postgresql/contrib/pageinspect/btreefuncs.c
Michael Paquier 2275d044d0 pageinspect: Fix handling of all-zero pages
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
2022-04-14 15:09:36 +09:00

723 lines
20 KiB
C

/*
* contrib/pageinspect/btreefuncs.c
*
*
* btreefuncs.c
*
* Copyright (c) 2006 Satoshi Nagayasu <nagayasus@nttdata.co.jp>
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose, without fee, and without a
* written agreement is hereby granted, provided that the above
* copyright notice and this paragraph and the following two
* paragraphs appear in all copies.
*
* IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
* DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
* IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*/
#include "postgres.h"
#include "access/nbtree.h"
#include "access/relation.h"
#include "catalog/namespace.h"
#include "catalog/pg_am.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "pageinspect.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/rel.h"
#include "utils/varlena.h"
PG_FUNCTION_INFO_V1(bt_metap);
PG_FUNCTION_INFO_V1(bt_page_items);
PG_FUNCTION_INFO_V1(bt_page_items_bytea);
PG_FUNCTION_INFO_V1(bt_page_stats);
#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
#define IS_BTREE(r) ((r)->rd_rel->relam == BTREE_AM_OID)
#define DatumGetItemPointer(X) ((ItemPointer) DatumGetPointer(X))
#define ItemPointerGetDatum(X) PointerGetDatum(X)
/* note: BlockNumber is unsigned, hence can't be negative */
#define CHECK_RELATION_BLOCK_RANGE(rel, blkno) { \
if ( RelationGetNumberOfBlocks(rel) <= (BlockNumber) (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;
char type;
/* opaque data */
BlockNumber btpo_prev;
BlockNumber btpo_next;
union
{
uint32 level;
TransactionId xact;
} btpo;
uint16 btpo_flags;
BTCycleId btpo_cycleid;
} BTPageStat;
/* -------------------------------------------------
* GetBTPageStatistics()
*
* Collect statistics of single b-tree page
* -------------------------------------------------
*/
static void
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';
stat->btpo.xact = opaque->btpo.xact;
return;
}
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;
stat->btpo.level = opaque->btpo.level;
stat->btpo_flags = opaque->btpo_flags;
stat->btpo_cycleid = opaque->btpo_cycleid;
/* 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 (!ItemIdIsDead(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;
}
/* -----------------------------------------------
* bt_page_stats()
*
* Usage: SELECT * FROM bt_page_stats('t1_pkey', 1);
* -----------------------------------------------
*/
Datum
bt_page_stats(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_PP(0);
uint32 blkno = PG_GETARG_UINT32(1);
Buffer buffer;
Relation rel;
RangeVar *relrv;
Datum result;
HeapTuple tuple;
TupleDesc tupleDesc;
int j;
char *values[11];
BTPageStat stat;
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")));
if (blkno == 0)
elog(ERROR, "block 0 is a meta page");
CHECK_RELATION_BLOCK_RANGE(rel, blkno);
buffer = ReadBuffer(rel, blkno);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
/* keep compiler quiet */
stat.btpo_prev = stat.btpo_next = InvalidBlockNumber;
stat.btpo_flags = stat.free_size = stat.avg_item_size = 0;
GetBTPageStatistics(blkno, buffer, &stat);
UnlockReleaseBuffer(buffer);
relation_close(rel, AccessShareLock);
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
j = 0;
values[j++] = psprintf("%d", stat.blkno);
values[j++] = psprintf("%c", stat.type);
values[j++] = psprintf("%d", stat.live_items);
values[j++] = psprintf("%d", stat.dead_items);
values[j++] = psprintf("%d", stat.avg_item_size);
