Re: Informix vs. Sybase vs. Oracle vs. (gasp) MS SQL Server

Pablo Sanchez wrote: > > In article <0v8awLAcPRVzEwpS@smooth1.demon.co.uk>, David Williams <djw@smooth1.demon.co.uk> writes: > > >I can do a *moderate* comparison between Informix and Sybase (32 bit > > >port): > > > > > >Sybase 11.0.X Informix 7.22 > > >------------- ------------- > > >o ~2 gig max for data cache o 1 gig max for data cache > > > > > > Drawback Informix. With a smaller data cache there's less data you > > > can cache in memory. > > Primarily you would use this amount of memory for data warehouses for which Informix offers XPS, where you can have unlimited amount of memory, simply by adding more nodes. In a recent record breaking TPC-D benchmark, Informix used 24GB of memory. > > I've asked this before and perhaps you can shed some light, by doing > RA_PAGES this only configures how many I/O's to read-ahead however, I > do not *believe, it increase the *size* of the I/O. That is, the I/O > is still performed as 2/4K... you are just issuing more of them. Big > problem(*) > > Can you track that down? Elizabeth Suto's book isn't clear on it. According to some material I have from Informix, the engine allocates for every 100 buffers configured, a big buffer of eight pages, which will be used to read and write physically contiguous pages in a single I/O. On a HP9000/K400 with four CPUs and data striped across several disks I have seen the overall I/O throughput measured by iostat during a sequential scan exceed 24MB/sek, which I wouldn't call a bottleneck. -- Sveinn Sveinsson | mailto:svenni@strengur.is Strengur ltd Computer Consultants | http://www.strengur.is 'rm'la 7 | Phone: +354-550-9000 IS-108 Reykjavik | Fax: +354-550-9010 Iceland