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Re: mysql's join too slow; using Perl to compare two tables

by monarch (Priest)
on Feb 04, 2006 at 22:59 UTC ( [id://528009]=note: print w/replies, xml ) Need Help??


in reply to mysql's join too slow; using Perl to compare two tables

I have personally found myself somewhat disgusted with MySQL performance when it comes to simple joins. I don't know if this is because I didn't index the tables properly of some inherent disability in MySQL.

Postgres, on the other hand, seems to take the same time to do inner, outer, or whatever style joins with no performance penalty.

So, no, it's not wrong to scan each table one at a time and getting perl to do the intelligent work with MySQL.

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Re^2: mysql's join too slow; using Perl to compare two tables
by friedo (Prior) on Feb 04, 2006 at 23:15 UTC
    I don't know if this is because I didn't index the tables properly...

    That's probably it. Proper indexing is essential with any non-trivial amount of data.

[reply]
Re^2: mysql's join too slow; using Perl to compare two tables
by dws (Chancellor) on Feb 05, 2006 at 21:00 UTC

    Postgres, on the other hand, seems to take the same time to do inner, outer, or whatever style joins with no performance penalty.

    ... Unless you don't have the necessary columns indexed, in which case performance can appear to suck mightily, particularly once you've left a small, tidy test environment and start dealing with huge piles of customer data.

[reply]

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