work if either of the join relations are empty. The logic is:
(1) if the inner relation's startup cost is less than the outer
relation's startup cost and this is not an outer join, read
a single tuple from the inner relation via ExecHash()
- if NULL, we're done
(2) read a single tuple from the outer relation
- if NULL, we're done
(3) build the hash table on the inner relation
- if hash table is empty and this is not an outer join,
we're done
(4) otherwise, do hash join as usual
The implementation uses the new MultiExecProcNode API, per a
suggestion from Tom: invoking ExecHash() now produces the first
tuple from the Hash node's child node, whereas MultiExecHash()
builds the hash table.
I had to put in a bit of a kludge to get the row count returned
for EXPLAIN ANALYZE to be correct: since ExecHash() is invoked to
return a tuple, and then MultiExecHash() is invoked, we would
return one too many tuples to EXPLAIN ANALYZE. I hacked around
this by just manually detecting this situation and subtracting 1
from the EXPLAIN ANALYZE row count.
"AT TIME ZONE", and not just the shorlist previously available. For
example:
SELECT CURRENT_TIMESTAMP AT TIME ZONE 'Europe/London';
works fine now. It will also obey whatever DST rules were in effect at
just that date, which the previous implementation did not.
It also supports the AT TIME ZONE on the timetz datatype. The whole
handling of DST is a bit bogus there, so I chose to make it use whatever
DST rules are in effect at the time of executig the query. not sure if
anybody is actuallyi *using* timetz though, it seems pretty
unpredictable just because of this...
Magnus Hagander
it is sufficient to track whether a backend holds a lock or not, and
store information about transaction vs. session locks only in the
inside-the-backend LocalLockTable. Since there can now be but one
PROCLOCK per lock per backend, LockCountMyLocks() is no longer needed,
thus eliminating some O(N^2) behavior when a backend holds many locks.
Also simplify the LockAcquire/LockRelease API by passing just a
'sessionLock' boolean instead of a transaction ID. The previous API
was designed with the idea that per-transaction lock holding would be
important for subtransactions, but now that we have subtransactions we
know that this is unwanted. While at it, add an 'isTempObject' parameter
to LockAcquire to indicate whether the lock is being taken on a temp
table. This is not used just yet, but will be needed shortly for
two-phase commit.
part of service principal. If not set, any service principal matching
an entry in the keytab can be used.
NEW KERBEROS MATCHING BEHAVIOR FOR 8.1.
Todd Kover
if geqo_rand() returns exactly 1.0, resulting in failure due to indexing
off the end of the pool array. Also, since this is using inexact float math,
it seems wise to guard against roundoff error producing values slightly
outside the expected range. Per report from bug@zedware.org.
constraint while determining whether the index sort order matches the
query's ORDER BY. This for example allows an index on (x,y) to match
... WHERE x = 42 ORDER BY y;
It only works for btree indexes, but since those are the only ones we
currently have that are ordered at all, that's good enough for now.
Per popular demand.
nonconsecutive columns of a multicolumn index, as per discussion around
mid-May (pghackers thread "Best way to scan on-disk bitmaps"). This
turns out to require only minimal changes in btree, and so far as I can
see none at all in GiST. btcostestimate did need some work, but its
original assumption that index selectivity == heap selectivity was
quite bogus even before this.
a descriptor that uses the current transaction snapshot, rather than
SnapshotNow as it did before (and still does if INV_WRITE is set).
This means pg_dump will now dump a consistent snapshot of large object
contents, as it never could do before. Also, add a lo_create() function
that is similar to lo_creat() but allows the desired OID of the large
object to be specified. This will simplify pg_restore considerably
(but I'll fix that in a separate commit).
These contain the SQLSTATE and error message of the current exception,
respectively. They are scope-local variables that are only defined
in exception handlers (so attempting to reference them outside an
exception handler is an error). Update the regression tests and the
documentation.
