Operator startegies for an access method - Mailing list pgsql-hackers

Hello everyone.   When I studied system catolog,I can't understand a concept "operator strategies for an access
method",Who can tell me what it's that and where I could find document on the Web. Thanks for your reponse very much,
especiallythank Hannu Krosing.
 
         Guo longjiang  Harbin China
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