Use Hive on Tez:
set hive.execution.engine=tez;
With the above setting, every HIVE query you execute will take advantage of Tez.
Use ORCFile:
Using ORCFile for every HIVE table should really be a no-brainer and extremely beneficial to get fast response times for your HIVE queries.
As an example, consider two large tables A and B (stored as text files, with some columns not all specified here), and a simple query like:
SELECT A.customerID, A.name, A.age, A.address join
B.role, B.department, B.salary
ON A.customerID=B.customerID;
This query may take a long time to execute since tables A and B are both stored as TEXT. Converting these tables to ORCFile format will usually reduce query time significantly:
CREATE TABLE A_ORC (
customerID int, name string, age int, address string
) STORED AS ORC tblproperties (“orc.compress" = “SNAPPY”);
INSERT INTO TABLE A_ORC SELECT * FROM A;
CREATE TABLE B_ORC (
customerID int, role string, salary float, department string
) STORED AS ORC tblproperties (“orc.compress" = “SNAPPY”);
INSERT INTO TABLE B_ORC SELECT * FROM B;
SELECT A_ORC.customerID, A_ORC.name,
A_ORC.age, A_ORC.address join
B_ORC.role, B_ORC.department, B_ORC.salary
ON A_ORC.customerID=B_ORC.customerID;
ORC supports compressed storage (with ZLIB or as shown above with SNAPPY) but also uncompressed storage.
Use Vectorization:
Vectorized query execution improves performance of operations like scans, aggregations, filters and joins, by performing them in batches of 1024 rows at once instead of single row each time.
Introduced in Hive 0.13, this feature significantly improves query execution time, and is easily enabled with two parameters settings:
set hive.vectorized.execution.enabled = true;
set hive.vectorized.execution.reduce.enabled = true;
Cost based query optimization:
Hive optimizes each query’s logical and physical execution plan before submitting for final execution. These optimizations are not based on the cost of the query – that is, until now.
A recent addition to Hive, Cost-based optimization, performs further optimizations based on query cost, resulting in potentially different decisions: how to order joins, which type of join to perform, degree of parallelism and others.
To use cost-based optimization (also known as CBO), set the following parameters at the beginning of your query:
set hive.cbo.enable=true;
set hive.compute.query.using.stats=true;
set hive.stats.fetch.column.stats=true;
set hive.stats.fetch.partition.stats=true;
Then, prepare the data for CBO by running Hive’s “analyze” command to collect various statistics on the tables for which we want to use CBO.
For example, in a table tweets we want to collect statistics about the table and about 2 columns: “sender” and “topic”:
analyze table tweets compute statistics;
analyze table tweets compute statistics for columns sender, topic;
With HIVE 0.14 (on HDP 2.2) the analyze command works much faster, and you don’t need to specify each column, so you can just issue:
analyze table tweets compute statistics for columns;
That’s it. Now executing a query using this table should result in a different execution plan that is faster because of the cost calculation and different execution plan created by Hive.
