method_save in meta/__init__.py could make use of mysql features

[Ian@…]

I was looking at method_save, and noticed it might not be the best way of doing it for mysql

in mysql you have got 2 features which might help out a bit.

REPLACE [LOW_PRIORITY | DELAYED]
    [INTO] tbl_name [(col_name,...)]
    VALUES ({expr | DEFAULT},...),(...),...

​http://dev.mysql.com/doc/refman/5.0/en/replace.html

which will replace the record if it already exists

and

INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
    [INTO] tbl_name [(col_name,...)]
    VALUES ({expr | DEFAULT},...),(...),...
    [ ON DUPLICATE KEY UPDATE col_name=expr, ... ]

​http://dev.mysql.com/doc/refman/5.0/en/insert.html

with the ON DUPLICATE KEY UPDATE part allowing you to deal with a duplicate record.

using one of these might simplify the logic going on here, as well as possibly reducing the number of trips to the DB server.

[Adrian Holovaty]

This would be a pretty good improvement, I think.

[Simon Greenhill, dev@…]

Just a few points to consider

1) When using InnoDB tables REPLACE INTO will silently delete anything in other tables that reference the replaced field with an ON DELETE CASCADE constraint. This can be quite shocking if you're not expecting it.

2) REPLACE INTO is veeeeeeery slow when compared with an UPDATE.

[Adrian Holovaty]

Closing as a wontfix due to the reasons pointed out by Simon Greenhill.