Mostly ALTER can be used to alter database or schema properties and owner change. In Hive, we can perform modifications in the existing table like changing the table name, column name, comments, and table properties. Below example describes about to change the user role to admin in schema. [database_name.] Alter Database in Hive. Let’s rename our table name from the demo to the customer. alter table new_tbl set fileformat parquet; ALTER Statement on HIVE Column. 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. Go to Hive shell by giving the command sudo hive and enter the command ‘create database
’ to create the new database in the Hive. 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. The following queries rename the column name and column data type using the above data: If a particular property was already set, If a particular property was already set, this overrides the old value with the new one. ALTER TABLE ADD COLUMNS ( COMMENT ”, COMMENT ”, ….. ). Hive DDL Database Commands. Instead use ALTER TABLE table_name ALTER COLUMN column_name DROP NOT NULL. Alter table statement in Hive. REPLACE COLUMNS. @Mathi Murugan. No other metadata about the database can be changed, including its name and directory location: ALTER (DATABASE|SCHEMA) DATABASE_NAME . How to Execute Character Count Program in MapReduce Hadoop? Before you proceed make sure you have HiveServer2 started and connected to Hive using Beeline. Below are the steps to launch a hive on your local system. You can set key-value pairs in the DBPROPERTIES associated with a database using the ALTER DATABASE command. ALTER TABLE command can be used to perform alterations on the tables. It is used to build or modify the tables and other objects in the database. Writing code in comment? ALTER DATABASE hql SET DBPROPERTIES('database usage'='Hive SQL tutorials. It provides SQL like commands to alter the table. Hive DDL stands for (Data Definition Language) which are used to define or change the structure of a Databases and Tables. The database creates … Default database cannot be altered as it creates by system as a default. We can modify multiple numbers of properties associated with the table schema in the Hive. Can I change the datatype in Hive database? '); Output: OK Use database USE database_name; Example: USE hql; Output: OK. Example: Step 1: Describe the database student to see its parent-directory. SCHEMA in ALTER added in Hive 0.14.0. Hive provides us the functionality to perform Alteration on the Tables and Databases. To revert to the default database, use the keyword " default " instead of a database name. Our table new_tbl stores the data in Text format, lets change it to Parquet. The database and schema are interchangeable. As of version 0.6, a rename on a managed table moves its HDFS location as well. I have a database named "test". Select your cookie preferences We use cookies and similar tools to enhance your experience, provide our services, deliver relevant advertising, and make improvements. Mostly ALTER can be used to alter database or schema properties and owner change. [admin@host1 ~]$ cd /usr/local/mysql/bin. The specified property values override any existing value with the same property name. I am using MySQL database for hive so let’s connect it first: [admin@host1 ~]$ ps -ef | grep mysql. In general when we made some mistakes while creating the table structure then we use ALTER TABLE to change the characteristics of the schema. SHOW. Let’s change the demo_name attribute to customer_name. Hive deals with two types of table structures like Internal and External tables depending on the loading and design of schema in Hive. DATABASE or SCHEMA is same thing in behavior. hive> ALTER DATABSE financial SET DBPROPERTIES (‘edited by’ = ‘kmak’); HIVE CREATE Table Syntax. The JDBC program to create a database is given below. Alter the Owner. Use Databases. You can use hive CLI property to show the existing database on the hive CLI. To list out the databases in Hive warehouse, enter the command ‘ show databases’. ALTER command is used to alter the database and syntax for altering would be like below. Example: ALTER (DATABASE| SCHEMA) database name SET OWNER [USER|ROLE ] user or role; 3. Unfortunately there is no way to know which database is in use currently selected in hive shell. We can change the file formats using the SET FILEFORMAT statement. We can perform multiple operations with table schema like renaming the table name, add the column, change or replace the column name, etc. The several types of Hive DDL commands are: CREATE. To perform the below operation make sure your hive is running. For example in our customer table, we have 2 attributes customer_name and contact. A user defined database can be altered according to the user requirements. CHANGE in ALTER TABLE is used to change the name or data type of an existing column or attribute. The above command sets current database to hql. If a property was already set, overrides the old value with the new one. https://cwiki.apache.org/confluence/display/Hive/Hive+Transactions One option is to always use "USE DATABASE" command to be sure every time you need to check the working database. Below is a query I … Please use ide.geeksforgeeks.org,
