Re: Postgres performance - Mailing list pgsql-sql

From PFC
Subject Re: Postgres performance
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Msg-id opsm4y44r8th1vuj@musicbox
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In response to Re: Postgres performance  (Mauro Bertoli <bertolima@yahoo.it>)
List pgsql-sql
> I don't require transaction because the query aren't
> complex and update a single tuple (in SELECT
> transactions are useless)
You mean, you have no foreign keys in your database ?In SELECT they are definitely useful (think select for update,
isolation 
 
level serializable...)

> - start quote -
>  You'll find inserts/updates with lots of users is
>  where PostgreSQL works
>  well compared to other systems.
> - end quote -
> Uhhmm.. this is interesting...
pg does not lock the whole table everytime anyone wants to write in it.  
In MySQL when you run a big select, all write activity stops during that.  
If you run a big update, all activity other than this update has to wait.

> - why postgres use a new process for every query ?
> (mySQL, if I'm not wrong, use threads... I think its
> faster)
Not for every query, for every CONNECTION.You are using persistant connections are you. Are you ?

> - why connection time is slower? (compared to mySQL)?
This is of no importance as everyone uses persistent connections anyway.

> - why postgres require analyze? (mySQL, if I'm not
> wrong, don't require it)
> Yours answers will be very apreciated! Thx
So it has a planner which knows what it's doing ;) instead of just  
guessing in the dark.
And MySQL requires analyze too (read the docs), optimize table which  
looks like vacuum to me, and sometimes repair table...



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