from http://www.sqlite.org/limits.html
Maximum length of a string or BLOB
The maximum number of bytes in a
string or BLOB in SQLite is defined by
the preprocessor macro
SQLITE_MAX_LENGTH. The default value of this macro is 1 billion (1 thousand
million or 1,000,000,000). You can
raise or lower this value at
compile-time using a command-line
option like this:-DSQLITE_MAX_LENGTH=123456789 The current implementation will only
support a string or BLOB length up to
231-1 or 2147483647. And some built-in
functions such as hex() might fail
well before that point. In
security-sensitive applications it is
best not to try to increase the
maximum string and blob length. In
fact, you might do well to lower the
maximum string and blob length to
something more in the range of a few
million if that is possible.During part of SQLite’s INSERT and
SELECT processing, the complete
content of each row in the database is
encoded as a single BLOB. So the
SQLITE_MAX_LENGTH parameter also
determines the maximum number of bytes
in a row.