Robert Haas [Wed, 18 Apr 2012 14:49:37 +0000 (10:49 -0400)]
After PageSetAllVisible, use MarkBufferDirty.
Previously, we used SetBufferCommitInfoNeedsSave, but that's really
intended for dirty-marks we can theoretically afford to lose, such as
hint bits. As for 9.2, the PD_ALL_VISIBLE mustn't be lost in this
way, since we could then end up with a heap page that isn't
all-visible and a visibility map page that is all visible, causing
index-only scans to return wrong answers.
Robert Haas [Wed, 18 Apr 2012 14:43:16 +0000 (10:43 -0400)]
Fix various infelicities in node functions.
Mostly, this consists of adding support for fields which exist in the
structure but aren't handled by copy/equal/outfuncs; but the create
foreign table case can actually produce garbage output.
Andrew Dunstan [Tue, 17 Apr 2012 22:30:34 +0000 (18:30 -0400)]
Don't override arguments set via options with positional arguments.
A number of utility programs were rather careless about paremeters
that can be set via both an option argument and a positional
argument. This leads to results which can violate the Principal
Of Least Astonishment. These changes refuse to use positional
arguments to override settings that have been made via positional
arguments. The changes are backpatched to all live branches.
Don't wait for the commit record to be replicated if we wrote no WAL.
When using synchronous replication, we waited for the commit record to be
replicated, but if we our transaction didn't write any other WAL records,
that's not required because we don't even flush the WAL locally to disk in
that case. This lead to long waits when committing a transaction that only
modified a temporary table. Bug spotted by Thom Brown.
Install plpgsql.h to to include/server at "make install".
The header file is needed by any module that wants to use the PL/pgSQL
instrumentation plugin interface. Most notably, the pldebugger plugin needs
this. With this patch, it can be built using pgxs, without having the full
server source tree available.
Add missing descriptions about '--timeout' and '--mode' to help
message. They are already implemented in the source code.
Suggestions about the message formatting from Tom Lane.
Robert Haas [Sat, 14 Apr 2012 12:04:11 +0000 (08:04 -0400)]
pg_size_pretty(numeric)
The output of the new pg_xlog_location_diff function is of type numeric,
since it could theoretically overflow an int8 due to signedness; this
provides a convenient way to format such values.
Peter Eisentraut [Sat, 14 Apr 2012 06:29:54 +0000 (09:29 +0300)]
Update contrib/README
Remove lots of outdated information that is duplicated by the
better-maintained SGML documentation. In particular, remove the
outdated listing of contrib modules. Update the installation
instructions to mention CREATE EXTENSION, but don't go into too much
detail.
Tom Lane [Fri, 13 Apr 2012 20:03:16 +0000 (16:03 -0400)]
Remove the "last ditch" code path in join_search_one_level().
So far as I can tell, it is no longer possible for this heuristic to do
anything useful, because the new weaker definition of
have_relevant_joinclause means that any relation with a joinclause must be
considered joinable to at least one other relation. It would still be
possible for the code block to be entered, for example if there are join
order restrictions that prevent any join of the current level from being
formed; but in that case it's just a waste of cycles to attempt to form
cartesian joins, since the restrictions will still apply.
Furthermore, IMO the existence of this code path can mask bugs elsewhere;
we would have noticed the problem with cartesian joins a lot sooner if
this code hadn't compensated for it in the simplest case.
Accordingly, let's remove it and see what happens. I'm committing this
separately from the prerequisite changes in have_relevant_joinclause,
just to make the question easier to revisit if there is some fault in
my logic.
Tom Lane [Fri, 13 Apr 2012 19:32:34 +0000 (15:32 -0400)]
Weaken the planner's tests for relevant joinclauses.
We should be willing to cross-join two small relations if that allows us
to use an inner indexscan on a large relation (that is, the potential
indexqual for the large table requires both smaller relations). This
worked in simple cases but fell apart as soon as there was a join clause
to a fourth relation, because the existence of any two-relation join clause
caused the planner to not consider clauseless joins between other base
relations. The added regression test shows an example case adapted from
a recent complaint from Benoit Delbosc.
Adjust have_relevant_joinclause, have_relevant_eclass_joinclause, and
has_relevant_eclass_joinclause to consider that a join clause mentioning
three or more relations is sufficient grounds for joining any subset of
those relations, even if we have to do so via a cartesian join. Since such
clauses are relatively uncommon, this shouldn't affect planning speed on
typical queries; in fact it should help a bit, because the latter two
functions in particular get significantly simpler.
