Hi List,
In the past few weeks we have been developing a read-heavy
mysql-benchmark to have an alternative take at cpu/platform-performance.
Not really to have a look at how fast mysql can be.
This benchmark runs on mysql 4.1.x, 5.0.x and 5.1.x and is modelled
after our website's production
On Tue, May 16, 2006 at 12:31:41AM -0400, Tom Lane wrote:
It's true that the system *could* memoize (or in our more usual
parlance, cache function values) given the assumptions embodied in
IMMUTABLE. But we don't, and I don't see any statement in the docs
that promises that we do. For 99% of
Arjen van der Meijden [EMAIL PROTECTED] wrote
Long story short, we think the test is a nice example of the relatively
lightweight, read-heavy webapplications out there and therefore decided
to have a go at postgresql as well.
Some sort of web query behavior is quite optimized in MySQL. For
Qingqing Zhou wrote:
Arjen van der Meijden [EMAIL PROTECTED] wrote
Some sort of web query behavior is quite optimized in MySQL. For example,
the query below is runing very fast due to the query result cache
implementation in MySQL.
Loop N times
SELECT * FROM A WHERE i = 1;
End loop.
Yeah,
Hi Arjen,
Looking at your outputs...of syscall and usrcall it looks like
* Spending too much time in semsys which means you have too many
connections and they are contending to get a lock.. which is potentially
the WAL log lock
* llseek is high which means you can obviously gain a bit
Joachim Wieland [EMAIL PROTECTED] writes:
So irrespective of caching to prevent evaluation across statements, within a
single statement, is there a strong reason why for example in
WHERE col = f(const) with f() declared as immutable or stable and without an
index on col, f() still gets called
Hi Jignesh,
Jignesh K. Shah wrote:
Hi Arjen,
Looking at your outputs...of syscall and usrcall it looks like
* Spending too much time in semsys which means you have too many
connections and they are contending to get a lock.. which is potentially
the WAL log lock
* llseek is high
Hi Arjen,
Can you send me my colleagues's names in a private email?
One of the drawbacks of the syscall.d script is relative timings and
hence if system CPU usage is very low, it gives the relative weightage
about what portion in that low is associated with what call.. So even if
you have
On Tue, May 16, 2006 at 09:33:14AM -0400, Tom Lane wrote:
Joachim Wieland [EMAIL PROTECTED] writes:
So irrespective of caching to prevent evaluation across statements, within a
single statement, is there a strong reason why for example in
WHERE col = f(const) with f() declared as immutable
On May 15, 2006, at 21:31, Tom Lane wrote:
Sure. As I read it, that's talking about a static transformation:
planner sees 2 + 2 (or if you prefer, int4pl(2,2)), planner runs the
function and replaces the expression with 4. Nothing there about
memoization.
Oh, I see. So it's more like a
Hi Jignesh,
The settings from that 'special T2000 dvd' differed from the recommended
settings on the website you provided. But I don't see much difference in
performance with any of the adjustments, it appears to be more or less
the same.
Here are a few iostat lines by the way:
sd0
I have a table of about 500,000 rows.
I need to add a new column and populate it.
So, I have tried to run the following command. The command
never finishes (I gave up after about and hour and a half!).
Note that none of the columns have indexes.
Update mytable set new_column =
I am creating an application that gets the value of a large table and write
it to a file.
Why I want to use offset and limit is for me to create a threaded
application so that they will not get the same results.
For example:
Thread 1 : gets offset 0 limit 5000
Thread 2 : gets offset 5000 limit
On May 16, 2006, at 18:29, Christopher Kings-Lynne wrote:
Yes, but there are definitely programming cases where memoization/
caching definitely helps. And it's easy to tell for a given
function whether or not it really helps by simply trying it with
CACHED and without.
Would this be a
Christian Paul Cosinas wrote:
I am creating an application that gets the value of a large table and write
it to a file.
Why I want to use offset and limit is for me to create a threaded
application so that they will not get the same results.
For example:
Thread 1 : gets offset 0 limit 5000
On Wed, May 17, 2006 at 03:19:26AM +0200, Jonathan Blitz wrote:
I have a table of about 500,000 rows.
I need to add a new column and populate it.
So, I have tried to run the following command. The command never finishes (I
gave up after about and hour and a half!).
If you install
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