If we had not been holding buffer pin continuously since the tuple was
initially fetched by the UPDATE or DELETE query, it would be possible for
VACUUM or a page-prune operation to move the tuple while we're trying to
copy it. This would result in a garbage "old" tuple value being passed to
an AFTER ROW UPDATE or AFTER ROW DELETE trigger. The preconditions for
this are somewhat improbable, and the timing constraints are very tight;
so it's not so surprising that this hasn't been reported from the field,
even though the bug has been there a long time.
Problem found by Andres Freund. Back-patch to all active branches.
This check was overlooked when we added function execute permissions to the
system years ago. For an ordinary trigger function it's not a big deal,
since trigger functions execute with the permissions of the table owner,
so they couldn't do anything the user issuing the CREATE TRIGGER couldn't
have done anyway. However, if a trigger function is SECURITY DEFINER,
that is not the case. The lack of checking would allow another user to
install it on his own table and then invoke it with, essentially, forged
input data; which the trigger function is unlikely to realize, so it might
do something undesirable, for instance insert false entries in an audit log
table.
Reported by Dinesh Kumar, patch by Robert Haas
Security: CVE-2012-0866
Due to tuple-slot mismanagement, evaluation of WHEN conditions for AFTER
ROW UPDATE triggers could crash if there had been a BEFORE ROW trigger
fired for the same update. Fix by not trying to overload the use of
estate->es_trig_tuple_slot. Per report from Yoran Heling.
Back-patch to 9.0, when trigger WHEN conditions were introduced.
There may be some other places where we should use errdetail_internal,
but they'll have to be evaluated case-by-case. This commit just hits
a bunch of places where invoking gettext is obviously a waste of cycles.
Regular aggregate functions in combination with, or within the arguments
of, window functions are OK per spec; they have the semantics that the
aggregate output rows are computed and then we run the window functions
over that row set. (Thus, this combination is not really useful unless
there's a GROUP BY so that more than one aggregate output row is possible.)
The case without GROUP BY could fail, as recently reported by Jeff Davis,
because sloppy construction of the Agg node's targetlist resulted in extra
references to possibly-ungrouped Vars appearing outside the aggregate
function calls themselves. See the added regression test case for an
example.
Fixing this requires modifying the API of flatten_tlist and its underlying
function pull_var_clause. I chose to make pull_var_clause's API for
aggregates identical to what it was already doing for placeholders, since
the useful behaviors turn out to be the same (error, report node as-is, or
recurse into it). I also tightened the error checking in this area a bit:
if it was ever valid to see an uplevel Var, Aggref, or PlaceHolderVar here,
that was a long time ago, so complain instead of ignoring them.
Backpatch into 9.1. The failure exists in 8.4 and 9.0 as well, but seeing
that it only occurs in a basically-useless corner case, it doesn't seem
worth the risks of changing a function API in a minor release. There might
be third-party code using pull_var_clause.
The initial commit of the ALTER TABLE ADD FOREIGN KEY NOT VALID feature
failed to support labeling such constraints as deferrable. The best fix
for this seems to be to fold NOT VALID into ConstraintAttributeSpec.
That's a bit more general than the documented syntax, but it allows
better-targeted syntax error messages.
In addition, do some mostly-but-not-entirely-cosmetic code review for
the whole NOT VALID patch.
Since collation is effectively an argument, not a property of the function,
FmgrInfo is really the wrong place for it; and this becomes critical in
cases where a cached FmgrInfo is used for varying purposes that might need
different collation settings. Fix by passing it in FunctionCallInfoData
instead. In particular this allows a clean fix for bug #5970 (record_cmp
not working). This requires touching a bit more code than the original
method, but nobody ever thought that collations would not be an invasive
patch...
Previous patches took care of assorted places that call transformExpr from
outside the main parser, but I overlooked the fact that some places use
transformWhereClause as a shortcut for transformExpr + coerce_to_boolean.
