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Transaction IDs wrap around, per my proposal of 13-Aug-01. More

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documentation to come, but the code is all here.  initdb forced.
This commit is contained in:
Tom Lane
2001-08-26 16:56:03 +00:00
parent d1ee78f296
commit bc7d37a525
29 changed files with 617 additions and 171 deletions
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67
src/backend/access/transam/transam.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/transam/transam.c,v 1.47 2001/08/25 18:52:41 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/transam/transam.c,v 1.48 2001/08/26 16:55:59 tgl Exp $
*
* NOTES
* This file contains the high level access-method interface to the
@ -236,3 +236,68 @@ TransactionIdAbort(TransactionId transactionId)
TransactionLogUpdate(transactionId, TRANSACTION_STATUS_ABORTED);
}
/*
* TransactionIdPrecedes --- is id1 logically < id2?
*/
bool
TransactionIdPrecedes(TransactionId id1, TransactionId id2)
{
/*
* If either ID is a permanent XID then we can just do unsigned
* comparison. If both are normal, do a modulo-2^31 comparison.
*/
int32 diff;
if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
return (id1 < id2);
diff = (int32) (id1 - id2);
return (diff < 0);
}
/*
* TransactionIdPrecedesOrEquals --- is id1 logically <= id2?
*/
bool
TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2)
{
int32 diff;
if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
return (id1 <= id2);
diff = (int32) (id1 - id2);
return (diff <= 0);
}
/*
* TransactionIdFollows --- is id1 logically > id2?
*/
bool
TransactionIdFollows(TransactionId id1, TransactionId id2)
{
int32 diff;
if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
return (id1 > id2);
diff = (int32) (id1 - id2);
return (diff > 0);
}
/*
* TransactionIdFollowsOrEquals --- is id1 logically >= id2?
*/
bool
TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2)
{
int32 diff;
if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
return (id1 >= id2);
diff = (int32) (id1 - id2);
return (diff >= 0);
}