this is my query in DB2 Database:
CREATE TABLE MY_TABLE
(COD_SOC CHAR(5) NOT NULL);
Is possible reproduce the 'NOT NULL' in HIVE?
What about PIG?
No it is not possible at this time. It would be very difficult for Hive to enforce column constraints.
With Hive 3.0, you can have DEFAULT Constraints on the hive table
Refer
1. https://www.adaltas.com/en/2019/07/25/hive-3-features-tips-tricks/
2. https://www.slideshare.net/Hadoop_Summit/what-is-new-in-apache-hive-30
Related
I created a hive table with a storage handler and now I want to add a column to that table but it gives me below error:
[Code: 10134, SQL State: 42000] Error while compiling statement: FAILED:
SemanticException [Error 10134]: ALTER TABLE can only be used for [ADDPROPS,
DROPPROPS] to a non-native table
As per the hive documentation any hive table you create with storage handler is non native table.
Here's a link https://cwiki.apache.org/confluence/display/Hive/StorageHandlers
There is a JIRA case for enhancement is open with Apache for the same.
https://issues.apache.org/jira/browse/HIVE-1240
For ex, I am using Druid Storage Handler in my case.
I created a hive table using:
CREATE TABLE druid_table_1
(`__time` TIMESTAMP, `dimension1` STRING, `metric1` int)
STORED BY 'org.apache.hadoop.hive.druid.DruidStorageHandler';
and then I am trying to add a column:
ALTER TABLE druid_table_1 ADD COLUMNS (`dimension2` STRING);
With above approach I am getting an error.
Is there any other way to add a column to non native tables in hive without recreating it?
Patch is available in HDP 2.5+ from Hortonworks. Support for ADD columns has been added in ALTER statement.
Column can be added into druid table using ALTER table DDL in hive.
ALTER TABLE ADD COLUMNS (col_name data_type)
There is no need to specify partition spec as these are druid backed hive tables and partition/storage is maintained by druid.
I had sqooped the data from teradata to Hive using sqoop import command.
For one of the tables in teradata, I have a date field . After sqooping, my date field is appearing as a timestamp with bigint datatype.
But I need the date field as a date datatype in hive table. Can anyone please suggest me in achieving this?
select to_date(from_unixtime(your timestamp));
example:
select to_date(from_unixtime(1490985000));
output:2017-04-01
I hope it will work. please let me know if i am wrong.
I've had this problem. My approach was to create the Hive table first. You should make an equivalence between Teradata datatypes and your Hive version datatypes. After that you can use the Sqoop argument --hive-table <table-name> to insert into that table.
I have a massive table stored as parquet and I need to add columns based on conditions.
Is there a way to do that without having to recreate a new table in Hive or Impala?
Something like this?
ALTER TABLE xyz
ADD COLUMN flag AS (CASE WHEN ... END)
Thank you
I don't believe that Hive or Impala support computed columns. This type of calculation is often done using a view:
CREATE VIEW v_xyz AS
SELECT xyz.*,
(CASE WHEN ... END) as flag
FROM xyz;
You can then update the view at any time to adjust the logic or add new columns.
Is it possible to create bucketing and partitioning for a table that already contains data? I have a table in hive with more than 100M of records and I want to create a partition on the table. Also I need to create the bucketing.
Is it possible?
Thanks,
Bala
No, it's not possible to alter bucketing and partitioning within a preloaded table, you may have to create a new table with required bucketing and partitioning properties and then load it from the old table.
set hive.enforce.bucketing = true;
FROM old_table insert into table new_bucketed_partitioned_table select * ;
ALTER TABLE testTable ADD column1 NUMBER(1) DEFAULT 0 NOT NULL AFTER column2;
Why can't I use mySql syntax in Oracle too? The above command works in MySql. Can you give me an equivalent that works?
Error report:
SQL Error: ORA-01735: invalid ALTER TABLE option
01735. 00000 - "invalid ALTER TABLE option"
I am asking if there is any way to use after clause in Oracle command that I provided?
Because SQL is a relational algebra. It doesn't care one bit about "where" columns are located within a table, only that they exist.
To get it to work in Oracle, just get rid of the after clause. The Oracle documentation for alter table is here but it boils down to:
alter table testTable
add ( column1 number(1) default 0 not null )
There is no after clause for the alter table command.
Oracle does not support adding columns in the middle of a table, only adding them to the end. Your database design and app functionality should not depend on the order of columns in the database schema. You can always specify an order in your select statement, after all.
However if for some reason you simply must have a new column in the middle of your table there is a work around.
CREATE TABLE tab1New AS SELECT 0 AS col1, col1 AS col2 FROM tab1;
DROP TABLE tab1 PURGE;
RENAME tan1New to tab1;
Where the SELECT 0 AS col1 is your new column and then you specify other columns as needed from your original table. Put the SELECT 0 AS col1 at the appropriate place in the order you want.
Afterwards you may want to run an alter table statement on the column to make sure it's the data type you desire.
Try this :
ALTER TABLE testTable ADD column1 NUMBER(1) DEFAULT 0 NOT NULL