In particular this broke collation-sensitive index WHERE clauses, as per
report from Thom Brown. Trigger WHEN and rule WHERE clauses too.
I'm not forcing initdb for this fix, but any affected indexes, triggers,
or rules will need to be dropped and recreated.
The originally committed patch for modifying CTEs didn't interact well
with EXPLAIN, as noted by myself, and also had corner-case problems with
triggers, as noted by Dean Rasheed. Those problems show it is really not
practical for ExecutorEnd to call any user-defined code; so split the
cleanup duties out into a new function ExecutorFinish, which must be called
between the last ExecutorRun call and ExecutorEnd. Some Asserts have been
added to these functions to help verify correct usage.
It is no longer necessary for callers of the executor to call
AfterTriggerBeginQuery/AfterTriggerEndQuery for themselves, as this is now
done by ExecutorStart/ExecutorFinish respectively. If you really need to
suppress that and do it for yourself, pass EXEC_FLAG_SKIP_TRIGGERS to
ExecutorStart.
Also, refactor portal commit processing to allow for the possibility that
PortalDrop will invoke user-defined code. I think this is not actually
necessary just yet, since the portal-execution-strategy logic forces any
non-pure-SELECT query to be run to completion before we will consider
committing. But it seems like good future-proofing.
ExecUpdate checked for whether ExecBRUpdateTriggers had returned a new
tuple value by seeing if the returned tuple was pointer-equal to the old
one. But the "old one" was in estate->es_junkFilter's result slot, which
would be scribbled on if we had done an EvalPlanQual update in response to
a concurrent update of the target tuple; therefore we were comparing a
dangling pointer to a live one. Given the right set of circumstances we
could get a false match, resulting in not forcing the tuple to be stored in
the slot we thought it was stored in. In the case reported by Maxim Boguk
in bug #5798, this led to "cannot extract system attribute from virtual
tuple" failures when trying to do "RETURNING ctid". I believe there is a
very-low-probability chance of more serious errors, such as generating
incorrect index entries based on the original rather than the
trigger-modified version of the row.
In HEAD, change all of ExecBRInsertTriggers, ExecIRInsertTriggers,
ExecBRUpdateTriggers, and ExecIRUpdateTriggers so that they continue to
have similar APIs. In the back branches I just changed
ExecBRUpdateTriggers, since there is no bug in the ExecBRInsertTriggers
case.
FK constraints that are marked NOT VALID may later be VALIDATED, which uses an
ShareUpdateExclusiveLock on constraint table and RowShareLock on referenced
table. Significantly reduces lock strength and duration when adding FKs.
New state visible from psql.
Simon Riggs, with reviews from Marko Tiikkaja and Robert Haas
After a SQL object is created, we provide an opportunity for security
or logging plugins to get control; for example, a security label provider
could use this to assign an initial security label to newly created
objects. The basic infrastructure is (hopefully) reusable for other types
of events that might require similar treatment.
KaiGai Kohei, with minor adjustments.
This patch adds the SQL-standard concept of an INSTEAD OF trigger, which
is fired instead of performing a physical insert/update/delete. The
trigger function is passed the entire old and/or new rows of the view,
and must figure out what to do to the underlying tables to implement
the update. So this feature can be used to implement updatable views
using trigger programming style rather than rule hacking.
In passing, this patch corrects the names of some columns in the
information_schema.triggers view. It seems the SQL committee renamed
them somewhere between SQL:99 and SQL:2003.
Dean Rasheed, reviewed by Bernd Helmle; some additional hacking by me.
transaction snapshots, i.e. a snapshot registered at the beginning of
a transaction. Change variable naming and comments to reflect this reality
in preparation for a future, truly serializable mode, e.g.
Serializable Snapshot Isolation (SSI).
