Mailing-List: contact issues-help@drill.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@drill.apache.org
Date: Fri, 11 Mar 2016 18:21:39 +0000 (UTC)
From: "Jiang Wu (JIRA)" <jira@apache.org>
To: issues@drill.apache.org
Message-ID: <JIRA.12949261.1457720452000.885.1457720499030@Atlassian.JIRA>
In-Reply-To: <JIRA.12949261.1457720452000@Atlassian.JIRA>
References: <JIRA.12949261.1457720452000@Atlassian.JIRA>
 <JIRA.12949261.1457720452361@arcas>
Subject: [jira] [Created] (DRILL-4498) Projecting a map key within an array
 produces incorrect results
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit

Jiang Wu created DRILL-4498:
-------------------------------

             Summary: Projecting a map key within an array produces incorrect results
                 Key: DRILL-4498
                 URL: https://issues.apache.org/jira/browse/DRILL-4498
             Project: Apache Drill
          Issue Type: Bug
          Components: Execution - Data Types
    Affects Versions: 1.4.0
            Reporter: Jiang Wu


To reproduce:

1) place the following 3 JSON objects in a file:
{noformat}
{"r":1,"c1":[{"c2":1,"c3":"a"},{"c2":2,"c3":"b"},{"c2":3,"c3":"c"}]}
{"r":2,"c1":[{"c2":4,"c3":"d"}]}
{"r":3,"c1":[{"c2":5,"c3":"e"},{"c2":6,"c3":"f"},{"c2":7,"c3":"g"}]}
{noformat}
2) Run query:
{noformat}
select t.r, t.c1.c2 from dfs.`c:\tmp\data.json` t;
+----+---------+
| r  | EXPR$1  |
+----+---------+
| 1  | 1       |
| 2  | 2       | <-- not OK
| 3  | 3       | <-- not OK
+----+---------+
{noformat}

3) The above results are incorrect.  The returned values for "c1.c2" are not correlated with the values from r after the first row.  Expecting the result contains information for r = 1 has 3 values for c1.c2: 1, 2, and 3.

For example, the same conceptual query in MongoDB, returns the proper information:

{noformat}
> db.t.find({}, {"r":1, "c1.c2":1}):
{"r":1,"c1":[{"c2":1},{"c2":2},{"c2":3}]}
{"r":2,"c1":[{"c2":4}]}
{"r":3,"c1":[{"c2":5},{"c2":6},{"c2":7}]}
{noformat}

For Drill, the same information can be returned, even if it is differently formatted in a more relational style.  For example:

{noformat}
select t.r, t.c1.c2 from dfs.`c:\tmp\data.json` t;
+----+-----------+
| r  | EXPR$1    |
+----+-----------+
| 1  | [1, 2, 3] |
| 2  | [4]       | 
| 3  | [5, 6, 7] |
+----+-----------+
{noformat}

Or choose some other formatting for the output.

Returning an array of value can be an important use case to support operations such as forming a single string of comma separated value "1, 2, 3" without going through flatten and then re-aggregate, or predicates such as "where ... xyz in c1.c2 ..."


--
This message was sent by Atlassian JIRA
(v6.3.4#6332)