Steve
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Registered: 30th Mar 02
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How would you make this query better/faster?
code:
$sqlgetduplicate = "SELECT m.coordx, m.coordy, u.postcode, u.user_id
FROM USER_TABLE u, MAP TABLE m
WHERE m.name = '". $postcheckname . "'
AND m.coordx >= '".($rowurl['coordx']-4780)."'
AND m.coordx <= '".($rowurl['coordx']+4780)."'
AND m.coordy >= '".($rowurl['coordy']-7000)."'
AND m.coordy <= '".($rowurl['coordy']+7000)."'
AND u.postcode = m.post
AND u.username <> 'Anonymous'
ORDER BY u.username DESC";
im assuming using join or union, what would be the syntax?
[Edited on 12-12-2007 by Steve]
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Steve
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the bit slowing it down is this line
AND u.postcode = m.post
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James
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Location: Surrey
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code:
$sqlgetduplicate = "SELECT m.coordx, m.coordy, u.postcode, u.user_id
FROM USER_TABLE u JOIN MAP TABLE m ON u.postcode = m.post
WHERE m.name = '". $postcheckname . "'
AND m.coordx >= '".($rowurl['coordx']-4780)."'
AND m.coordx <= '".($rowurl['coordx']+4780)."'
AND m.coordy >= '".($rowurl['coordy']-7000)."'
AND m.coordy <= '".($rowurl['coordy']+7000)."'
AND u.username <> 'Anonymous'
ORDER BY u.username DESC";
Dunno how much faster it will be though.
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Steve
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works but is as slow 
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James
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Location: Surrey
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Got any indexes on those tables?
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Steve
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yes the postcode on the map table is a primary index, there is a normal index on the postcode field in the users table
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Gavin
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Location: West Midlands
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throw more hardware at it... usually helps 
I'm more of an oracle man tbh
Other than indexing..... the "order by" would be fairly costly
pew pew pew pewwwww
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Steve
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Location: Worcestershire Drives: Defender
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nah as soon as i remove the line that compares the two tables its fine
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Steve
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with that line, the page processes in 1.3 seconds
without that line 0.07
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Tim
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Registered: 21st Apr 00
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You are effectively joining in the first statement (just with a slightly more standard SQL syntax).
Indexes on u.postcode and m.post critical. They both exist?
Run the query with a prefix of 'EXPLAIN SELECT...' -- it will tell you exactly why it's slow. Watch for anything doing a file sort, table scan, or using temporary tables.
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Steve
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yeah tim field1 has a primary key index, field2 a normal index, will try that though ta
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Ian
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Registered: 28th Aug 99
Location: Liverpool
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I would hazard a guess that the additional WHEREs are meaning the index can't be used.
An EXPLAIN will shed more light.
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Steve
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sorted, query for map now is down to 0.2 seconds or thereabouts
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Ian
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Location: Liverpool
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When are you making it fast? 
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Steve
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36 database queries in 0.5304830 seconds
taken from yours
[Edited on 13-12-2007 by Steve]
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Ian
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Location: Liverpool
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Yeah 36 queries, not one. 
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Steve
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thats just the one that was causing problems theres loads of other queries in there too
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Steve
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hold on il work out how many its doing
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Ian
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Location: Liverpool
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How did you sort it?
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Steve
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if theres a query inside a query does that query get multiplied how many times it takes the query its looping in to finish ?
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Ian
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Registered: 28th Aug 99
Location: Liverpool
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A joined select is one.
Subselects inside brackets which run as dependent subqueries would be two or more.
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Steve
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21 queries altogether by my calculations
maybe my hardwares shit
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Steve
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Battle of the DB queries
i need a dedicated server 
i bet the one mines on is hosting 20 vbulletin forums all taking up valuable resources 
[Edited on 13-12-2007 by Steve]
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Steve
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quote:
Originally posted by Ian
How did you sort it?
rethought the way it finds duplicates, realised i didnt actually have to compare the two tables as the query it was already inside was generating a postcode on each pass, i just modified the query i posted in here to get all users from the users table which had the postcode it was generating on that pass, and filtered duplicates using GROUP BY on the usernames
[Edited on 13-12-2007 by Steve]
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Ian
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Location: Liverpool
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GROUP BY won't always remove duplicates from the JOIN as it depends on what order they're done. Query optimiser should sort it out but you really need to have done an EXPLAIN before and after to see the exact affect of your changes.
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