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Track latest completed xid as a FullTransactionId.

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The reason for doing so is that a subsequent commit will need that to
avoid wraparound issues. As the subsequent change is large this was
split out for easier review.

The reason this is not a perfect straight-forward change is that we do
not want track 64bit xids in the procarray or the WAL. Therefore we
need to advance lastestCompletedXid in relation to 32 bit xids. The
code for that is now centralized in MaintainLatestCompletedXid*.

Author: Andres Freund
Reviewed-By: Thomas Munro, Robert Haas, David Rowley
Discussion: https://postgr.es/m/20200301083601.ews6hz5dduc3w2se@alap3.anarazel.de
This commit is contained in:
Andres Freund
2020-08-11 17:41:18 -07:00
parent fea10a6434
commit 3bd7f9969a
4 changed files with 191 additions and 29 deletions
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4
src/backend/access/transam/xlog.c
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@ -7865,8 +7865,8 @@ StartupXLOG(void)
/* also initialize latestCompletedXid, to nextXid - 1 */
LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
ShmemVariableCache->latestCompletedXid = XidFromFullTransactionId(ShmemVariableCache->nextXid);
TransactionIdRetreat(ShmemVariableCache->latestCompletedXid);
ShmemVariableCache->latestCompletedXid = ShmemVariableCache->nextXid;
FullTransactionIdRetreat(&ShmemVariableCache->latestCompletedXid);
LWLockRelease(ProcArrayLock);
/*