For the moment transaction snapshots are still used to implement
SERIALIZABLE, but hopefully not for too much longer. Patch by Kevin
Grittner and Dan Ports with review and some minor wording changes by me.
afterTriggerInvokeEvents failed to adjust events->tailfree when truncating
the last chunk of an event list. This could result in the data being
"de-truncated" by afterTriggerRestoreEventList during a subsequent
subtransaction abort. Even that wouldn't kill us, because the re-added data
would just be events marked DONE --- unless the data had been partially
overwritten by new events. Then we might crash, or in any case misbehave
(perhaps fire triggers twice, or fire triggers with the wrong event data).
Per bug #5622 from Thue Janus Kristensen.
Back-patch to 8.4 where the current trigger list representation was introduced.
- Rename TSParserGetPrsid to get_ts_parser_oid.
- Rename TSDictionaryGetDictid to get_ts_dict_oid.
- Rename TSTemplateGetTmplid to get_ts_template_oid.
- Rename TSConfigGetCfgid to get_ts_config_oid.
- Rename FindConversionByName to get_conversion_oid.
- Rename GetConstraintName to get_constraint_oid.
- Add new functions get_opclass_oid, get_opfamily_oid, get_rewrite_oid,
get_rewrite_oid_without_relid, get_trigger_oid, and get_cast_oid.
The name of each function matches the corresponding catalog.
Thanks to KaiGai Kohei for the review.
Avoid hard-coding lockmode used for many altering DDL commands, allowing easier
future changes of lock levels. Implementation of initial analysis on DDL
sub-commands, so that many lock levels are now at ShareUpdateExclusiveLock or
ShareRowExclusiveLock, allowing certain DDL not to block reads/writes.
First of number of planned changes in this area; additional docs required
when full project complete.
The purpose of this change is to eliminate the need for every caller
of SearchSysCache, SearchSysCacheCopy, SearchSysCacheExists,
GetSysCacheOid, and SearchSysCacheList to know the maximum number
of allowable keys for a syscache entry (currently 4). This will
make it far easier to increase the maximum number of keys in a
future release should we choose to do so, and it makes the code
shorter, too.
Design and review by Tom Lane.
AbortTransaction or AbortSubTransaction, when trying to clean up after an
error that prevented (sub)transaction start from completing:
* access to TopTransactionResourceOwner that might not exist
* assert failure in AtEOXact_GUC, if AtStart_GUC not called yet
* assert failure or core dump in AfterTriggerEndSubXact, if
AfterTriggerBeginSubXact not called yet
Per testing by injecting elog(ERROR) at successive steps in StartTransaction
and StartSubTransaction. It's not clear whether all of these cases could
really occur in the field, but at least one of them is easily exposed by
simple stress testing, as per my accidental discovery yesterday.
pg_constraint before searching pg_trigger. This allows saner handling of
corner cases; in particular we now say "constraint is not deferrable"
rather than "constraint does not exist" when the command is applied to
a constraint that's inherently non-deferrable. Per a gripe several months
ago from hubert depesz lubaczewski.
To make this work without breaking user-defined constraint triggers,
we have to add entries for them to pg_constraint. However, in return
we can remove the pgconstrname column from pg_constraint, which represents
a fairly sizable space savings. I also replaced the tgisconstraint column
with tgisinternal; the old meaning of tgisconstraint can now be had by
testing for nonzero tgconstraint, while there is no other way to get
the old meaning of nonzero tgconstraint, namely that the trigger was
internally generated rather than being user-created.
In passing, fix an old misstatement in the docs and comments, namely that
pg_trigger.tgdeferrable is exactly redundant with pg_constraint.condeferrable.
Actually, we mark RI action triggers as nondeferrable even when they belong to
a nominally deferrable FK constraint. The SET CONSTRAINTS code now relies on
that instead of hard-coding a list of exception OIDs.
checked to determine whether the trigger should be fired.
For BEFORE triggers this is mostly a matter of spec compliance; but for AFTER
triggers it can provide a noticeable performance improvement, since queuing of
a deferred trigger event and re-fetching of the row(s) at end of statement can
be short-circuited if the trigger does not need to be fired.