Although this is arguably a bug fix, I'm not going to risk back-patching
it, since it might have currently-unforeseen consequences.
Peter Eisentraut [Fri, 13 Apr 2012 18:36:59 +0000 (21:36 +0300)]
Rename bytea_agg to string_agg and add delimiter argument
Per mailing list discussion, we would like to keep the bytea functions
parallel to the text functions, so rename bytea_agg to string_agg,
which already exists for text.
Also, to satisfy the rule that we don't want aggregate functions of
the same name with a different number of arguments, add a delimiter
argument, just like string_agg for text already has.
Tom Lane [Thu, 12 Apr 2012 00:24:17 +0000 (20:24 -0400)]
Fix cost estimation for indexscan filter conditions.
cost_index's method for estimating per-tuple costs of evaluating filter
conditions (a/k/a qpquals) was completely wrong in the presence of derived
indexable conditions, such as range conditions derived from a LIKE clause.
This was largely masked in common cases as a result of all simple operator
clauses having about the same costs, but it could show up in a big way when
dealing with functional indexes containing expensive functions, as seen for
example in bug #6579 from Istvan Endredy. Rejigger the calculation to give
sane answers when the indexquals aren't a subset of the baserestrictinfo
list. As a side benefit, we now do the calculation properly for cases
involving join clauses (ie, parameterized indexscans), which we always
overestimated before.
There are still cases where this is an oversimplification, such as clauses
that can be dropped because they are implied by a partial index's
predicate. But we've never accounted for that in cost estimates before,
and I'm not convinced it's worth the cycles to try to do so.
Tom Lane [Wed, 11 Apr 2012 15:29:22 +0000 (11:29 -0400)]
Silently ignore any nonexistent schemas that are listed in search_path.
Previously we attempted to throw an error or at least warning for missing
schemas, but this was done inconsistently because of implementation
restrictions (in many cases, GUC settings are applied outside transactions
so that we can't do system catalog lookups). Furthermore, there were
exceptions to the rule even in the beginning, and we'd been poking more
and more holes in it as time went on, because it turns out that there are
lots of use-cases for having some irrelevant items in a common search_path
value. It seems better to just adopt a philosophy similar to what's always
been done with Unix PATH settings, wherein nonexistent or unreadable
directories are silently ignored.
This commit also fixes the documentation to point out that schemas for
which the user lacks USAGE privilege are silently ignored. That's always
been true but was previously not documented.
This is mostly in response to Robert Haas' complaint that 9.1 started to
throw errors or warnings for missing schemas in cases where prior releases
had not. We won't adopt such a significant behavioral change in a back
branch, so something different will be needed in 9.1.
Accept postgres:// URIs in libpq connection functions
postgres:// URIs are an attempt to "stop the bleeding" in this general
area that has been said to occur due to external projects adopting their
own syntaxes. The syntaxes supported by this patch:
should be enough to cover most interesting cases without having to
resort to "param=value" pairs, but those are provided for the cases that
need them regardless.
libpq documentation has been shuffled around a bit, to avoid stuffing
all the format details into the PQconnectdbParams description, which was
already a bit overwhelming. The list of keywords has moved to its own
subsection, and the details on the URI format live in another subsection.
This includes a simple test program, as requested in discussion, to
ensure that interesting corner cases continue to work appropriately in
the future.
Author: Alexander Shulgin
Some tweaking by Álvaro Herrera, Greg Smith, Daniel Farina, Peter Eisentraut
Reviewed by Robert Haas, Alexey Klyukin (offlist), Heikki Linnakangas,
Marko Kreen, and others
Oh, it also supports postgresql:// but that's probably just an accident.
Tom Lane [Wed, 11 Apr 2012 01:42:46 +0000 (21:42 -0400)]
Make pg_tablespace_location(0) return the database's default tablespace.
This definition is convenient when applying the function to the
reltablespace column of pg_class, since that's what zero means there;
and it doesn't interfere with any other plausible use of the function.
Per gripe from Bruce Momjian.
Bruce Momjian [Tue, 10 Apr 2012 23:57:14 +0000 (19:57 -0400)]
Fix pg_upgrade to properly upgrade a table that is stored in the cluster
default tablespace, but part of a database that is in a user-defined
tablespace. Caused "file not found" error during upgrade.
