Preventing duplicate inserts?

Rails
1

Apologies if this looks like a dupe. I posted something similar a
couple days ago but I can’t seem to find the thread. In my profile it
claims I posted the thread, but then won’t give me a link to it.
anyway…

I have 2 ruby processes that are chugging along adding or updating
email addresses from different sources. Occasionally, they both see the
same email address at the same time. They’re inserting into a table
that has a unique index on the email address.

So I have code along the lines of:

def address_seen(newaddr)
transaction
addrinfo = AddrInfo.find(:addr => newaddr)
if addrinfo == nil
addrinfo = AddrInfo.create!(:addr => newaddr, …)
end
end
end

The problem is this doesn’t prevent a duplicate insert error (resulting
in Mysql::Error: #23000Duplicate entry).

How, using rails, can I make 2 or more ruby processes coordinate
through the DB so that they don’t try to insert the same row more than
once?

2

So I have code along the lines of:
The problem is this doesn’t prevent a duplicate insert error (resulting
in Mysql::Error: #23000Duplicate entry).

How, using rails, can I make 2 or more ruby processes coordinate
through the DB so that they don’t try to insert the same row more than
once?

Wrap your ‘create’ line in a begin/rescue/end block and catch the error
coming from mysql…

Although the error you give above suggests that mysql is NOT allowing
duplicate entries. If you simply wanted to shut it up just do:

begin
addrinfo = AddrInfo.create!(:addr => newaddr, …)
rescue
nil
end

and get rid of the transaction all together…