August Zajonc wrote:
Alessandro Baretta wrote:
Alessandro,
I've very much enjoyed reading your thoughts and the problem your facing
and everyone's responses.
Thank you for your interest, Agust.
Since you control the middle layer, could you not use a cookie to keep a
cursor open on the
Alessandro Baretta wrote:
What I could do relatively easily is instantiate a thread to iteratively
scan a traditional cursor N rows at a time, retrieving only record keys,
and finally send them to the query-cache-manager. The application thread
would then scan through the cursor results by
[EMAIL PROTECTED] wrote:
On Tue, Jan 17, 2006 at 08:56:00PM +0100, Alessandro Baretta wrote:
I understand most of these issues, and expected this kind of reply. Please,
allow me to insist that we reason on this problem and try to find a
solution. My reason for doing so is that the future
Alessandro Baretta schrieb:
[EMAIL PROTECTED] wrote:
...
It looks like this is the only possible solution at present--and in the
future, too--but it has a tremendouse performance impact on queries
returning thousands of rows.
Well actually one of the better solutions would be persistent
Josh Berkus wrote:
People:
To follow up further, what Alessandro is talking about is known as a
keyset cursor. Sybase and SQL Server used to support them; I beleive
that they were strictly read-only and had weird issues with record
visibility.
I would like to thank everyone for sharing
On Wed, Jan 18, 2006 at 09:57:50AM +0100, Alessandro Baretta wrote:
[EMAIL PROTECTED] wrote:
On Tue, Jan 17, 2006 at 08:56:00PM +0100, Alessandro Baretta wrote:
I understand most of these issues, and expected this kind of reply.
Please, allow me to insist that we reason on this problem and
[EMAIL PROTECTED] wrote:
On Wed, Jan 18, 2006 at 09:57:50AM +0100, Alessandro Baretta wrote:
I there is to be a change to PostgreSQL to optimize for this case, I
suggest it involve the caching of query plans, executor plans, query
results (materialized views?), LIMIT and OFFSET. If we had all
Your experiment made far too many assumptions and the data does not
stand up to scrutiny.
On 1/18/06, Alessandro Baretta [EMAIL PROTECTED] wrote:
Results: I'll omit the numerical data, which everyone can easily obtain in
only
a few minutes, repeating the experiment. I used several query
On Wed, Jan 18, 2006 at 03:41:57PM +, Harry Jackson wrote:
There are various reason why google might want to limit the search
result returned ie to encourage people to narrow their search. Prevent
screen scrapers from hitting them really hard blah blah. Perhaps less
than 0.0001% of
Tom Lane wrote:
Alessandro Baretta [EMAIL PROTECTED] writes:
I am aware that what I am dreaming of is already available through
cursors, but in a web application, cursors are bad boys, and should be
avoided. What I would like to be able to do is to plan a query and run
the plan to retreive a
On Tue, Jan 17, 2006 at 08:56:00PM +0100, Alessandro Baretta wrote:
I understand most of these issues, and expected this kind of reply. Please,
allow me to insist that we reason on this problem and try to find a
solution. My reason for doing so is that the future software industry is
likely to
Craig A. James wrote:
Alessandro Baretta [EMAIL PROTECTED] writes:
I think you're trying to do something at the wrong layer of your
architecture. This task normally goes in your middleware layer, not
your database layer.
I am developing my applications in Objective Caml, and I have
Alessandro Baretta [EMAIL PROTECTED] writes:
* When the cursor state is pushed back to the backend, no new
transaction is instantiated, but the XID of the original transaction
is reused. In the MVCC system, this allows us to achieve a perfectly
consistent view of the database at the instant
On Tue, Jan 17, 2006 at 09:06:53PM +0100, Alessandro Baretta wrote:
Craig A. James wrote:
Alessandro Baretta [EMAIL PROTECTED] writes:
I think you're trying to do something at the wrong layer of your
architecture. This task normally goes in your middleware layer, not
your database
On Tue, Jan 17, 2006 at 08:56:00PM +0100, Alessandro Baretta wrote:
I understand most of these issues, and expected this kind of reply. Please,
allow me to insist that we reason on this problem and try to find a
solution. My reason for doing so is that the future software industry is
likely
I am developing my applications in Objective Caml, and I have written the
middleware layer myself. I could easily implement a cursor-pooling strategy,
but
there is no perfect solution to the problem of guaranteeing that cursors be
closed. Remember that web applications require the user to
On Tue, 17 Jan 2006 16:12:59 -0500
[EMAIL PROTECTED] wrote:
In the mean time, I successfully use LIMIT and OFFSET without such an
optimization, and things have been fine for me.
