Re: [PHP-DB] Slooooow query in MySQL.
Stut wrote: Chris wrote: Stut wrote: Chris wrote: Rob Adams wrote: I have a query that I run using mysql that returns about 60,000 plus rows. It's been so large that I've just been testing it with a limit 0, 1 (ten thousand) on the query. That used to take about 10 minutes to run, including processing time in PHP which spits out xml from the query. I decided to chunk the query down into 1,000 row increments, and tried that. The script processed 10,000 rows in 23 seconds! I was amazed! But unfortunately it takes quite a bit longer than 6*23 to process the 60,000 rows that way (1,000 at a time). It takes almost 8 minutes. I can't figure out why it takes so long, or how to make it faster. The data for 60,000 rows is about 120mb, so I would prefer not to use a temporary table. Any other suggestions? This is probably more a db issue than a php issue, but I thought I'd try here first. Sounds like missing indexes or something. Use explain: http://dev.mysql.com/doc/refman/4.1/en/explain.html If that were the case I wouldn't expect limiting the number of rows returned to make a difference since the actual query is the same. Actually it can. I don't think mysql does this but postgresql does take the limit/offset clauses into account when generating a plan. http://www.postgresql.org/docs/current/static/sql-select.html#SQL-LIMIT Not really relevant to the problem though :P How many queries do you run with an order? But you're right, if there is no order by clause adding a limit probably will make a difference, but there must be an order by when you use limit to ensure the SQL engine doesn't give you the same rows in response to more than one of the queries. Oops, that was meant to say How many queries do you run *without* an order? -Stut -- http://stut.net/ -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DB] Slooooow query in MySQL.
select h.addr, h.city, h.county, h.state, h.zip, 'yes' as show_prop,
h.askingprice, '' as year_built, h.rooms, h.baths,
'' as apt, '' as lot, h.sqft, h.listdate, '' as date_sold, h.comments,
h.mlsnum,
r.agency, concat(r.fname, ' ', r.lname) as rname,
r.phone as rphone, '' as remail, '' as status, '' as prop_type,
ts.TSCNfile as picture,
h.homeid as homeid, 'yes' as has_virt
from ProductStatus ps, home h, realtor r, ProductBin pb
left join TourScene ts on ts.TSCNtourId = pb.PBINid and ts.TSCN_MEDIAid
= '3'
where ps.PSTSstatus = 'posted' and pb.PBINid = PSTS_POid and h.id =
pb.PBINid
and h.listdate DATE_SUB(NOW(), INTERVAL 2 YEAR)
and (h.homeid is not null and h.homeid '')
and r.realtorid = pb.PBIN_HALOid limit {l1}, {l2}
Here is the query. I didn't know that it needed to have an ORDER clause in
it for the limit to work properly. I'll probably order by h.listdate
-- Rob
Stut [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
Chris wrote:
Stut wrote:
Chris wrote:
Rob Adams wrote:
I have a query that I run using mysql that returns about 60,000 plus
rows. It's been so large that I've just been testing it with a limit
0, 1 (ten thousand) on the query. That used to take about 10
minutes to run, including processing time in PHP which spits out xml
from the query. I decided to chunk the query down into 1,000 row
increments, and tried that. The script processed 10,000 rows in 23
seconds! I was amazed! But unfortunately it takes quite a bit longer
than 6*23 to process the 60,000 rows that way (1,000 at a time). It
takes almost 8 minutes. I can't figure out why it takes so long, or
how to make it faster. The data for 60,000 rows is about 120mb, so I
would prefer not to use a temporary table. Any other suggestions?
This is probably more a db issue than a php issue, but I thought I'd
try here first.
Sounds like missing indexes or something.
Use explain: http://dev.mysql.com/doc/refman/4.1/en/explain.html
If that were the case I wouldn't expect limiting the number of rows
returned to make a difference since the actual query is the same.
