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https://issues.apache.org/jira/browse/HIVE-9815?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15944488#comment-15944488
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Naveen Gangam commented on HIVE-9815:
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[~leftylev] Nope, no new documentation is required. I do not believe we
document the schema columns and their datatypes (nor do I see a need to).
[~sambit19] To answer your questions
1) I ended up using CLOB datatypes for these columns which expand way beyond
what an EXTENDED VARCHAR can offer and no additional database configuration is
needed for this change.
2) The upgrade, from an existing version of hive, should work seamlessly if you
use the upgrade script provided. There should be no data loss.
> Metastore column"SERDE_PARAMS"."PARAM_VALUE" limited to 4000 bytes
> -------------------------------------------------------------------
>
> Key: HIVE-9815
> URL: https://issues.apache.org/jira/browse/HIVE-9815
> Project: Hive
> Issue Type: Bug
> Components: Metastore
> Affects Versions: 0.14.0
> Reporter: Naveen Gangam
> Assignee: Naveen Gangam
> Priority: Critical
> Fix For: 3.0.0, 2.3.0
>
> Attachments: Hv2.txt
>
>
> Currently, in the hive metastore schema, the length of the column
> SERDE_PARAMS.PARAM_VALUE is set to 4000 bytes. This is not enough for users
> that have a key with a value larger than 4000 bytes. Say something like
> hbase.columns.mapping.
> I am not a database historian but appears that this limitation may have been
> put in place because Oracle's varchar2 was restricted to 4k bytes for a long
> time until recently.
> According to the following documentation, even today Oracle DB's varchar2
> only supports a max size of 4000 unless a configuration parameter
> MAX_STRING_SIZE is set to EXTENDED.
> http://docs.oracle.com/database/121/SQLRF/sql_elements001.htm#SQLRF55623
> {code}
> MAX_STRING_SIZE=EXTENDED
> {code}
> Postgres supports a max of 1GB for character datatype according to
> http://www.postgresql.org/docs/8.3/static/datatype-character.html
> MySQL can support upto 65535 bytes for the entire row. So long as the
> PARAM_KEY value + PARAM_VALUE is less than 65535, we should be good.
> http://dev.mysql.com/doc/refman/5.0/en/char.html
> SQL Server's varchar max length is 8000 and can go beyond using
> "varchar(max)".
> http://dev.mysql.com/doc/refman/5.0/en/char.html
> Derby's varchar can be upto 32672 bytes.
> https://db.apache.org/derby/docs/10.7/ref/rrefsqlj41207.html
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