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From "Eugene Koifman (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-9481) allow column list specification in INSERT statement
Date Tue, 10 Feb 2015 22:41:11 GMT

     [ https://issues.apache.org/jira/browse/HIVE-9481?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Eugene Koifman updated HIVE-9481:
---------------------------------
    Attachment: HIVE-9481.5.patch

[~alangates], could you review patch 5 please

> allow column list specification in INSERT statement
> ---------------------------------------------------
>
>                 Key: HIVE-9481
>                 URL: https://issues.apache.org/jira/browse/HIVE-9481
>             Project: Hive
>          Issue Type: Bug
>          Components: Parser, Query Processor, SQL
>    Affects Versions: 0.14.0
>            Reporter: Eugene Koifman
>            Assignee: Eugene Koifman
>         Attachments: HIVE-9481.2.patch, HIVE-9481.4.patch, HIVE-9481.5.patch, HIVE-9481.patch
>
>
> Given a table FOO(a int, b int, c int), ANSI SQL supports insert into FOO(c,b) select
x,y from T.  The expectation is that 'x' is written to column 'c' and 'y' is written column
'b' and 'a' is set to NULL, assuming column 'a' is NULLABLE.
> Hive does not support this.  In Hive one has to ensure that the data producing statement
has a schema that matches target table schema.
> Since Hive doesn't support DEFAULT value for columns in CREATE TABLE, when target schema
is explicitly provided, missing columns will be set to NULL if they are NULLABLE, otherwise
an error will be raised.
> If/when DEFAULT clause is supported, this can be enhanced to set default value rather
than NULL.
> Thus, given {noformat}
> create table source (a int, b int);
> create table target (x int, y int, z int);
> create table target2 (x int, y int, z int);
> {noformat}
> {noformat}insert into target(y,z) select * from source;{noformat}
> will mean 
> {noformat}insert into target select null as x, a, b from source;{noformat}
> and 
> {noformat}insert into target(z,y) select * from source;{noformat}
> will meant 
> {noformat}insert into target select null as x, b, a from source;{noformat}
> Also,
> {noformat}
> from source 
>   insert into target(y,z) select null as x, * 
>   insert into target2(y,z) select null as x, source.*;
> {noformat}
> and for partitioned tables, given
> {noformat}
> Given:
> CREATE TABLE pageviews (userid VARCHAR(64), link STRING, "from" STRING)
>   PARTITIONED BY (datestamp STRING) CLUSTERED BY (userid) INTO 256 BUCKETS STORED AS
ORC;
> INSERT INTO TABLE pageviews PARTITION (datestamp = '2014-09-23')(userid,link)  
>    VALUES ('jsmith', 'mail.com');
> {noformat}
> And dynamic partitioning
> {noformat}
> INSERT INTO TABLE pageviews PARTITION (datestamp)(userid,datestamp,link) 
>     VALUES ('jsmith', '2014-09-23', 'mail.com');
> {noformat}
> In all cases, the schema specification contains columns of the target table which are
matched by position to the values produced by VALUES clause/SELECT statement.  If the producer
side provides values for a dynamic partition column, the column should be in the specified
schema.  Static partition values are part of the partition spec and thus are not produced
by the producer and should not be part of the schema specification.



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