Robert Haas <robertmh...@gmail.com> writes: > Forgive me if this is discussed before, but why does this store the > strategy numbers of the relevant operators instead of the operators > themselves? It seems like this could lead to surprising behavior if > the user modifies the definition of the operator class.
Wild guess: http://www.postgresql.org/docs/8.4/static/xindex.html 34.14.2. Index Method Strategies The operators associated with an operator class are identified by "strategy numbers", which serve to identify the semantics of each operator within the context of its operator class. For example, B-trees impose a strict ordering on keys, lesser to greater, and so operators like "less than" and "greater than or equal to" are interesting with respect to a B-tree. Because PostgreSQL allows the user to define operators, PostgreSQL cannot look at the name of an operator (e.g., < or >=) and tell what kind of comparison it is. Instead, the index method defines a set of "strategies", which can be thought of as generalized operators. Each operator class specifies which actual operator corresponds to each strategy for a particular data type and interpretation of the index semantics. Regards, -- dim -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