Tom Lane [Tue, 10 Apr 2012 16:04:42 +0000 (12:04 -0400)]
Measure epoch of timestamp-without-time-zone from local not UTC midnight.
This patch reverts commit 191ef2b407f065544ceed5700e42400857d9270f
and thereby restores the pre-7.3 behavior of EXTRACT(EPOCH FROM
timestamp-without-tz). Per discussion, the more recent behavior was
misguided on a couple of grounds: it makes it hard to get a
non-timezone-aware epoch value for a timestamp, and it makes this one
case dependent on the value of the timezone GUC, which is incompatible
with having timestamp_part() labeled as immutable.
The other behavior is still available (in all releases) by explicitly
casting the timestamp to timestamp with time zone before applying EXTRACT.
This will need to be called out as an incompatible change in the 9.2
release notes. Although having mutable behavior in a function marked
immutable is clearly a bug, we're not going to back-patch such a change.
Tom Lane [Tue, 10 Apr 2012 00:49:01 +0000 (20:49 -0400)]
Adjust various references to GEQO being non-deterministic.
It's still non-deterministic in some sense ... but given fixed settings
and identical planning problems, it will now always choose the same plan,
so we probably shouldn't tar it with that brush. Per bug #6565 from
Guillaume Cottenceau. Back-patch to 9.0 where the behavior was fixed.
Tom Lane [Mon, 9 Apr 2012 15:58:24 +0000 (11:58 -0400)]
Fix an Assert that turns out to be reachable after all.
estimate_num_groups() gets unhappy with
create table empty();
select * from empty except select * from empty e2;
I can't see any actual use-case for such a query (and the table is illegal
per SQL spec), but it seems like a good idea that it not cause an assert
failure.
Tom Lane [Mon, 9 Apr 2012 15:41:54 +0000 (11:41 -0400)]
Don't bother copying empty support arrays in a zero-column MergeJoin.
The case could not arise when this code was originally written, but it can
now (since we made zero-column MergeJoins work for the benefit of FULL JOIN
ON TRUE). I don't think there is any actual bug here, but we might as well
treat it consistently with other uses of COPY_POINTER_FIELD(). Per comment
from Ashutosh Bapat.
Tom Lane [Mon, 9 Apr 2012 15:16:04 +0000 (11:16 -0400)]
Save a few cycles while creating "sticky" entries in pg_stat_statements.
There's no need to sit there and increment the stats when we know all the
increments would be zero anyway. The actual additions might not be very
expensive, but skipping acquisition of the spinlock seems like a good
thing. Pushing the logic about initialization of the usage count down into
entry_alloc() allows us to do that while making the code actually simpler,
not more complex. Expansion on a suggestion by Peter Geoghegan.
Tom Lane [Sun, 8 Apr 2012 19:49:47 +0000 (15:49 -0400)]
Improve management of "sticky" entries in contrib/pg_stat_statements.
This patch addresses a deficiency in the previous pg_stat_statements patch.
We want to give sticky entries an initial "usage" factor high enough that
they probably will stick around until their query is completed. However,
if the query never completes (eg it gets an error during execution), the
entry shouldn't persist indefinitely. Manage this by starting out with
a usage setting equal to the (approximate) median usage value within the
whole hashtable, but decaying the value much more aggressively than we
do for normal entries.
set_stack_base() no longer needs to be called in PostgresMain.
This was a thinko in previous commit. Now that stack base pointer is now set
in PostmasterMain and SubPostmasterMain, it doesn't need to be set in
PostgresMain anymore.
Do stack-depth checking in all postmaster children.
We used to only initialize the stack base pointer when starting up a regular
backend, not in other processes. In particular, autovacuum workers can run
arbitrary user code, and without stack-depth checking, infinite recursion
in e.g an index expression will bring down the whole cluster.
The comment about PL/Java using set_stack_base() is not yet true. As the
code stands, PL/java still modifies the stack_base_ptr variable directly.
However, it's been discussed in the PL/Java mailing list that it should be
changed to use the function, because PL/Java is currently oblivious to the
register stack used on Itanium. There's another issues with PL/Java, namely
that the stack base pointer it sets is not really the base of the stack, it
could be something close to the bottom of the stack. That's a separate issue
that might need some further changes to this code, but that's a different
story.
Tom Lane [Fri, 6 Apr 2012 22:10:21 +0000 (18:10 -0400)]
Fix misleading output from gin_desc().
