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Commit fdc7efc

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anarazelanarazel
committed
Allow pg_class xid & multixid horizons to not be set.
This allows table AMs that don't need these horizons. This was already documented in the tableam relation_set_new_filenode callback, but an assert prevented if from actually working (the test AM code contained the change itself). Defang the asserts in the general code, and move the stronger ones into heap AM. Relatedly, after CLUSTER/VACUUM, we'd always assign a relfrozenxid / relminmxid. Change the table_relation_copy_for_cluster() interface to allow the AM to overwrite the horizons that get set on the pg_class entry. This'd also in the future allow AMs like heap to compute a relfrozenxid during rewrite that's the table's actual minimum rather than a pre-determined value. Arguably it'd have been better to move the whole computation / setting of those values into the callback, but it seems likely that for other reasons it'd be better to be able to use one value to vacuum/cluster multiple tables (e.g. a toast's horizon shouldn't be different than the table's). Reported-By: Heikki Linnakangas Author: Andres Freund Discussion: https://postgr.es/m/9a7fb9cc-2419-5db7-8840-ddc10c93f122@iki.fi
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6 files changed

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‎src/backend/access/heap/heapam_handler.c

Copy file name to clipboardExpand all lines: src/backend/access/heap/heapam_handler.c
+4-4Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -668,8 +668,8 @@ static void
668668
heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
669669
Relation OldIndex, bool use_sort,
670670
TransactionId OldestXmin,
671-
TransactionId FreezeXid,
672-
MultiXactId MultiXactCutoff,
671+
TransactionId *xid_cutoff,
672+
MultiXactId *multi_cutoff,
673673
double *num_tuples,
674674
double *tups_vacuumed,
675675
double *tups_recently_dead)
@@ -707,8 +707,8 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
707707
isnull = (bool *) palloc(natts * sizeof(bool));
708708

709709
/* Initialize the rewrite operation */
710-
rwstate = begin_heap_rewrite(OldHeap, NewHeap, OldestXmin, FreezeXid,
711-
MultiXactCutoff, use_wal);
710+
rwstate = begin_heap_rewrite(OldHeap, NewHeap, OldestXmin, *xid_cutoff,
711+
*multi_cutoff, use_wal);
712712

713713

714714
/* Set up sorting if wanted */

‎src/backend/access/heap/vacuumlazy.c

Copy file name to clipboardExpand all lines: src/backend/access/heap/vacuumlazy.c
+4Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -213,6 +213,10 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
213213
Assert(params != NULL);
214214
Assert(params->index_cleanup != VACOPT_TERNARY_DEFAULT);
215215

216+
/* not every AM requires these to be valid, but heap does */
217+
Assert(TransactionIdIsNormal(onerel->rd_rel->relfrozenxid));
218+
Assert(MultiXactIdIsValid(onerel->rd_rel->relminmxid));
219+
216220
/* measure elapsed time iff autovacuum logging requires it */
217221
if (IsAutoVacuumWorkerProcess() && params->log_min_duration >= 0)
218222
{

‎src/backend/commands/cluster.c

Copy file name to clipboardExpand all lines: src/backend/commands/cluster.c
+14-10Lines changed: 14 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -870,19 +870,17 @@ copy_table_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex, bool verbose,
870870
* FreezeXid will become the table's new relfrozenxid, and that mustn't go
871871
* backwards, so take the max.
872872
*/
873-
if (TransactionIdPrecedes(FreezeXid, OldHeap->rd_rel->relfrozenxid))
873+
if (TransactionIdIsValid(OldHeap->rd_rel->relfrozenxid) &&
874+
TransactionIdPrecedes(FreezeXid, OldHeap->rd_rel->relfrozenxid))
874875
FreezeXid = OldHeap->rd_rel->relfrozenxid;
875876

876877
/*
877878
* MultiXactCutoff, similarly, shouldn't go backwards either.
878879
*/
879-
if (MultiXactIdPrecedes(MultiXactCutoff, OldHeap->rd_rel->relminmxid))
880+
if (MultiXactIdIsValid(OldHeap->rd_rel->relminmxid) &&
881+
MultiXactIdPrecedes(MultiXactCutoff, OldHeap->rd_rel->relminmxid))
880882
MultiXactCutoff = OldHeap->rd_rel->relminmxid;
881883

882-
/* return selected values to caller */
883-
*pFreezeXid = FreezeXid;
884-
*pCutoffMulti = MultiXactCutoff;
885-
886884
/*
887885
* Decide whether to use an indexscan or seqscan-and-optional-sort to scan
888886
* the OldHeap. We know how to use a sort to duplicate the ordering of a
@@ -915,13 +913,19 @@ copy_table_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex, bool verbose,
915913

