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Performance: Faster algorithm to count unique visitors #3120

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mattab opened this issue Apr 23, 2012 · 1 comment
Open

Performance: Faster algorithm to count unique visitors #3120

mattab opened this issue Apr 23, 2012 · 1 comment
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c: Performance For when we could improve the performance / speed of Matomo. Task Indicates an issue is neither a feature nor a bug and it's purely a "technical" change.
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@mattab
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mattab commented Apr 23, 2012

Suggested in forum post

Currently we count the number of distinct idvisitor, to get unique per week/month/etc.

Instead, we could count each time a visitor is new (he didn't have the idcookie or wasn't match to recent visit), set a flag. Then count the number of times the flag was set. This will be slightly more inaccurate but much faster than running a new SELECT count(disctinct) on very large datasets.
@anonymous-matomo-user
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I started to look into this bug and found the following:
http://bugs.mysql.com/bug.php?id=21849
It looks like it might have been fixed in MySQL 5.5.0 and/or we can replace the code with something like:
"select count(*) from (select distinct somefield from sometable group by somefield) as somelabel;" which has much better performance on mysql pre-5.5.0.

@mattab mattab added this to the Future releases milestone Jul 8, 2014
@mattab mattab removed the P: normal label Aug 3, 2014
@mattab mattab modified the milestones: Long term, Mid term Dec 23, 2015
@mattab mattab modified the milestones: Long term, Mid term Dec 5, 2016
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c: Performance For when we could improve the performance / speed of Matomo. Task Indicates an issue is neither a feature nor a bug and it's purely a "technical" change.
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