How do I copy a partitioned table in hive?

Best way to duplicate a partitioned table in Hive

1. Create the new target table with the schema from the old table.
2. Use hadoop fs -cp to copy all the partitions from source to target table.
3. Run MSCK REPAIR TABLE table_name; on the target table.

Similarly, how do I load a partitioned table in hive?

Solution

1. Step 1: Data Preparation. Once you downloaded the data given above, copy it to HDFS location.
2. Step 2: Create Partitioned Table. Let's create the hive partitioned table:
3. Step 3: Load data into Partitioned Table. In this step, We will load the same files which are present in HDFS location.

Beside above, how do you drop a table in hive? Use Drop command (e.g. Drop employee) to drop hive table data.

1. Check the table is External or Internal.
2. Check whether any Down Stream applications or using the Table.
3. If there is no problem you can delete using DROP TABLE <TABLE-NAME>it will delete both Schema and Data Or else use Truncate it will keep your schema.

Then, how do I backup my hive tables?

1. Stop Hive on the target cluster.
2. Distcp all the necessary files on HDFS to the secondary cluster.
3. Take a SQL dump of your Hive Metastore (which is in MySQL or Postgres).
4. Restore the SQL dump on your target cluster.

How do I rename a table in hive?

ALTER TABLE table_name RENAME TO new_table_name; This statement lets you change the name of a table to a different name. As of version 0.6, a rename on a managed table moves its HDFS location as well. (Older Hive versions just renamed the table in the metastore without moving the HDFS location.)

How do you load data into a hive table?

You can load the text file into a textfile Hive table and then insert the data from this table into your sequencefile.

You must do this:

1. Create a table stored as text.
2. Insert the text file into the text table.
3. Do a CTAS to create the table stored as a sequence file.
4. Drop the text table if desired.

How do I load data into a dynamic partitioned table in hive?

For dynamic partitioning, you have to use INSERT SELECT query (Hive insert). Inserting data into Hive table having DP, is a two step process. Create staging table in staging database in hive and load data into that table from external source such as RDBMS, document database or local files using Hive load.

What is the difference between static and dynamic partitioning in hive?

Partitions are created when data is inserted into table. Usually when loading files (big files) into Hive tables static partitions are preferred. That saves your time in loading data compared to dynamic partition. You "statically" add a partition in table and move the file into the partition of the table.

What is hive staging?

The Hive staging directory is a temporary directory used during processing, and the end data will be copied to the final destination upon completion.

Can we create partition on external table in hive?

Yes, you have to tell Hive explicitly what is your partition field. Consider you have a following HDFS directory on which you want to create a external table.

How do I use overwrite in hive?

Synopsis

1. INSERT OVERWRITE will overwrite any existing data in the table or partition. unless IF NOT EXISTS is provided for a partition (as of Hive 0.9. 0).
2. INSERT INTO will append to the table or partition, keeping the existing data intact. (Note: INSERT INTO syntax is only available starting in version 0.8.)

How do I import a CSV file into hive?

Load CSV file in hive

1. Step 1: Sample CSV File. Create a sample CSV file named as sample_1.
2. Step 2: Copy CSV to HDFS. Run the below commands in the shell for initial setup.
3. Step 3: Create Hive Table and Load data. Now, you have the file in Hdfs, you just need to create an external table on top of it.
4. Step 4: Verify data.

What is bucket in hive?

The bucketing in Hive is a data organizing technique. It is similar to partitioning in Hive with an added functionality that it divides large datasets into more manageable parts known as buckets.

How do I copy data from one external table to another in Hive?

Moving Hive Tables to Another Metastore

1. Get the Hive DDL from the source metastore. On the source cluster run the following command, saving the output to a file:
2. Run the saved DDL on the target cluster/Workbench.
3. Find the HDFS path to the data in the Warehouse.
4. Run the distcp command to perform the data copy.
5. Repair the target table.

How do I copy a hive table from one cluster to another?

Examples to Move Hive Table from one cluster (grid) to another

1. On Cluster A, use EXPORT command to exports the data of a table or a partition, along with the metadata to a specified output location named hdfs_path_a;
2. Use discp to copy the data in cluster A to cluster B.

Which of the clause is used to limit the number of rows?

In MySQL the LIMIT clause is used with the SELECT statement to restrict the number of rows in the result set. The Limit Clause accepts one or two arguments which are offset and count. The value of both the parameters can be zero or positive integers.

How does partitioning help in hive?

Hive - Partitioning. Hive organizes tables into partitions. It is a way of dividing a table into related parts based on the values of partitioned columns such as date, city, and department. Using partition, it is easy to query a portion of the data.

Which of the following file format was designed to overcome the limitations?

The Optimized Row Columnar (ORC) file format provides a highly efficient way to store Hive data. It was designed to overcome limitations of the other Hive file formats. Using ORC files improves performance when Hive is reading, writing, and processing data.

What can be altered using alter command?

alter command is used for altering the table structure, such as,

• to add a column to existing table.
• to rename any existing column.
• to change datatype of any column or to modify its size.
• to drop a column from the table.

Can we delete records from Hive table?

Delete can be performed on the table that supports ACID. Instead, you can follow other easy steps such as create hive temporary table and select records from the original table by excluding data that you want to delete from table. Sounds easy!

How do I find my hive database?

To list out the databases in Hive warehouse, enter the command 'show databases'. The database creates in a default location of the Hive warehouse. In Cloudera, Hive database store in a /user/hive/warehouse. Copy the input data to HDFS from local by using the copy From Local command.

How do you speed up Hive queries?

How to Improve Hive Query Performance With Hadoop

1. Use Tez Engine. Apache Tez Engine is an extensible framework for building high-performance batch processing and interactive data processing.
2. Use Vectorization.
3. Use ORCFile.
4. Use Partitioning.
5. Use Bucketing.
6. Cost-Based Query Optimization.