alter database in hive

We can associate key-value pairs with a database in the DBPROPERTIES using ALTER DATABASE command. The JDBC program to create a database is given below. Mostly ALTER can be used to alter database or schema properties and owner change. Hive does not have any DROP statement to drop columns inside the table. We have successfully added the contact column to the customer table. Let’s change the demo_name attribute to customer_name. Hive DDL Database Commands. We can modify multiple numbers of properties associated with the table schema in the Hive. If a property was already set, overrides the old value with the new one. ALTER TABLE ADD COLUMNS (    COMMENT ”,    COMMENT ”, ….. ). The REPLACE with ALTER TABLE is used to remove all the existing columns from the table in Hive. We can change the file formats using the SET FILEFORMAT statement. ALTER (DATABASE|SCHEMA) database_name SET LOCATION hdfs_path; Though it is documented that the database location can be changed, however it is not allowing to do so in Hive 1.1.0 in CDH 5.10.0. The above command sets current database to hql. Hive supports various file formats like CSV , TEXT, ORC , PARQUET etc. Hive deals with two types of table structures like Internal and External tables depending on the loading and design of schema in Hive. Internal tables Internal Table is tightly coupled in nature.In this type of table, first we have to create table and load the data. @Mathi Murugan. You can add or remove the database comments, properties etc by using alter database statements. Database Name: ALTER DATABASE test_db RENAME TO test_db_new; Though this is also documented but renaming a database is not allowed in Hive 1.1.0 in CDH 5.10.0. In general when we made some mistakes while creating the table structure then we use ALTER TABLE to change the characteristics of the schema. CHANGE in ALTER TABLE is used to change the name or data type of an existing column or attribute. HIVE ALTER Database Syntax. To check which database is currently being used: SELECT current_database () (as of Hive 0.13.0 ). Default database cannot be altered as it creates by system as a default. Before you proceed make sure you have HiveServer2 started and connected to Hive using Beeline. ALTER command is used to alter the database and syntax for altering would be like below. alter database Alters metadata associated with a database by setting DBPROPERTIES . Let’s add a column contact to the customer table that we have obtained after renaming the demo. Below example describes about to change the user role to admin in database. We have to use REPLACE if we want to drop a particular column. Hive provides us the functionality to perform Alteration on the Tables and Databases. Come write articles for us and get featured, Learn and code with the best industry experts. ALTER TABLE command can be used to perform alterations on the tables. Use Databases. Hadoop Hive alter database is a statement used to change the properties of a databases in Hive. The specified property values override any existing value with the same property name. ALTER TABLE with RENAME is used to change the name of an already existing table in the hive. '); Output: OK Use database USE database_name; Example: USE hql; Output: OK. Our table new_tbl stores the data in Text format, lets change it to Parquet. Apache Hive Installation and Configuring MySql Metastore for Hive, Creating Database Table Using Hive Query Language (HQL), Apache Hive Installation With Derby Database And Beeline, Apache Hive - Getting Started With HQL Database Creation And Drop Database, Difference Between Hive Internal and External Tables, Database Operations in HIVE Using CLOUDERA - VMWARE Work Station, Data Structures and Algorithms – Self Paced Course, Ad-Free Experience – GeeksforGeeks Premium, We use cookies to ensure you have the best browsing experience on our website. Query: SHOW. Below is a query I … You can also manually update or drop a Hive partition directly on HDFS using Hadoop commands, if you do so you need to run the MSCK command to synch up HDFS files with Hive Metastore. The use of DATABASE and SCHEMA are interchangeable; they mean the same thing. ALTER DATABASE hql SET DBPROPERTIES('database usage'='Hive SQL tutorials. generate link and share the link here. In the above image, we can observe that we have successfully dropped the column contact. The following queries rename the column name and column data type using the above data: REPLACE COLUMNS. Select your cookie preferences We use cookies and similar tools to enhance your experience, provide our services, deliver relevant advertising, and make improvements. Writing code in comment? To list out the databases in Hive warehouse, enter the command ‘ show databases’. There is a workaround for this. It has a table "name". Below is a complete information about the same. One option is to always use "USE DATABASE" command to be sure every time you need to check the working