rel) || !IS_BTREE(rel))
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("\"%s\" is not a %s index",
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RelationGetRelationName(rel), "btree")));
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/*
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* Reject attempts to read non-local temporary relations; we would be
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* likely to get wrong data since we have no visibility into the owning
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* session's local buffers.
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*/
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if (RELATION_IS_OTHER_TEMP(rel))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("cannot access temporary tables of other sessions")));
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if (blkno == 0)
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elog(ERROR, "block 0 is a meta page");
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CHECK_RELATION_BLOCK_RANGE(rel, blkno);
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buffer = ReadBuffer(rel, blkno);
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LockBuffer(buffer, BUFFER_LOCK_SHARE);
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/* keep compiler quiet */
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stat.btpo_prev = stat.btpo_next = InvalidBlockNumber;
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stat.btpo_flags = stat.free_size = stat.avg_item_size = 0;
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GetBTPageStatistics(blkno, buffer, &stat);
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UnlockReleaseBuffer(buffer);
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relation_close(rel, AccessShareLock);
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/* Build a tuple descriptor for our result type */
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if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
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elog(ERROR, "return type must be a row type");
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j = 0;
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values[j++] = psprintf("%d", stat.blkno);
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values[j++] = psprintf("%c", stat.type);
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values[j++] = psprintf("%d", stat.live_items);
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values[j++] = psprintf("%d", stat.dead_items);
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values[j++] = psprintf("%d", stat.avg_item_size);
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values[j++] = psprintf("%d", stat.page_size);
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values[j++] = psprintf("%d", stat.free_size);
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values[j++] = psprintf("%d", stat.btpo_prev);
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values[j++] = psprintf("%d", stat.btpo_next);
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values[j++] = psprintf("%d", (stat.type == 'd') ? stat.btpo.xact : stat.btpo.level);
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values[j++] = psprintf("%d", stat.btpo_flags);
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tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
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values);
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result = HeapTupleGetDatum(tuple);
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PG_RETURN_DATUM(result);
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}
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/*
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* cross-call data structure for SRF
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*/
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struct user_args
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{
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Page page;
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OffsetNumber offset;
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};
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/*-------------------------------------------------------
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* bt_page_print_tuples()
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*
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* Form a tuple describing index tuple at a given offset
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* ------------------------------------------------------
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*/
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static Datum
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bt_page_print_tuples(FuncCallContext *fctx, Page page, OffsetNumber offset)
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{
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char *values[6];
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HeapTuple tuple;
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ItemId id;
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IndexTuple itup;
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int j;
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int off;
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int dlen;
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char *dump;
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char *ptr;
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id = PageGetItemId(page, offset);
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if (!ItemIdIsValid(id))
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elog(ERROR, "invalid ItemId");
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itup = (IndexTuple) PageGetItem(page, id);
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j = 0;
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values[j++] = psprintf("%d", offset);
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values[j++] = psprintf("(%u,%u)",
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ItemPointerGetBlockNumberNoCheck(&itup->t_tid),
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ItemPointerGetOffsetNumberNoCheck(&itup->t_tid));
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values[j++] = psprintf("%d", (int) IndexTupleSize(itup));
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values[j++] = psprintf("%c", IndexTupleHasNulls(itup) ? 't' : 'f');
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values[j++] = psprintf("%c", IndexTupleHasVarwidths(itup) ? 't' : 'f');
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ptr = (char *) itup + IndexInfoFindDataOffset(itup->t_info);
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dlen = IndexTupleSize(itup) - IndexInfoFindDataOffset(itup->t_info);
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dump = palloc0(dlen * 3 + 1);
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values[j] = dump;
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for (off = 0; off < dlen; off++)
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{
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if (off > 0)
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*dump++ = ' ';
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sprintf(dump, "%02x", *(ptr + off) & 0xff);
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dump += 2;
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}
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tuple = BuildTupleFromCStrings(fctx->attinmeta, values);
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return HeapTupleGetDatum(tuple);
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}
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/*-------------------------------------------------------
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* bt_page_items()
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*
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* Get IndexTupleData set in a btree page
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*
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* Usage: SELECT * FROM bt_page_items('t1_pkey', 1);
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*-------------------------------------------------------
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*/
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Datum
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bt_page_items(PG_FUNCTION_ARGS)
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{
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text *relname = PG_GETARG_TEXT_PP(0);
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uint32 blkno = PG_GETARG_UINT32(1);
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Datum result;
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FuncCallContext *fctx;
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MemoryContext mctx;
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struct user_args *uargs;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use pageinspect functions"))));
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if (SRF_IS_FIRSTCALL())
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{
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RangeVar *relrv;
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Relation rel;
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Buffer buffer;
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BTPageOpaque opaque;
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TupleDesc tupleDesc;
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fctx = SRF_FIRSTCALL_INIT();
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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
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rel = relation_openrv(relrv, AccessShareLock);
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if (!IS_INDEX(rel) || !IS_BTREE(rel))
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("\"%s\" is not a %s index",
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RelationGetRelationName(rel), "btree")));
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/*
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* Reject attempts to read non-local temporary relations; we would be
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* likely to get wrong data since we have no visibility into the
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* owning session's local buffers.