Takahiro Itagaki, reviewed by KaiGai Kohei.
that it's called within an AfterTriggerBeginQuery/AfterTriggerEndQuery pair.
The RI cascade triggers suppress that overhead on the assumption that they
are always run non-deferred, so it's possible to violate the condition if
someone mistakenly changes pg_trigger to mark such a trigger deferred.
We don't really care about supporting that, but throwing an error instead
of crashing seems desirable. Per report from Marcelo Costa.
a lot of strange behaviors that occurred in join cases. We now identify the
"current" row for every joined relation in UPDATE, DELETE, and SELECT FOR
UPDATE/SHARE queries. If an EvalPlanQual recheck is necessary, we jam the
appropriate row into each scan node in the rechecking plan, forcing it to emit
only that one row. The former behavior could rescan the whole of each joined
relation for each recheck, which was terrible for performance, and what's much
worse could result in duplicated output tuples.
Also, the original implementation of EvalPlanQual could not re-use the recheck
execution tree --- it had to go through a full executor init and shutdown for
every row to be tested. To avoid this overhead, I've associated a special
runtime Param with each LockRows or ModifyTable plan node, and arranged to
make every scan node below such a node depend on that Param. Thus, by
signaling a change in that Param, the EPQ machinery can just rescan the
already-built test plan.
This patch also adds a prohibition on set-returning functions in the
targetlist of SELECT FOR UPDATE/SHARE. This is needed to avoid the
duplicate-output-tuple problem. It seems fairly reasonable since the
other restrictions on SELECT FOR UPDATE are meant to ensure that there
is a unique correspondence between source tuples and result tuples,
which an output SRF destroys as much as anything else does.
are named in the UPDATE's SET list.
Note: the schema of pg_trigger has not actually changed; we've just started
to use a column that was there all along. catversion bumped anyway so that
this commit is included in the history of potentially interesting changes
to system catalog contents.
Itagaki Takahiro
They are now handled by a new plan node type called ModifyTable, which is
placed at the top of the plan tree. In itself this change doesn't do much,
except perhaps make the handling of RETURNING lists and inherited UPDATEs a
tad less klugy. But it is necessary preparation for the intended extension of
allowing RETURNING queries inside WITH.
Marko Tiikkaja
Both hex format and the traditional "escape" format are automatically
handled on input. The output format is selected by the new GUC variable
bytea_output.
As committed, bytea_output defaults to HEX, which is an *incompatible
change*. We will keep it this way for awhile for testing purposes, but
should consider whether to switch to the more backwards-compatible
default of ESCAPE before 8.5 is released.
Peter Eisentraut
This was foreseen to be a good idea long ago, but nobody had got round
to doing it. The recent patch for deferred unique constraints made
transformConstraintAttrs() ugly enough that I decided it was time.
This change will also greatly simplify parsing of deferred CHECK constraints,
if anyone ever gets around to implementing that.
While at it, add a location field to Constraint, and use that to provide
an error cursor for some of the constraint-related error messages.
The current implementation fires an AFTER ROW trigger for each tuple that
looks like it might be non-unique according to the index contents at the
time of insertion. This works well as long as there aren't many conflicts,
but won't scale to massive unique-key reassignments. Improving that case
is a TODO item.
Dean Rasheed
conindid is the index supporting a constraint. We can use this not only for
unique/primary-key constraints, but also foreign-key constraints, which
depend on the unique index that constrains the referenced columns.
tgconstrindid is just copied from the constraint's conindid field, or is
zero for triggers not associated with constraints.
This is mainly intended as infrastructure for upcoming patches, but it has
some virtue in itself, since it exposes a relationship that you formerly
had to grovel in pg_depend to determine. I simplified one information_schema
view accordingly. (There is a pg_dump query that could also use conindid,
but I left it alone because it wasn't clear it'd get any faster.)
types in CREATE TRIGGER. While at it, clean up the amazingly tedious and
inextensible way that the trigger event type list was handled. Per report
from Greg Sabino Mullane.
when they are invoked by the parser. We had been setting up a snapshot at
plan time but really it needs to be done earlier, before parse analysis.
