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Avoid uselessly looking up old LOCK_ONLY multixacts

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Commit 0ac5ad5134 removed an optimization in multixact.c that skipped
fetching members of MultiXactId that were older than our
OldestVisibleMXactId value.  The reason this was removed is that it is
possible for multixacts that contain updates to be older than that
value.  However, if the caller is certain that the multi does not
contain an update (because the infomask bits say so), it can pass this
info down to GetMultiXactIdMembers, enabling it to use the old
optimization.

Pointed out by Andres Freund in 20131121200517.GM7240@alap2.anarazel.de
This commit is contained in:
Alvaro Herrera
2014-07-29 15:41:06 -04:00
parent c2581794f3
commit 0531549801
5 changed files with 62 additions and 25 deletions
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33
src/backend/access/heap/heapam.c
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@ -4183,7 +4183,9 @@ l3:
* the case, HeapTupleSatisfiesUpdate would have returned
* MayBeUpdated and we wouldn't be here.
*/
nmembers = GetMultiXactIdMembers(xwait, &members, false);
nmembers =
GetMultiXactIdMembers(xwait, &members, false,
HEAP_XMAX_IS_LOCKED_ONLY(infomask));
for (i = 0; i < nmembers; i++)
{
@ -4204,7 +4206,8 @@ l3:
}
}
pfree(members);
if (members)
pfree(members);
}
/*
@ -4353,7 +4356,9 @@ l3:
* been the case, HeapTupleSatisfiesUpdate would have returned
* MayBeUpdated and we wouldn't be here.
*/
nmembers = GetMultiXactIdMembers(xwait, &members, false);
nmembers =
GetMultiXactIdMembers(xwait, &members, false,
HEAP_XMAX_IS_LOCKED_ONLY(infomask));
if (nmembers <= 0)
{
@ -4834,7 +4839,7 @@ l5:
* MultiXactIdExpand if we weren't to do this, so this check is not
* incurring extra work anyhow.
*/
if (!MultiXactIdIsRunning(xmax))
if (!MultiXactIdIsRunning(xmax, HEAP_XMAX_IS_LOCKED_ONLY(old_infomask)))
{
if (HEAP_XMAX_IS_LOCKED_ONLY(old_infomask) ||
TransactionIdDidAbort(MultiXactIdGetUpdateXid(xmax,
@ -5175,7 +5180,8 @@ l4:
int i;
MultiXactMember *members;
nmembers = GetMultiXactIdMembers(rawxmax, &members, false);
nmembers = GetMultiXactIdMembers(rawxmax, &members, false,
HEAP_XMAX_IS_LOCKED_ONLY(old_infomask));
for (i = 0; i < nmembers; i++)
{
HTSU_Result res;
@ -5533,7 +5539,8 @@ FreezeMultiXactId(MultiXactId multi, uint16 t_infomask,
*/
Assert((!(t_infomask & HEAP_LOCK_MASK) &&
HEAP_XMAX_IS_LOCKED_ONLY(t_infomask)) ||
!MultiXactIdIsRunning(multi));
!MultiXactIdIsRunning(multi,
HEAP_XMAX_IS_LOCKED_ONLY(t_infomask)));
if (HEAP_XMAX_IS_LOCKED_ONLY(t_infomask))
{
*flags |= FRM_INVALIDATE_XMAX;
@ -5576,7 +5583,9 @@ FreezeMultiXactId(MultiXactId multi, uint16 t_infomask,
allow_old = !(t_infomask & HEAP_LOCK_MASK) &&
HEAP_XMAX_IS_LOCKED_ONLY(t_infomask);
nmembers = GetMultiXactIdMembers(multi, &members, allow_old);
nmembers =
GetMultiXactIdMembers(multi, &members, allow_old,
HEAP_XMAX_IS_LOCKED_ONLY(t_infomask));
if (nmembers <= 0)
{
/* Nothing worth keeping */
@ -5983,7 +5992,7 @@ GetMultiXactIdHintBits(MultiXactId multi, uint16 *new_infomask,
* We only use this in multis we just created, so they cannot be values
* pre-pg_upgrade.
*/
nmembers = GetMultiXactIdMembers(multi, &members, false);
nmembers = GetMultiXactIdMembers(multi, &members, false, false);
for (i = 0; i < nmembers; i++)
{
@ -6062,7 +6071,7 @@ MultiXactIdGetUpdateXid(TransactionId xmax, uint16 t_infomask)
* Since we know the LOCK_ONLY bit is not set, this cannot be a multi from
* pre-pg_upgrade.
*/
nmembers = GetMultiXactIdMembers(xmax, &members, false);
nmembers = GetMultiXactIdMembers(xmax, &members, false, false);
if (nmembers > 0)
{
@ -6148,7 +6157,8 @@ Do_MultiXactIdWait(MultiXactId multi, MultiXactStatus status,
int remain = 0;
allow_old = !(infomask & HEAP_LOCK_MASK) && HEAP_XMAX_IS_LOCKED_ONLY(infomask);
nmembers = GetMultiXactIdMembers(multi, &members, allow_old);
nmembers = GetMultiXactIdMembers(multi, &members, allow_old,
HEAP_XMAX_IS_LOCKED_ONLY(infomask));
if (nmembers >= 0)
{
@ -6294,7 +6304,8 @@ heap_tuple_needs_freeze(HeapTupleHeader tuple, TransactionId cutoff_xid,
allow_old = !(tuple->t_infomask & HEAP_LOCK_MASK) &&
HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask);
nmembers = GetMultiXactIdMembers(multi, &members, allow_old);
nmembers = GetMultiXactIdMembers(multi, &members, allow_old,
HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask));
for (i = 0; i < nmembers; i++)
{