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*/
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if (RELATION_IS_OTHER_TEMP(rel))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("cannot access temporary tables of other sessions")));
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if (blkno == 0)
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elog(ERROR, "block 0 is a meta page");
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CHECK_RELATION_BLOCK_RANGE(rel, blkno);
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buffer = ReadBuffer(rel, blkno);
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LockBuffer(buffer, BUFFER_LOCK_SHARE);
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/*
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* We copy the page into local storage to avoid holding pin on the
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* buffer longer than we must, and possibly failing to release it at
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* all if the calling query doesn't fetch all rows.
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*/
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mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
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uargs = palloc(sizeof(struct user_args));
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uargs->page = palloc(BLCKSZ);
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memcpy(uargs->page, BufferGetPage(buffer), BLCKSZ);
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UnlockReleaseBuffer(buffer);
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relation_close(rel, AccessShareLock);
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uargs->offset = FirstOffsetNumber;
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opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page);
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if (P_ISDELETED(opaque))
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elog(NOTICE, "page is deleted");
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fctx->max_calls = PageGetMaxOffsetNumber(uargs->page);
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/* Build a tuple descriptor for our result type */
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if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
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elog(ERROR, "return type must be a row type");
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fctx->attinmeta = TupleDescGetAttInMetadata(tupleDesc);
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fctx->user_fctx = uargs;
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MemoryContextSwitchTo(mctx);
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}
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fctx = SRF_PERCALL_SETUP();
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uargs = fctx->user_fctx;
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if (fctx->call_cntr < fctx->max_calls)
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{
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result = bt_page_print_tuples(fctx, uargs->page, uargs->offset);
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uargs->offset++;
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SRF_RETURN_NEXT(fctx, result);
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}
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else
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{
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pfree(uargs->page);
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pfree(uargs);
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SRF_RETURN_DONE(fctx);
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}
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}
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/*-------------------------------------------------------
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* bt_page_items_bytea()
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*
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* Get IndexTupleData set in a btree page
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*
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* Usage: SELECT * FROM bt_page_items(get_raw_page('t1_pkey', 1));
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*-------------------------------------------------------
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*/
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Datum
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bt_page_items_bytea(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Datum result;
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FuncCallContext *fctx;
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struct user_args *uargs;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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if (SRF_IS_FIRSTCALL())
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{
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BTPageOpaque opaque;
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MemoryContext mctx;
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TupleDesc tupleDesc;
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fctx = SRF_FIRSTCALL_INIT();
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mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
