From e24d1dc069bd44b6311166f9ba23b39639f55968 Mon Sep 17 00:00:00 2001
From: Simon Riggs <simon@2ndQuadrant.com>
Date: Mon, 30 Aug 2010 14:16:48 +0000
Subject: [PATCH] Teach GetOldestXmin() about KnownAssignedXids during
recovery. Very minor issue, though this is required for a later patch.
Reported by Heikki Linnakangas.
---
src/backend/storage/ipc/procarray.c | 42 ++++++++++++++++++++++++++++-
1 file changed, 41 insertions(+), 1 deletion(-)
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 239688cd9d4..b2ce0b25f2a 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -37,7 +37,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.73 2010/08/12 23:24:54 rhaas Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.74 2010/08/30 14:16:48 sriggs Exp $
*
*-------------------------------------------------------------------------
*/
@@ -156,6 +156,7 @@ static int KnownAssignedXidsGet(TransactionId *xarray, TransactionId xmax);
static int KnownAssignedXidsGetAndSetXmin(TransactionId *xarray,
TransactionId *xmin,
TransactionId xmax);
+static int KnownAssignedXidsGetOldestXmin(void);
static void KnownAssignedXidsDisplay(int trace_level);
/*
@@ -1112,6 +1113,18 @@ GetOldestXmin(bool allDbs, bool ignoreVacuum)
}
}
+ if (RecoveryInProgress())
+ {
+ /*
+ * Check to see whether KnownAssignedXids contains an xid value
+ * older than the main procarray.
+ */
+ TransactionId kaxmin = KnownAssignedXidsGetOldestXmin();
+ if (TransactionIdIsNormal(kaxmin) &&
+ TransactionIdPrecedes(kaxmin, result))
+ result = kaxmin;
+ }
+
LWLockRelease(ProcArrayLock);
/*
@@ -3015,6 +3028,33 @@ KnownAssignedXidsGetAndSetXmin(TransactionId *xarray, TransactionId *xmin,
return count;
}
+static int
+KnownAssignedXidsGetOldestXmin(void)
+{
+ /* use volatile pointer to prevent code rearrangement */
+ volatile ProcArrayStruct *pArray = procArray;
+ int head,
+ tail;
+ int i;
+
+ /*
+ * Fetch head just once, since it may change while we loop.
+ */
+ SpinLockAcquire(&pArray->known_assigned_xids_lck);
+ tail = pArray->tailKnownAssignedXids;
+ head = pArray->headKnownAssignedXids;
+ SpinLockRelease(&pArray->known_assigned_xids_lck);
+
+ for (i = tail; i < head; i++)
+ {
+ /* Skip any gaps in the array */
+ if (KnownAssignedXidsValid[i])
+ return KnownAssignedXids[i];
+ }
+
+ return InvalidTransactionId;
+}
+
/*
* Display KnownAssignedXids to provide debug trail
*
--
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