916914
/*
917915
* Hand of the actual copying to AM specific function, the generic code
918-
* cannot know how to deal with visibility across AMs.
916+
* cannot know how to deal with visibility across AMs. Note that this
917+
* routine is allowed to set FreezeXid / MultiXactCutoff to different
918+
* values (e.g. because the AM doesn't use freezing).
919919
*/
920920
table_relation_copy_for_cluster(OldHeap, NewHeap, OldIndex, use_sort,
921-
OldestXmin, FreezeXid, MultiXactCutoff,
921+
OldestXmin, &FreezeXid, &MultiXactCutoff,
922922
&num_tuples, &tups_vacuumed,
923923
&tups_recently_dead);
924924

925+
/* return selected values to caller, get set as relfrozenxid/minmxid */
926+
*pFreezeXid = FreezeXid;
927+
*pCutoffMulti = MultiXactCutoff;
928+
925929
/* Reset rd_toastoid just to be tidy --- it shouldn't be looked at again */
926930
NewHeap->rd_toastoid = InvalidOid;
927931

@@ -1118,9 +1122,9 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class,
11181122
/* set rel1's frozen Xid and minimum MultiXid */
11191123
if (relform1->relkind != RELKIND_INDEX)
11201124
{
1121-
Assert(TransactionIdIsNormal(frozenXid));
1125+
Assert(!TransactionIdIsValid(frozenXid) ||
1126+
TransactionIdIsNormal(frozenXid));
11221127
relform1->relfrozenxid = frozenXid;
1123-
Assert(MultiXactIdIsValid(cutoffMulti));
11241128
relform1->relminmxid = cutoffMulti;
11251129
}
11261130

‎src/backend/commands/vacuum.c

Copy file name to clipboardExpand all lines: src/backend/commands/vacuum.c
+39-14Lines changed: 39 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -1313,36 +1313,61 @@ vac_update_datfrozenxid(void)
13131313

13141314
/*
13151315
* Only consider relations able to hold unfrozen XIDs (anything else
1316-
* should have InvalidTransactionId in relfrozenxid anyway.)
1316+
* should have InvalidTransactionId in relfrozenxid anyway).
13171317
*/
13181318
if (classForm->relkind != RELKIND_RELATION &&
13191319
classForm->relkind != RELKIND_MATVIEW &&
13201320
classForm->relkind != RELKIND_TOASTVALUE)
1321+
{
1322+
Assert(!TransactionIdIsValid(classForm->relfrozenxid));
1323+
Assert(!MultiXactIdIsValid(classForm->relminmxid));
13211324
continue;
1322-
1323-
Assert(TransactionIdIsNormal(classForm->relfrozenxid));
1324-
Assert(MultiXactIdIsValid(classForm->relminmxid));
1325+
}
13251326

13261327
/*
1328+
* Some table AMs might not need per-relation xid / multixid
1329+
* horizons. It therefore seems reasonable to allow relfrozenxid and
1330+
* relminmxid to not be set (i.e. set to their respective Invalid*Id)
1331+
* independently. Thus validate and compute horizon for each only if
1332+
* set.
1333+
*
13271334
* If things are working properly, no relation should have a
13281335
* relfrozenxid or relminmxid that is "in the future". However, such
13291336
* cases have been known to arise due to bugs in pg_upgrade. If we
13301337
* see any entries that are "in the future", chicken out and don't do
1331-
* anything. This ensures we won't truncate clog before those
1332-
* relations have been scanned and cleaned up.
1338+
* anything. This ensures we won't truncate clog & multixact SLRUs
1339+
* before those relations have been scanned and cleaned up.
13331340
*/
1334-
if (TransactionIdPrecedes(lastSaneFrozenXid, classForm->relfrozenxid) ||
1335-
MultiXactIdPrecedes(lastSaneMinMulti, classForm->relminmxid))
1341+
1342+
if (TransactionIdIsValid(classForm->relfrozenxid))
13361343
{
1337-
bogus = true;
1338-
break;
1344+
Assert(TransactionIdIsNormal(classForm->relfrozenxid));
1345+
1346+
/* check for values in the future */
1347+
if (TransactionIdPrecedes(lastSaneFrozenXid, classForm->relfrozenxid))
1348+
{
1349+
bogus = true;
1350+
break;
1351+
}
1352+
1353+
/* determine new horizon */
1354+
if (TransactionIdPrecedes(classForm->relfrozenxid, newFrozenXid))
1355+
newFrozenXid = classForm->relfrozenxid;
13391356
}
13401357

