postgres.git / summary / log / commit / refs

commit    0eac283bfc8b893d91a1ecf184d2c8373a1ed906
Author:   Amit Kapila <akapila@postgresql.org>
Date:     Thu Dec 12 06:21:30 2019 +0000
First released in: 13.0, 11.7, 12.2

    Change overly strict Assert in TransactionGroupUpdateXidStatus.
    
    This Assert thought that an overflowed transaction can never get registered
    for the group update.  But that is not true, because even when the number
    of children for a transaction got reduced, the overflow flag is not
    changed.  And, for group update, we only care about the current number of
    children for a transaction that is being committed.
    
    Based on comments by Andres Freund, remove a redundant Assert in
    TransactionIdSetPageStatus as we already had a static Assert for the same
    condition a few lines earlier.
    
    Reported-by: Vignesh C
    Author: Dilip Kumar
    Reviewed-by: Amit Kapila
    Backpatch-through: 11
    Discussion: https://postgr.es/m/CAFiTN-s5=uJw-Z6JC9gcqtBSjXsrHnU63PXBrA=pnBjqnkm5UA@mail.gmail.com


 src/backend/access/transam/clog.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index 47db7a8a88c..8a706445230 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -299,13 +299,6 @@ TransactionIdSetPageStatus(TransactionId xid, int nsubxids,
 		memcmp(subxids, MyProc->subxids.xids,
 			   nsubxids * sizeof(TransactionId)) == 0)
 	{
-		/*
-		 * We don't try to do group update optimization if a process has
-		 * overflowed the subxids array in its PGPROC, since in that case we
-		 * don't have a complete list of XIDs for it.
-		 */
-		Assert(THRESHOLD_SUBTRANS_CLOG_OPT <= PGPROC_MAX_CACHED_SUBXIDS);
-
 		/*
 		 * If we can immediately acquire CLogControlLock, we update the status
 		 * of our own XID and release the lock.  If not, try use group XID
@@ -520,10 +513,10 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
 		PGXACT	   *pgxact = &ProcGlobal->allPgXact[nextidx];
 
 		/*
-		 * Overflowed transactions should not use group XID status update
-		 * mechanism.
+		 * Transactions with more than THRESHOLD_SUBTRANS_CLOG_OPT sub-XIDs
+		 * should not use group XID status update mechanism.
 		 */
-		Assert(!pgxact->overflowed);
+		Assert(pgxact->nxids <= THRESHOLD_SUBTRANS_CLOG_OPT);
 
 		TransactionIdSetPageStatusInternal(proc->clogGroupMemberXid,
 										   pgxact->nxids,


[parent: 95f43fee9179]