Return-Path: X-Original-To: apmail-cassandra-commits-archive@www.apache.org Delivered-To: apmail-cassandra-commits-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id BC943187E6 for ; Mon, 7 Dec 2015 09:02:11 +0000 (UTC) Received: (qmail 99921 invoked by uid 500); 7 Dec 2015 09:02:11 -0000 Delivered-To: apmail-cassandra-commits-archive@cassandra.apache.org Received: (qmail 99874 invoked by uid 500); 7 Dec 2015 09:02:11 -0000 Mailing-List: contact commits-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: dev@cassandra.apache.org Delivered-To: mailing list commits@cassandra.apache.org Received: (qmail 99513 invoked by uid 99); 7 Dec 2015 09:02:11 -0000 Received: from arcas.apache.org (HELO arcas) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 07 Dec 2015 09:02:11 +0000 Received: from arcas.apache.org (localhost [127.0.0.1]) by arcas (Postfix) with ESMTP id 3F5862C1F60 for ; Mon, 7 Dec 2015 09:02:11 +0000 (UTC) Date: Mon, 7 Dec 2015 09:02:11 +0000 (UTC) From: "Benjamin Lerer (JIRA)" To: commits@cassandra.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Updated] (CASSANDRA-8131) Short-circuited query results from collection index query 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/CASSANDRA-8131?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Benjamin Lerer updated CASSANDRA-8131: -------------------------------------- Component/s: CQL > Short-circuited query results from collection index query > --------------------------------------------------------- > > Key: CASSANDRA-8131 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8131 > Project: Cassandra > Issue Type: Bug > Components: CQL > Environment: Debian Wheezy, Oracle JDK, Cassandra 2.1 > Reporter: Catalin Alexandru Zamfir > Assignee: Benjamin Lerer > Labels: collections, cql3, cqlsh, query, queryparser, triaged > Fix For: 2.1.1 > > Attachments: CASSANDRA-8131-V2.txt, CASSANDRA-8131.txt > > > After watching Jonathan's 2014 summit video, I wanted to give collection indexes a try as they seem to be a fit for a "search by key/values" usage pattern we have in our setup. Doing some test queries that I expect users would do against the table, a short-circuit behavior came up: > Here's the whole transcript: > {noformat} > CREATE TABLE by_sets (id int PRIMARY KEY, datakeys set, datavars set); > CREATE INDEX by_sets_datakeys ON by_sets (datakeys); > CREATE INDEX by_sets_datavars ON by_sets (datavars); > INSERT INTO by_sets (id, datakeys, datavars) VALUES (1, {'a'}, {'b'}); > INSERT INTO by_sets (id, datakeys, datavars) VALUES (2, {'c'}, {'d'}); > INSERT INTO by_sets (id, datakeys, datavars) VALUES (3, {'e'}, {'f'}); > INSERT INTO by_sets (id, datakeys, datavars) VALUES (4, {'a'}, {'z'}); > SELECT * FROM by_sets; > id | datakeys | datavars > ----+----------+---------- > 1 | {'a'} | {'b'} > 2 | {'c'} | {'d'} > 4 | {'a'} | {'z'} > 3 | {'e'} | {'f'} > {noformat} > We then tried this query which short-circuited: > {noformat} > SELECT * FROM by_sets WHERE datakeys CONTAINS 'a' AND datakeys CONTAINS 'c'; > id | datakeys | datavars > ----+----------+---------- > 1 | {'a'} | {'b'} > 4 | {'a'} | {'z'} > (2 rows) > {noformat} > Instead of receveing 3 rows, which match the datakeys CONTAINS 'a' AND datakeys CONTAINS 'c' we only got the first. > Doing the same, but with CONTAINS 'c' first, ignores the second AND. > {noformat} > SELECT * FROM by_sets WHERE datakeys CONTAINS 'c' AND datakeys CONTAINS 'a' ; > id | datakeys | datavars > ----+----------+---------- > 2 | {'c'} | {'d'} > (1 rows) > {noformat} > Also, on a side-note, I have two indexes on both datakeys and datavars. But when trying to run a query such as: > {noformat} > select * from by_sets WHERE datakeys CONTAINS 'a' AND datavars CONTAINS 'z'; > code=2200 [Invalid query] message="Cannot execute this query as it might involve data filtering and thus may have unpredictable performance. > If you want to execute this query despite the performance unpredictability, use ALLOW FILTERING" > {noformat} > The second column, after AND (even if I inverse the order) requires an "allow filtering" clause yet the column is indexed an an in-memory "join" of the primary keys of these sets on the coordinator could build up the result. > Could anyone explain the short-circuit behavior? > And the requirement for "allow-filtering" on a secondly indexed column? > If they're not bugs but intended they should be documented better, at least their limitations. -- This message was sent by Atlassian JIRA (v6.3.4#6332)