On Wed, Apr 18, 2012 at 09:43:23PM +0200, Petr Jakeš wrote: > > Although this might work in the particular application, but > > it is hardly ideal to make two queries, nor to load a long list > > of IDs. Is there a way to do it with a single query? > > > > 1) > Is your task really "time critical"?
In my case, yes; it is number crunching. Question should be «is it /that/ "time critical"» :-) I have had some difficulties with slow operations due to multiple queries, and it feels more satisfactory get rid of any avoidable query, even if the saving is only a fraction of a percent of the total running time. > How many records (IDs) do you expect to be returned using the first select? thousands in current tests; hundreds of thousands is likely in future tests, and millions is plausible. > How many kb will it take? Is the list size a real problem for your Internet > connection? Might be; especially when it is over the Internet as opposed to over a LAN. Yet, I am as concerned with query processing time than transmission time. > How often do you expect to release the select querry? Could vary. About 50 clients querying once a minute each may be typical, but I am sure I will see faster jobs completing in seconds, in which case each client would query correspondingly often. > 2) > what is your target database engine? postgres at the moment. > some databases allow "rand" in the select query. > see: > http://stackoverflow.com/questions/19412/how-to-request-a-random-row-in-sql Ah. Thanks for the tip. I will look into it; obviously, I would prefer the solution to be engine independent, but this feature might be more valuable :-) :-- George > > Petr -- :-- Hans Georg ------------------------------------------------------------------------------ Better than sec? Nothing is better than sec when it comes to monitoring Big Data applications. Try Boundary one-second resolution app monitoring today. Free. http://p.sf.net/sfu/Boundary-dev2dev _______________________________________________ sqlobject-discuss mailing list sqlobject-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlobject-discuss