Also, do some minor related cleanup: export an unpack_sql_state()
function from the backend and use it to unpack a SQLSTATE into a
string, and add a free_var() function to pl_exec.c
Original patch from Pavel Stehule, review by Neil Conway.
to a subquery if the outer query is simple enough that the LIMIT can
be reflected directly to the subquery. This didn't use to be very
interesting, because a subquery that couldn't have been flattened into
the upper query was usually not going to be very responsive to
tuple_fraction anyway. But with new code that allows UNION ALL subqueries
to pay attention to tuple_fraction, this is useful to do. In particular
this lets the optimization occur when the UNION ALL is directly inside
a view.
if the limit were directly applied to it. This does not actually
add a LIMIT plan node to the generated subqueries --- that would be
useless overhead --- but it does cause the planner to prefer fast-
start plans when the limit is small. After an idea from Phil Endecott.
this in turn causes CREATE TABLE AS in plpgsql to set ROW_COUNT.
This is how it behaved before 7.4; I had unintentionally changed the
behavior in a bit of sloppy micro-optimization.
of a relation in a flat 'joininfo' list. The former arrangement grouped
the join clauses according to the set of unjoined relids used in each;
however, profiling on test cases involving lots of joins proves that
that data structure is a net loss. It takes more time to group the
join clauses together than is saved by avoiding duplicate tests later.
It doesn't help any that there are usually not more than one or two
clauses per group ...
as well as the existing pg_catalog entries for prefix and postfix %.
These have never been documented, though they did appear in one old
regression test. This avoids surprising behavior in cases like
"SELECT -25 % -10". Per recent discussion.
Note: although there is a catalog change here, I did not force initdb
since there's no harm in leaving the inaccessible entries in one's
copy of pg_operator.
transaction IDs, rather than like subtrans; in particular, the information
now survives a database restart. Per previous discussion, this is
essential for PITR log shipping and for 2PC.
last nextval() or setval() performed by the current session. Update the
docs, add regression tests, and bump the catalog version. Patch from
Dennis Björklund, various improvements by Neil Conway.
---------------------------------------------------------------------------
While playing around, I got the following error message:
--
FATAL: pre-existing shared memory block (key 5432001, ID 90898435) is
still in use
HINT: If you're sure there are no old server processes still running,
remove the shared memory block with the command "ipcrm", or just delete
the file "/home/hlinnaka/pgsql/data/postmaster.pid".
---
Thats normal because I used "kill -9 postmaster" to shut down.
The hint advises me to use "ipcrm", but there's the "ipcclean" script in
bin for just this purpose. The hint should probably advise to use
ipcclean.
The attached patch replaces all occurances of "ipcrm" with "ipcclean" in
src/backend/utils/init/miscinit.c and all the translations in
src/backend/po.
While reviewing the patch, I noticed a likely typo in hr.po. While I
don't
speak Croatian, the translation seems to advise to use the "icpm(1)"
command. I changed that to "ipcclean" too.
Heikki Linnakangas
up have the standard layout with unused space between pd_lower and pd_upper.
When this is set, XLogInsert will omit the unused space without bothering
to scan it to see if it's zero. That saves time in XLogInsert, and also
allows reversion of my earlier patch to make PageRepairFragmentation et al
explicitly re-zero freed space. Per suggestion by Heikki Linnakangas.
other_rel_list with a single array indexed by rangetable index.
This reduces find_base_rel from O(N) to O(1) without any real penalty.
While find_base_rel isn't one of the major bottlenecks in any profile
I've seen so far, it was starting to creep up on the radar screen
for complex queries --- so might as well fix it.
a new PlannerInfo struct, which is passed around instead of the bare
Query in all the planning code. This commit is essentially just a
code-beautification exercise, but it does open the door to making
larger changes to the planner data structures without having to muck
with the widely-known Query struct.
representation as the jointree) with two lists of RTEs, one showing
the RTEs accessible by qualified names, and the other showing the RTEs
accessible by unqualified names. I think this is conceptually simpler
than what we did before, and it's sure a whole lot easier to search.
This seems to eliminate the parse-time bottleneck for deeply nested
JOIN structures that was exhibited by phil@vodafone.
---------------------------------------------------------------------------
Tom Lane <tgl@sss.pgh.pa.us> writes:
> a_ogawa <a_ogawa@hi-ho.ne.jp> writes:
> > It is a reasonable idea. However, the majority part of MemSet was not
> > able to be avoided by this idea. Because the per-tuple contexts are used
> > at the early stage of executor.
>
> Drat. Well, what about changing that? We could introduce additional
> contexts or change the startup behavior so that the ones that are
> frequently reset don't have any data in them unless you are working
> with pass-by-ref values inside the inner loop.
