Is the COMMUTATOR clause required for self commutative operators?
От | |
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Тема | Is the COMMUTATOR clause required for self commutative operators? |
Дата | |
Msg-id | 64892.216.238.112.88.1070921195.squirrel@$HOSTNAME обсуждение исходный текст |
Ответы |
Re: Is the COMMUTATOR clause required for self commutative operators?
Re: Is the COMMUTATOR clause required for self commutative operators? |
Список | pgsql-general |
In the command CREATE OPERATOR name ( PROCEDURE = func_name [, LEFTARG = lefttype ] [, RIGHTARG = righttype ] [, COMMUTATOR = com_op ] [, NEGATOR = neg_op ] [, RESTRICT = res_proc ] [, JOIN = join_proc ] [, HASHES ] [, MERGES ] [, SORT1 = left_sort_op ] [, SORT2 = right_sort_op ] [, LTCMP = less_than_op ] [, GTCMP = greater_than_op ] ) Is omitting the COMMUTATOR option a problem at all in case of self-commutative operators? That is, if I define CREATE OPERATOR public.+( PROCEDURE = numeric_add_null, LEFTARG = numeric, RIGHTARG = numeric, COMMUTATOR = +) (where numeric_add_null is a function that handles in NULLs in a non-standard, but more useful way), since "+" is self commutative, is it necessary to include it here? Any advantage or disadvantage to ommitting or including it? ~Berend Tober
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