XLOG_GIN_UPDATE_META_PAGE and XLOG_GIN_DELETE_LISTPAGE records were printed
with a list link field labeled as "blkno", which was confusing, especially
when the link was empty (InvalidBlockNumber). Print the metapage block
number instead, since that's what's actually being updated. We could
include the link values too as a separate field, but not clear it's worth
the trouble.
Back-patch to 8.4 where the dubious code was added.
Tom Lane [Fri, 6 Apr 2012 20:58:17 +0000 (16:58 -0400)]
Fix broken comparetup_datum code.
Commit 337b6f5ecf05b21b5e997986884d097d60e4e3d0 contained the entirely
fanciful assumption that it had made comparetup_datum unreachable.
Reported and patched by Takashi Yamamoto.
Fix up some not terribly accurate/useful comments from that commit, too.
Tom Lane [Fri, 6 Apr 2012 20:04:10 +0000 (16:04 -0400)]
Dept of second thoughts: improve the API for AnalyzeForeignTable.
If we make the initially-called function return the table physical-size
estimate, acquire_inherited_sample_rows will be able to use that to
allocate numbers of samples among child tables, when the day comes that
we want to support foreign tables in inheritance trees.
Tom Lane [Fri, 6 Apr 2012 19:02:35 +0000 (15:02 -0400)]
Allow statistics to be collected for foreign tables.
ANALYZE now accepts foreign tables and allows the table's FDW to control
how the sample rows are collected. (But only manual ANALYZEs will touch
foreign tables, for the moment, since among other things it's not very
clear how to handle remote permissions checks in an auto-analyze.)
contrib/file_fdw is extended to support this.
Etsuro Fujita, reviewed by Shigeru Hanada, some further tweaking by me.
Robert Haas [Thu, 5 Apr 2012 15:37:31 +0000 (11:37 -0400)]
Expose track_iotiming data via the statistics collector.
Ants Aasma's original patch to add timing information for buffer I/O
requests exposed this data at the relation level, which was judged too
costly. I've here exposed it at the database level instead.
Tom Lane [Thu, 5 Apr 2012 01:50:31 +0000 (21:50 -0400)]
Fix plpgsql named-cursor-parameter feature for variable name conflicts.
The parser got confused if a cursor parameter had the same name as
a plpgsql variable. Reported and diagnosed by Yeb Havinga, though
this isn't exactly his proposed fix.
Also, some mostly-but-not-entirely-cosmetic adjustments to the original
named-cursor-parameter patch, for code readability and better error
diagnostics.
Tom Lane [Wed, 4 Apr 2012 22:39:08 +0000 (18:39 -0400)]
Improve efficiency of dblink by using libpq's new row processor API.
This patch provides a test case for libpq's row processor API.
contrib/dblink can deal with very large result sets by dumping them into
a tuplestore (which can spill to disk) --- but until now, the intermediate
storage of the query result in a PGresult meant memory bloat for any large
result. Now we use a row processor to convert the data to tuple form and
dump it directly into the tuplestore.
A limitation is that this only works for plain dblink() queries, not
dblink_send_query() followed by dblink_get_result(). In the latter
case we don't know the desired tuple rowtype soon enough. While hack
solutions to that are possible, a different user-level API would
probably be a better answer.
Kyotaro Horiguchi, reviewed by Marko Kreen and Tom Lane
Tom Lane [Wed, 4 Apr 2012 22:27:56 +0000 (18:27 -0400)]
Add a "row processor" API to libpq for better handling of large results.
Traditionally libpq has collected an entire query result before passing
it back to the application. That provides a simple and transactional API,
but it's pretty inefficient for large result sets. This patch allows the
application to process each row on-the-fly instead of accumulating the
rows into the PGresult. Error recovery becomes a bit more complex, but
often that tradeoff is well worth making.
Kyotaro Horiguchi, reviewed by Marko Kreen and Tom Lane
Tom Lane [Wed, 4 Apr 2012 20:15:04 +0000 (16:15 -0400)]
Remove useless PGRES_COPY_BOTH "support" in psql.
There is no existing or foreseeable case in which psql should see a
PGRES_COPY_BOTH PQresultStatus; and if such a case ever emerges, it's a
pretty good bet that these code fragments wouldn't do the right thing
anyway. Remove them, and let the existing default cases do the appropriate
thing, namely emit an "unexpected PQresultStatus" bleat.
