Re: Db transactions and locking

Path	csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!us.feeder.erje.net!news2.arglkargh.de!news.albasani.net!newsreader4.netcologne.de!news.netcologne.de!bcyclone03.am1.xlned.com!bcyclone03.am1.xlned.com!newsfeed.xs4all.nl!newsfeed1a.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Return-Path	<rosuav@gmail.com>
X-Original-To	python-list@python.org
Delivered-To	python-list@mail.python.org
X-Spam-Status	OK 0.059
X-Spam-Evidence	'H': 0.88; 'S': 0.00; 'correct.': 0.07; 'correspond': 0.09; 'cc:addr:python-list': 0.11; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; 'statements,': 0.16; 'wrote:': 0.18; 'library': 0.18; 'commit': 0.19; 'work,': 0.20; 'seems': 0.21; 'cc:addr:python.org': 0.22; 'logical': 0.24; 'cc:2**0': 0.24; 'header:In-Reply-To:1': 0.27; 'database,': 0.30; 'message-id:@mail.gmail.com': 0.30; 'that.': 0.31; 'usually': 0.31; 'fri,': 0.33; 'connection': 0.35; 'received:google.com': 0.35; 'there': 0.35; 'should': 0.36; 'nov': 0.38; 'issue': 0.38; 'pm,': 0.38; 'even': 0.60; 'units': 0.60; 'different': 0.65; 'between': 0.67; 'frank': 0.68; '4:44': 0.91; 'to:none': 0.92; 'state.': 0.95
DKIM-Signature	v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:cc :content-type; bh=2oyNzdku+0XnSJgzUS9hulvU9fTwYsqs+xrz8Sp2WwI=; b=y2nbfoKpkpKdCubNUCRtwVPDjxfF7ZPx5AMhmNmytdDExSNddOTdmK7heL1rgpYJZe C3i9B97/zwdW4HG7Tcf61efYeWD/y5So6+CugPFd66UjBX1JxMklg++pIZY5Z8fgIp0a 8SH9QYUccIw81yHhthUHz6Wer7RYggzNSCvIuC4NIwoIV/MxtknFtPiO7OMsTLLcHgu/ wTt4XdCTup1NNx6FtzSdXS5bkVfEAnzMKcqFAPpS2HJnISqtPYRKdGf1IGjiO86RqHyJ bZtVhnxi1ObzQWvz6R8yPbj0/dvZZF1ZN813yt7A2yWmNnUbZj9jzli1TDj+nGhS8U9I 4m4w==
MIME-Version	1.0
X-Received	by 10.42.130.194 with SMTP id w2mr17654569ics.12.1417154097924; Thu, 27 Nov 2014 21:54:57 -0800 (PST)
In-Reply-To	<m5924d$nbq$1@ger.gmane.org>
References	<m56u4s$baa$1@ger.gmane.org> <4loe7at2ls7tfq0oe041ru9svvsm8aksik@4ax.com> <m5924d$nbq$1@ger.gmane.org>
Date	Fri, 28 Nov 2014 16:54:57 +1100
Subject	Re: Db transactions and locking
From	Chris Angelico <rosuav@gmail.com>
Cc	"python-list@python.org" <python-list@python.org>
Content-Type	text/plain; charset=UTF-8
X-BeenThere	python-list@python.org
X-Mailman-Version	2.1.15
Precedence	list
List-Id	General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe	<https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive	<http://mail.python.org/pipermail/python-list/>
List-Post	<mailto:python-list@python.org>
List-Help	<mailto:python-list-request@python.org?subject=help>
List-Subscribe	<https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups	comp.lang.python
Message-ID	<mailman.16395.1417154102.18130.python-list@python.org> (permalink)
Lines	17
NNTP-Posting-Host	2001:888:2000:d::a6
X-Trace	1417154102 news.xs4all.nl 2900 [2001:888:2000:d::a6]:59399
X-Complaints-To	abuse@xs4all.nl
X-Received-Bytes	3696
X-Received-Body-CRC	2180759790
Xref	csiph.com comp.lang.python:81668

Show key headers only | View raw

On Fri, Nov 28, 2014 at 4:44 PM, Frank Millman <frank@chagford.com> wrote:
> There seems to be a difference between conn.commit() and
> cur.execute('commit'), which leaves the connection in a different state.

Yes, if a connection library offers a way to commit/roll back, it's
usually best to use that.

> However, for my purposes, this is academic.
>
> The main lesson I have learned is that you should always issue a commit
> after any logical set of SQL statements, even if they are only SELECTs,
> otherwise the locks are not released.

Correct. Every time you use any database, you should think in terms of
units of work, which correspond precisely to transactions.

ChrisA

Back to comp.lang.python | Previous | Next | Find similar | Unroll thread

Thread

Re: Db transactions and locking Chris Angelico <rosuav@gmail.com> - 2014-11-28 16:54 +1100

csiph-web