Re: why vacuum

On 10/26/2005 11:19 AM, Scott Marlowe wrote:

> On Tue, 2005-10-25 at 23:45, Kenneth Gonsalves wrote:
>> hi,
>> i was in a minor flame war with a mysql guy - his major grouse was that
>> 'I wouldnt commit mission critical data to a database that needs to be
>> vacuumed once a week'. So why does pg need vacuum?
>
> Oh man oh man. After reading the article, I realized he was saying that
> he wouldn't trust PostgreSQL to replace Oracle. He apparently wouldn't
> trust MySQL to replace oracle either.
>
> But, the next time someone says that slony is a toy add on, and MySQL
> has REAL replication, point them to THIS page on the same blog:
>
> http://ebergen.net/wordpress/?p=70
>

You must have missed the FAQ and other side notes about replication in
the MySQL manual. Essentially MySQL replication is nothing but a query
duplicating system, with the added sugar of taking care of now() and
some other non-deterministic things, but not all of them.

Non-deterministic user defined procedures, functions and triggers will
simply blow MySQL's sophisticated replication apart.

Jan

> In short, it basically shows that MySQL replication is incredibly
> fragile, and not fit for production on any real system. The lack of
> system wide transaction support, like postgresql has, makes the problem
> he outlines that much worse.
>
> The hoops people will jump through to use their favorite toys...
>
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> TIP 5: don't forget to increase your free space map settings

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