On 9/17/14 10:46 AM, Greg Stark wrote: > You could have a problem if you have an expression index on (timestamp > AT TIME ZONE '...'). I may have the expression slightly wrong but I > believe it is posisble to write an immutable expression that depends > on the tzdata data as long as it doesn't depend on not the user's > current time zone (which would be stable but not immutable). The > actual likelihood of that situation might be much lower and the > ability to avoid it higher but in theory I think Peter's right that > it's the same class of problem.
I was thinking of something like a text column with "natural" input of time stamp information, and and index on that_column::timestamp. > Generally speaking we try to protect against most environment > dependencies that lead to corrupt databases by encoding them in the > control file. Obviously we can't encode an entire collation in the > controlfile though. We could conceivably have a corpus of > representative strings that we sort and then checksum in the > controlfile. It wouldn't be foolproof but if we collect interesting > examples as we find them it might be a worthwhile safety check. I think it could be useful in a number of situations if a type could stick some arbitrary additional information into a new column in pg_type, such as versions of libraries it depends on or storage format versions. Then again, collation isn't actually a property of any single type. -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers