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From: Dennis Lee Bieber <wlfraed@ix.netcom.com>
Subject: Re: How to find bad row with db api executemany()?
Date: Fri, 29 Mar 2013 18:25:24 -0400
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Xref: csiph.com comp.lang.python:42289

On Fri, 29 Mar 2013 14:53:30 -0400, Dave Angel <davea@davea.name>
declaimed the following in gmane.comp.python.general:

> On 03/29/2013 10:48 AM, Roy Smith wrote:
> > I'm inserting a gazillion rows into a MySQL database using MySQLdb and cursor.executemany() for efficiency.  Every once in a while, I get a row which violates some kind of database constraint and raises Error.
> >
> > I can catch the exception, but don't see any way to tell which row caused the problem.  Is this information obtainable, short of retrying each row one by one?
> >
> 
> I don't know the direct answer, or even if there is one (way to get 
> MySQL to tell you which one failed), but ...
> 
> Assuming that executeMany is much cheaper than a million calls to 
> executeOne (or whatever).

	If using MySQLdb, there isn't all that much difference... MySQLdb is
still compatible with MySQL v4 (and maybe even v3), and since those
versions don't have "prepared statements", .executemany() essentially
turns into something that creates a newline delimited "list" of
"identical" (but for argument substitution) statements and submits that
to MySQL.

	Just look at the source code (cursors.py in MySQLdb package).

	Hmmm... That gives a rally point. If it IS submitting one massive
string containing all the data copies, could the failure be coming from
submitting something too big for the client/server communication
channel?
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
        wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/