Hi, SAPDB uses log devspaces and data devspaces. During 'db_warm' the restart is executed, which uses the log devspace to put itself in a transaction consistent state. If you stopped the database with 'db_stop' it is disrupted. If you use 'db_offline' it is shutdown orderly. This means that a 'db_stop' does NOT do an orderly shutdown, especially not writing a savepoint. The restart must now use the last savepoint found in LOG and REDO all transactions since last savepoint. The fills the database data cache with those pages, it was filled with during your first execution. This leads to the same execution times as if you would have executed your statement again. Bad for a benchmark...
Look in http://www.sapdb.org/htmhelp/19/774939e5523668e10000000a114084/frameset.htm Select Functions for Database Operation where you find 'db_offline' and 'db_stop'. NOTE: db_stop should be used in COLD(Admin) mode only! CU jrg > -----Original Message----- > From: Koller S�bastien [mailto:Sebastien.Koller@;cpln.ch] > Sent: Freitag, 1. November 2002 16:28 > To: '[EMAIL PROTECTED]' > Subject: What does the database during db_start db_warm? > > > Hello, > > I would like to know what's happening when we execute this > command: db_start > and db_warm. > > This question comes from the following situation: We are > trying to do a > benchmark and here is the procedure: > > 1. db_start > 2. db_warm > 3. execute the query: select count(*) .... -> we get the > execution time (for > example 4 min.) > 4. execute a second time the same query: 56 sec. > 5. db_stop > 6. db_warm > 7. execute the query: select count(*) .... -> we get the > execution time 56 > sec (again!) > > I don't know why after a shutdown of the database(db_stop) > the query doesn't > take the same time than the first time we executed the > query?????????????? > > What does the database during a db_start and b_warm????? > Thanks, > S�bastien > > E-mail: [EMAIL PROTECTED] > > _______________________________________________ > sapdb.general mailing list > [EMAIL PROTECTED] > http://listserv.sap.com/mailman/listinfo/sapdb.general > _______________________________________________ sapdb.general mailing list [EMAIL PROTECTED] http://listserv.sap.com/mailman/listinfo/sapdb.general
