1. xact.c: update comments about changing MyProc->xid and MyProc->xmin.

2. varsup.c:ReadNewTransactionId(): don't read nextXid from disk -
   this func doesn't allocate next xid, so ShmemVariableCache->nextXid
   may be used (but GetNewTransactionId() must be called first).
3. vacuum.c: change elog(ERROR, "Child item....") to elog(NOTICE) -
   this is not ERROR, proper handling is just not implemented, yet.
4. s_lock.c: increase S_MAX_BUSY by 2 times.
5. shmem.c:GetSnapshotData(): have to call ReadNewTransactionId()
   _after_ SpinAcquire(ShmemIndexLock).

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fd23de1d98463810ef4614ff08696cbeef0e8ced..0ec7ede4e79dec6966c6940fe597508ec701179e 100644 (file)
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/access/transam/varsup.c,v 1.21 1999/06/03 04:41:40 vadim Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/access/transam/varsup.c,v 1.22 1999/06/06 20:19:33 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -335,16 +335,13 @@ ReadNewTransactionId(TransactionId *xid)
 
        SpinAcquire(OidGenLockId);      /* not good for concurrency... */
 
-       if (ShmemVariableCache->xid_count == 0)
-       {
-               TransactionId nextid;
-
-               VariableRelationGetNextXid(&nextid);
-               TransactionIdStore(nextid, &(ShmemVariableCache->nextXid));
-               ShmemVariableCache->xid_count = VAR_XID_PREFETCH;
-               TransactionIdAdd(&nextid, VAR_XID_PREFETCH);
-               VariableRelationPutNextXid(nextid);
-       }
+       /*
+        * Note that we don't check is ShmemVariableCache->xid_count equal
+        * to 0 or not. This will work as long as we don't call 
+        * ReadNewTransactionId() before GetNewTransactionId().
+        */
+       if (ShmemVariableCache->nextXid == 0)
+               elog(ERROR, "ReadNewTransactionId: ShmemVariableCache->nextXid is not initialized");
 
        TransactionIdStore(ShmemVariableCache->nextXid, xid);
 

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6bde05733ac829b51776bfc4cc8ca09a4f4f7f41..d03136b5085f350d5dd371f293fb462eedbc6958 100644 (file)
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.39 1999/06/03 13:33:12 vadim Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.40 1999/06/06 20:19:34 vadim Exp $
  *
  * NOTES
  *             Transaction aborts can now occur two ways:
@@ -942,15 +942,11 @@ CommitTransaction()
        /*
         * Let others know about no transaction in progress by me.
         * Note that this must be done _before_ releasing locks we hold 
-        * and SpinAcquire(ShmemIndexLock) is required - or bad (too high) 
-        * XmaxRecent value might be used by vacuum: UPDATE with xid 0 is 
+        * and SpinAcquire(ShmemIndexLock) is required: UPDATE with xid 0 is 
         * blocked by xid 1' UPDATE, xid 1 is doing commit while xid 2 
         * gets snapshot - if xid 2' GetSnapshotData sees xid 1 as running
-        * then it must see xid 0 as running as well or XmaxRecent = 1
-        * might be used by concurrent vacuum causing
-        *         ERROR:  Child itemid marked as unused
-        * This bug was reported by Hiroshi Inoue and I was able to reproduce
-        * it with 3 sessions and gdb.  - vadim 06/03/99
+        * then it must see xid 0 as running as well or it will see two
+        * tuple versions - one deleted by xid 1 and one inserted by xid 0.
         */
        if (MyProc != (PROC *) NULL)
        {

diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 80a554d7d9a86ddd06175a678e4a45ca80d8baf7..7c1a8cd600125dbacd670a76989c4d8df22d4284 100644 (file)
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.106 1999/06/03 13:25:54 vadim Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.107 1999/06/06 20:19:34 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1238,11 +1238,28 @@ vc_rpfheap(VRelStats *vacrelstats, Relation onerel,
                                        Citemid = PageGetItemId(Cpage,
                                                                          ItemPointerGetOffsetNumber(&Ctid));
                                        if (!ItemIdIsUsed(Citemid))
-                                               elog(ERROR, "Child itemid marked as unused");
+                                       {
+                                               /*
+                                                * This means that in the middle of chain there was
+                                                * tuple updated by older (than XmaxRecent) xaction
+                                                * and this tuple is already deleted by me. Actually,
+                                                * upper part of chain should be removed and seems 
+                                                * that this should be handled in vc_scanheap(), but
+                                                * it's not implemented at the moment and so we
+                                                * just stop shrinking here.
+                                                */
+                                               ReleaseBuffer(Cbuf);
+                                               pfree(vtmove);
+                                               vtmove = NULL;
+                                               elog(NOTICE, "Child itemid in update-chain marked as unused - can't continue vc_rpfheap");
+                                               break;
+                                       }
                                        tp.t_data = (HeapTupleHeader) PageGetItem(Cpage, Citemid);
                                        tp.t_self = Ctid;
                                        tlen = tp.t_len = ItemIdGetLength(Citemid);
                                }
+                               if (vtmove == NULL)
+                                       break;
                                /* first, can chain be moved ? */
                                for (;;)
                                {
@@ -1336,6 +1353,7 @@ vc_rpfheap(VRelStats *vacrelstats, Relation onerel,
                                                Ptp.t_data = (HeapTupleHeader) PageGetItem(Ppage, Pitemid);
                                                Assert(Ptp.t_data->t_xmax == tp.t_data->t_xmin);
 
+#ifdef NOT_USED                        /* I'm not sure that this will wotk properly... */
                                                /*
                                                 * If this tuple is updated version of row and it
                                                 * was created by the same transaction then no one
@@ -1353,6 +1371,7 @@ vc_rpfheap(VRelStats *vacrelstats, Relation onerel,
                                                        WriteBuffer(Pbuf);
                                                        continue;
                                                }
+#endif
                                                tp.t_data = Ptp.t_data;
                                                tlen = tp.t_len = ItemIdGetLength(Pitemid);
                                                if (freeCbuf)
@@ -1763,7 +1782,7 @@ Elapsed %u/%u sec.",
                        page = BufferGetPage(buf);
                        num_tuples = 0;
                        for (offnum = FirstOffsetNumber;
-                                offnum < maxoff;
+                                offnum <= maxoff;
                                 offnum = OffsetNumberNext(offnum))
                        {
                                itemid = PageGetItemId(page, offnum);

diff --git a/src/backend/storage/buffer/s_lock.c b/src/backend/storage/buffer/s_lock.c
index 38370ea1e9dc29a3af5411486c1366d7a4414f6c..cf25e7e06c4818f99c1a9d52546aba03b065f94f 100644 (file)
--- a/src/backend/storage/buffer/s_lock.c
+++ b/src/backend/storage/buffer/s_lock.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/storage/buffer/Attic/s_lock.c,v 1.20 1999/05/25 22:04:32 momjian Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/storage/buffer/Attic/s_lock.c,v 1.21 1999/06/06 20:19:35 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -28,7 +28,7 @@
  * note: total time to cycle through all 16 entries might be about .07 sec.
  */
 #define S_NSPINCYCLE   20
-#define S_MAX_BUSY             500 * S_NSPINCYCLE
+#define S_MAX_BUSY             1000 * S_NSPINCYCLE
 
 int                    s_spincycle[S_NSPINCYCLE] =
 {0, 0, 0, 0, 10000, 0, 0, 0, 10000, 0,

diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c
index 04cfa1a812eaa49c9e9ecf95f2c707fab0e35431..e317c0e1adf5be7238f8e39459b5d4d31927e2a5 100644 (file)
--- a/src/backend/storage/ipc/shmem.c
+++ b/src/backend/storage/ipc/shmem.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.41 1999/06/03 13:33:13 vadim Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.42 1999/06/06 20:19:35 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -652,9 +652,15 @@ GetSnapshotData(bool serializable)
 
        snapshot->xip = (TransactionId *) malloc(have * sizeof(TransactionId));
        snapshot->xmin = cid;
-       ReadNewTransactionId(&(snapshot->xmax));
 
        SpinAcquire(ShmemIndexLock);
+       /*
+        * Unfortunately, we have to call ReadNewTransactionId()
+        * after acquiring ShmemIndexLock above. It's not good because of
+        * ReadNewTransactionId() does SpinAcquire(OidGenLockId) but
+        * _necessary_.
+        */
+       ReadNewTransactionId(&(snapshot->xmax));
 
        hash_seq((HTAB *) NULL);
        while ((result = (ShmemIndexEnt *) hash_seq(ShmemIndex)) != NULL)