Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id F3BE74026 for ; Thu, 7 Jul 2011 19:21:58 +0000 (UTC) Received: (qmail 6046 invoked by uid 500); 7 Jul 2011 19:21:56 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 5955 invoked by uid 500); 7 Jul 2011 19:21:56 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 5946 invoked by uid 99); 7 Jul 2011 19:21:55 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 07 Jul 2011 19:21:55 +0000 X-ASF-Spam-Status: No, hits=3.2 required=5.0 tests=FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM,HK_RANDOM_ENVFROM,HK_RANDOM_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of teddyyyy123@gmail.com designates 209.85.160.172 as permitted sender) Received: from [209.85.160.172] (HELO mail-gy0-f172.google.com) (209.85.160.172) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 07 Jul 2011 19:21:48 +0000 Received: by gyd5 with SMTP id 5so611732gyd.31 for ; Thu, 07 Jul 2011 12:21:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=fNsHfEc76uB0tkvqYqLfD1AJQRFHOFVxRVuTqDETm5c=; b=cH06HZ2UHTcONzYQgoFoQNo5uDP/J1RO7SpQcfYdtOT43NE4JHLG+ciWsDYKyTOvFm mTted5BolBP98VfC9zxoulfJgj9GyPD0IaaLLoAMFLO7okIp5llhiiGJSDT6lL5bkzgP onezP7fM57mKGx1x55T3Ou9Z3TgEG0rspmpAo= MIME-Version: 1.0 Received: by 10.236.79.69 with SMTP id h45mr415348yhe.342.1310066487723; Thu, 07 Jul 2011 12:21:27 -0700 (PDT) Received: by 10.236.202.166 with HTTP; Thu, 7 Jul 2011 12:21:27 -0700 (PDT) Received: by 10.236.202.166 with HTTP; Thu, 7 Jul 2011 12:21:27 -0700 (PDT) In-Reply-To: References: Date: Thu, 7 Jul 2011 12:21:27 -0700 Message-ID: Subject: Re: What does a write lock ? From: Yang To: user@cassandra.apache.org Content-Type: multipart/alternative; boundary=20cf300fb07ba204d504a77f9f57 X-Virus-Checked: Checked by ClamAV on apache.org --20cf300fb07ba204d504a77f9f57 Content-Type: text/plain; charset=ISO-8859-1 just to add onto what jonathan said the columns are immutable . if u overwrite/ reconcile a new obj is created and shoved into the memtable there is a shared lock for all writes though which guard against an exclusive lock on memtable switching/flushing On Jul 7, 2011 7:51 AM, "A J" wrote: > Does a write lock: > 1. Just the columns in question for the specific row in question ? > 2. The full row in question ? > 3. The full CF ? > > I doubt read does any locks. > > Thanks. --20cf300fb07ba204d504a77f9f57 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

just to add onto what jonathan said

the columns are immutable=A0=A0 .=A0=A0 if u overwrite/ reconcile=A0 a n= ew obj is created and shoved into the memtable

there is a shared lock=A0 for all writes though which guard against an e= xclusive lock on memtable switching/flushing

On Jul 7, 2011 7:51 AM, "A J" <s5alye@gmail.com> wrote:
> Does a write lock:
> 1. Just the columns in questio= n for the specific row in question ?
> 2. The full row in question ?
> 3. The full CF ?
>
>= ; I doubt read does any locks.
>
> Thanks.
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