hubgeter opened a new pull request, #41825:
URL: https://github.com/apache/doris/pull/41825

   bp #38432
   ## Proposed changes
   
   Add `hive_parquet_use_column_names` and `hive_orc_use_column_names` session 
variables to read the table after rename column in `Hive`.
   
   These two session variables are referenced from `parquet_use_column_names` 
and `orc_use_column_names` of `Trino` hive connector.
   
   By default, these two session variables are true. When they are set to 
false, reading orc/parquet will access the columns according to the ordinal 
position in the Hive table definition.
   
   For example:
   ```mysql
   in Hive : 
   hive> create table tmp (a int , b string) stored as parquet;
   hive> insert into table tmp values(1,"2");
   hive> alter table tmp  change column  a new_a int;
   hive> insert into table tmp values(2,"4");
   
   in Doris : 
   mysql> set hive_parquet_use_column_names=true;
   Query OK, 0 rows affected (0.00 sec)
   
   mysql> select  * from tmp;
   +-------+------+
   | new_a | b    |
   +-------+------+
   |  NULL | 2    |
   |     2 | 4    |
   +-------+------+
   2 rows in set (0.02 sec)
   
   mysql> set hive_parquet_use_column_names=false;
   Query OK, 0 rows affected (0.00 sec)
   
   mysql> select  * from tmp;
   +-------+------+
   | new_a | b    |
   +-------+------+
   |     1 | 2    |
   |     2 | 4    |
   +-------+------+
   2 rows in set (0.02 sec)
   ```
   
   You can use   `set 
parquet.column.index.access/orc.force.positional.evolution = true/false`   in 
hive 3 to control the results of reading the table like these two  session 
variables. However, for the rename struct inside column parquet table, the 
effects of hive and doris are different. 
   


-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: commits-unsubscr...@doris.apache.org

For queries about this service, please contact Infrastructure at:
us...@infra.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: commits-unsubscr...@doris.apache.org
For additional commands, e-mail: commits-h...@doris.apache.org

Reply via email to