Actually it can. I don't think mysql does this but postgresql does take
the limit/offset clauses into account when generating a plan.
http://www.postgresql.org/docs/current/static/sql-select.html#SQL-LIMIT
Not really relevant to the problem though :P
How many queries do you run with an order? But you're right, if there is
no order by clause adding a limit probably will make a difference, but
there must be an order by when you use limit to ensure the SQL engine
doesn't give you the same rows in response to more than one of the
queries.
-Stut
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Re: [PHP-DB] Slooooow query in MySQL.
Stut wrote: Stut wrote: Chris wrote: Stut wrote: Chris wrote: Rob Adams wrote: I have a query that I run using mysql that returns about 60,000 plus rows. It's been so large that I've just been testing it with a limit 0, 1 (ten thousand) on the query. That used to take about 10 minutes to run, including processing time in PHP which spits out xml from the query. I decided to chunk the query down into 1,000 row increments, and tried that. The script processed 10,000 rows in 23 seconds! I was amazed! But unfortunately it takes quite a bit longer than 6*23 to process the 60,000 rows that way (1,000 at a time). It takes almost 8 minutes. I can't figure out why it takes so long, or how to make it faster. The data for 60,000 rows is about 120mb, so I would prefer not to use a temporary table. Any other suggestions? This is probably more a db issue than a php issue, but I thought I'd try here first. Sounds like missing indexes or something. Use explain: http://dev.mysql.com/doc/refman/4.1/en/explain.html If that were the case I wouldn't expect limiting the number of rows returned to make a difference since the actual query is the same. Actually it can. I don't think mysql does this but postgresql does take the limit/offset clauses into account when generating a plan. http://www.postgresql.org/docs/current/static/sql-select.html#SQL-LIMIT Not really relevant to the problem though :P How many queries do you run with an order? But you're right, if there is no order by clause adding a limit probably will make a difference, but there must be an order by when you use limit to ensure the SQL engine doesn't give you the same rows in response to more than one of the queries. Oops, that was meant to say How many queries do you run *without* an order? Almost never - but my point was actually this sentence: The query planner takes LIMIT into account when generating a query plan, so you are very likely to get different plans (yielding different row orders) depending on what you use for LIMIT and OFFSET. -- Postgresql php tutorials http://www.designmagick.com/ -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DB] Slooooow query in MySQL.
Rob Adams wrote:
select h.addr, h.city, h.county, h.state, h.zip, 'yes' as show_prop,
h.askingprice, '' as year_built, h.rooms, h.baths,
'' as apt, '' as lot, h.sqft, h.listdate, '' as date_sold,
h.comments, h.mlsnum,
r.agency, concat(r.fname, ' ', r.lname) as rname,
r.phone as rphone, '' as remail, '' as status, '' as prop_type,
ts.TSCNfile as picture,
h.homeid as homeid, 'yes' as has_virt
from ProductStatus ps, home h, realtor r, ProductBin pb
left join TourScene ts on ts.TSCNtourId = pb.PBINid and
ts.TSCN_MEDIAid = '3'
where ps.PSTSstatus = 'posted' and pb.PBINid = PSTS_POid and h.id =
pb.PBINid
and h.listdate DATE_SUB(NOW(), INTERVAL 2 YEAR)
and (h.homeid is not null and h.homeid '')
and r.realtorid = pb.PBIN_HALOid limit {l1}, {l2}
Here is the query. I didn't know that it needed to have an ORDER clause
in it for the limit to work properly. I'll probably order by h.listdate
If you don't have an ORDER BY clause then you're going to get
inconsistent results. The database will never guarantee returning
results in a set order unless you tell it to by specifying an order by
clause.
To speed up your query, make sure you have indexes on:
TourScene(TSCNtourId, TSCN_MEDIAid)
ProductBin(PBINid, PBIN_HALOid)
home(id, listdate)
realtor(realtorid)
If you can't get it fast, then post the EXPLAIN output.
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