1341-
if (TransactionIdPrecedes(classForm->relfrozenxid, newFrozenXid))
1342-
newFrozenXid = classForm->relfrozenxid;
1358+
if (MultiXactIdIsValid(classForm->relminmxid))
1359+
{
1360+
/* check for values in the future */
1361+
if (MultiXactIdPrecedes(lastSaneMinMulti, classForm->relminmxid))
1362+
{
1363+
bogus = true;
1364+
break;
1365+
}
13431366

1344-
if (MultiXactIdPrecedes(classForm->relminmxid, newMinMulti))
1345-
newMinMulti = classForm->relminmxid;
1367+
/* determine new horizon */
1368+
if (MultiXactIdPrecedes(classForm->relminmxid, newMinMulti))
1369+
newMinMulti = classForm->relminmxid;
1370+
}
13461371
}
13471372

13481373
/* we're done with pg_class */

‎src/backend/postmaster/autovacuum.c

Copy file name to clipboardExpand all lines: src/backend/postmaster/autovacuum.c
+2-2Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -3033,8 +3033,8 @@ relation_needs_vacanalyze(Oid relid,
30333033
multiForceLimit = recentMulti - multixact_freeze_max_age;
30343034
if (multiForceLimit < FirstMultiXactId)
30353035
multiForceLimit -= FirstMultiXactId;
3036-
force_vacuum = MultiXactIdPrecedes(classForm->relminmxid,
3037-
multiForceLimit);
3036+
force_vacuum = MultiXactIdIsValid(classForm->relminmxid) &&
3037+
MultiXactIdPrecedes(classForm->relminmxid, multiForceLimit);
30383038
}
30393039
*wraparound = force_vacuum;
30403040

‎src/include/access/tableam.h

Copy file name to clipboardExpand all lines: src/include/access/tableam.h
+20-15Lines changed: 20 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -452,8 +452,8 @@ typedef struct TableAmRoutine
452452
Relation OldIndex,
453453
bool use_sort,
454454
TransactionId OldestXmin,
455-
TransactionId FreezeXid,
456-
MultiXactId MultiXactCutoff,
455+
TransactionId *xid_cutoff,
456+
MultiXactId *multi_cutoff,
457457
double *num_tuples,
458458
double *tups_vacuumed,
459459
double *tups_recently_dead);
@@ -1297,32 +1297,37 @@ table_relation_copy_data(Relation rel, RelFileNode newrnode)
12971297
* Copy data from `OldHeap` into `NewHeap`, as part of a CLUSTER or VACUUM
12981298
* FULL.
12991299
*
1300-
* If `use_sort` is true, the table contents are sorted appropriate for
1301-
* `OldIndex`; if use_sort is false and OldIndex is not InvalidOid, the data
1302-
* is copied in that index's order; if use_sort is false and OidIndex is
1303-
* InvalidOid, no sorting is performed.
1300+
* Additional Input parameters:
1301+
* - use_sort - if true, the table contents are sorted appropriate for
1302+
* `OldIndex`; if false and OldIndex is not InvalidOid, the data is copied
1303+
* in that index's order; if false and OidIndex is InvalidOid, no sorting is
1304+
* performed
1305+
* - OidIndex - see use_sort
1306+
* - OldestXmin - computed by vacuum_set_xid_limits(), even when
1307+
* not needed for the relation's AM
1308+
* - *xid_cutoff - dito
1309+
* - *multi_cutoff - dito
13041310
*
1305-
* OldestXmin, FreezeXid, MultiXactCutoff must be currently valid values for
1306-
* the table.
1307-
*
1308-
* *num_tuples, *tups_vacuumed, *tups_recently_dead will contain statistics
1309-
* computed while copying for the relation. Not all might make sense for every
1310-
* AM.
1311+
* Output parameters:
1312+
* - *xid_cutoff - rel's new relfrozenxid value, may be invalid
1313+
* - *multi_cutoff - rel's new relminmxid value, may be invalid
1314+
* - *tups_vacuumed - stats, for logging, if appropriate for AM
1315+
* - *tups_recently_dead - stats, for logging, if appropriate for AM
13111316
*/
13121317
static inline void
13131318
table_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
13141319
Relation OldIndex,
13151320
bool use_sort,
13161321
TransactionId OldestXmin,
1317-
TransactionId FreezeXid,
1318-
MultiXactId MultiXactCutoff,
1322+
TransactionId *xid_cutoff,
1323+
MultiXactId *multi_cutoff,
13191324
double *num_tuples,
13201325
double *tups_vacuumed,
13211326
double *tups_recently_dead)
13221327
{
13231328
OldHeap->rd_tableam->relation_copy_for_cluster(OldHeap, NewHeap, OldIndex,
13241329
use_sort, OldestXmin,
1325-
FreezeXid, MultiXactCutoff,
1330+
xid_cutoff, multi_cutoff,
13261331
num_tuples, tups_vacuumed,
13271332
tups_recently_dead);
13281333
}

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