Partition is helpful when the table has one or more Partition keys. hive> CREATE VIEW emp_30000 AS SELECT * FROM employee WHERE salary>30000; Dropping a View. Data needs to stay within the underlying location even after a DROP TABLE. You can use views to protect sensitive data, for data aggregation, and to hide data complexity from users. In Hive, the table is stored as files in HDFS. Hive Partitions is a way to organizes tables into partitions by dividing tables into different parts based on partition keys. These details are not required on regular basis but very useful when you do a Manual Migration of Hive Metadata. A view can combine data from multiple underlying data sources and provide the illusion that all of the data is from one source. Hi Suresh, In this case you will need to quote the strings, so that they are in the proper CSV file format, like below: column1,column2 “1,2,3,4”,”5,6,7,8″ It is nothing but a directory that contains the chunk of data. 'a' and 'b' and 'c' are the aliases of 'orders' and 'customer' and 'agents' table, 2. This view runs on top of two tables, table1 and table2, where each table is a different SELECT query. The result will contain rows with key = '5' because in the view's query statement the CTE defined in the view definition takes effect. A view that combines data from multiple tables enables you to show relevant information in multiple tables together. 'cust_code' of 'orders' and 'customer' table must be same, In the following example, we create a view named view1 that enables you to hide more complex query syntax.. Complex View: A view based on multiple tables, which contain GROUP BY clause and functions. The CREATE VIEW command creates a virtual structure for the result set of a stored query. Hive Partitions. As per… An Index is nothing but a pointer on a particular column of a table. 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. To create a view 'ordersview' by three tables 'orders', 'customer' and ' agents' with following conditions - 1. In the second View example, a query's CTE is different from the CTE used when creating the view. It creates replicas of data by storing it physically. Partition keys are basic elements for determining how the data is stored in the table. The view selects columns from table1 and joins the results with table2. Partitioning is the way to dividing the table based on the key columns and organize the records in a partitioned manner. External tables. Such external tables can be over a variety of data formats, including Parquet. Hive does not contain own data and control settings, dirs, etc.In Hive existing table (i.e) not modify. Also see this JIRA: HIVE-1180 Support Common Table Expressions (CTEs) in Hive You can create a view that combines data from two or more tables by naming more than one table in the FROM clause. Spark also provides ways to create external tables over existing data, either by providing the LOCATION option or using the Hive format. Inline View: A view based on a subquery in FROM Clause, that subquery creates a temporary table and simplifies the complex query. Pointing multiple patterns at a single data it sets repeats via possible patterns.User can use custom location like ASV. Materialized View: A view that stores the definition as well as data. In this Post, we will see what are the important Hive Metastore Tables that you may need to modify/query for different Hive Purposes that can not be achieved from Hive CLI or Beeline.
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