mysql-question

[ojorus]

Hi!
My company make several flash-based games, and I use php to communicate with
mysql to provide highscore-lists.

My problem is this:
When I save a player's score in the mysql-table, I want to find which place
the player got with his score (today). To get this I have tried two
different solutions, which both works, but are very ineffective: (The
Time-field is a DateTime type, and I have Score and Time as Indexes)

1) SELECT COUNT(*) FROM table WHERE Score>=$score AND Time>CURDATE().
- or -
2) SELECT Score FROM table WHERE Score>=$score AND Time>CURDATE().

.... $place = mysql_num_rows($result)

Both give the right result, but the problem is that when there are many
players playing at the same time, and the table consists of several million
records, the query is just too heavy for the mysql-server, and it breakes
down.

So my question is: Are there any better ways of getting a player's place?

Ole Johan, Norway

[Michael Boutros]

ojorus wrote:

Hi!
My company make several flash-based games, and I use php to communicate with
mysql to provide highscore-lists.

My problem is this:
When I save a player's score in the mysql-table, I want to find which place
the player got with his score (today). To get this I have tried two
different solutions, which both works, but are very ineffective: (The
Time-field is a DateTime type, and I have Score and Time as Indexes)

1) SELECT COUNT(*) FROM table WHERE Score>=$score AND Time>CURDATE().
- or -
2) SELECT Score FROM table WHERE Score>=$score AND Time>CURDATE().

... $place = mysql_num_rows($result)

Both give the right result, but the problem is that when there are many
players playing at the same time, and the table consists of several million
records, the query is just too heavy for the mysql-server, and it breakes
down.

So my question is: Are there any better ways of getting a player's place?

Ole Johan, Norway

If I understand you correctly, you can use:

SELECT score FROM table ORDER BY score DESC LIMIT 1

I don't understand why you are using Time>CURDATE(), because it isn't
needed in this situation.

Thanks,
Michael Boutros

[Rik]

Michael Boutros wrote:

ojorus wrote:

>Hi!
My company make several flash-based games, and I use php to
communicate with mysql to provide highscore-lists.

My problem is this:
When I save a player's score in the mysql-table, I want to find
which place the player got with his score (today). To get this I
have tried two different solutions, which both works, but are very
ineffective: (The Time-field is a DateTime type, and I have Score
and Time as Indexes)

1) SELECT COUNT(*) FROM table WHERE Score>=$score AND Time>CURDATE().
- or -
2) SELECT Score FROM table WHERE Score>=$score AND Time>CURDATE().

... $place = mysql_num_rows($result)

Both give the right result, but the problem is that when there are
many players playing at the same time, and the table consists of
several million records, the query is just too heavy for the
mysql-server, and it breakes down.

So my question is: Are there any better ways of getting a player's
place?

Ole Johan, Norway

If I understand you correctly, you can use:

SELECT score FROM table ORDER BY score DESC LIMIT 1

I don't understand why you are using Time>CURDATE(), because it isn't
needed in this situation.

That's not what the op wants.
To rephrase what I gather from his post:
He wants the placing of the score compared to other scores on that
particular day.

"SELECT COUNT(*) FROM table WHERE Score>=$score AND Time>CURDATE()"
Would be my choice, but seems to slow. Indexes are already created according
to the OP, so that's no way to go either. Maybe save only the day of the
score in the YYYYMMDD format, and use Time=CURDATE()+0.

About using COUNT(*):
"COUNT(*) is optimized to return very quickly if the SELECT retrieves from
one table, no other columns are retrieved, and there is no WHERE clause."

There is a WHERE clause here, hence the optimization is lost. So, maybe use
COUNT(score). I don't know wether this will be faster, but it's worth a
shot.

Grtz,
--
Rik Wasmus

[ojorus]

"Michael Boutros" <mi*************@gmail.comskrev i melding
news:11**********************@i42g2000cwa.googlegr oups.com...

>
ojorus wrote:

>Hi!
My company make several flash-based games, and I use php to communicate
with
mysql to provide highscore-lists.

My problem is this:
When I save a player's score in the mysql-table, I want to find which
place
the player got with his score (today). To get this I have tried two
different solutions, which both works, but are very ineffective: (The
Time-field is a DateTime type, and I have Score and Time as Indexes)

1) SELECT COUNT(*) FROM table WHERE Score>=$score AND Time>CURDATE().
- or -
2) SELECT Score FROM table WHERE Score>=$score AND Time>CURDATE().