Per report from Dmitry Koterov.
Also fix two related problems discovered while poking at this one:
exec_bind_message called datatype input functions without establishing a
snapshot, and SET CONSTRAINTS IMMEDIATE could call trigger functions without
establishing a snapshot.
Backpatch to 8.2. The underlying problem goes much further back, but it is
masked in 8.1 and before because we didn't attempt to invoke domain check
constraints within datatype input. It would only be exposed if a C-language
datatype input function used the snapshot; which evidently none do, or we'd
have heard complaints sooner. Since this code has changed a lot over time,
a back-patch is hardly risk-free, and so I'm disinclined to patch further
than absolutely necessary.
("there might be triggers") rather than an exact count. This is necessary
catalog infrastructure for the upcoming patch to reduce the strength of
locking needed for trigger addition/removal. Split out and committed
separately for ease of reviewing/testing.
In passing, also get rid of the unused pg_class columns relukeys, relfkeys,
and relrefs, which haven't been maintained in many years and now have no
chance of ever being maintained (because of wishing to avoid locking).
Simon Riggs
and heap_deformtuple in favor of the newer functions heap_form_tuple et al
(which do the same things but use bool control flags instead of arbitrary
char values). Eliminate the former duplicate coding of these functions,
reducing the deprecated functions to mere wrappers around the newer ones.
We can't get rid of them entirely because add-on modules probably still
contain many instances of the old coding style.
Kris Jurka
recent proposal. In typical cases, we now need 12 bytes per insert or delete
event and 16 bytes per update event; previously we needed 40 bytes per
event on 32-bit hardware and 80 bytes per event on 64-bit hardware. Even
in the worst case usage pattern with a large number of distinct triggers being
fired in one query, usage is at most 32 bytes per event. It seems to be a
bit faster than the old code as well, due to reduction of palloc overhead.
This commit doesn't address the TODO item of allowing the event list to spill
to disk; rather it's trying to stave off the need for that. However, it
probably makes that task a bit easier by reducing the data structure's
dependency on pointers. It would now be practical to dump an event list to
disk by "chunks" instead of individual events.
a portal are never NULL, but reliably provide the source text of the query.
It turns out that there was only one place that was really taking a short-cut,
which was the 'EXECUTE' utility statement. That doesn't seem like a
sufficiently critical performance hotspot to justify not offering a guarantee
of validity of the portal source text. Fix it to copy the source text over
from the cached plan. Add Asserts in the places that set up cached plans and
portals to reject null source strings, and simplify a bunch of places that
formerly needed to guard against nulls.
There may be a few places that cons up statements for execution without
having any source text at all; I found one such in ConvertTriggerToFK().
It seems sufficient to inject a phony source string in such a case,
for instance
ProcessUtility((Node *) atstmt,
"(generated ALTER TABLE ADD FOREIGN KEY command)",
NULL, false, None_Receiver, NULL);
We should take a second look at the usage of debug_query_string,
particularly the recently added current_query() SQL function.
ITAGAKI Takahiro and Tom Lane
SizeOfPageHeaderData instead of sizeof(PageHeaderData) in places where that
makes the code clearer, and avoid casting between Page and PageHeader where
possible. Zdenek Kotala, with some additional cleanup by Heikki Linnakangas.
I did not apply the parts of the proposed patch that would have resulted in
slightly changing the on-disk format of hash indexes; it seems to me that's
not a win as long as there's any chance of having in-place upgrade for 8.4.
functions.
Note that because this patch changes FmgrInfo, any external C functions
you might be testing with 8.4 will need to be recompiled.
Patch by Martin Pihlak, some editorialization by me (principally, removing
tracking of getrusage() numbers)
