Subject RE: [IB-Architect] Index Sync/Rebuild Question
Author Claudio Valderrama C.
> -----Original Message-----
> From: Ann Harrison [mailto:harrison@...]
> Sent: Viernes 28 de Abril de 2000 10:50
> As with deactivating and reactivating the indexes (which can have
> secondary benefits) or just resetting the selectivity.

Activating/deactivating the indexes seems to be a more complete solution
than resetting selectivity, right or wrong? It seems that with selectivity
recalculation, there's a chance to get unbalances indexes (page 26 of IB6's
LangRef; I don't know if this has a real impact) whereas switching
active/inactive state yields balanced indexes.
And now on the subject of being able to deactivate indexes produced by
PK/UK/FK declarations. :-)
I wonder if this description in LangRef about SET STATISTICS is accurate:
«Index selectivity is a calculation, based on the number of distinct rows in
a table, that is made by the InterBase optimizer when a table is accessed.
It is cached in memory, where the optimizer can access it to calculate the
optimal retrieval plan for a given query.» But Jim said:
«Design the beast so its insenstive to selectivities
(it mostly is -- you guys are barking up the wrong tree).»

Claudio Valderrama C.
Ingeniero en Informática - Consultor independiente