Re: Database backups

}Message-Id: <9205061401.AA13406@rmy.rmy.emory.edu> }Date: Wed, 6 May 92 13:47:40 GMT }From: "Robert F. Kane" <uunet!worms-emh2.army.mil!bob> }Subject: Re: Database backups }X-Informix-List-Id: <list.1140> }> The annoying feature of DBEXPORT is that it does an "update }> statistics" (6 hours on a 10GB database) before writing anything to }> tape. But once it starts writing, it is fast. I can't imagine why }> it needs to do that because doing a select count(*) on each table is }> virtually instant. }I find that curious, I have a database with approxiamately a million records }and I can do an update statistics in about 20 seconds. Another difference }between SE and ONLINE perhaps. We are using SE 4.0 UG1 on a AT&T 3B2. Yes: a major difference. UPDATE STATISTICS in SE simply opens the index file of each table, collects the number of rows form it, and updates the corresponding record in Systables. In OnLine, UPDATE STATISTICS processes all the indexes in the table, recording the number of distinct values and the degree of clustering. This is what takes the time! Jonathan Leffler (johnl@obelix.informix.com) #include <disclaimer.h>