... $place = mysql_num_rows($result)

Both give the right result, but the problem is that when there are many
players playing at the same time, and the table consists of several
million
records, the query is just too heavy for the mysql-server, and it breakes
down.

So my question is: Are there any better ways of getting a player's place?

Ole Johan, Norway

If I understand you correctly, you can use:

SELECT score FROM table ORDER BY score DESC LIMIT 1

I don't understand why you are using Time>CURDATE(), because it isn't
needed in this situation.

Thanks,
Michael Boutros

Hi! Thanks for your replay.
The Score-table contain scores for many days. Since I want to get the
player's place for TODAY, I'll have to use Time>CURDATE(). (Which means
Time>'2006-08-04 00:00:00').
The query you propose will by the way only return the best score ever, which
I'm not interessted in. It is the player's PLACE for today I want, based on
his score.

Ole Johan

[Rik]

Rik wrote:

Michael Boutros wrote:

>ojorus wrote:

>>Hi!
My company make several flash-based games, and I use php to
communicate with mysql to provide highscore-lists.

My problem is this:
When I save a player's score in the mysql-table, I want to find
which place the player got with his score (today). To get this I
have tried two different solutions, which both works, but are very
ineffective: (The Time-field is a DateTime type, and I have Score
and Time as Indexes)

1) SELECT COUNT(*) FROM table WHERE Score>=$score AND
Time>CURDATE(). - or -
2) SELECT Score FROM table WHERE Score>=$score AND Time>CURDATE().

... $place = mysql_num_rows($result)

Both give the right result, but the problem is that when there are
many players playing at the same time, and the table consists of
several million records, the query is just too heavy for the
mysql-server, and it breakes down.

So my question is: Are there any better ways of getting a player's
place?

Ole Johan, Norway

If I understand you correctly, you can use:

SELECT score FROM table ORDER BY score DESC LIMIT 1

I don't understand why you are using Time>CURDATE(), because it isn't
needed in this situation.

That's not what the op wants.
To rephrase what I gather from his post:
He wants the placing of the score compared to other scores on that
particular day.

"SELECT COUNT(*) FROM table WHERE Score>=$score AND Time>CURDATE()"
Would be my choice, but seems to slow. Indexes are already created
according to the OP, so that's no way to go either. Maybe save only
the day of the score in the YYYYMMDD format, and use Time=CURDATE()+0.

About using COUNT(*):
"COUNT(*) is optimized to return very quickly if the SELECT retrieves
from one table, no other columns are retrieved, and there is no WHERE
clause."

There is a WHERE clause here, hence the optimization is lost. So,
maybe use COUNT(score). I don't know wether this will be faster, but
it's worth a shot.

Adding:
Is score an integer? That's how the database will work best. If it isn't an
integer, consider making it one.

BTW: if this isn't a solution, try (alt.)comp.databases.mysql. Those guys
will know a lot more about mysql optimization.

Grtz,
--
Rik Wasmus

[ojorus]

"Rik" <lu************@hotmail.comskrev i melding
news:18*************************@news2.tudelft.nl. ..

Rik wrote:

>Michael Boutros wrote:

>>ojorus wrote:
Hi!
My company make several flash-based games, and I use php to
communicate with mysql to provide highscore-lists.

My problem is this:
When I save a player's score in the mysql-table, I want to find
which place the player got with his score (today). To get this I
have tried two different solutions, which both works, but are very
ineffective: (The Time-field is a DateTime type, and I have Score
and Time as Indexes)

1) SELECT COUNT(*) FROM table WHERE Score>=$score AND
Time>CURDATE(). - or -
2) SELECT Score FROM table WHERE Score>=$score AND Time>CURDATE().

... $place = mysql_num_rows($result)

Both give the right result, but the problem is that when there are
many players playing at the same time, and the table consists of
several million records, the query is just too heavy for the
mysql-server, and it breakes down.

So my question is: Are there any better ways of getting a player's
place?

Ole Johan, Norway

If I understand you correctly, you can use:

SELECT score FROM table ORDER BY score DESC LIMIT 1

I don't understand why you are using Time>CURDATE(), because it isn't
needed in this situation.

