Re: BUG #5126: convert_to preventing index scan

>>>>> "Peter" == Peter Eisentraut <peter_e(at)gmx(dot)net> writes:

>> I have table with bytea column, which is indexed (1)
>> I want to use index during pattern matching (eg. dir like
>> someDirectoryName
>> || '/%'), but concatenation of two strings cause error (2)
>> So I have to use function convert_to (converting text to bytea), but
>> this
>> has awful explain plan (3)

Peter> You haven't told us how the convert_to function is defined.

convert_to is a builtin function. If there's a bug here, it's that
convert_to is defined as stable rather than immutable. (Sure it depends
on server_encoding, but that can't exactly change... if there's any
other reason why it's not immutable, I can't think what it is.)

Example (5) from the original message is the correct approach in any
case; as long as either operand of the || is explicitly passed as, or
cast to, a bytea, then it should work.

--
Andrew (irc:RhodiumToad)