Question

I am using character varying data type in PostgreSQL.
I was not able to find this information in PostgreSQL manual.
What is max limit of characters in character varying data type?

Answer 1

Referring to the documentation, there is no explicit limit given for the varchar(n) type definition. But:

…
In any case, the longest possible
character string that can be stored is
about 1 GB. (The maximum value that
will be allowed for n in the data type
declaration is less than that. It
wouldn’t be very useful to change this
because with multibyte character
encodings the number of characters and
bytes can be quite different anyway.
If you desire to store long strings
with no specific upper limit, use text
or character varying without a length
specifier, rather than making up an
arbitrary length limit.)

Also note this:

Tip: There is no performance
difference among these three types,
apart from increased storage space
when using the blank-padded type, and
a few extra CPU cycles to check the
length when storing into a
length-constrained column. While
character(n) has performance
advantages in some other database
systems, there is no such advantage in
PostgreSQL; in fact character(n) is
usually the slowest of the three
because of its additional storage
costs. In most situations text or
character varying should be used
instead.