Query Optimization 
Author Message
 Query Optimization

Hi!,

I am having a problem with query optimzation. I use sys(3054) to check
my optimzation level and
it always gives me partial level. Here is the example of my query:

sele * from client where city = "New York"

(client.dbf has index on city). and it gives me partial optimization
level. Is there anything else I
have to setup to get fully optimization level?

Thanks.



Mon, 26 Jan 2004 04:22:25 GMT  
 Query Optimization
Set DELETED off and try again; or index on DELETED().  With DELETED on, Fox
has to check the deleted status of each record.  With DELETED off, it
doesn't.  Indexing on DELETED() allows Fox to use the index tag (instead of
the actual record) to filter on DELETED() status, resulting in full
optimization.

Note that indexing on DELETED() can have a negative effect under certain
circumstances (large tables, few deleted records, using a network), and
should not be automatically added.  (See
http://fox.wikis.com/wc.dll?Wiki~NonDiscriminatingIndex for more on this)
OTOH, temporarily setting DELETED off can be useful for using SYS(3054),
since it will show optimization as 'full.'

 - Rush

When

Quote:
> Hi!,

> I am having a problem with query optimzation. I use sys(3054) to check
> my optimzation level and
> it always gives me partial level. Here is the example of my query:

> sele * from client where city = "New York"

> (client.dbf has index on city). and it gives me partial optimization
> level. Is there anything else I
> have to setup to get fully optimization level?

> Thanks.



Mon, 26 Jan 2004 04:57:49 GMT  
 Query Optimization
Thanks Rush, It works.
Quote:

> Set DELETED off and try again; or index on DELETED().  With DELETED on, Fox
> has to check the deleted status of each record.  With DELETED off, it
> doesn't.  Indexing on DELETED() allows Fox to use the index tag (instead of
> the actual record) to filter on DELETED() status, resulting in full
> optimization.

> Note that indexing on DELETED() can have a negative effect under certain
> circumstances (large tables, few deleted records, using a network), and
> should not be automatically added.  (See
> http://fox.wikis.com/wc.dll?Wiki~NonDiscriminatingIndex for more on this)
> OTOH, temporarily setting DELETED off can be useful for using SYS(3054),
> since it will show optimization as 'full.'

>  - Rush

> When


> > Hi!,

> > I am having a problem with query optimzation. I use sys(3054) to check
> > my optimzation level and
> > it always gives me partial level. Here is the example of my query:

> > sele * from client where city = "New York"

> > (client.dbf has index on city). and it gives me partial optimization
> > level. Is there anything else I
> > have to setup to get fully optimization level?

> > Thanks.



Mon, 26 Jan 2004 05:42:04 GMT  
 
 [ 3 post ] 

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