On Mon, Nov 29, 2010 at 9:08 PM, Daniel Loureiro <loureir...@gmail.com> wrote: > frequently i have accidents with DELETE/UPDATE commands. In fact, sometimes > in the last 8 or 9 years (ok, a lot of times) I forget the entire WHERE > clause or have a “not so perfectly“ WHERE clause, with an awful suprise. > There’s no words to figure the horror ever time i see that the number of > affected rows its not 1 or two how expected, but the entire table. So I > planned to make a hack to make the “LIMIT” directive available to “DELETE” > command. > > So, can anyone help-me in how to do this ? This its my plan: 1) change the > lex grammar (wheres the file ?) 2) change the parser to accept the new > grammar 3) change the executor to stop after “n” successful iterations. Is > this correct ?
I don't think your use case sounds very compelling - as Jaime says, you could still easily blow away data that you have no easy way to get back - but I agree that DELETE (or UPDATE) is useful in combination with LIMIT. For example, suppose you want to roll your own replication solution for a table with no primary key. So you set up some triggers. Whenever you see an INSERT on the source table, you do a matching INSERT on the target table. When you see a DELETE on the source table, you do a DELETE on the target table that constrains all the columns to be equal and also includes LIMIT 1. Similarly for UPDATE. Then, your boss gives you a big raise and commends you for your awesome programming skills. Woot! -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
