RE: [firebird-support] (When to) recalculate statistics ?

[liviuslivius liviusliv...@poczta.onet.pl [firebird-support]]

HiTo take decision you first must know what statistics are for server e.g. 
Firebird. Statistics contain info how selective is some index. If it is PK you 
know that every entry have only one record. For UK you have same but you can 
have multiple nulls. For other indexes you can have for one entry multiple 
references to records. Simple sample index of people name. You can have 
multiple people with same name.Index selectivity is used when Firebird 
optimizer choose plan for the query. Without information about selectivity or 
with not recent information it can decide wrongly and generate "wrong" query 
plan. And query can then run slow. If your queries have good plan and run fast 
then you can e.g stop recalculating statistics at all.As you can see it 
depend..You must decide how offten. Regards,Karol Bieniaszewski
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