values[j++] = psprintf("%d", stat.page_size);
values[j++] = psprintf("%d", stat.free_size);
values[j++] = psprintf("%d", stat.btpo_prev);
values[j++] = psprintf("%d", stat.btpo_next);
values[j++] = psprintf("%d", (stat.type == 'd') ? stat.btpo.xact : stat.btpo.level);
values[j++] = psprintf("%d", stat.btpo_flags);
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
values);
result = HeapTupleGetDatum(tuple);
PG_RETURN_DATUM(result);
}
/*
* cross-call data structure for SRF
*/
struct user_args
{
Page page;
OffsetNumber offset;
bool leafpage;
bool rightmost;
TupleDesc tupd;
};
/*-------------------------------------------------------
* bt_page_print_tuples()
*
* Form a tuple describing index tuple at a given offset
* ------------------------------------------------------
*/
static Datum
bt_page_print_tuples(FuncCallContext *fctx, struct user_args *uargs)
{
Page page = uargs->page;
OffsetNumber offset = uargs->offset;
bool leafpage = uargs->leafpage;
bool rightmost = uargs->rightmost;
bool ispivottuple;
Datum values[9];
bool nulls[9];
HeapTuple tuple;
ItemId id;
IndexTuple itup;
int j;
int off;
int dlen;
char *dump,
*datacstring;
char *ptr;
ItemPointer htid;
id = PageGetItemId(page, offset);
if (!ItemIdIsValid(id))
elog(ERROR, "invalid ItemId");
itup = (IndexTuple) PageGetItem(page, id);
j = 0;
memset(nulls, 0, sizeof(nulls));
values[j++] = DatumGetInt16(offset);
values[j++] = ItemPointerGetDatum(&itup->t_tid);
values[j++] = Int32GetDatum((int) IndexTupleSize(itup));
values[j++] = BoolGetDatum(IndexTupleHasNulls(itup));
values[j++] = BoolGetDatum(IndexTupleHasVarwidths(itup));
ptr = (char *) itup + IndexInfoFindDataOffset(itup->t_info);
dlen = IndexTupleSize(itup) - IndexInfoFindDataOffset(itup->t_info);
/*
* Make sure that "data" column does not include posting list or pivot
* tuple representation of heap TID(s).
*
* Note: BTreeTupleIsPivot() won't work reliably on !heapkeyspace indexes
* (those built before BTREE_VERSION 4), but we have no way of determining
* if this page came from a !heapkeyspace index. We may only have a bytea
* nbtree page image to go on, so in general there is no metapage that we
* can check.
*
* That's okay here because BTreeTupleIsPivot() can only return false for
* a !heapkeyspace pivot, never true for a !heapkeyspace non-pivot. Since
* heap TID isn't part of the keyspace in a !heapkeyspace index anyway,
* there cannot possibly be a pivot tuple heap TID representation that we
* fail to make an adjustment for. A !heapkeyspace index can have
* BTreeTupleIsPivot() return true (due to things like suffix truncation
* for INCLUDE indexes in Postgres v11), but when that happens
* BTreeTupleGetHeapTID() can be trusted to work reliably (i.e. return
* NULL).
*
* Note: BTreeTupleIsPosting() always works reliably, even with
* !heapkeyspace indexes.
*/
if (BTreeTupleIsPosting(itup))
dlen -= IndexTupleSize(itup) - BTreeTupleGetPostingOffset(itup);
else if (BTreeTupleIsPivot(itup) && BTreeTupleGetHeapTID(itup) != NULL)
dlen -= MAXALIGN(sizeof(ItemPointerData));
if (dlen < 0 || dlen > INDEX_SIZE_MASK)
elog(ERROR, "invalid tuple length %d for tuple at offset number %u",
dlen, offset);
dump = palloc0(dlen * 3 + 1);
datacstring = dump;
for (off = 0; off < dlen; off++)
{
if (off > 0)
*dump++ = ' ';
sprintf(dump, "%02x", *(ptr + off) & 0xff);
dump += 2;
}
values[j++] = CStringGetTextDatum(datacstring);
pfree(datacstring);
/*
* We need to work around the BTreeTupleIsPivot() !heapkeyspace limitation
* again. Deduce whether or not tuple must be a pivot tuple based on
* whether or not the page is a leaf page, as well as the page offset
* number of the tuple.
