database length restrictions on properties are silent

[dustin]

If you create a property that's too long, the database fails to tell you about it, and you get an error reading the JSON back. We should detect this and error out at insert/update time. See

 https://github.com/tardyp/buildbot/commit/03f8fcb35552991663a177c7ff160993741f921a

[dustin]

I need to figure out the function for MySQL's maximum number of characters given a text limit -- I don't think it's the identity function :(

[dustin]

Actually, in my test script, I do get a warning from msyql-python, but only the first time:

/home/dustin/code/buildbot/t/buildbot/sand26/lib/python2.6/site-packages/sqlalchemy/engine/default.py:330: Warning: Data truncated for column 't' at row 1

On the bright side, MySQL's and Python's length functions seem to agree!

[dustin]

The trac hook failed, but this is fixed in

commit 967b74ecaf1f0bbae842534280b3e56e5d52c17f
Author: Dustin J. Mitchell <dustin@mozilla.com>
Date:   Sat Feb 25 22:59:04 2012 -0600

    check database column length on insert for MySQL
    
    SQLite ignores length and just stores all the bytes you give it.
    Postgres will kindly produce an error rather than silently truncating.
    So this support is only really useful for MySQL, and stubs itself out
    everywhere else.
    
    Fixes #2114.