I sent this message to the list and although it shows up in the archives,
I did not receive a copy of it through the list, so I'm resending as I
suspect others did not see it either.
-- Forwarded message --
Date: Sat, 13 Mar 2004 22:48:01 -0500 (EST)
From: Kris Jurka [EMAIL
multiple times because table rows are in the same
page, but were found in different places in the index.
Kris Jurka
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TIP 6: Have you searched our list archives?
http://archives.postgresql.org
is sufficient.
http://archives.postgresql.org/pgsql-jdbc/2003-12/msg00186.php
Kris Jurka
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TIP 5: Have you checked our extensive FAQ?
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? (For that matter, would that
also be true of a transaction consisting of a set of
inserts?)
The table is not locked in either the copy or the insert case.
Kris Jurka
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TIP 6: Have you searched our list archives
would agree with Dave's suggestion to use log_duration and compare the
values for the first and subsequent fetches.
Kris Jurka
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that is something that is really required.
Kris Jurka
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TIP 8: explain analyze is your friend
one.
Kris Jurka
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a complete or nearly
complete overlap so it thinks it will need to fetch 10% of the rows from
both the index and the heap and chooses a seqscan.
Kris Jurka
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TIP 5: Have you checked our extensive FAQ?
http
is not in the postgres 7.3.7 docs. Does this mean 7.3 the JDBC driver
for postgres 7.4 doesn't support this ?
You need the 7.4 JDBC driver, but can run it against a 7.3 (or 7.2)
database. Also note the 8.0 JDBC driver can only do this against a 7.4 or
8.0 database and not older versions.
Kris
) (actual
time=0.118..12.126 rows=3288 loops=1)
Kris Jurka
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statistics there is no way it could expect all of the rows to match.
Thanks for the analysis.
Kris Jurka
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TIP 8: explain analyze is your friend
at once and stashes them in a Vector. This makes
next, absolute, and relative positioning all equal cost.
Kris Jurka
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to
flush that cache.
Kris Jurka
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TIP 7: don't forget to increase your free space map settings
is why are you calling these methods if they didn't
work previously?
Kris Jurka
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TIP 4: Don't 'kill -9' the postmaster
objections
that kept the original patch out of the driver in the first place (we want
a friendlier API than just a data stream).
Kris Jurka
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TIP 9: the planner will ignore your desire to choose an index scan if your
there is the potential to deadlock
if both sides of network buffers are filled up and each side is blocked
waiting on a write. The JDBC driver has conservatively selected 256 as
the maximum number of queries to send at once.
Kris Jurka
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TIP 3
On Wed, 4 May 2005, Mischa Sandberg wrote:
Quoting Kris Jurka [EMAIL PROTECTED]:
Not true. A client may send any number of Bind/Execute messages on
a prepared statement before a Sync message.
Hunh. Interesting optimization in the JDBC driver. I gather it is
sending a string
On Wed, 27 Jul 2005, Josh Berkus wrote:
b) you can't index a temp table.
jurka# create temp table t (a int);
CREATE
jurka# create index myi on t(a);
CREATE
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... (this is on 8.1.2, btw).
This has been fixed in CVS HEAD as part of a patch to allow additional
options to CREATE TABLE AS.
http://archives.postgresql.org/pgsql-patches/2006-02/msg00211.php
Kris Jurka
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TIP 9: In versions below 8.0
On Fri, 24 Mar 2006, Jim C. Nasby wrote:
On Wed, Mar 22, 2006 at 02:37:28PM -0500, Kris Jurka wrote:
On Wed, 22 Mar 2006, Jim C. Nasby wrote:
Ok, I saw disk activity on the base directory and assumed it was pg_xlog
stuff. Turns out that both SELECT INTO and CREATE TABLE AS ignore
have to use
createStatement(resultSetType, resultSetConcurrency) respectively
prepareStatement (resultSetType, resultSetConcurrency) to achieve the
cursor behaviour?
http://jdbc.postgresql.org/documentation/81/query.html#query-with-cursor
Kris Jurka
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later point. I believe prepareThreshold=0
should work. Do you have a test case showing it doesn't?
Kris Jurka
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this situation would be to
implement per column permissions as the sql spec has, so that you could
revoke select on just the prosrc column and allow clients to retrieve the
metadata they need.
Kris Jurka
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TIP 5: don't forget
On Thu, 20 Mar 2008, Albe Laurenz wrote:
PostgreSQL doesn't write into the table files when it SELECTs data.
It could easily be hint bit updates that are set by selects getting
written.
Kris Jurka
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To make
]
Disabling mergejoin pushes it back to a nestloop join. Why can't it hash
join these two together?
Kris Jurka
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On Thu, 16 Apr 2009, Tom Lane wrote:
Kris Jurka bo...@ejurka.com writes:
PG (8.3.7) doesn't seem to want to do a hash join across two partitioned
tables.
Could we see the whole declaration of these tables? (pg_dump -s output
would be convenient)
The attached table definition
On Thu, 16 Apr 2009, Kris Jurka wrote:
Perhaps the cost estimates for the real data are so high because of this
bogus row count that the fudge factor to disable mergejoin isn't enough?
Indeed, I get these cost estimates on 8.4b1 with an increased
disable_cost value:
nestloop
killed after five minutes. I can try to collect explain analyze results
later today if you'd like.
Kris Jurka
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Tom Lane wrote:
Kris Jurka bo...@ejurka.com writes:
The hash join takes less than twenty seconds, the other two joins I
killed after five minutes. I can try to collect explain analyze results
later today if you'd like.
Attached are the explain analyze results. The analyze part hits
this better and send the full batch size, but at the moment
that's not possible and we're hoping the gains beyond this size aren't too
large.
Kris Jurka
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Scott Marlowe wrote:
On Sun, Apr 26, 2009 at 11:07 AM, Kris Jurka bo...@ejurka.com wrote:
As a note for non-JDBC users, the JDBC driver's batch interface allows
executing multiple statements in a single network roundtrip. This is
something you can't get in libpq, so beware
.
You can disable the named statement by adding the parameter
prepareThreshold=0 to your connection URL.
Kris Jurka
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time a message is sent to
the backend we'll also send the cursor close message. This avoids an
extra network roundtrip for the close action.
In any case Statement.close isn't helping you here either. It's really
Connection.commit/rollback that's releasing the locks.
Kris Jurka
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On Tue, 20 Apr 2010, Nikolas Everett wrote:
You can absolutely use copy if you like but you need to use a non-standard
jdbc driver: kato.iki.fi/sw/db/postgresql/jdbc/copy/. I've used it in the
past and it worked.
Copy support has been added to the 8.4 driver.
Kris Jurka
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rows that the driver must deal with, the driver
only gets the rows it asks for. Once the ResultSet is closed, it won't
ask for any more.
Kris Jurka
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On Wed, 21 Apr 2010, Robert Haas wrote:
On Tue, Apr 20, 2010 at 5:05 PM, Kris Jurka bo...@ejurka.com wrote:
b) Using the parameter values for statistics, but not making any stronger
guarantees about them. So the parameters will be used for evaluating the
selectivity, but not to perform
protocol (use
URL option protocolVersion=2). This does remove some functionality of
the driver that is only available for V3 protocol, but will work just
fine for query execution.
Kris Jurka
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