hive interview questions and answers for experienced - Wikitechy https://www.wikitechy.com/interview-questions/tag/hive-interview-questions-and-answers-for-experienced/ Interview Questions Mon, 13 Sep 2021 06:07:09 +0000 en-US hourly 1 https://wordpress.org/?v=6.9.4 https://www.wikitechy.com/interview-questions/wp-content/uploads/2025/10/cropped-wikitechy-icon-32x32.png hive interview questions and answers for experienced - Wikitechy https://www.wikitechy.com/interview-questions/tag/hive-interview-questions-and-answers-for-experienced/ 32 32 What is the difference between a normal hive table and hive table stored as ORC ? https://www.wikitechy.com/interview-questions/hive/what-is-the-difference-between-a-normal-hive-table-and-hive-table-stored-as-orc/ https://www.wikitechy.com/interview-questions/hive/what-is-the-difference-between-a-normal-hive-table-and-hive-table-stored-as-orc/#respond Tue, 13 Jul 2021 21:51:40 +0000 https://www.wikitechy.com/interview-questions/?p=584 Difference between a normal hive table and hive table stored as ORC
Normal hive table Hive table stored as orc
Hive data is organized into Databases:
Namespaces function to avoid naming conflicts for tables,
views, partitions, columns, and so on.		 It produce efficient way to store Hive data.It designed to overcome the drawback of others Hive file formats Using Optimized Row Columnar files improves speed when Hive is reading, writing, and processing data.
Databases can also be used to enforce security for a
user or group of users.		 Advantages- Single file as the output of each task, that reduces the NameNode’s load.
There are two types of tables in Hive,
one is Managed table and second is external table.
The difference is, when you drop a table,
if it is managed table hive deletes both data and meta data,
if it is external table Hive
only deletes metadata.		 An Optimized Row Columnar file contains types of data define as stripes,along with information in a file footer. At the end of the file a postscript holds compression parameters and the size of the compressed footer.
It damage how data is loaded,
controlled, and managed in Hive ;By use external
tables when the data is also used outside of Hive.		 Default stripe size is 250 MB. large stripe sizes enable large, efficient reads from HDFS.
The data files are read and processed by an existing
program that doesn’t lock the files. Data needs to
remain in the underlying location even after a DROP		 File footer having a list of stripes and number of rows,each columns contains count, min, max, and sum.
Storing data in Hive is nothing but
storing data in HDFS (Hadoop).		 The stripe file footer contains a directory of stream locations.Row data is used in table scans
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DDL statement in hive

webhcat server

DDL (Data Definition Language):

  • The outline of the database schema typically change by SQL statements they are creating, deleting, or modifying schema objects such as databases, tables, and views.
  • Most statements starts with the keywords CREATE, DROP, or ALTER.

Some of Data Definition Language statements are:

  • CREATE – To create an object.
  • ALTER – To alter the structure of the existing object·
  • DROP – It used to delete objects.
  • TRUNCATE – Remove all records from a table, including spaces.
  • MSCK REPAIR TABLE – Refresh metadata information.

The DML statement define as INSERT statement, it involves metadata that must be have nodes, and is also damage the SYNC_DDL query option.

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System registry hive

  • The logical group of keys, subkeys, and values in the registry that has a set of supporting files containing backups of its data is called as Hive.
  • Each time a new user logs on to a computer, a new hive is created for that user with a separate file for the user profile. This is called the user profile hive.
  • It supports for files containing backups of the data and logical group of keys, subkeys, values in the registry.
what is system registry hive
  • The two formats contain the registry files: standard and latest.

Standard

  • The standard format is supported by Windows 2000. It is also supported by new versions of Windows for backward compatibility.

Latest

  • The latest format is supported starting with Windows XP.
  • Windows version that support the latest format, but hives use the standard format: HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE\SAM, HKEY_LOCAL_MACHINE\Security, and HKEY_USERS\.DEFAULT; all other hives use the latest format.
  • Maximum the supporting files for the hives are in the %SystemRoot%\System32\Config directory. These files are updated each time a user logs on.

List of Standard hive and their suppoting files

registry hives in standard format
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Hive

  • Hive is a component of Hortonworks Data Platform(HDP).
  • Hive provides a SQL interface to data stored in HDP.
  • Hive has 3 main functions:
    • Data Summarization
    • Query
    • Analysis.
  • It supports queries expressed language called HiveQL, which automatically translates SQL like queries into MapReduce jobs executed on Hadoop.
  • It also enables data serialization and increases flexibility in schema architecture including a system catalog called Hive Metastore.

Architecture of hive :

what is hive

Features of hive:

  • Different storage such as plain text, RCFile, ORC, HBase, and others.
  • Pre-defined functions (UDFs) to manipulate dates, strings, and other data-mining tools.
  • Hive supports extending the UDF set to handle use-cases not supported by built-in functions.

Limitations of Hive:

  • Hive supports overwriting or hold data, but not updates and deletes.
  • In Hive, sub queries are not supported
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