database. The database creates … We can modify multiple numbers of properties associated with the table schema in the Hive. No other metadata about the database can be changed, including its name and directory location: ALTER (DATABASE|SCHEMA) DATABASE_NAME . To revert to the default database, use the keyword " default " instead of a database name. It provides SQL like commands to alter the table. I am using MySQL database for hive so let’s connect it first: [admin@host1 ~]$ ps -ef | grep mysql. The following query is executed to create a database named userdb: hive> CREATE DATABASE [IF NOT EXISTS] userdb; or. The database and schema are interchangeable. Get access to ad-free content, doubt assistance and more! I see that currently ALTER (DATABASE|SCHEMA) database_name SET OWNER [USER|ROLE] user_or_role; does not give the desired fine-grained option for only a specific table in a schema/database, so I think the best option would be to use Ranger and give a select privilege on the particular database or underlying table to the new user who can then issue a Create Table As Select … You May Also Like Alteration on table modify’s or changes its metadata and does not affect the actual data available inside the table. ... Sets the SERDE or SERDEPROPERTIES in Hive tables. For the DB rename to work properly, we need to update three tables in the HMS DB. Alter the HDFS Location. Hive DDL commands are the statements used for defining and changing the structure of a table or database in Hive. If we want to remove the contact attribute the query should be like as shown below. Altering database can be done on any user defined database at any point of time, but the database should be successfully created. Experience. DATABASE or SCHEMA is same thing in behavior. Some common DDL statements are CREATE, ALTER, and DROP. Among several Hive DDL Commands, here I will be covering the most commonly used DDL commands.. DDL commands are used to create databases, tables, modify the structure of the table, and drop the database and tables e.t.c. Here is the general syntax that you should use when working with Hive – ALTER TABLE command can be used to perform alterations on the tables. Let’s make a table demo with one attribute demo_name of type string in the hive (By default hive makes tables in its default database if not specified). In this topic, we described about the Alter Database with detailed example. You can use hive CLI property to show the existing database on the hive CLI. It sets the current database to be used for further hive operations. To perform the below operation make sure your hive is running. DDL statements create and modify database objects such as tables, indexes, and users. For example in our customer table, we have 2 attributes customer_name and contact. You can set key-value pairs in the DBPROPERTIES associated with a database using the ALTER DATABASE command. USE sets the current database for all subsequent HiveQL statements. It allows us to rename the table,add columns/partitions,rename columns/partitions and so on in Hive table.Hive versions prior to 0.6 just renamed the table in the … I have a database named "test". Below are the steps to launch a hive on your local system. [admin@host1 ~]$ cd /usr/local/mysql/bin. Go to Hive shell by giving the command sudo hive and enter the command ‘create database’ to create the new database in the Hive. SCHEMA in ALTER added in Hive 0.14.0. As of version 0.6, a rename on a managed table moves its HDFS location as well. Alter Database in Hive. The following table contains the fields of employeetable and it shows the fields to be changed (in bold). Here are the illustrated steps to change a custom database location, for instance "dummy.db", along with the contents of the database. The attributes or columns which are added in the ALTER TABLE REPLACE statement will be replaced with the older columns. Can I change the datatype in Hive database? Alter table statement helps to change the structure of the table in Hive. It is used to build or modify the tables and other objects in the database. Hadoop - File Permission and ACL(Access Control List), Write Interview Let’s rename our table name from the demo to the customer. We can set the database on which we need to work with USE command in hive. Unfortunately there is no way to know which database is in use currently selected in hive shell. ALTER ( DATABASE | SCHEMA ) database name SET database properties ( property name = property value, ...); 2. Alter the Owner. ALTER database in Hive; If you wanted to change the metadata associated with the databases then ALTER is just the perfect choice to get your job done within seconds. Example: ALTER (DATABASE|SCHEMA ) database name SET LOCATION HDFS Path; Hive Query to Alter Database. [database_name.] ALTER TABLE SET command is used for setting the SERDE or SERDE properties in Hive tables. https://cwiki.apache.org/confluence/display/Hive/Hive+Transactions hive> ALTER DATABSE financial