On 4-8-2014 16:42, Aldo Caruso [email protected] [firebird-support] wrote: > Hello, > > I have three questions relating CONTAINING predicate. > > In "The Firebird Book" I read on page 318 that indexes are used > also on search conditions against CONTAING predicates. I did some test > and, inspecting its PLAN, I found that it uses NATURAL order instead of > using an index. > > 1) ¿ Under which circumstances an index is used when the search has a > CONTAINING condition ? > > Given the following two SQL clauses > > SELECT * FROM TABLE1 WHERE UPPER(FIELD1) LIKE '%TEST%' > SELECT * FROM TABLE1 WHERE FIELD1 CONTAINING 'TEST' > > 2) Are they logically equivalent ? > 3) Which of them is faster ?
They are logically equivalent, and I'd assume they perform similar (although a CONTAINING might have the benefit that it doesn't need to support more complex patterns). I am not 100% sure, but I think Helen's book is wrong here (btw: page 270 in The Firebird book second edition). Mark -- Mark Rotteveel ------------------------------------ ------------------------------------ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Visit http://www.firebirdsql.org and click the Documentation item on the main (top) menu. Try FAQ and other links from the left-side menu there. Also search the knowledgebases at http://www.ibphoenix.com/resources/documents/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------------ Yahoo Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/firebird-support/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/firebird-support/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> To unsubscribe from this group, send an email to: [email protected] <*> Your use of Yahoo Groups is subject to: https://info.yahoo.com/legal/us/yahoo/utos/terms/
