Subject Re: [firebird-support] Re: Basic tests shows very poor performance
Author grostoon
Hi Pavel,

Ok, I understand that garbage collection has work to do but :
- why does it takes so much time for just 50Mo database file ?
- why does FB2.0 give the result in a few seconds ???

So garbage collection is the sole problem, may I have much better times if I
set the sweep interval to 0 ?

BTW, I'm using isql with direct access to the database file (i.e I'm not using the fb_inet_server but direct connect '/home/toon/fbtest.fdb'). Does this make a difference ?



Pavel Cisar <pcisar@...> wrote:grostoon wrote:
> FIREBIRD 1.53 ----------------------
> delete from tbl1 : 1.68 s
> select count(*) tbl1 : 2430 s !!!
> Seriously, spending 45 minutes to discover that a table is actually
> empty for a database of less than 50Mo, it's all but a normal
> behaviour even for a scenario that, I admit it, is not representative
> of real database access...

Again, you have witnessed the automatic garbage collection in action on
most horrible scenario (all table data were taken out, with multiple
indices with lot of duplicates, in fact, all duplicates, and have to be
discovered (and in some cases removed) at once due to full table scan).
Everyone who uses Firebird knows that, and in most cases it's easy to
avoid it. A ZAP TABLE SQL command that would drop all data and index
B-trees by simply deallocating these db pages would fix all that, and
would make such operation instant. It was discussed in FB-architect
lists, and sometime in the future we would probably implement it, but
it's a low priority feature.

best regards
Pavel Cisar


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