Noted while working on libpq row processor patch, for which I was
considering adding a PGRES_SUSPENDED status code --- the same default-case
treatment would be appropriate for that.
Tom Lane [Wed, 4 Apr 2012 19:05:10 +0000 (15:05 -0400)]
Fix syslogger to not lose log coherency under high load.
The original coding of the syslogger had an arbitrary limit of 20 large
messages concurrently in progress, after which it would just punt and dump
message fragments to the output file separately. Our ambitions are a bit
higher than that now, so allow the data structure to expand as necessary.
Reported and patched by Andrew Dunstan; some editing by Tom
Tom Lane [Wed, 4 Apr 2012 00:43:15 +0000 (20:43 -0400)]
Fix a couple of contrib/dblink bugs.
dblink_exec leaked temporary database connections if any error occurred
after connection setup, for example
SELECT dblink_exec('...connect string...', 'select 1/0');
Add a PG_TRY block to ensure PQfinish gets done when it is needed.
(dblink_record_internal is on the hairy edge of needing similar treatment,
but seems not to be actively broken at the moment.)
Also, in 9.0 and up, only one of the three functions using tuplestore
return mode was properly checking that the query context would allow
a tuplestore result.
Noted while reviewing dblink patch. Back-patch to all supported branches.
Tom Lane [Sat, 31 Mar 2012 19:51:07 +0000 (15:51 -0400)]
Fix O(N^2) behavior in pg_dump when many objects are in dependency loops.
Combining the loop workspace with the record of already-processed objects
might have been a cute trick, but it behaves horridly if there are many
dependency loops to repair: the time spent in the first step of findLoop()
grows as O(N^2). Instead use a separate flag array indexed by dump ID,
which we can check in constant time. The length of the workspace array
is now never more than the actual length of a dependency chain, which
should be reasonably short in all cases of practical interest. The code
is noticeably easier to understand this way, too.
Per gripe from Mike Roest. Since this is a longstanding performance bug,
backpatch to all supported versions.
Tom Lane [Sat, 31 Mar 2012 18:42:17 +0000 (14:42 -0400)]
Fix O(N^2) behavior in pg_dump for large numbers of owned sequences.
The loop that matched owned sequences to their owning tables required time
proportional to number of owned sequences times number of tables; although
this work was only expended in selective-dump situations, which is probably
why the issue wasn't recognized long since. Refactor slightly so that we
can perform this work after the index array for findTableByOid has been
set up, reducing the time to O(M log N).
Per gripe from Mike Roest. Since this is a longstanding performance bug,
backpatch to all supported versions.
Tom Lane [Sat, 31 Mar 2012 17:15:53 +0000 (13:15 -0400)]
Rename frontend keyword arrays to avoid conflict with backend.
ecpg and pg_dump each contain keyword arrays with structure similar
to the backend's keyword array. Up to now, we actually named those
arrays the same as the backend's and relied on parser/keywords.h
to declare them. This seems a tad too cute, though, and it breaks
now that we need to PGDLLIMPORT-decorate the backend symbols.
Rename to avoid the problem. Per buildfarm.
(It strikes me that maybe we should get rid of the separate keywords.c
files altogether, and just define these arrays in the modules that use
them, but that's a rather more invasive change.)
Tom Lane [Sat, 31 Mar 2012 15:19:23 +0000 (11:19 -0400)]
Fix glitch recently introduced in psql tab completion.
Over-optimization (by me, looks like :-() broke the case of recognizing
a word boundary just before a quoted identifier. Reported and diagnosed
by Dean Rasheed.
Peter Eisentraut [Fri, 30 Mar 2012 17:42:06 +0000 (20:42 +0300)]
Add new files to NLS file lists
Some of these are newly added, some are older and were forgotten, some
don't contain any translatable strings right now but look like they
could in the future.
Tom Lane [Thu, 29 Mar 2012 21:52:28 +0000 (17:52 -0400)]
Fix dblink's failure to report correct connection name in error messages.
The DBLINK_GET_CONN and DBLINK_GET_NAMED_CONN macros did not set the
surrounding function's conname variable, causing errors to be incorrectly
reported as having occurred on the "unnamed" connection in some cases.
This bug was actually visible in two cases in the regression tests,
but apparently whoever added those cases wasn't paying attention.
Noted by Kyotaro Horiguchi, though this is different from his proposed
patch.
