simple
(field1,field2) (field2,field1)
 1        1            1        1
 2        x             1       4
 3        x             1       8
 4        1             x       2
 5        x             x       3
 6        x             x       5
 7        x             x       6
 8        1             x       7
 etc
 select where field2=1
 in one case value = 1 could also be the last field1
 in the second case the search ends after the third element 
                                   there may be other elements 
 

 
 
 
-------Messaggio originale-------
 
Da: brucedickin...@wp.pl [firebird-support]
Data: 20/07/2015 14.20.37
A: firebird-support@yahoogroups.com
Oggetto: Re: Rif: [firebird-support] Re: Is it possible to use only "part"
of the index?
 
  
So, if I change the order of fields in the index I can speed things up.
Could someone explain me why it works like it works? What are the internals
behind this?

 

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  • [firebird-su... brucedickin...@wp.pl [firebird-support]
    • Rif: [f... 'Raffaele Confalone' r.confal...@libero.it [firebird-support]
    • [firebi... Virgo Pärna virgo.pa...@mail.ee [firebird-support]
      • Rif... 'Raffaele Confalone' r.confal...@libero.it [firebird-support]
        • ... brucedickin...@wp.pl [firebird-support]
          • ... 'Raffaele Confalone' r.confal...@libero.it [firebird-support]
          • ... 'Raffaele Confalone' r.confal...@libero.it [firebird-support]
          • ... Mark Rotteveel m...@lawinegevaar.nl [firebird-support]
            • ... 'Raffaele Confalone' r.confal...@libero.it [firebird-support]
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