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Consolidate VACUUM xid cutoff logic.

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Push the logic for determining whether or not a VACUUM operation will be
aggressive down into vacuum_set_xid_limits().  This makes the function's
signature significantly simpler, and seems clearer overall.

Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WzkymFbz6D_vL+jmqSn_5q1wsFvFrE+37yLgL_Rkfd6Gzg@mail.gmail.com
This commit is contained in:
Peter Geoghegan
2022-02-11 18:26:15 -08:00
parent 872770fd6c
commit efa4a9462a
4 changed files with 79 additions and 95 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
src/backend/commands/cluster.c
View File

@@ -857,8 +857,7 @@ copy_table_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex, bool verbose,
* not to be aggressive about this.
*/
vacuum_set_xid_limits(OldHeap, 0, 0, 0, 0,
&OldestXmin, &FreezeXid, NULL, &MultiXactCutoff,
NULL);
&OldestXmin, &FreezeXid, &MultiXactCutoff);
/*
* FreezeXid will become the table's new relfrozenxid, and that mustn't go

131
src/backend/commands/vacuum.c
View File

@@ -943,24 +943,18 @@ get_all_vacuum_rels(int options)
* Input parameters are the target relation, applicable freeze age settings.
*
* The output parameters are:
* - oldestXmin is the cutoff value used to distinguish whether tuples are
* DEAD or RECENTLY_DEAD (see HeapTupleSatisfiesVacuum).
* - oldestXmin is the Xid below which tuples deleted by any xact (that
* committed) should be considered DEAD, not just RECENTLY_DEAD.
* - freezeLimit is the Xid below which all Xids are replaced by
* FrozenTransactionId during vacuum.
* - xidFullScanLimit (computed from freeze_table_age parameter)
* represents a minimum Xid value; a table whose relfrozenxid is older than
* this will have a full-table vacuum applied to it, to freeze tuples across
* the whole table. Vacuuming a table younger than this value can use a
* partial scan.
* - multiXactCutoff is the value below which all MultiXactIds are removed from
* Xmax.
* - mxactFullScanLimit is a value against which a table's relminmxid value is
* compared to produce a full-table vacuum, as with xidFullScanLimit.
* - multiXactCutoff is the value below which all MultiXactIds are removed
* from Xmax.
*
* xidFullScanLimit and mxactFullScanLimit can be passed as NULL if caller is
* not interested.
* Return value indicates if vacuumlazy.c caller should make its VACUUM
* operation aggressive. An aggressive VACUUM must advance relfrozenxid up to
* FreezeLimit, and relminmxid up to multiXactCutoff.
*/
void
bool
vacuum_set_xid_limits(Relation rel,
int freeze_min_age,
int freeze_table_age,
@@ -968,9 +962,7 @@ vacuum_set_xid_limits(Relation rel,
int multixact_freeze_table_age,
TransactionId *oldestXmin,
TransactionId *freezeLimit,
TransactionId *xidFullScanLimit,
MultiXactId *multiXactCutoff,
MultiXactId *mxactFullScanLimit)
MultiXactId *multiXactCutoff)
{
int freezemin;
int mxid_freezemin;
@@ -980,6 +972,7 @@ vacuum_set_xid_limits(Relation rel,
MultiXactId oldestMxact;
MultiXactId mxactLimit;
MultiXactId safeMxactLimit;
int freezetable;
/*
* We can always ignore processes running lazy vacuum. This is because we
@@ -1097,64 +1090,60 @@ vacuum_set_xid_limits(Relation rel,
*multiXactCutoff = mxactLimit;
if (xidFullScanLimit != NULL)
{
int freezetable;
/*
* Done setting output parameters; just need to figure out if caller needs
* to do an aggressive VACUUM or not.
*
* Determine the table freeze age to use: as specified by the caller, or
* vacuum_freeze_table_age, but in any case not more than
* autovacuum_freeze_max_age * 0.95, so that if you have e.g nightly
* VACUUM schedule, the nightly VACUUM gets a chance to freeze tuples
* before anti-wraparound autovacuum is launched.
*/
freezetable = freeze_table_age;
if (freezetable < 0)
freezetable = vacuum_freeze_table_age;
freezetable = Min(freezetable, autovacuum_freeze_max_age * 0.95);
Assert(freezetable >= 0);
Assert(mxactFullScanLimit != NULL);
/*
* Compute XID limit causing an aggressive vacuum, being careful not to
* generate a "permanent" XID
*/
limit = ReadNextTransactionId() - freezetable;
if (!TransactionIdIsNormal(limit))
limit = FirstNormalTransactionId;
if (TransactionIdPrecedesOrEquals(rel->rd_rel->relfrozenxid,
limit))
return true;
/*
* Determine the table freeze age to use: as specified by the caller,
* or vacuum_freeze_table_age, but in any case not more than
* autovacuum_freeze_max_age * 0.95, so that if you have e.g nightly
* VACUUM schedule, the nightly VACUUM gets a chance to freeze tuples
* before anti-wraparound autovacuum is launched.
*/
freezetable = freeze_table_age;
if (freezetable < 0)
freezetable = vacuum_freeze_table_age;
freezetable = Min(freezetable, autovacuum_freeze_max_age * 0.95);
Assert(freezetable >= 0);
/*
* Similar to the above, determine the table freeze age to use for
* multixacts: as specified by the caller, or
* vacuum_multixact_freeze_table_age, but in any case not more than
* autovacuum_multixact_freeze_table_age * 0.95, so that if you have e.g.
* nightly VACUUM schedule, the nightly VACUUM gets a chance to freeze
* multixacts before anti-wraparound autovacuum is launched.
*/
freezetable = multixact_freeze_table_age;
if (freezetable < 0)
freezetable = vacuum_multixact_freeze_table_age;
freezetable = Min(freezetable,
effective_multixact_freeze_max_age * 0.95);
Assert(freezetable >= 0);
/*
* Compute XID limit causing a full-table vacuum, being careful not to
* generate a "permanent" XID.
*/
limit = ReadNextTransactionId() - freezetable;
if (!TransactionIdIsNormal(limit))
limit = FirstNormalTransactionId;
/*
* Compute MultiXact limit causing an aggressive vacuum, being careful to
* generate a valid MultiXact value
*/
mxactLimit = ReadNextMultiXactId() - freezetable;
if (mxactLimit < FirstMultiXactId)
mxactLimit = FirstMultiXactId;
if (MultiXactIdPrecedesOrEquals(rel->rd_rel->relminmxid,
mxactLimit))
return true;
*xidFullScanLimit = limit;
/*
* Similar to the above, determine the table freeze age to use for
* multixacts: as specified by the caller, or
* vacuum_multixact_freeze_table_age, but in any case not more than
* autovacuum_multixact_freeze_table_age * 0.95, so that if you have
* e.g. nightly VACUUM schedule, the nightly VACUUM gets a chance to
* freeze multixacts before anti-wraparound autovacuum is launched.
*/
freezetable = multixact_freeze_table_age;
if (freezetable < 0)
freezetable = vacuum_multixact_freeze_table_age;
freezetable = Min(freezetable,
effective_multixact_freeze_max_age * 0.95);
Assert(freezetable >= 0);
/*
* Compute MultiXact limit causing a full-table vacuum, being careful
* to generate a valid MultiXact value.
*/
mxactLimit = ReadNextMultiXactId() - freezetable;
if (mxactLimit < FirstMultiXactId)
mxactLimit = FirstMultiXactId;
*mxactFullScanLimit = mxactLimit;
}
else
{
Assert(mxactFullScanLimit == NULL);
}
return false;
}
/*