question querying partitions in impala in Support Questions

querying partitions in impala

Bluetruth — Thu, 16 Jun 2022 13:22:44 GMT

How can I make Impala read only required partitions not all partitions

we are using the results from a sql query

Regards

Philip

ChethanYM — Thu, 23 Jun 2022 15:53:45 GMT

Have you tried query like below? Here year is a partition it shows the name in the year 2010.

## select name from census where year=2010;

If you need data only from partition column use query like below:

## select <col-name> from <table-name>;

Regards,

Chethan YM

Bluetruth — Fri, 24 Jun 2022 15:59:10 GMT

Hi Chethan

Thanks for the reply

as per your examples

1. select name from census where year=2010;

This works fine ie it only queries the partition but our problem is when the condition is not a literal

like ='2010'

but when we try to dynamically retrieve the data like your second example

We are finding that the query scans the whole table not just the partition - ie takes much longer in larger tables