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uargs = palloc(sizeof(struct user_args));
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uargs->page = get_page_from_raw(raw_page);
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if (PageIsNew(uargs->page))
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{
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MemoryContextSwitchTo(mctx);
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PG_RETURN_NULL();
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}
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uargs->offset = FirstOffsetNumber;
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/* verify the special space has the expected size */
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if (PageGetSpecialSize(uargs->page) != MAXALIGN(sizeof(BTPageOpaqueData)))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("input page is not a valid %s page", "btree"),
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errdetail("Expected special size %d, got %d.",
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(int) MAXALIGN(sizeof(BTPageOpaqueData)),
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(int) PageGetSpecialSize(uargs->page))));
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opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page);
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if (P_ISMETA(opaque))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("block is a meta page")));
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if (P_ISLEAF(opaque) && opaque->btpo.level != 0)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("block is not a valid btree leaf page")));
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if (P_ISDELETED(opaque))
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elog(NOTICE, "page is deleted");
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fctx->max_calls = PageGetMaxOffsetNumber(uargs->page);
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/* Build a tuple descriptor for our result type */
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if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
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elog(ERROR, "return type must be a row type");
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fctx->attinmeta = TupleDescGetAttInMetadata(tupleDesc);
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fctx->user_fctx = uargs;
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MemoryContextSwitchTo(mctx);
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}
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fctx = SRF_PERCALL_SETUP();
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uargs = fctx->user_fctx;
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if (fctx->call_cntr < fctx->max_calls)
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{
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result = bt_page_print_tuples(fctx, uargs->page, uargs->offset);
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|
uargs->offset++;
|
|
SRF_RETURN_NEXT(fctx, result);
|
|
}
|
|
else
|
|
{
|
|
pfree(uargs);
|
|
SRF_RETURN_DONE(fctx);
|
|
}
|
|
}
|
|
|
|
|
|
/* ------------------------------------------------
|
|
* bt_metap()
|
|
*
|
|
* Get a btree's meta-page information
|
|
*
|
|
* Usage: SELECT * FROM bt_metap('t1_pkey')
|
|
* ------------------------------------------------
|
|
*/
|
|
Datum
|
|
bt_metap(PG_FUNCTION_ARGS)
|
|
{
|
|
text *relname = PG_GETARG_TEXT_PP(0);
|
|
Datum result;
|
|
Relation rel;
|
|
RangeVar *relrv;
|
|
BTMetaPageData *metad;
|
|
TupleDesc tupleDesc;
|
|
int j;
|
|
char *values[8];
|
|
Buffer buffer;
|
|
Page page;
|
|
HeapTuple tuple;
|
|
|
|
if (!superuser())
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
|
|
(errmsg("must be superuser to use pageinspect functions"))));
|
|
|
|
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
|
|
rel = relation_openrv(relrv, AccessShareLock);
|
|
|
|
if (!IS_INDEX(rel) || !IS_BTREE(rel))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
|
|
errmsg("\"%s\" is not a %s index",
|
|
RelationGetRelationName(rel), "btree")));
|
|
|
|
/*
|
|
* 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")));
|
|
|
|
buffer = ReadBuffer(rel, 0);
|
|
LockBuffer(buffer, BUFFER_LOCK_SHARE);
|
|
|
|
page = BufferGetPage(buffer);
|
|
metad = BTPageGetMeta(page);
|
|
|
|
/* 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", metad->btm_magic);
|
|
values[j++] = psprintf("%d", metad->btm_version);
|
|
values[j++] = psprintf("%d", metad->btm_root);
|
|
values[j++] = psprintf("%d", metad->btm_level);
|
|
values[j++] = psprintf("%d", metad->btm_fastroot);
|
|
values[j++] = psprintf("%d", metad->btm_fastlevel);
|
|
|
|
/*
|
|
* Get values of extended metadata if available, use default values
|
|
* otherwise.
|
|
*/
|
|
if (metad->btm_version >= BTREE_NOVAC_VERSION)
|
|
{
|
|
/*
|
|
* kludge: btm_oldest_btpo_xact is declared as int4, which is wrong.
|
|
* We should at least avoid raising an error when its value happens to
|
|
* exceed PG_INT32_MAX, though.
|
|
*/
|
|
values[j++] = psprintf("%d", (int) metad->btm_oldest_btpo_xact);
|
|
values[j++] = psprintf("%f", metad->btm_last_cleanup_num_heap_tuples);
|
|
}
|
|
else
|
|
{
|
|
values[j++] = "0";
|
|
values[j++] = "-1";
|
|
}
|
|
|
|
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
|
|
values);
|
|
|
|
result = HeapTupleGetDatum(tuple);
|
|
|
|
UnlockReleaseBuffer(buffer);
|
|
relation_close(rel, AccessShareLock);
|
|
|
|
PG_RETURN_DATUM(result);
|
|
}
|