bug fixes

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@4569 57a11ea4-9604-0410-9ed3-97b8803252fd

src/engine/sql/PostgresBackend.c

@@ -1951,10 +1951,36 @@ pgend_trans_commit_edit (Backend * bend,
       }
       }
 #else
+      /* roll things back is sql version is newer */
+      if (0 < pgendTransactionCompareVersion (be, oldtrans)) { rollback = 1; }
+
       /* first, see if someone else has already deleted this transaction */
-      if (-1 < pgendTransactionGetDeletedVersion (be, oldtrans)) { rollback ++; }
-      else
-      if (0 < pgendTransactionCompareVersion (be, oldtrans)) { rollback ++; }
+      if (-1 < pgendTransactionGetDeletedVersion (be, oldtrans)) 
+      { 
+         if (rollback)
+         {
+            /* Although this situation should never happen, we'll try
+             * to gracefully handle it anyway, because otherwuise the 
+             * transaction becomes un-modifiable, undeleteable.
+             * (This situation might occur with the right combo of bugs 
+             * and crashes. We've fixed the bugs, but ...
+             */
+            char buf[80];
+            gnc_timespec_to_iso8601_buff (xaccTransRetDatePostedTS (trans), buf);
+            PERR ("The impossible has happened, and thats not good!\n"
+                  "\tThe SQL database contains an active transaction that\n"
+                  "\talso appears in the audit trail as deleted !!\n"
+                  "\tWill try to delete transaction for good\n"
+                  "\ttransaction is '%s' %s\n",
+                  xaccTransGetDescription (trans), buf);
+            rollback = 0;
+            trans->do_free = TRUE;
+         }
+         else
+         {
+            rollback = 1;
+         }
+      }
 #endif
    
       if (rollback) {

src/engine/sql/checkpoint.c

@@ -360,6 +360,8 @@ pgendAccountGetCheckpoint (PGBackend *be, Checkpoint *chk)
    p = stpcpy (p, "'   ORDER BY date_start DESC LIMIT 1;");
    SEND_QUERY (be,be->buff, );
    
+   /* provide default value, in case there are no checkpoints */
+   chk->date_start = gnc_iso8601_to_timespec_local (CK_EARLIEST_DATE);
    pgendGetResults (be, get_checkpoint_date_cb, chk);
 
    LEAVE("be=%p", be);

src/engine/sql/design.txt

@@ -155,6 +155,21 @@ Prices need to have version numbers added.
  */
 
 
+Audit Trails
+------------
+The backend keeps an audit trail of created, modified and deleted
+transactions.  These are stored in s set of tables inheriting from
+the gncAuditTrail table.  Identified are the date of modification,
+the the session id, and the type of change.  
+
+There is currently no support within the GUI to view the audit trails,
+nor is there any way to rollback to some previous state based on this 
+trail.
+
+The audit trails are used internally to resolve certain multi-user 
+editing conflicts, for example, when one user attempts to edit a 
+transaction that has been deleteed by another.
+
 
 Balances
 --------