*/
ispivottuple = (!leafpage || (!rightmost && offset == P_HIKEY));
/* LP_DEAD bit can never be set for pivot tuples, so show a NULL there */
if (!ispivottuple)
values[j++] = BoolGetDatum(ItemIdIsDead(id));
else
{
Assert(!ItemIdIsDead(id));
nulls[j++] = true;
}
htid = BTreeTupleGetHeapTID(itup);
if (ispivottuple && !BTreeTupleIsPivot(itup))
{
/* Don't show bogus heap TID in !heapkeyspace pivot tuple */
htid = NULL;
}
if (htid)
values[j++] = ItemPointerGetDatum(htid);
else
nulls[j++] = true;
if (BTreeTupleIsPosting(itup))
{
/* Build an array of item pointers */
ItemPointer tids;
Datum *tids_datum;
int nposting;
tids = BTreeTupleGetPosting(itup);
nposting = BTreeTupleGetNPosting(itup);
tids_datum = (Datum *) palloc(nposting * sizeof(Datum));
for (int i = 0; i < nposting; i++)
tids_datum[i] = ItemPointerGetDatum(&tids[i]);
values[j++] = PointerGetDatum(construct_array(tids_datum,
nposting,
TIDOID,
sizeof(ItemPointerData),
false, TYPALIGN_SHORT));
pfree(tids_datum);
}
else
nulls[j++] = true;
/* Build and return the result tuple */
tuple = heap_form_tuple(uargs->tupd, values, nulls);
return HeapTupleGetDatum(tuple);
}
/*-------------------------------------------------------
* bt_page_items()
*
* Get IndexTupleData set in a btree page
*
* Usage: SELECT * FROM bt_page_items('t1_pkey', 1);
*-------------------------------------------------------
*/
Datum
bt_page_items(PG_FUNCTION_ARGS)
{
text *relname = PG_GETARG_TEXT_PP(0);
uint32 blkno = PG_GETARG_UINT32(1);
Datum result;
FuncCallContext *fctx;
MemoryContext mctx;
struct user_args *uargs;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to use pageinspect functions")));
if (SRF_IS_FIRSTCALL())
{
RangeVar *relrv;
Relation rel;
Buffer buffer;
BTPageOpaque opaque;
TupleDesc tupleDesc;
fctx = SRF_FIRSTCALL_INIT();
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")));
if (blkno == 0)
elog(ERROR, "block 0 is a meta page");
CHECK_RELATION_BLOCK_RANGE(rel, blkno);
buffer = ReadBuffer(rel, blkno);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
/*
* We copy the page into local storage to avoid holding pin on the
* buffer longer than we must, and possibly failing to release it at
* all if the calling query doesn't fetch all rows.
*/
mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
uargs = palloc(sizeof(struct user_args));
uargs->page = palloc(BLCKSZ);
memcpy(uargs->page, BufferGetPage(buffer), BLCKSZ);
UnlockReleaseBuffer(buffer);
relation_close(rel, AccessShareLock);
uargs->offset = FirstOffsetNumber;
opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page);
if (P_ISDELETED(opaque))
elog(NOTICE, "page is deleted");
fctx->max_calls = PageGetMaxOffsetNumber(uargs->page);
uargs->leafpage = P_ISLEAF(opaque);
uargs->rightmost = P_RIGHTMOST(opaque);
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
tupleDesc = BlessTupleDesc(tupleDesc);
uargs->tupd = tupleDesc;
fctx->user_fctx = uargs;
MemoryContextSwitchTo(mctx);
}
fctx = SRF_PERCALL_SETUP();
uargs = fctx->user_fctx;
if (fctx->call_cntr < fctx->max_calls)
{
result = bt_page_print_tuples(fctx, uargs);
uargs->offset++;
SRF_RETURN_NEXT(fctx, result);
}
SRF_RETURN_DONE(fctx);
}
/*-------------------------------------------------------
* bt_page_items_bytea()
*
* Get IndexTupleData set in a btree page
*
* Usage: SELECT * FROM bt_page_items(get_raw_page('t1_pkey', 1));
*-------------------------------------------------------
*/
Datum
bt_page_items_bytea(PG_FUNCTION_ARGS)
{
bytea *raw_page = PG_GETARG_BYTEA_P(0);
Datum result;
FuncCallContext *fctx;
struct user_args *uargs;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to use raw page functions")));
if (SRF_IS_FIRSTCALL())
{
