[jira] [Commented] (HIVE-6028) Partition predicate literals are not interpreted correctly.

["Xuefu Zhang (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-6028?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13847700#comment-13847700 ] 

Xuefu Zhang commented on HIVE-6028:
-----------------------------------

If I understand correctly, the "workaround" mentioned is what a user is expected to be doing. The partition key has string as type, so the constant value for the key should be string literals instead of integers. Further, Hive allows implicit conversions, such the case demonstrated, which is common in many DBs. Disallowing that is too restrictive and less usable.

In my opinion, user should be aware of the implicit conversion and its consequence. If not sure, match the type explicitly.

> Partition predicate literals are not interpreted correctly.
> -----------------------------------------------------------
>
>                 Key: HIVE-6028
>                 URL: https://issues.apache.org/jira/browse/HIVE-6028
>             Project: Hive
>          Issue Type: Bug
>    Affects Versions: 0.12.0
>            Reporter: Pala M Muthaia
>         Attachments: Hive-6028-explain-plan.txt
>
>
> When parsing/analyzing query, hive treats partition predicate value as int instead of string. This breaks down and leads to incorrect result when the partition predicate value starts with int 0, e.g: hour=00, hour=05 etc.
> The following repro illustrates the bug:
> -- create test table and partition, populate with some data
> create table test_partition_pred(col1 int) partitioned by (hour STRING);
> insert into table test_partition_pred partition (hour=00) select 21 FROM  some_table limit 1;
> -- this query returns incorrect results, i.e. just empty set.
> select * from test_partition_pred where hour=00;
> OK
> -- this query returns correct result. Note predicate value is string literal
> select * from test_partition_pred where hour='00';
> OK
> 21	00
> explain plan illustrates how the query was interpreted. Particularly the partition predicate is pushed down as regular filter clause, with hour=0 as predicate. See attached explain plan file.
> Note:
> 1. The type of the partition column is defined as string, not int.
> 2. This is a regression in Hive 0.12. This used to work in Hive 0.11
> 3. Not an issue when the partition value starts with integer other than 0, e.g hour=10, hour=11 etc.
> 4. As seen above, workaround is to use string literal hour='00' etc.
> This should not be too bad if in the failing case hive complains that partition hour=0 is not found, or complains literal type doesn't match column type. Instead hive silently pushes it down as filter clause, and query succeeds with empty set as result.
> We found this out in our production tables partitioned by hour, only a few days after it started occurring, when there were empty data sets for partitions hour=00 to hour=09.



--
This message was sent by Atlassian JIRA
(v6.1.4#6159)