performance - Database indices that cover only one value -

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I have a large table (millions of records) in which some hundreds of thousands of numbers boolean fields (instead of 0 = 1)

I only care about those records which are true (value = 1). Is there a way to create an index that 'indexes' these records? What kind of index should I use? 

  Select Count (*) from records where boolean_field = 1   
 environment: Oracle 10G (but also  
 
 
 If your "false" value is zero instead of zero, you can get the result you want Otherwise, you can create a function-based pointer like this:    index IDX (case boolean_field when 1 again 1 end) on create records;   
 This will only be an index of 1s But for Oracle, your questions should be used in your questions:  
  Choose from the record where the case boolean_field when 1 then 1 end = 1;  < / Pre>

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