Fix timing of Startup CLOG and MultiXact during Hot Standby

Patch by me, bug report by Chris Redekop, analysis by Florian Pflug

diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index cb3f91a76b09e57c208a8f01c436a992e71b652e..e594a55c399a251ad0e6f73c73b22095fd27fb25 100644 (file)
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -490,6 +490,25 @@ StartupCLOG(void)
     */
    ClogCtl->shared->latest_page_number = pageno;
 
+   LWLockRelease(CLogControlLock);
+}
+
+/*
+ * This must be called ONCE at the end of startup/recovery.
+ */
+void
+TrimCLOG(void)
+{
+   TransactionId xid = ShmemVariableCache->nextXid;
+   int         pageno = TransactionIdToPage(xid);
+
+   LWLockAcquire(CLogControlLock, LW_EXCLUSIVE);
+
+   /*
+    * Re-Initialize our idea of the latest page number.
+    */
+   ClogCtl->shared->latest_page_number = pageno;
+
    /*
     * Zero out the remainder of the current clog page.  Under normal
     * circumstances it should be zeroes already, but it seems at least

diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 3f3bdc03353a819b5242664f0d9a638a23241ff2..1cb3dfab3750fce93519d947fcc4babf3fbd2393 100644 (file)
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -1568,7 +1568,7 @@ StartupMultiXact(void)
 
    /*
     * Zero out the remainder of the current members page.  See notes in
-    * StartupCLOG() for motivation.
+    * TrimCLOG() for motivation.
     */
    entryno = MXOffsetToMemberEntry(offset);
    if (entryno != 0)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 6c18db4050fd3744324b9479f059cbfb9ffdd7d3..906292690d6658d3b55cf38450cfbb8f8b2639ad 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6067,10 +6067,12 @@ StartupXLOG(void)
                oldestActiveXID = checkPoint.oldestActiveXid;
            Assert(TransactionIdIsValid(oldestActiveXID));
 
-           /* Startup commit log and related stuff */
+           /*
+            * Startup commit log and subtrans only. Other SLRUs are not
+            * maintained during recovery and need not be started yet.
+            */
            StartupCLOG();
            StartupSUBTRANS(oldestActiveXID);
-           StartupMultiXact();
 
            /*
             * If we're beginning at a shutdown checkpoint, we know that
@@ -6530,16 +6532,21 @@ StartupXLOG(void)
    TransactionIdRetreat(ShmemVariableCache->latestCompletedXid);
 
    /*
-    * Start up the commit log and related stuff, too. In hot standby mode we
-    * did this already before WAL replay.
+    * Start up the commit log and subtrans, if not already done for
+    * hot standby.
     */
    if (standbyState == STANDBY_DISABLED)
    {
        StartupCLOG();
        StartupSUBTRANS(oldestActiveXID);
-       StartupMultiXact();
    }
 
+   /*
+    * Perform end of recovery actions for any SLRUs that need it.
+    */
+   StartupMultiXact();
+   TrimCLOG();
+
    /* Reload shared-memory state for prepared transactions */
    RecoverPreparedTransactions();
 

diff --git a/src/include/access/clog.h b/src/include/access/clog.h
index a1f4c9dc6a95bf00351a6f056a1d1e2ed8378d2f..873732e80ef96c73dc9252a3b21b7d6a44fb04c3 100644 (file)
--- a/src/include/access/clog.h
+++ b/src/include/access/clog.h
@@ -40,6 +40,7 @@ extern Size CLOGShmemSize(void);
 extern void CLOGShmemInit(void);
 extern void BootStrapCLOG(void);
 extern void StartupCLOG(void);
+extern void TrimCLOG(void);
 extern void ShutdownCLOG(void);
 extern void CheckPointCLOG(void);
 extern void ExtendCLOG(TransactionId newestXact);