That might be possible. However, I think that we should change only
aset.c about this article.
I thought further: We can check whether context was used from the last
reset even when blocks list is not empty. Please see attached patch.
postgresql.conf.
---------------------------------------------------------------------------
Here's an updated version of the patch, with the following changes:
1) No longer uses "service name" as "application version". It's instead
hardcoded as "postgres". It could be argued that this part should be
backpatched to 8.0, but it doesn't make a big difference until you can
start changing it with GUC / connection parameters. This change only
affects kerberos 5, not 4.
2) Now downcases kerberos usernames when the client is running on win32.
3) Adds guc option for "krb_caseins_users" to make the server ignore
case mismatch which is required by some KDCs such as Active Directory.
Off by default, per discussion with Tom. This change only affects
kerberos 5, not 4.
4) Updated so it doesn't conflict with the rendevouz/bonjour patch
already in ;-)
Magnus Hagander
> a_ogawa <a_ogawa@hi-ho.ne.jp> writes:
> > It is a reasonable idea. However, the majority part of MemSet was not
> > able to be avoided by this idea. Because the per-tuple contexts are used
> > at the early stage of executor.
>
> Drat. Well, what about changing that? We could introduce additional
> contexts or change the startup behavior so that the ones that are
> frequently reset don't have any data in them unless you are working
> with pass-by-ref values inside the inner loop.
That might be possible. However, I think that we should change only
aset.c about this article.
I thought further: We can check whether context was used from the last
reset even when blocks list is not empty. Please see attached patch.
The effect of the patch that I measured is as follows:
o Execution time that executed the SQL ten times.
(1)Linux(CPU: Pentium III, Compiler option: -O2)
- original: 24.960s
- patched : 23.114s
(2)Linux(CPU: Pentium 4, Compiler option: -O2)
- original: 8.730s
- patched : 7.962s
(3)Solaris(CPU: Ultra SPARC III, Compiler option: -O2)
- original: 37.0s
- patched : 33.7s
Atsushi Ogawa (a_ogawa)
RTE of interest, rather than the whole rangetable list. This makes
the API more understandable and avoids duplicate RTE lookups. This
patch reverts no-longer-needed portions of my patch of 2004-08-19.
performance problem pointed out by phil@vodafone: to wit, we were
spending O(N^2) time to check dropped-ness in an N-deep join tree,
even in the case where the tree was freshly constructed and couldn't
possibly mention any dropped columns. Instead of recursing in
get_rte_attribute_is_dropped(), change the data structure definition:
the joinaliasvars list of a JOIN RTE must have a NULL Const instead
of a Var at any position that references a now-dropped column. This
costs nothing during normal parse-rewrite-plan path, and instead we
have a linear-time update to make when loading a stored rule that
might contain now-dropped columns. While at it, move the responsibility
for acquring locks on relations referenced by rules into this separate
function (which I therefore chose to call AcquireRewriteLocks).
This saves effort --- namely, duplicated lock grabs in parser and rewriter
--- in the normal path at a cost of one extra non-locked heap_open()
in the stored-rule path; seems a good tradeoff. A fringe benefit is
that it is now *much* clearer that we acquire lock on relations referenced
in rules before we make any rewriter decisions based on their properties.
(I don't know of any bug of that ilk, but it wasn't exactly clear before.)
to just around the bare recv() call that gets a command from the client.
The former placement in PostgresMain was unsafe because the intermediate
processing layers (especially SSL) use facilities such as malloc that are
not necessarily re-entrant. Per report from counterstorm.com.
Instead of a separate CRC on each backup block, include backup blocks
in their parent WAL record's CRC; this is important to ensure that the
backup block really goes with the WAL record, ie there was not a page
tear right at the start of the backup block. Implement a simple form
of compression of backup blocks: drop any run of zeroes starting at
pd_lower, so as not to store the unused 'hole' that commonly exists in
PG heap and index pages. Tweak PageRepairFragmentation and related
routines to ensure they keep the unused space zeroed, so that the above
compression method remains effective. All per recent discussions.
and RelationNameGetTupleDesc() as deprecated; remove uses of the
latter in the contrib library. Along the way, clean up crosstab()
code and documentation a little.
key, compare the new and old row versions. If the foreign key column has
not changed, we needn't enqueue the trigger, since the update cannot
violate the foreign key. This optimization was previously applied in the
RI trigger function, but it is more efficient to avoid firing the trigger
altogether. Per recent discussion on pgsql-hackers.