Same here.
-
Frank Wiles [EMAIL PROTECTED]
http://www.wiles.org
Alessandro,
I understand most of these issues, and expected this kind of reply.
Please, allow me to insist that we reason on this problem and try to
find a solution. My reason for doing so is that the future software
industry is likely to see more and more web applications retrieving data
People:
To follow up further, what Alessandro is talking about is known as a
keyset cursor. Sybase and SQL Server used to support them; I beleive
that they were strictly read-only and had weird issues with record
visibility.
--
--Josh
Josh Berkus
Aglio Database Solutions
San Francisco
[EMAIL PROTECTED] wrote:
On Tue, Jan 17, 2006 at 08:56:00PM +0100, Alessandro Baretta wrote:
What is wrong with LIMIT and OFFSET? I assume your results are ordered
in some manner.
Especially with web users, who become bored if the page doesn't flicker
in a way that appeals to them, how could
Alessandro Baretta wrote:
I think you're trying to do something at the wrong layer of your
architecture. This task normally goes in your middleware layer, not
your database layer.
I am developing my applications in Objective Caml, and I have written
the middleware layer myself. I could
Mark Kirkwood [EMAIL PROTECTED] writes:
SELECT ... FROM table WHERE ... ORDER BY id LIMIT 20;
Suppose this displays records for id 1 - 10020.
When the user hits next, and page saves id=10020 in the session state
and executes:
SELECT ... FROM table WHERE ... AND id 10020 ORDER BY id
Tom Lane wrote:
Mark Kirkwood [EMAIL PROTECTED] writes:
SELECT ... FROM table WHERE ... ORDER BY id LIMIT 20;
Suppose this displays records for id 1 - 10020.
When the user hits next, and page saves id=10020 in the session state
and executes:
SELECT ... FROM table WHERE ... AND id
I am aware that what I am dreaming of is already available through cursors, but
in a web application, cursors are bad boys, and should be avoided. What I would
like to be able to do is to plan a query and run the plan to retreive a limited
number of rows as well as the executor's state. This
Alessandro Baretta [EMAIL PROTECTED] writes:
I am aware that what I am dreaming of is already available through
cursors, but in a web application, cursors are bad boys, and should be
avoided. What I would like to be able to do is to plan a query and run
the plan to retreive a limited number of
Tom Lane wrote:
Alessandro Baretta [EMAIL PROTECTED] writes:
I am aware that what I am dreaming of is already available through
cursors, but in a web application, cursors are bad boys, and should be
avoided. What I would like to be able to do is to plan a query and run
the plan to
Alvaro Herrera [EMAIL PROTECTED] writes:
I wonder if we could have a way to suspend a transaction and restart
it later in another backend. I think we could do something like this
using the 2PC machinery.
Not that I'm up for coding it; just an idea that crossed my mind.
It's not impossible,
On Mon, 2006-01-16 at 11:13 +0100, Alessandro Baretta wrote:
I am aware that what I am dreaming of is already available through cursors,
but
in a web application, cursors are bad boys, and should be avoided. What I
would
like to be able to do is to plan a query and run the plan to
Alessandro Baretta [EMAIL PROTECTED] writes:
I am aware that what I am dreaming of is already available through
cursors, but in a web application, cursors are bad boys, and should be
avoided. What I would like to be able to do is to plan a query and run
the plan to retreive a limited number of
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