Back-patch to 8.4; 8.3 does not have the same type of error reporting
so the patch is not relevant.
Tom Lane [Thu, 29 Mar 2012 20:42:09 +0000 (16:42 -0400)]
Improve contrib/pg_stat_statements' handling of PREPARE/EXECUTE statements.
It's actually more useful for the module to ignore these. Ignoring
EXECUTE (and not incrementing the nesting level) allows the executor
hooks to charge the time to the underlying prepared query, which
shows up as a stats entry with the original PREPARE as query string
(possibly modified by suppression of constants, which might not be
terribly useful here but it's not worth avoiding). This is much more
useful than cluttering the stats table with a distinct entry for each
textually distinct EXECUTE.
Experimentation with this idea shows that it's also preferable to ignore
PREPARE. If we don't, we get two stats table entries, one with the query
string hash and one with the jumble-derived hash, but with the same visible
query string (modulo those constants). This is confusing and not very
helpful, since the first entry will only receive costs associated with
initial planning of the query, which is not something counted at all
normally by pg_stat_statements. (And if we do start tracking planning
costs, we'd want them blamed on the other hash table entry anyway.)
Tom Lane [Thu, 29 Mar 2012 19:32:50 +0000 (15:32 -0400)]
Improve handling of utility statements containing plannable statements.
When tracking nested statements, contrib/pg_stat_statements formerly
double-counted the execution costs of utility statements that directly
contain an executable statement, such as EXPLAIN and DECLARE CURSOR.
This was not obvious since the ProcessUtility and Executor hooks
would each add their measured costs to the same stats table entry.
However, with the new implementation that hashes utility and plannable
statements differently, this showed up as seemingly-duplicate stats
entries. Fix that by disabling the Executor hooks when the query has a
queryId of zero, which was the case already for such statements but is now
more clearly specified in the code. (The zero queryId was causing problems
anyway because all such statements would add to a single bogus entry.)
The PREPARE/EXECUTE case still results in counting the same execution
in two different stats table entries, but it should be much less surprising
to users that there are two entries in such cases.
In passing, include a CommonTableExpr's ctename in the query hash.
I had left it out originally on the grounds that we wanted to omit all
inessential aliases, but since RTE_CTE RTEs are hashing their referenced
names, we'd better hash the CTE names too to make sure we don't hash
semantically different queries the same.
Simon Riggs [Thu, 29 Mar 2012 13:55:30 +0000 (14:55 +0100)]
Correct epoch of txid_current() when executed on a Hot Standby server.
Initialise ckptXidEpoch from starting checkpoint and maintain the correct
value as we roll forwards. This allows GetNextXidAndEpoch() to return the
correct epoch when executed during recovery. Backpatch to 9.0 when the
problem is first observable by a user.
Inherit max_safe_fds to child processes in EXEC_BACKEND mode.
Postmaster sets max_safe_fds by testing how many open file descriptors it
can open, and that is normally inherited by all child processes at fork().
Not so on EXEC_BACKEND, ie. Windows, however. Because of that, we
effectively ignored max_files_per_process on Windows, and always assumed
a conservative default of 32 simultaneous open files. That could have an
impact on performance, if you need to access a lot of different files
in a query. After this patch, the value is passed to child processes by
save/restore_backend_variables() among many other global variables.
It has been like this forever, but given the lack of complaints about it,
I'm not backpatching this.
Tom Lane [Thu, 29 Mar 2012 01:00:31 +0000 (21:00 -0400)]
Improve contrib/pg_stat_statements to lump "similar" queries together.
pg_stat_statements now hashes selected fields of the analyzed parse tree
to assign a "fingerprint" to each query, and groups all queries with the
same fingerprint into a single entry in the pg_stat_statements view.
In practice it is expected that queries with the same fingerprint will be
equivalent except for values of literal constants. To make the display
more useful, such constants are replaced by "?" in the displayed query
strings.
This mechanism currently supports only optimizable queries (SELECT,
INSERT, UPDATE, DELETE). Utility commands are still matched on the
basis of their literal query strings.
There remain some open questions about how to deal with utility statements
that contain optimizable queries (such as EXPLAIN and SELECT INTO) and how
to deal with expiring speculative hashtable entries that are made to save
the normalized form of a query string. However, fixing these issues should
require only localized changes, and since there are other open patches
involving contrib/pg_stat_statements, it seems best to go ahead and commit
what we've got.