Also add a regression test for some unintuitive foreign key behavior, and
refactor some code that deals with the OIDs of the various RI trigger
functions.
keys, rather than a single trigger for both events. This should not change
functionality, but it is more consistent: previously, there were trigger
functions for both "check_insert" and "check_update", but the former was
used for both events.
Bump catalog version number (not strictly necessary, but best to be
cautious).
would be evaluated only once anyway (ie, it's just a SELECT with no
FROM or an INSERT ... VALUES). The planner can't do it any faster than
the executor, so no point in an extra copying of the expression tree.
pg_class_aclmask(). We only need to do this when we have to check
pg_shadow.usecatupd, and that's not relevant unless the target table
is a system catalog. So we can usually avoid one syscache lookup.
are now reported via elog, eliminating the need to test the result code
at most call sites. Make it possible for the caller to distinguish a
freshly acquired lock from one already held in the current transaction.
Use that capability to avoid redundant AcceptInvalidationMessages() calls
in LockRelation().
status of the most recently queried userid. Since the common pattern is
many successive queries about the same user (ie, the current user) this
can save a lot of syscache probes.
were pretty expensive and I believe the case they were put in to
defend against can no longer arise, now that we have dependency checks
to prevent deletion of a type entry that is still referenced. Certainly
the example given in the CVS log entry can't happen anymore.
Since this was the only use of typeidIsValid(), remove the routine too.
to columns of an RTE that was a function returning RECORD with a column
definition list. Apparently no one has tried to use non-default typmod
with a function returning RECORD before.
spotted by Qingqing Zhou. The HASH_ENTER action now automatically
fails with elog(ERROR) on out-of-memory --- which incidentally lets
us eliminate duplicate error checks in quite a bunch of places. If
you really need the old return-NULL-on-out-of-memory behavior, you
can ask for HASH_ENTER_NULL. But there is now an Assert in that path
checking that you aren't hoping to get that behavior in a palloc-based
hash table.
Along the way, remove the old HASH_FIND_SAVE/HASH_REMOVE_SAVED actions,
which were not being used anywhere anymore, and were surely too ugly
and unsafe to want to see revived again.
hash table. This is a pretty unlikely scenario, since the table
should be tiny, but we can't guarantee continued correct operation
if it does occur. Spotted by Qingqing Zhou.
from a RECORD Const node, because that's what it may be faced with
after constant-folding of a function returning RECORD. Per example
from Michael Fuhr.
routines in the index's relcache entry, instead of doing a fresh fmgr_info
on every index access. We were already doing this for the index's opclass
support functions; not sure why we didn't think to do it for the AM
functions too. This supersedes the former method of caching (only)
amgettuple in indexscan scan descriptors; it's an improvement because the
function lookup can be amortized across multiple statements instead of
being repeated for each statement. Even though lookup for builtin
functions is pretty cheap, this seems to drop a percent or two off some
simple benchmarks.
Display only 9 not 10 digits of precision for timestamp values when
using non-integer timestamps. This prevents the display of rounding
errors for common values like days < 32.
working buffer into ParseDateTime() and reject too-long input there,
rather than checking the length of the input string before calling
ParseDateTime(). The old method was bogus because ParseDateTime() can use
a variable amount of working space, depending on the content of the
input string (e.g. how many fields need to be NUL terminated). This fixes
a minor stack overrun -- I don't _think_ it's exploitable, although I
won't claim to be an expert.
Along the way, fix a bug reported by Mark Dilger: the working buffer
allocated by interval_in() was too short, which resulted in rejecting
some perfectly valid interval input values. I added a regression test for
this fix.
scanner anyway) to avoid having any backup states. According to the
flex manual, this should speed things up, and indeed the backend scanner
is about a third faster according to some quick profiling checks.
I haven't tried to measure the speed change in psql, but it probably
is similar.
using pg_mblen. Therefore, pg_mblen is executed many times, and it
becomes a bottleneck.
This patch makes a short cut, and reduces execution frequency of
pg_mblen by comparing the first byte first.
a_ogawa
