Level Extreme platform
Subscription
Corporate profile
Products & Services
Support
Legal
Français
How much data returned
Message
 
 
To
03/05/2006 00:09:32
General information
Forum:
Visual FoxPro
Category:
Databases,Tables, Views, Indexing and SQL syntax
Miscellaneous
Thread ID:
01118142
Message ID:
01118658
Views:
18
>Hi Naomi,
>>Do you know if filtered indexes allow optimization in VFP9 SP1?
>
>AFAIR a filtered index ( FOR...) or one with "not" in its expresion
>is not rushmore-usable.
>
>Most of the time a single compound index is faster for querying or joining
>(iif(iActive_flag, "1", "0") + cTrans_fk)
>but "overindexing" slows down insert/update operation. Since changes in PK/FK are
>probably not happening very often, you'ld have to decide if the speed gain
>from using only one compound rushmore bitmap vs. 2 single bitmaps or
>vs. one single bitmap and record checks on the logical field is worth
>the added overhead writing to the cdx.
>
>regds
>
>thomas

The field is Integer (iActive_Flag <g>), but I think there is a change in VFP9 regarding filtered indexes. I'm wondering, if it's documented in Help (it's too late right now to look for VFP Focus CoDe magazine issue, where I read it).
If it's not broken, fix it until it is.


My Blog
Previous
Next
Reply
Map
View

Click here to load this message in the networking platform