RE: To fragment or not to fragment - opinion

Chris - Can you elaborate a bit. Your response has me very concerned, as I am = about to implement fragmentation. I thought that with fragmentation, if = a query could rule-out a fragment, it would not scan it. This a = significant piece of functionality which, according to you, fails. The need for temp tables if your index is in another dbspace, is again, = another significant problem. Have you been able to identify if this is query or query-type = dependent?? If not, how could Informix possibly expect people to wait = for 7.2 ?? Can anyone from Informix shine any light on this???? Jon Vemo ---------- From: Chris Wegener[SMTP:chrispw@mincom.oz.au] Sent: Sunday, September 17, 1995 2:31 PM To: informix-list@rmy.emory.edu Subject: To fragment or not to fragment - opinion Whatever you choose to do, be aware that when fragmenting the optimiser will need to search all fragments (or all index fragments) when processing your query. In fact in INFORMIX-OnLine 7.10.UD1 even if your table is not fragmented but it's index is in another dbspace, when you do an OPEN on a cursor all selectable rows are retrieved into a temporary table. This happens even if the index could be used to identify the selected rows. Refer problem no 40006 to be resolved in 7.20. So, I respectfully suggest, if you decide to fragment, use SET EXPLAIN to check that the optimiser is getting confused. -- Regards, Chris -------------------------------------------------------------------------= ----- Chris Wegener Mincom Pty Ltd, Database Consultant Wyandra Street, | | | | = | | chrispw@tenmail.mincom.oz.au Teneriffe, Brisbane, | | | | = | | Phone: +61 7 3303 3333 X2288 Queensland, | | | | = | | Fax: +61 7 3303 3232 Australia 4005 |M |I |N |C = |O |M -------------------------------------------------------------------------= -----