pg_stat_replication.sync_state was displayed incorrectly at page boundary.

XLogRecPtrIsInvalid() only checks the xrecoff field, which is correct when
checking if a WAL record could legally begin at the given position, but WAL
sending can legally be paused at a page boundary, in which case xrecoff is
0. Use XLByteEQ(..., InvalidXLogRecPtr) instead, which checks that both
xlogid and xrecoff are 0.

9.3 doesn't have this problem because XLogRecPtr is now a single 64-bit
integer, so XLogRecPtrIsInvalid() does the right thing. Apply to 9.2, and
9.1 where pg_stat_replication view was introduced.

Kyotaro HORIGUCHI, reviewed by Fujii Masao.

diff --git a/src/backend/replication/syncrep.c b/src/backend/replication/syncrep.c
index 10af4e85c1302c5e3d2ad472c9f876bd7db104fa..7fe9b09adfadf898fa6ced66c72e4a86a9af3cb3 100644 (file)
--- a/src/backend/replication/syncrep.c
+++ b/src/backend/replication/syncrep.c
@@ -375,6 +375,7 @@ SyncRepReleaseWaiters(void)
    int         numprocs = 0;
    int         priority = 0;
    int         i;
+   XLogRecPtr  InvalidXLogRecPtr = {0, 0};
 
    /*
     * If this WALSender is serving a standby that is not on the list of
@@ -384,7 +385,7 @@ SyncRepReleaseWaiters(void)
     */
    if (MyWalSnd->sync_standby_priority == 0 ||
        MyWalSnd->state < WALSNDSTATE_STREAMING ||
-       XLogRecPtrIsInvalid(MyWalSnd->flush))
+       XLByteEQ(MyWalSnd->flush, InvalidXLogRecPtr))
        return;
 
    /*
@@ -405,7 +406,7 @@ SyncRepReleaseWaiters(void)
            walsnd->sync_standby_priority > 0 &&
            (priority == 0 ||
             priority > walsnd->sync_standby_priority) &&
-           !XLogRecPtrIsInvalid(walsnd->flush))
+           !XLByteEQ(walsnd->flush, InvalidXLogRecPtr))
        {
            priority = walsnd->sync_standby_priority;
            syncWalSnd = walsnd;

diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index c5391676c4ae24853b950fd361bf9b20d5345770..7ccab20b13e6592cb6bb05af4c0228181fa2bb81 100644 (file)
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1403,6 +1403,7 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
    int         priority = 0;
    int         sync_standby = -1;
    int         i;
+   XLogRecPtr  InvalidXLogRecPtr = {0, 0};
 
    /* check to see if caller supports us returning a tuplestore */
    if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
@@ -1448,14 +1449,14 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
             * which always returns an invalid flush location, as an
             * asynchronous standby.
             */
-           sync_priority[i] = XLogRecPtrIsInvalid(walsnd->flush) ?
+           sync_priority[i] = XLByteEQ(walsnd->flush, InvalidXLogRecPtr) ?
                0 : walsnd->sync_standby_priority;
 
            if (walsnd->state == WALSNDSTATE_STREAMING &&
                walsnd->sync_standby_priority > 0 &&
                (priority == 0 ||
                 priority > walsnd->sync_standby_priority) &&
-               !XLogRecPtrIsInvalid(walsnd->flush))
+               !XLByteEQ(walsnd->flush, InvalidXLogRecPtr))
            {
                priority = walsnd->sync_standby_priority;
                sync_standby = i;