[admin@host1 ~]$./mysql -u root -p. Now we are into mysql shell. You can also use the ALTER command to modify the OWNER property and change the role of the OWNER. table_name: A table name, optionally qualified with a database name. alter database Alters metadata associated with a database by setting DBPROPERTIES . Step 2: Use ALTER to change the parent-directory location (NOTE: /hive_db is the available directory on my HDFS ). To check which database is currently being used: SELECT current_database () (as of Hive 0.13.0 ). 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. DATABASE or SCHEMA is same thing in behavior. It sets the current database to be used for further hive operations. 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. You can add or remove the database comments, properties etc by using alter database statements. In Impala, this is primarily a logical operation that updates the table metadata in the metastore database that Impala shares with Hive. 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. 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. Example: ALTER (DATABASE|SCHEMA ) database name SET LOCATION HDFS Path; Hive Query to Alter Database. ... Sets the SERDE or SERDEPROPERTIES in Hive tables. Here are the illustrated steps to change a custom database location, for instance "dummy.db", along with the contents of the database. USE sets the current database for all subsequent HiveQL statements. You May Also Like Come write articles for us and get featured, Learn and code with the best industry experts. Experience. We can set the database on which we need to work with USE command in hive. Hadoop Hive alter database is a statement used to change the properties of a databases in Hive. 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. ALTER TABLE table_name RENAME TO new_table_name; This statement lets you change the name of a table to a different name. Hive provides us the functionality to perform Alteration on the Tables and Databases. ALTER TABLE SET command is used for setting the SERDE or SERDE properties in Hive tables. The attributes or columns which are added in the ALTER TABLE REPLACE statement will be replaced with the older columns. 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. 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. Query: Alter the HDFS Location. Hadoop - File Permission and ACL(Access Control List), Write Interview
The syntax for Hive alter database statement is as follows: ALTER (DATABASE|SCHEMA) database_name SET DBPROPERTIES (property_name=property_value,...); SCHEMA in ALTER added in Hive 0.14.0. Internal tables Internal Table is tightly coupled in nature.In this type of table, first we have to create table and load the data. We have to use REPLACE if we want to drop a particular column. Below example describes about to change the user role to admin in database. Some common DDL statements are CREATE, ALTER, and DROP. In this topic, we described about the Alter Database with detailed example. We can modify multiple numbers of properties associated with the table schema in the Hive. The REPLACE with ALTER TABLE is used to remove all the existing columns from the table in Hive. Here is the general syntax that you should use when working with Hive – The database and schema are interchangeable. mysql> use hive; Get the DB_ID value of … Drop database DROP (DATABASE|SCHEMA) [IF EXISTS] database_name [RESTRICT|CASCADE]; Alteration on table modify’s or changes its metadata and does not affect the actual data available inside the table. 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 … Below is a complete information about the same. For the DB rename to work properly, we need to update three tables in the HMS DB. By default, the location for default and custom databases is defined within the value of hive.metastore.warehouse.dir, which is /apps/hive/warehouse. 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. Let’s add a column contact to the customer table that we have obtained after renaming the demo. Hive does not have any DROP statement to drop columns inside the table. generate link and share the link here. (Older Hive versions just renamed the table in the metastore without moving the HDFS location.) It has a table "name". The following table contains the fields of employeetable and it shows the fields to be changed (in bold). Altering database can be done on any user defined database at any point of time, but the database should be successfully created. ALTER TABLE with RENAME is used to change the name of an already existing table in the hive. ALTER TABLE command can be used to perform alterations on the tables. In the above image, we can observe that we have successfully dropped the column contact. We have successfully added the contact column to the customer table. Hive DDL commands are the statements used for defining and changing the structure of a table or database in Hive. By using our site, you
USE database_name was added in Hive 0.6 ( HIVE-675 ). hive> CREATE SCHEMA userdb; The following query is used to verify a databases list: hive> SHOW DATABASES; default userdb JDBC Program. Let’s perform each of the operations we can perform with ALTER TABLE one by one. We can associate key-value pairs with a database in the DBPROPERTIES using ALTER DATABASE command. DDL statements create and modify database objects such as tables, indexes, and users. 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. The following query is executed to create a database named userdb: hive> CREATE DATABASE [IF NOT EXISTS] userdb; or. ALTER ( DATABASE | SCHEMA ) database name SET database properties ( property name = property value, ...); 2. The ALTER TABLE statement changes the structure or properties of an existing Impala table.. Change DB to hive. HIVE ALTER Database Syntax. There is a workaround for this. Hive supports various file formats like CSV , TEXT, ORC , PARQUET etc. 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). If we want to remove the contact attribute the query should be like as shown below. In the above, the image we can observe that our table name has changed to customer. 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 … The use of DATABASE and SCHEMA are interchangeable; they mean the same thing. Get access to ad-free content, doubt assistance and more! We can use SCHEMA in place of DATABASE in this command. Alter table statement helps to change the structure of the table in Hive. Apache Hive Hive ALTER TABLE command is used to update or drop a partition from a Hive Metastore and HDFS location (managed table).