Re: RESIDENT and PDQ

> > Also, as we all know, memory is cheap now. We would like to max out our > > Sun UltraEnterprise 3000 to 6G and cache up the entire database as > > resident, while still allowing substantial amount virtual memory. But > > it seems as though Informix is quite limited, permitting only 512K > > buffers of 2k each (total of 1G RAM for buffers). Of course, even if > > Informix permitted us to use as buffers the max memory our machine > > supports (6G), PDQ would still ignore and read in (light scans) from > > physical disk each time (I think). You can get better shared memory access with a 64-bit version of IDS if you're running a 64-bit OS (I'm not a Sun person, sorry). As for light scans--those only happen if the table being read is larger than the buffer pool. So if you max out your buffers, you won't get light scans unless they're huge tables...

Chuck Renaud wrote in message <7ddp91$hpf$1@news.xmission.com>... > >As for light scans--those only happen if the table being read is >larger than the buffer pool. So if you max out your buffers, you >won't get light scans unless they're huge tables... So, would this mean that if we set up max number of buffers allowed by Informix (only 512K), and made some tables resident, and set PDQ 100, then query execution would 1) read from buffers [as opposed to light scan read from physical drive] and 2) do all other processing related to query in parallel, etc. [in other words, execute as PDQ 100]. If answer to these questions is yes, what about if one of the cached tables is fragmented. Would fragment elimination still occurr? In other words, would fragmentation change answer to either 1) or 2)?