On 12/9/2010 3:22 PM, Vander Clock Stephane wrote:
<horrible table, indexes, and query omitted>
>
> ON MYSQL it's takes very very lot of time (hourS) to return
> but on Firebird with same amount of data they return immediatly ... (firebird soo good?)
Yes. You've hit one of Firebird's sweet spots, the ability to use
multiple indexes on a single query. It reads all the indexes,
setting and clearing bits to indicate whether a particular records
meets all current criteria, then reads the surviving records in
storage order.
Most databases read an index entry, get a record, read the next
index, get the next record ... so they can't use more than one
index per table. That method has the advantage that records are
returned in index order, but it doesn't perform well o the sort
of query you're doing.
> so i definitivelly make a bad point to Mysql against firebird
> or i do something wrong (want to be honest in the report) ?
>
Which MySQL are you using? 4.x, 5.1, 5.5? InnoDB, MyISAM?
Blackhole is scorchingly fast, but you give up something in
accuracy. How much do you know about MySQL tuning. When my
group was benchmarking an InnoDB implementation of DBT2, we
got about a 5x improvement in performance by tuning ... and not
the way the documentation says.