slim bouguerra created HIVE-19474:
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Summary: Decimal type should be casted as part of the CTAS or
INSERT Clause.
Key: HIVE-19474
URL: https://issues.apache.org/jira/browse/HIVE-19474
Project: Hive
Issue Type: Bug
Reporter: slim bouguerra
Assignee: slim bouguerra
HIVE-18569 introduced a runtime config variable to allow the indexing of
Decimal as Double, this leads to kind of messy state, Hive metadata think the
column is still decimal while it is stored as double. Since the Hive metadata
of the column is Decimal the logical optimizer will not push down aggregates. i
tried to fix this by adding some logic to the application but it makes the code
very clumsy with lot of branches. Instead i propose to revert this patch and
let the user introduce an explicit cast this will be better since the metada
reflects actual storage type and push down aggregates will kick in and there is
no config needed.
cc [~ashutoshc] and [~nishantbangarwa]
You can see the difference with the following DDL
{code}
create table test_base_table(`timecolumn` timestamp, `interval_marker` string,
`num_l` DECIMAL(10,2));
insert into test_base_table values ('2015-03-08 00:00:00', 'i1-start', 4.5);
set hive.druid.approx.result=true;
CREATE TABLE druid_test_table
STORED BY 'org.apache.hadoop.hive.druid.DruidStorageHandler'
TBLPROPERTIES ("druid.segment.granularity" = "DAY")
AS
select cast(`timecolumn` as timestamp with local time zone) as `__time`,
`interval_marker`, cast(`num_l` as double)
FROM test_base_table;
describe druid_test_table;
explain select sum(num_l), min(num_l) FROM druid_test_table;
CREATE TABLE druid_test_table_2
STORED BY 'org.apache.hadoop.hive.druid.DruidStorageHandler'
TBLPROPERTIES ("druid.segment.granularity" = "DAY")
AS
select cast(`timecolumn` as timestamp with local time zone) as `__time`,
`interval_marker`, `num_l`
FROM test_base_table;
describe druid_test_table_2;
explain select sum(num_l), min(num_l) FROM druid_test_table_2;
{code}
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