Re: Fragmentation and Extent Size

Gregory Moye wrote: > > I just today started playing with 7.10.UC1 (Solaris 2.4), so this may be > an easy question. I dbimported a database exported from 5.05, and then > fragmented a few large tables by expression over 6 volumes/dbspaces. the > tables in their source dbspace consumed about 45Mbytes of space. In the > target dbspaces they consumed over 700 Mbytes. Very Strange. > > I snooped around a little and found that in each of the fragments, huge > initial extents were allocated, and then only a small portion (7-10%) was > actually used, accounting for all of that growth in allocated pages. The extent size specified at CREATE time applies to each of the fragments. So creating a table with an extent size of 45Mb, for example, would actually cause (45*6)Mb of space to be allocated, i.e. 45Mb in each of the 6 dbspaces. When you size extents for a frag'ed table, get the size needed for the whole table and divide by the number of frags. Use that as your initial extent size. -- Dave Kosenko Advanced Services Manager Informix Professional Services http://ww.informix.com