Return-Path: X-Original-To: apmail-accumulo-notifications-archive@minotaur.apache.org Delivered-To: apmail-accumulo-notifications-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 6715617B0A for ; Fri, 25 Sep 2015 18:00:05 +0000 (UTC) Received: (qmail 35402 invoked by uid 500); 25 Sep 2015 18:00:05 -0000 Delivered-To: apmail-accumulo-notifications-archive@accumulo.apache.org Received: (qmail 35362 invoked by uid 500); 25 Sep 2015 18:00:05 -0000 Mailing-List: contact notifications-help@accumulo.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: jira@apache.org Delivered-To: mailing list notifications@accumulo.apache.org Received: (qmail 35346 invoked by uid 99); 25 Sep 2015 18:00:05 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 25 Sep 2015 18:00:05 +0000 Date: Fri, 25 Sep 2015 18:00:05 +0000 (UTC) From: "Keith Turner (JIRA)" To: notifications@accumulo.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Commented] (ACCUMULO-4011) Allow combiners reduce to return null MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-JIRA-FingerPrint: 30527f35849b9dde25b450d4833f0394 [ https://issues.apache.org/jira/browse/ACCUMULO-4011?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14908417#comment-14908417 ] Keith Turner commented on ACCUMULO-4011: ---------------------------------------- Yeah if something would have previously failed and now deletes stuff (when thats not the users intention) that is not a good thing. We could add a config option to the combiner that determines how it deals with null return types. By default it would fail when null is retuned, but it could optionally be configured to delete data when null is returned. > Allow combiners reduce to return null > ------------------------------------- > > Key: ACCUMULO-4011 > URL: https://issues.apache.org/jira/browse/ACCUMULO-4011 > Project: Accumulo > Issue Type: Improvement > Reporter: Keith Turner > Fix For: 1.8.0 > > > Opening based on discussion from [PR 47|https://github.com/apache/accumulo/pull/47]. If the reduce function in a combiner could return null to indicate that data should be dropped, this could offer a solution to ACCUMULO-2232. > For example assume someone was using a summing combiner and wanted to delete a column with a current value of 18. They could insert -18. If the combiner returned null when everything summed to 0, this would delete the row col. This method of deleting data would safe during partial compactions and would work correctly with new data being inserted after the -18 was inserted. > If this done, needs to be done in a way that is compatible with existing combiners. -- This message was sent by Atlassian JIRA (v6.3.4#6332)