Operators and schemas
От | Tom Lane |
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Тема | Operators and schemas |
Дата | |
Msg-id | 24026.1018889037@sss.pgh.pa.us обсуждение исходный текст |
Ответы |
Re: Operators and schemas
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Список | pgsql-hackers |
After some fooling around with gram.y, I have come to the conclusion that there's just no way to use a schema-qualified name for an operator in an expression. I was hoping we might be able to write something likeoperand1 schema.+ operand2 but I can't find any way to make this work without tons of shift/reduce conflicts. One counterexample suggesting it can't be done is thatfoo.* might be either a reference to all the columns of foo, or a qualified operator name. We can still put operators into namespaces and allow qualified names in CREATE/DROP OPERATOR. However, lookup of operators in expressions would have to be completely dependent on the search path. That's not real cool; among other things, pg_dump couldn't guarantee that dumped expressions would be interpreted the same way when reloaded. Things we might do to reduce the uncertainty: 1. Keep operators as database-wide objects, instead of putting them into namespaces. This seems a bit silly though: if the types and functions that underlie an operator are private to a namespace, shouldn't the operator be as well? 2. Use a restricted, perhaps fixed search-path for searching for operators. For example, we might force the search path to have pg_catalog first even when this is not true for the table name search path. But I'm not sure what an appropriate definition would be. A restricted search path might limit the usefulness of private operators to the point where we might as well have kept them database-wide. Comments anyone? I'm really unsure what's the best way to proceed. regards, tom lane
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