Answer:

Hive is a data warehouse software which is used for facilitates querying and managing large data sets residing in distributed storage.Hive language almost look like SQL language called HiveQL.Hive also allows traditional map reduce programs to customize mappers and reducers when it is inconvenient or inefficient to execute the logic in HiveQL (User Defined Functions UDFS).

Answer:

Facebook data stored on HDFS,everyday millions of photos uploaded into facebook with the help of Hadoop Facebook Messages,Likes and statues updates running on top of Hbase Hive to generate reports for third-party developers and advertisers who need to track the success of their applications or campaigns.

Answer:

Both hive and hbase can be used in different technologies that are based on Hadoop. Hive happens to be a infrastructure warehouse of data which is used on Hadoop whereas HBase is NoSQL. The key value stores which run on Hadoop themselves. Hive will also help those who know about SQL run a few jobs in MapReduce when Hbase will also support 4 of the operations such as put, get, scan and delete. The Hbase happens to be good for querying for data but Hive on the other hand is good for querying data is analytical and is collected over a while.

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Hive Meta store is a database that stores metadata of your hive tables like table name,column name,data types,table location,number of buckets in the table etc.

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This release works with Hadoop 0.20.x, 0.23.x.y, 1.x.y, 2.x.y

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Facebook,Netflix

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Whenever you run the hive in embedded mode, it creates the local metastore. And before creating the metastore it looks whether metastore already exist or not. This property is defined in configuration file hive – site.xml. Property is “javax.jdo.option.ConnectionURL” with default value “jdbc:derby:;databaseName=metastore_db;create=true”. So to change the behavior change the location to absolute path, so metastore will be used from that location.

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No, it is not possible to use metastore in sharing mode. It is recommended to use standalone “real” database like MySQL or PostGresSQL.

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This component implements the processing framework for converting SQL to a graph of map/reduce jobs and the execution time framework to run those jobs in the order of dependencies.

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NO

Answer:

This components implements the processing framework for converting SQL to graph of map/reduce jobs and the execution time framework to run those jobs in the order od dependencies.

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Hive Metastore is a central repository that stores metadata in external database.

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In SMB join in Hive, each mapper reads a bucket from the first table and the corresponding bucket from the second table and then a merge sort join is performed. Sort Merge Bucket (SMB) join in hive is mainly used as there is no limit on file or partition or table join. SMB join can best be used when the tables are large. In SMB join the columns are bucketed and sorted using the join columns. All tables should have the same number of buckets in SMB join.

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ObjectInspector is used to analyze the structure of individual columns and the internal structure of the row objects. ObjectInspector in Hive provides access to complex objects which can be stored in multiple formats.

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No, it is not possible to use metastore in sharing mode. It is recomended to use standalone “real” database like MySQL or PostGreSQL.

Answer:

HiveQL has 4 different types of joins – JOIN- Similar to Outer Join in SQL

1. FULL OUTER JOIN – Combines the records of both the left and right outer tables that fulfil the join condition.
2. LEFT OUTER JOIN- All the rows from the left table are returned even if there are no matches in the right table.
3. RIGHT OUTER JOIN-All the rows from the right table are returned even if there are no matches in the left table.

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Yes, we can change the default location of Managed tables using the LOCATION keyword while creating the managed table. The user has to specify the storage path of the managed table as the value to the LOCATION keyword.

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When running Hive as a server, the application can be connected in one of the 3 ways-

1. ODBC Driver-This supports the ODBC protocol
2. JDBC Driver- This supports the JDBC protocol
3. Thrift Client- This client can be used to make calls to all hive commands using different programming language like PHP, Python, Java, C++ and Ruby.

Answer:

Following classes are used by Hive to read and write HDFS files:

• TextInputFormat/HiveIgnoreKeyTextOutputFormat: These 2 classes read/write data in plain text file format.
• SequenceFileInputFormat/SequenceFileOutputFormat: These 2 classes read/write data in hadoop SequenceFile format.

Answer:

There are two types of tables.

1. Managed tables.
2. External tables.

Only the drop table command differentiates managed and external tables. Otherwise, both type of tables are very similar.