Re: Do selects fill logical logs?

Andrew Cilia wrote: > > I am currently investigating an incident on a 5.03 ONLINE > engine where a select statement with a correlated subquery > seems to populate the logical logs. Reputable sources tell > me that this is standard procedure on complicated queries. > Can anyone confirm this? Where is it documented? > Precisely under what conditions are logs used by queries. > Why does it need to be this way? > > Customer is more than disgruntled since the log requirements > of this infamous query far exceeds those of all other processes > in the system!!! > > Any Ideas? Check out $INFORMIXDIR/release ENGREL_5.0. Search for Correlated Subqueries and you should find a section that says the following: SQL statements which include correlated subqueries often build and erease a temporary table for each row in the dominant table. In databases with logging, these builds and erases are logged. Plan for at least 128 bytes of log space for each dominant table row. One thing I will add is that even if the database doesn't have logging you should still see the creation and erase of temp tables logged because they are Data Definition statements which are logged reguardless of logging status of a database. Jacques -- ******************************************************************** * Jacques P. Renaut "I'd dazzle you with brilliance * * Informix Advanced Support if I only had the knack..." * * email: jrenaut@informix.com #include <disclamier.h> * ********************************************************************