change datatype column

[#1]

Hi,

is there a way we can change the datatype from int to double for a column on Impala? Table size is around 3 billion records. I do not plan to drop and recreate it.

ALTER TABLE cbs.gprs_home_cdrs CHANGE percentage_val_n percentage_val_n double;

• AnalysisException: Cannot change the type of a Kudu column using an ALTER TABLE CHANGE COLUMN statement: (INT vs DOUBLE)

impalad version 3.4.0-SNAPSHOT RELEASE (build 134517e42b7b6085e758195465f956f431e0e575) Built on Sat Dec 12 11:15:02 UTC 2020
Version: Cloudera Enterprise 7.1.3 (#4999720 built by jenkins on 20200805-1701 git: fa596184790377f07ba80e9cd4da8b875237939c)

Java VM Name: OpenJDK 64-Bit Server VM

Java Version: 11.0.10

Thanks,

Roshan

[#2 · Accepted solution]

Hi @roshanbi ,

We can confirm you that the type of Kudu's column cannot be changed after it is created.

One is that in the Known issue of document [1], the following information is explained.

Non-alterable Column Types

Kudu does not allow the type of a column to be altered.

The second is that in the Impala documentation, there is no description that you can change the field type of Kudu.

[1]. 

https://kudu.apache.org/docs/schema_design.html#known-limitations

After your review you can accept this as a solution and it helps others who are looking for the same.

Thank you,

Chethan YM