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* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.273 2009/05/13 20:27:17 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.274 2009/06/11 14:48:54 momjian Exp $
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*-------------------------------------------------------------------------
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* "used" must be TRUE if the caller intends to use the command ID to mark
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* inserted/updated/deleted tuples. FALSE means the ID is being fetched
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* for read-only purposes (ie, as a snapshot validity cutoff). See
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* for read-only purposes (ie, as a snapshot validity cutoff). See
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* CommandCounterIncrement() for discussion.
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CommandCounterIncrement(void)
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* If the current value of the command counter hasn't been "used" to
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* mark tuples, we need not increment it, since there's no need to
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* distinguish a read-only command from others. This helps postpone
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* command counter overflow, and keeps no-op CommandCounterIncrement
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* If the current value of the command counter hasn't been "used" to mark
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* tuples, we need not increment it, since there's no need to distinguish
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* a read-only command from others. This helps postpone command counter
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* overflow, and keeps no-op CommandCounterIncrement operations cheap.
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if (currentCommandIdUsed)
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currentCommandId += 1;
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if (currentCommandId == FirstCommandId) /* check for overflow */
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if (currentCommandId == FirstCommandId) /* check for overflow */
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currentCommandId -= 1;
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(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
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errmsg("cannot have more than 2^32-1 commands in a transaction")));
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errmsg("cannot have more than 2^32-1 commands in a transaction")));
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currentCommandIdUsed = false;
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/* Propagate new command ID into static snapshots */
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SnapshotSetCommandId(currentCommandId);
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* Make any catalog changes done by the just-completed command
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* visible in the local syscache. We obviously don't need to do
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* this after a read-only command. (But see hacks in inval.c
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* to make real sure we don't think a command that queued inval
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* messages was read-only.)
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* Make any catalog changes done by the just-completed command visible
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* in the local syscache. We obviously don't need to do this after a
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* read-only command. (But see hacks in inval.c to make real sure we
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* don't think a command that queued inval messages was read-only.)
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AtCommit_LocalCache();
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* Make any other backends' catalog changes visible to me.
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* XXX this is probably in the wrong place: CommandCounterIncrement
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* should be purely a local operation, most likely. However fooling
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* with this will affect asynchronous cross-backend interactions,
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* which doesn't seem like a wise thing to do in late beta, so save
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* improving this for another day - tgl 2007-11-30
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* XXX this is probably in the wrong place: CommandCounterIncrement should
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* be purely a local operation, most likely. However fooling with this
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* will affect asynchronous cross-backend interactions, which doesn't seem
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* like a wise thing to do in late beta, so save improving this for
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* another day - tgl 2007-11-30
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/* Allocate or enlarge the parent array if necessary */
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if (s->parent->maxChildXids < new_nChildXids)
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int new_maxChildXids;
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TransactionId *new_childXids;
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int new_maxChildXids;
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TransactionId *new_childXids;
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* Make it 2x what's needed right now, to avoid having to enlarge it
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* repeatedly. But we can't go above MaxAllocSize. (The latter
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* limit is what ensures that we don't need to worry about integer
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* overflow here or in the calculation of new_nChildXids.)
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* repeatedly. But we can't go above MaxAllocSize. (The latter limit
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* is what ensures that we don't need to worry about integer overflow
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* here or in the calculation of new_nChildXids.)
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new_maxChildXids = Min(new_nChildXids * 2,
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(int) (MaxAllocSize / sizeof(TransactionId)));
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if (s->parent->childXids == NULL)
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new_childXids =
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MemoryContextAlloc(TopTransactionContext,
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MemoryContextAlloc(TopTransactionContext,
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new_maxChildXids * sizeof(TransactionId));
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new_childXids = repalloc(s->parent->childXids,
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new_maxChildXids * sizeof(TransactionId));
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new_childXids = repalloc(s->parent->childXids,
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new_maxChildXids * sizeof(TransactionId));
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s->parent->childXids = new_childXids;
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s->parent->childXids = new_childXids;
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s->parent->maxChildXids = new_maxChildXids;
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* Note: We rely on the fact that the XID of a child always follows that
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* of its parent. By copying the XID of this subtransaction before the
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* XIDs of its children, we ensure that the array stays ordered. Likewise,
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* all XIDs already in the array belong to subtransactions started and
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* subcommitted before us, so their XIDs must precede ours.
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* XIDs of its children, we ensure that the array stays ordered.
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* Likewise, all XIDs already in the array belong to subtransactions
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* started and subcommitted before us, so their XIDs must precede ours.
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s->parent->childXids[s->parent->nChildXids] = s->transactionId;
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/* NOTIFY and flatfiles will be handled below */
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* Don't allow PREPARE TRANSACTION if we've accessed a temporary table
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* in this transaction. Having the prepared xact hold locks on another
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* Don't allow PREPARE TRANSACTION if we've accessed a temporary table in
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* this transaction. Having the prepared xact hold locks on another
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* backend's temp table seems a bad idea --- for instance it would prevent
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* the backend from exiting. There are other problems too, such as how
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* to clean up the source backend's local buffers and ON COMMIT state
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* if the prepared xact includes a DROP of a temp table.
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* the backend from exiting. There are other problems too, such as how to
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* clean up the source backend's local buffers and ON COMMIT state if the
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* prepared xact includes a DROP of a temp table.
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* We must check this after executing any ON COMMIT actions, because
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* they might still access a temp relation.
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* We must check this after executing any ON COMMIT actions, because they
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* might still access a temp relation.
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* XXX In principle this could be relaxed to allow some useful special
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* cases, such as a temp table created and dropped all within the
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* Reset user ID which might have been changed transiently. We need this
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* to clean up in case control escaped out of a SECURITY DEFINER function
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* or other local change of CurrentUserId; therefore, the prior value
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* of SecurityDefinerContext also needs to be restored.
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* or other local change of CurrentUserId; therefore, the prior value of
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* SecurityDefinerContext also needs to be restored.
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* (Note: it is not necessary to restore session authorization or role
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* settings here because those can only be changed via GUC, and GUC will
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/* Must CCI to ensure commands of subtransaction are seen as done */
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CommandCounterIncrement();
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* Prior to 8.4 we marked subcommit in clog at this point. We now only
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* Prior to 8.4 we marked subcommit in clog at this point. We now only
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* perform that step, if required, as part of the atomic update of the
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* whole transaction tree at top level commit or abort.
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appendStringInfo(buf, "; rels:");
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for (i = 0; i < xlrec->nrels; i++)
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char *path = relpath(xlrec->xnodes[i], MAIN_FORKNUM);
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char *path = relpath(xlrec->xnodes[i], MAIN_FORKNUM);
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appendStringInfo(buf, " %s", path);
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appendStringInfo(buf, "; rels:");
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for (i = 0; i < xlrec->nrels; i++)
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char *path = relpath(xlrec->xnodes[i], MAIN_FORKNUM);
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char *path = relpath(xlrec->xnodes[i], MAIN_FORKNUM);
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appendStringInfo(buf, " %s", path);
added
removed
src/backend/access/transam/xact.c
