Il 31/08/2011 0.03, Adriano dos Santos Fernandes ha scritto: > On 30-08-2011 18:27, Fulvio Senore wrote: >> >> Now I have installed Ubuntu 10.04 LTS 64 bit in my laptop, formatting >> the disk partitions with the ext4 file system. >> When I use the same program to open my catalog, it takes about 23 >> seconds. That is in incredibly long time and I really cannot imagine how >> can it be so slow. For the whole 23 seconds the hard disk works >> continuously and cpu usage is very low. If I close the program and I >> open the catalog again, it takes the same 23 seconds again. >> When opening a catalog the program executes only SELECT queries, so it >> is only reading the database. >> It looks like Firefox reads are not cached, but this is very strange. >> Disk reads are usually cached: if I open a large program for the first >> time the hard disk works, if I open it again the disk does not work any >> more, so those reads are cached. >> I cannot imagine why Firebird disk reads are not cached, but this could >> be an explanation. >> > > Are you sure you're not executing each query in a different transaction? > > Please also try to set the database to async mode (forced write off) and > see if it changes. >
Thank you for your quick answer. Setting the database to forced writes off made opening the catalog a very quick task. I must admit that I was executing each query in its own transaction. Since I was only executing SELECT statements I was thinking that there was no problem in working this way. I never had performance problems with Windows and Linux in virtual machines, so I did non think that this might be a problem. I have tried executing all the queries in a single transaction and now opening the catalog is lightning fast! It looks like opening and closing a transaction requires writing to the database, even if the transaction only executes SELECT statements. Lesson learned. Thank you for solving my problem. I am still wondering why performance was so bad with ext4 only, but this is not a real problem any more, just a matter of curiosity. Fulvio ------------------------------------------------------------------------------ Special Offer -- Download ArcSight Logger for FREE! Finally, a world-class log management solution at an even better price-free! And you'll get a free "Love Thy Logs" t-shirt when you download Logger. Secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsisghtdev2dev Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