SET DBPROPERTIES (‘edited by’ = ‘kmak’); HIVE CREATE Table Syntax. Hive DDL stands for (Data Definition Language) which are used to define or change the structure of a Databases and Tables. We can perform multiple operations with table schema like renaming the table name, add the column, change or replace the column name, etc. Example: ALTER (DATABASE| SCHEMA) database name SET OWNER [USER|ROLE ] user or role; 3. acknowledge that you have read and understood our, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, How to Execute WordCount Program in MapReduce using Cloudera Distribution Hadoop(CDH), Matrix Multiplication With 1 MapReduce Step, How to find top-N records using MapReduce, MapReduce Program - Weather Data Analysis For Analyzing Hot And Cold Days, Introduction to Hadoop Distributed File System(HDFS), Hadoop - Features of Hadoop Which Makes It Popular, MapReduce - Understanding With Real-Life Example, Hadoop - HDFS (Hadoop Distributed File System), Hadoop - Schedulers and Types of Schedulers, Django project - Creating a Basic E-commerce Website for Displaying Products, Hadoop Streaming Using Python - Word Count Problem, Hadoop - File Blocks and Replication Factor, Difference Between Hadoop 2.x vs Hadoop 3.x. table_name: A table name, optionally qualified with a database name. Let’s perform each of the operations we can perform with ALTER TABLE one by one. We can use SCHEMA in place of DATABASE in this command. USE database_name was added in Hive 0.6 ( HIVE-675 ). Alter table statement in Hive. (Older Hive versions just renamed the table in the metastore without moving the HDFS location.) ALTER TABLE table_name RENAME TO new_table_name; This statement lets you change the name of a table to a different name. DATABASE or SCHEMA is same thing in behavior. In the above, the image we can observe that our table name has changed to customer. A user defined database can be altered according to the user requirements. This article explains how to rename a database in Hive manually without modifying database locations, as the command: ALTER DATABASE test_db RENAME TO test_db_new; still does not work due to HIVE-4847 is not fixed yet. By default, the location for default and custom databases is defined within the value of hive.metastore.warehouse.dir, which is /apps/hive/warehouse. Note: As per the link here, there is no functionality to rename the existing database however there is a workaround to rename the database if you have necessary privileges on Hive metastore without changing the database location. By using our site, you mysql> use hive; Get the DB_ID value of … SCHEMA in ALTER added in Hive 0.14.0. alter table new_tbl set fileformat parquet; ALTER Statement on HIVE Column. [admin@host1 ~]$./mysql -u root -p. Now we are into mysql shell. If a particular property was already set, If a particular property was already set, this overrides the old value with the new one. In this example, we can also observe that SCHEMA and DATABASE can be used interchangeably, As we have used SCHEMA in Alter command and DATABASE in DESCRIBE command. The syntax for Hive alter database statement is as follows: ALTER (DATABASE|SCHEMA) database_name SET DBPROPERTIES (property_name=property_value,...); The database and schema are interchangeable. Example: Step 1: Describe the database student to see its parent-directory. Instead use ALTER TABLE table_name ALTER COLUMN column_name DROP NOT NULL. In Impala, this is primarily a logical operation that updates the table metadata in the metastore database that Impala shares with Hive. How to Execute Character Count Program in MapReduce Hadoop? Please use ide.geeksforgeeks.org, You can also use the ALTER command to modify the OWNER property and change the role of the OWNER. Hive provides us the functionality to perform Alteration on the Tables and Databases. Drop database DROP (DATABASE|SCHEMA) [IF EXISTS] database_name [RESTRICT|CASCADE]; Change DB to hive. Mostly ALTER can be used to alter database or schema properties and owner change. The ALTER TABLE statement changes the structure or properties of an existing Impala table.. hive> CREATE SCHEMA userdb; The following query is used to verify a databases list: hive> SHOW DATABASES; default userdb JDBC Program. Step 2: Use ALTER to change the parent-directory location (NOTE: /hive_db is the available directory on my HDFS ). Apache Hive Hive ALTER TABLE command is used to update or drop a partition from a Hive Metastore and HDFS location (managed table). Below example describes about to change the user role to admin in schema. ALTER TABLE customer ADD COLUMNS ( contact BIGINT COMMENT ‘Store the customer contact number’); We can describe the table to see its properties with the below command. In Hive, we can perform modifications in the existing table like changing the table name, column name, comments, and table properties. The several types of Hive DDL commands are: CREATE.

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