BTPageOpaque opaque;
MemoryContext mctx;
TupleDesc tupleDesc;
fctx = SRF_FIRSTCALL_INIT();
mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
uargs = palloc(sizeof(struct user_args));
uargs->page = get_page_from_raw(raw_page);
if (PageIsNew(uargs->page))
{
MemoryContextSwitchTo(mctx);
PG_RETURN_NULL();
}
uargs->offset = FirstOffsetNumber;
/* verify the special space has the expected size */
if (PageGetSpecialSize(uargs->page) != MAXALIGN(sizeof(BTPageOpaqueData)))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("input page is not a valid %s page", "btree"),
errdetail("Expected special size %d, got %d.",
(int) MAXALIGN(sizeof(BTPageOpaqueData)),
(int) PageGetSpecialSize(uargs->page))));
opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page);
if (P_ISMETA(opaque))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("block is a meta page")));
if (P_ISLEAF(opaque) && opaque->btpo.level != 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("block is not a valid btree leaf page")));
if (P_ISDELETED(opaque))
elog(NOTICE, "page is deleted");
fctx->max_calls = PageGetMaxOffsetNumber(uargs->page);
uargs->leafpage = P_ISLEAF(opaque);
uargs->rightmost = P_RIGHTMOST(opaque);
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
tupleDesc = BlessTupleDesc(tupleDesc);
uargs->tupd = tupleDesc;
fctx->user_fctx = uargs;
MemoryContextSwitchTo(mctx);
}
fctx = SRF_PERCALL_SETUP();
uargs = fctx->user_fctx;
if (fctx->call_cntr < fctx->max_calls)
{
result = bt_page_print_tuples(fctx, uargs);
uargs->offset++;
SRF_RETURN_NEXT(fctx, result);
}
SRF_RETURN_DONE(fctx);
}
/* Number of output arguments (columns) for bt_metap() */
#define BT_METAP_COLS_V1_8 9
/* ------------------------------------------------
* 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[9];
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");
/*
* We need a kluge here to detect API versions prior to 1.8. Earlier
* versions incorrectly used int4 for certain columns. This caused
* various problems. For example, an int4 version of the "oldest_xact"
* column would not work with TransactionId values that happened to exceed
* PG_INT32_MAX.
*
* There is no way to reliably avoid the problems created by the old
* function definition at this point, so insist that the user update the
* extension.
*/
if (tupleDesc->natts < BT_METAP_COLS_V1_8)
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("function has wrong number of declared columns"),
errhint("To resolve the problem, update the \"pageinspect\" extension to the latest version.")));
j = 0;
values[j++] = psprintf("%d", metad->btm_magic);
values[j++] = psprintf("%d", metad->btm_version);
values[j++] = psprintf(INT64_FORMAT, (int64) metad->btm_root);
values[j++] = psprintf(INT64_FORMAT, (int64) metad->btm_level);
values[j++] = psprintf(INT64_FORMAT, (int64) metad->btm_fastroot);
values[j++] = psprintf(INT64_FORMAT, (int64) metad->btm_fastlevel);
/*
* Get values of extended metadata if available, use default values
* otherwise. Note that we rely on the assumption that btm_allequalimage
* is initialized to zero with indexes that were built on versions prior
* to Postgres 13 (just like _bt_metaversion()).
*/
if (metad->btm_version >= BTREE_NOVAC_VERSION)
{
values[j++] = psprintf("%u", metad->btm_oldest_btpo_xact);
values[j++] = psprintf("%f", metad->btm_last_cleanup_num_heap_tuples);
values[j++] = metad->btm_allequalimage ? "t" : "f";
}
else
{
values[j++] = "0";
values[j++] = "-1";
values[j++] = "f";
}
tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
values);
result = HeapTupleGetDatum(tuple);
UnlockReleaseBuffer(buffer);
relation_close(rel, AccessShareLock);
PG_RETURN_DATUM(result);
}