Hive allows you to change the definition for columns, add new columns, or even replace all existing columns in a table with a new set. In above code, we do following things . Rename Hive table column. Use the following syntax to drop a view: DROP VIEW view_name The following query drops a view named as emp_30000: hive> DROP VIEW emp_30000; Creating an Index . The JDBC program to rename a table is as follows. Note that in V1 of the project, we will support only scalar statistics. I have a Hive (ver 0.11.0) table partitioned by column date, of type string. To drop the internal table Hive>DROP TABLE guruhive_external; From the following screen shot, we can observe the output . Display the content of the table Hive>select * from guruhive_external; 4. Related reading: Apache Hive Data Types and Best Practices; Apache Hive CREATE TABLE Command and Examples; Hive ALTER TABLE Command Syntax.
You can also exclude those partition columns if you don’t want to show them on your reports. Apache Hive support most of the relational database features such as partitioning large tables and store values according to partition column. You can add new column to the table. It can be a normal table (stored in Metastore) or an external table (stored in local file system); Hive treats both in … There are two approaches that you can follow if you want to drop column from Hive table: Use ALTER TABLE with REPLACE option Create intermediate or temporary table You can rename table and column of existing Hive tables.
Now, drop a column from the table. Hive Create, Alter & Drop Table . In the Below screenshot, we are creating a table with columns and altering the table name. When you drop a table from Hive Metastore, it removes the table/column data and their metadata. Let's check whether the column name has changed or not.
Creating table guru_sample with two column names such as "empid" and "empname" 2. The following query renames the table from employee to emp. Details Last Updated: 27 May 2020 . Delete or Replace Column. But, Hive stores partition column as a virtual column and is visible when you perform ‘select * from table’. Note that delete_column_statistics is needed to remove the entries from the metastore when a table is dropped.
Also note that currently Hive doesn’t support drop column. This chapter describes how to drop a table in Hive. Thus, we cannot drop the column directly. The PARTITION clause is available in Hive 0.14.0 and later; see Upgrading Pre-Hive 0.13.0 Decimal Columns for usage.
Creating an index means creating a pointer on a particular column of a table. ALTER TABLE name DROP [COLUMN] column_name ALTER TABLE name CHANGE column_name new_name new_type ALTER TABLE name REPLACE COLUMNS (col_spec[, col_spec ...]) Rename To… Statement. Let's see the existing schema of the table. I want to know if there exists a way in Hive by which I can drop partitions for a range of dates (say from 'date1' to 'date2'). In this article, we will check method to exclude Hive partition column from a SELECT query. It can be a normal table (stored in Metastore) or an external table (stored in local file system); Hive treats both in the same manner, irrespective of …
Hive>LOAD DATA INPATH '/user/guru99hive/data.txt' INTO TABLE guruhive_external; 3. hive> ALTER TABLE employee RENAME TO emp; JDBC Program.
Displaying tables present in … As of Hive 1.2 , the partition column values specified in partition_spec are type validated, converted and normalized to their column types when hive.typecheck.on.insert is set to true (default). REPLACE COLUMNS can also be used to drop columns. Presently, the column information associated with a particular partition is not used while preparing plans.
An Index is nothing but a pointer on a particular column of a table. This chapter describes how to drop a table in Hive. These values can be number literals. Add Hadoop archive option to Hive table. In the subsequent sections, we will check how to update or drop partition that are already present in Hive tables. Hive allows us to delete one or more columns by replacing them with the new columns. ADD COLUMNS lets you add new columns to the end of the existing columns but before the partition columns. 1. I have tried the following (SQL type) queries, but they don't seem to be syntactically correct: Create the External table For example, " ALTER TABLE test_change REPLACE COLUMNS (a int, b int);" will remove column 'c' from test_change's schema. Add or drop table partition. REPLACE COLUMNS removes all existing columns and adds the new set of columns. Partition columns are extra column visible in your Hive table. Table Operations such as Creation, Altering, and Dropping tables in Hive can be observed in this tutorial.
When you drop a table from Hive Metastore, it removes the table/column data and their metadata.