Re: BUG or strange behaviour of update on primary key - Mailing list pgsql-hackers

Hi there,
              I could workaround the behavior with deferred constraint, and it's ok, but as I show, I have different behavior for constraint with the same definition in two rdbms and Postgresql depends on the physical order of row (with the same definition of constraint NOT DEFERRABLE INITIALLY IMMEDIATE) , or better Postgresql seems to check for every row, even if the command is one (I am doing one update on all of rows) , right?  .

Moreover , in documentation the definition says that a not deferrable constraints will check after "every command" , not after every row of the command:

http://www.postgresql.org/docs/9.1/static/sql-createtable.html

DEFERRABLE
NOT DEFERRABLE

This controls whether the constraint can be deferred. A constraint that is not deferrable will be checked immediately after every command. Checking of constraints that are deferrable can be postponed until the end of the transaction (using the SET CONSTRAINTS command). NOT DEFERRABLE is the default. Currently, only UNIQUE, PRIMARY KEY, EXCLUDE, and REFERENCES (foreign key) constraints accept this clause. NOT NULL and CHECK constraints are not deferrable.

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If this is "historical buggy behavior for performance" , I think we have to change  the definition of NOT DEFERRABLE in documentation,
because Postgresql is not checking at end of a dml, but for every row  modified by the command or   there is something needs a patch.


Regards, Mat