That's not what the op wants.
To rephrase what I gather from his post:
He wants the placing of the score compared to other scores on that
particular day.

"SELECT COUNT(*) FROM table WHERE Score>=$score AND Time>CURDATE()"
Would be my choice, but seems to slow. Indexes are already created
according to the OP, so that's no way to go either. Maybe save only
the day of the score in the YYYYMMDD format, and use Time=CURDATE()+0.

About using COUNT(*):
"COUNT(*) is optimized to return very quickly if the SELECT retrieves
from one table, no other columns are retrieved, and there is no WHERE
clause."

There is a WHERE clause here, hence the optimization is lost. So,
maybe use COUNT(score). I don't know wether this will be faster, but
it's worth a shot.

Adding:
Is score an integer? That's how the database will work best. If it isn't
an
integer, consider making it one.

BTW: if this isn't a solution, try (alt.)comp.databases.mysql. Those guys
will know a lot more about mysql optimization.

Grtz,
--
Rik Wasmus

No, unfortunately the score is defined as decimal (20,2). So that's probably
one of the slow-down factors.

One solution to improve performance could be to have a table just containing
today's games, which will be cleared every midnight. Then I can skip the
CURDATE-thing, and the search will probably be a lot faster.

Thanks for the mysql-group-info.

Ole Johan

[Rik]

ojorus wrote:

"Rik" <lu************@hotmail.comskrev i melding
news:18*************************@news2.tudelft.nl. ..

>Rik wrote:

>>Michael Boutros wrote:
ojorus wrote:
Hi!
My company make several flash-based games, and I use php to
communicate with mysql to provide highscore-lists.
>
My problem is this:
When I save a player's score in the mysql-table, I want to find
which place the player got with his score (today). To get this I
have tried two different solutions, which both works, but are very
ineffective: (The Time-field is a DateTime type, and I have Score
and Time as Indexes)
>
1) SELECT COUNT(*) FROM table WHERE Score>=$score AND
Time>CURDATE(). - or -
2) SELECT Score FROM table WHERE Score>=$score AND Time>CURDATE().
>
... $place = mysql_num_rows($result)
>
Both give the right result, but the problem is that when there are
many players playing at the same time, and the table consists of
several million records, the query is just too heavy for the
mysql-server, and it breakes down.
>
So my question is: Are there any better ways of getting a player's
place?
>
Ole Johan, Norway

If I understand you correctly, you can use:

SELECT score FROM table ORDER BY score DESC LIMIT 1

I don't understand why you are using Time>CURDATE(), because it
isn't needed in this situation.
That's not what the op wants.
To rephrase what I gather from his post:
He wants the placing of the score compared to other scores on that
particular day.

"SELECT COUNT(*) FROM table WHERE Score>=$score AND Time>CURDATE()"
Would be my choice, but seems to slow. Indexes are already created
according to the OP, so that's no way to go either. Maybe save only
the day of the score in the YYYYMMDD format, and use
Time=CURDATE()+0.

About using COUNT(*):
"COUNT(*) is optimized to return very quickly if the SELECT
retrieves from one table, no other columns are retrieved, and there
is no WHERE clause."

There is a WHERE clause here, hence the optimization is lost. So,
maybe use COUNT(score). I don't know wether this will be faster, but
it's worth a shot.

Adding:
Is score an integer? That's how the database will work best. If it
isn't an
integer, consider making it one.

BTW: if this isn't a solution, try (alt.)comp.databases.mysql. Those
guys will know a lot more about mysql optimization.

Grtz,
--
Rik Wasmus

No, unfortunately the score is defined as decimal (20,2). So that's
probably one of the slow-down factors.

Is it just 1 decimal? In that case I'd suggest just multiplying it with 10
and store it like an integer.
The same goes for Time, if it's OK to have just a date, just store it like
an integer with date in YYYYMMDD format.

One solution to improve performance could be to have a table just
containing today's games, which will be cleared every midnight. Then
I can skip the CURDATE-thing, and the search will probably be a lot
faster.

It surely will, with a simple cronjob, but if you want to get info from past
days (which you want to save I presume, as you're keeping them in the
database), you'll have the same problem, only less often.

Thanks for the mysql-group-info.

NP

Grtz,
--
Rik Wasmus