From user-return-22017-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org Fri Nov 4 14:29:00 2011 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 C40909E9F for ; Fri, 4 Nov 2011 14:29:00 +0000 (UTC) Received: (qmail 43757 invoked by uid 500); 4 Nov 2011 14:28:58 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 43703 invoked by uid 500); 4 Nov 2011 14:28:58 -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 43695 invoked by uid 99); 4 Nov 2011 14:28:58 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 04 Nov 2011 14:28:58 +0000 X-ASF-Spam-Status: No, hits=2.9 required=5.0 tests=HTML_MESSAGE,SPF_NEUTRAL X-Spam-Check-By: apache.org Received-SPF: neutral (nike.apache.org: local policy) Received: from [217.149.130.193] (HELO mail.eventis.nl) (217.149.130.193) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 04 Nov 2011 14:28:50 +0000 Received: from MAIL.office.eventis.nl ([::1]) by MAIL.office.eventis.nl ([::1]) with mapi; Fri, 4 Nov 2011 15:28:29 +0100 From: Rene Kochen To: "user@cassandra.apache.org" Subject: Question about minor compaction Thread-Topic: Question about minor compaction Thread-Index: Acya/gSgUIudLNiORZ6OZmPNIGb3bw== Date: Fri, 4 Nov 2011 14:28:27 +0000 Message-ID: Accept-Language: nl-NL, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: Content-Type: multipart/alternative; boundary="_000_FA1DB4A23E65924B83E21462A78D5F6B02EF09MAILofficeeventis_" MIME-Version: 1.0 X-Virus-Checked: Checked by ClamAV on apache.org --_000_FA1DB4A23E65924B83E21462A78D5F6B02EF09MAILofficeeventis_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Assume the following default settings: min_compaction_threshold =3D 4, max_= compaction_threshold =3D 32. When I start a bulk insert in Cassandra, I see minor compactions work: all = similar sized files are compacted when there are four of them. However, whe= n files gets larger, Cassandra waits with minor compactions. For example: f= our files are compacted to a 1GB file. There were already 3 other 1GB files= . However, Cassandra does not immediately compact the four 1GB files. What = makes Cassandra decide to wait with this minor compaction? Thank! --_000_FA1DB4A23E65924B83E21462A78D5F6B02EF09MAILofficeeventis_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Assume the following default settings: min_compaction_threshold =3D 4, max= _compaction_threshold =3D 32.

 

When I start a bulk insert in Cassandra, I see minor compactions w= ork: all similar sized files are compacted when there are four of them. How= ever, when files gets larger, Cassandra waits with minor compactions. For e= xample: four files are compacted to a 1GB file. There were already 3 other = 1GB files. However, Cassandra does not immediately compact the four 1GB fil= es. What makes Cassandra decide to wait with this minor compaction?

 

Thank!

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