Enter your email address to subscribe to this blog and receive notifications of new posts by email. CREATE DATABASE was added in Hive 0.6 ().. 6. Your email address will not be published. Creating views. We will also show you crucial HiveQL commands to display data. When a Hive table has a skipAutoProvisioning property set to true, the BDD Hive Table Detector will skip the table for data processing.For details, see Skipped and auto-provisioned Hive tables. ; Major compaction: It takes one or more delta files and the base file for the bucket, and rewrites them into a new base file per bucket.Major compaction is more expensive but it is more effective. SHOW PARTITIONS LOG_TABLE PARTITION(LOG_DATE='2008-06-03') WHERE hr >= 5 DESC LIMIT 5; order by clause Lets check it with an example. We can use the below queries to list tables. Hive is designed to support a relatively low rate of transactions, as opposed to serving as an online analytical processing (OLAP) system. We can also add IF EXISTS clause to make sure we do not get an error if the table is not present in Hive. You can use either of one in a single query. Hive ACID supports these two types of compactions: Minor compaction: It takes a set of existing delta files and rewrites them to a single delta file per bucket. Because Hive has full control of managed tables, Hive can optimize these tables extensively. The second form prints/displays the value for the property specified. You can set these configuration properties either in the hive-site.xml file or in the start of the session before any query runs. This lists all the properties of the table. For now we can learn how to add new table property in the hive. Showing partitions. Table properties can be used to tell hive details about underlying data and can also be used to integrate hive with other databases like HBase or DyanmoDB. Change ). HCatalog. To view the properties of a table use the below command in hive prompt. For more information about these properties, see your Hive documentation. Change ), You are commenting using your Twitter account. We can also set up hive table properties as we did for databases. hive.merge.orcfile.stripe.level: true: When hive.merge.mapfiles, hive.merge.mapredfiles or hive.merge.tezfiles is enabled while writing a table with ORC file format, enabling this configuration property will do stripe-level fast merge for small ORC files. Hive supports the concept of a database as a logical collection of objects stored in separate catalogs or namespaces. We discussed many of these options in Text File Encoding of Data Values and we’ll return to more advanced options later in Chapter 15. Update Hive Table without Setting Table Properties Example Below example explain steps to update Hive tables using temporary tables: Let us consider you want to update col2 of table1 by taking data from staging table2. 57) If the schema of the table does not match with the data types present in the file containing the table then Hive. One of the most important pieces of Spark SQL’s Hive support is interaction with Hive metastore, which enables Spark SQL to access metadata of Hive tables. In this blog, we will learn how to filter rows from spark dataframe using Where and Filter functions. In the hive, we can use describe command to see table structure, its location as well as its table properties. In this chapter, we have learned basic commands for managing tables in the hive. Altering table properties. With ALTER query, We can add new table properties or change the existing ones. We can specify the database name in a query to list all tables from that database (query 2). SHOW TBLPROPERTIES tblname; This lists all the properties of the table. SHOW PARTITIONS table_name; Show Table Properties (Version: Hive 0.10.0): SHOW TABLE PROPERTIES lists all of the table properties for the table. Note. You can use the SHOW TRANSACTIONS command to list open and aborted transactions. The Show command will provide a view or lists of all databases that are stored in the Hive. Flink uses the property ‘is_generic’ to tell whether a table is Hive-compatible or generic. You’ll see if the transactional property set to true or false. rename hive table ALTER TABLE tbl_nm RENAME TO new_tbl_nm; In the above statement the table name was changed from tbl_nm to new_tbl_nm. The Hive Table Index Editor opens. The Table creation in Hive is similar to SQL but with many additional features. In this blog, we will discuss many of these options and different operations that we can perform on Hive tables. We can use the database name prefixed with a table in create a table in that database. Showing create table. # col_name              data_type               comment. We can also use like/rlike with a regular expression to list a subset of tables. DESCRIBE; This Hive command shows the name of the database in the Hive, its set comment and even its location on the file system. For example, create a database: hive> create database if not exists mydatabase; OK… Let us see it in action below. To see the properties in a table, use the SHOW TBLPROPERTIES command.. Apache Hive Managed tables are not supported, so setting 'EXTERNAL'='FALSE' has no effect.. Synopsis However, the Hive offers a lot of flexibility while creating tables from where to store data to which format to use store data. Use where clause to fetch specific partition information from the Hive table. Adds custom or predefined metadata properties to a table and sets their assigned values. Apache Hive is a data warehousing tool used to perform queries and analyze structured data in Apache Hadoop. To view the properties of a table use the below command in hive prompt. Creating a Hive table is similar like creating a table in SQL like databases. For now you can use the below query to attach simple properties to the table. Database,Table: SHOW: Databases,Tables,Table Properties,Partitions,Functions,Index: DESCRIBE: Database, Table ,View: Let’s look at the usage of the top hive commands in HQL on both databases and tables – ... Show Table Command in Hive. The CREATE TABLE statement follows SQL conventions, but Hive’s version offers significant extensions to support a wide range of flexibility where the data files for tables are stored, the formats used, etc. We can find the location on HDFS(Hadoop Distributed File System) where the directories for the database are made by checking hive.metastore.warehouse.dir property in /conf/hive … The WITH DBPROPERTIES clause was added in Hive 0.7 ().MANAGEDLOCATION was added to database in Hive 4.0.0 ().LOCATION now refers to the default directory for external tables and MANAGEDLOCATION refers to the default directory for managed tables.
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