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https://issues.apache.org/jira/browse/HIVE-16937?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gunther Hagleitner reassigned HIVE-16937:
-----------------------------------------
Assignee: Gunther Hagleitner
> INFORMATION_SCHEMA usability: everything is currently a string
> --------------------------------------------------------------
>
> Key: HIVE-16937
> URL: https://issues.apache.org/jira/browse/HIVE-16937
> Project: Hive
> Issue Type: Bug
> Affects Versions: 3.0.0
> Reporter: Carter Shanklin
> Assignee: Gunther Hagleitner
> Attachments: HIVE-16937.1.patch
>
>
> HIVE-1010 adds an information schema to Hive, also taking the opportunity to
> expose some non-standard but valuable things like statistics in a SYS table.
> A challenge I have noted with the SYS table is that all statistic counts are
> exposed as string types rather than numerics.
> {code}
> hive> show create table sys.tab_col_stats;
> OK
> CREATE TABLE `sys.tab_col_stats`(
> `cs_id` string COMMENT 'from deserializer',
> `db_name` string COMMENT 'from deserializer',
> `table_name` string COMMENT 'from deserializer',
> `column_name` string COMMENT 'from deserializer',
> `column_type` string COMMENT 'from deserializer',
> `tbl_id` string COMMENT 'from deserializer',
> `long_low_value` string COMMENT 'from deserializer',
> `long_high_value` string COMMENT 'from deserializer',
> `double_high_value` string COMMENT 'from deserializer',
> `double_low_value` string COMMENT 'from deserializer',
> `big_decimal_low_value` string COMMENT 'from deserializer',
> `big_decimal_high_value` string COMMENT 'from deserializer',
> `num_nulls` string COMMENT 'from deserializer',
> `num_distincts` string COMMENT 'from deserializer',
> `avg_col_len` string COMMENT 'from deserializer',
> `max_col_len` string COMMENT 'from deserializer',
> `num_trues` string COMMENT 'from deserializer',
> `num_falses` string COMMENT 'from deserializer',
> `last_analyzed` string COMMENT 'from deserializer')
> ROW FORMAT SERDE
> 'org.apache.hive.storage.jdbc.JdbcSerDe'
> STORED BY
> 'org.apache.hive.storage.jdbc.JdbcStorageHandler'
> {code}
> So you might run this query to try and find the column(s) which have the most
> distinct values.
> {code}
> select
> db_name, table_name, column_name
> from
> sys.tab_col_stats
> where
> num_distincts = ( select max(num_distincts) from sys.tab_col_stats );
> {code}
> Unfortunately this maximum is based on string sorting so it's not likely what
> you really want.
> It would be better to use numeric types where appropriate such as all the
> numbers in tab_col_stats, and most likely bigints should be used for stats
> like # rows, etc.
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