SEO
vBulletin Search Engine Optimization
| |||||||
| Register | FAQ | Members List | Calendar | Search | Today's Posts | Mark Forums Read |
03-04-2008, 06:23 AM
| ||||
| ||||
 Views & performance Hi, simple question I have 2 hugge tables Table A and Table B. I define a view over these 2 tables (select,..joint,...) My question is: Does the DB2 runs the query every time that I access the View? or only the first time that I create the view. Is the answer is Yes,...then: Can I set to refresh the view only 1 a day? I am asking this, because both tables are really big (about 100.000.000 rows),..and I suppose that running the query to refresh the view everytime I access it,...will slow down everything,.... thanks, Al      |
|
03-04-2008, 06:23 AM
| |||
| |||
| Re: Views & performance Gordowey wrote: > Hi, simple question > > I have 2 hugge tables Table A and Table B. I define a view over these > 2 tables (select,..joint,...) > > My question is: > Does the DB2 runs the query every time that I access the View? Yes, views are just "templates" of queries. Take a look at "Materialized Query Tables" (MQT). You define them with CREATE TABLE ... AS (SELECT...) ... Cheers Serge -- Serge Rielau DB2 Solutions Development IBM Toronto Lab |
|
03-04-2008, 06:23 AM
| |||
| |||
| Re: Views & performance While stranded on information super highway Gordowey wrote: > Hi, simple question > > I have 2 hugge tables Table A and Table B. I define a view over these > 2 tables (select,..joint,...) > > My question is: > Does the DB2 runs the query every time that I access the View? or only > the first time that I create the view. > > Is the answer is Yes,...then: Can I set to refresh the view only 1 a > day? > > I am asking this, because both tables are really big (about > 100.000.000 rows),..and I suppose that running the query to refresh > the view everytime I access it,...will slow down everything,.... > > thanks, Al I think what you nees is a materialized query table (MQT). -- Hemant Shah /"\ ASCII ribbon campaign E-mail: NoJunkMailshah@xnet.com \ / --------------------- X against HTML mail TO REPLY, REMOVE NoJunkMail / \ and postings FROM MY E-MAIL ADDRESS. -----------------[DO NOT SEND UNSOLICITED BULK E-MAIL]------------------ I haven't lost my mind, Above opinions are mine only. it's backed up on tape somewhere. Others can have their own. |
|
03-06-2008, 02:04 PM
| ||||
| ||||
| Re: Views & performance "Gordowey" <albertoiriarte@gmail.com> wrote in message news:2cc0ccbb-7db0-4ddb-9634-fb18dc1ece83@e25g2000prg.googlegroups.com... > Hi, simple question > > I have 2 hugge tables Table A and Table B. I define a view over these > 2 tables (select,..joint,...) > > My question is: > Does the DB2 runs the query every time that I access the View? or only > the first time that I create the view. > > Is the answer is Yes,...then: Can I set to refresh the view only 1 a > day? > > I am asking this, because both tables are really big (about > 100.000.000 rows),..and I suppose that running the query to refresh > the view everytime I access it,...will slow down everything,.... > > thanks, Al A view does not really exist with an data. When you have an SQL statement that references a view, at execution time DB2 resolves the view to the actual base tables and rewrites the SQL without the view, and then executes it. |
Linear Mode
