How to set variables in HIVE scripts - hive

Question

I'm looking for the SQL equivalent of SET varname = value in Hive QL
I know I can do something like this:
SET CURRENT_DATE = '2012-09-16';
SELECT * FROM foo WHERE day >= #CURRENT_DATE
But then I get this error:
character '#' not supported here

Answer 1

You need to use the special hiveconf for variable substitution.
e.g.
hive> set CURRENT_DATE='2012-09-16';
hive> select * from foo where day >= ${hiveconf:CURRENT_DATE}
similarly, you could pass on command line:
% hive -hiveconf CURRENT_DATE='2012-09-16' -f test.hql
Note that there are env and system variables as well, so you can reference ${env:USER} for example.
To see all the available variables, from the command line, run
% hive -e 'set;'
or from the hive prompt, run
hive> set;
Update:
I've started to use hivevar variables as well, putting them into hql snippets I can include from hive CLI using the source command (or pass as -i option from command line).
The benefit here is that the variable can then be used with or without the hivevar prefix, and allow something akin to global vs local use.
So, assume have some setup.hql which sets a tablename variable:
set hivevar:tablename=mytable;
then, I can bring into hive:
hive> source /path/to/setup.hql;
and use in query:
hive> select * from ${tablename}
or
hive> select * from ${hivevar:tablename}
I could also set a "local" tablename, which would affect the use of ${tablename}, but not ${hivevar:tablename}
hive> set tablename=newtable;
hive> select * from ${tablename} -- uses 'newtable'
vs
hive> select * from ${hivevar:tablename} -- still uses the original 'mytable'
Probably doesn't mean too much from the CLI, but can have hql in a file that uses source, but set some of the variables "locally" to use in the rest of the script.

Answer 2

Most of the answers here have suggested to either use hiveconf or hivevar namespace to store the variable. And all those answers are right. However, there is one more namespace.
There are total three namespaces available for holding variables.
hiveconf - hive started with this, all the hive configuration is stored as part of this conf. Initially, variable substitution was not part of hive and when it got introduced, all the user-defined variables were stored as part of this as well. Which is definitely not a good idea. So two more namespaces were created.
hivevar: To store user variables
system: To store system variables.
And so if you are storing a variable as part of a query (i.e. date or product_number) you should use hivevar namespace and not hiveconf namespace.
And this is how it works.
hiveconf is still the default namespace, so if you don't provide any namespace it will store your variable in hiveconf namespace.
However, when it comes to referring a variable, it's not true. By default it refers to hivevar namespace. Confusing, right? It can become clearer with the following example.
If you do not provide namespace as mentioned below, variable var will be stored in hiveconf namespace.
set var="default_namespace";
So, to access this you need to specify hiveconf namespace
select ${hiveconf:var};
And if you do not provide namespace it will give you an error as mentioned below, reason being that by default if you try to access a variable it checks in hivevar namespace only. And in hivevar there is no variable named var
select ${var};
We have explicitly provided hivevar namespace
set hivevar:var="hivevar_namespace";
as we are providing the namespace this will work.
select ${hivevar:var};
And as default, workspace used during referring a variable is hivevar, the following will work too.
select ${var};

Answer 3

Have you tried using the dollar sign and brackets like this:
SELECT *
FROM foo
WHERE day >= '${CURRENT_DATE}';

Answer 4

Just in case someone needs to parameterize hive query via cli.
For eg:
hive_query.sql
SELECT * FROM foo WHERE day >= '${hivevar:CURRENT_DATE}'
Now execute above sql file from cli:
hive --hivevar CURRENT_DATE="2012-09-16" -f hive_query.sql

Answer 5

Two easy ways:
Using hive conf
hive> set USER_NAME='FOO';
hive> select * from foobar where NAME = '${hiveconf:USER_NAME}';
Using hive vars
On your CLI set vars and then use them in hive
set hivevar:USER_NAME='FOO';
hive> select * from foobar where NAME = '${USER_NAME}';
hive> select * from foobar where NAME = '${hivevar:USER_NAME}';
Documentation: https://cwiki.apache.org/confluence/display/Hive/LanguageManual+VariableSubstitution

Answer 6

One thing to be mindful of is setting strings then referring back to them. You have to make sure the quotes aren't colliding.
set start_date = '2019-01-21';
select ${hiveconf:start_date};
When setting dates then referring to them in code as the strings can conflict. This wouldn't work with the start_date set above.
'${hiveconf:start_date}'
We have to be mindful of not setting twice single or double quotes for strings when referring back to them in the query.

Answer 7

There are multiple options to set variables in Hive.
If you're looking to set Hive variable from inside the Hive shell, you can set it using hivevar. You can set string or integer datatypes. There are no problems with them.
SET hivevar:which_date=20200808;
select ${which_date};
If you're planning to set variables from shell script and want to pass those variables into your Hive script (HQL) file, you can use --hivevar option while calling hive or beeline command.
# shell script will invoke script like this
beeline --hivevar tablename=testtable -f select.hql
-- select.hql file
select * from <dbname>.${tablename};

Answer 8

Try this method:
set t=20;
select *
from myTable
where age > '${hiveconf:t}';
it works well on my platform.

Answer 9

You can export the variable in shell script
export CURRENT_DATE="2012-09-16"
Then in hiveql you like
SELECT * FROM foo WHERE day >= '${env:CURRENT_DATE}'

Answer 10

You can store the output of another query in a variable and latter you can use the same in your code:
set var=select count(*) from My_table;
${hiveconf:var};