query optimisation

[Danielle et jean Thierry-Mieg]

somebody says:

 acedb> find probe
>                                        1 sec
> // Found 8169 objects in this class
> 
> acedb> follow sequence
>                                        7 sec
> // Found 1636 objects
> 
> acedb> query find sequence probe     [64570 Sequence objects]
>                                      150 sec
> // Found 1636 objects



actually is Probe was an indexed tag (declared in subclasses.wrm)
or simply a level 1 tag (from the first column) in which case it is
indexed by default in acedb 4_7
 acedb> query find sequence probe     [64570 Sequence objects]
 would probably take around 1 sec

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