data of partitioned columns in hive is physically present - Wikitechy https://www.wikitechy.com/interview-questions/tag/data-of-partitioned-columns-in-hive-is-physically-present/ Interview Questions Mon, 13 Sep 2021 06:07:09 +0000 en-US hourly 1 https://wordpress.org/?v=6.9 https://www.wikitechy.com/interview-questions/wp-content/uploads/2025/10/cropped-wikitechy-icon-32x32.png data of partitioned columns in hive is physically present - Wikitechy https://www.wikitechy.com/interview-questions/tag/data-of-partitioned-columns-in-hive-is-physically-present/ 32 32 What is the best way to take the back up of hive partitioned table into a disk ? https://www.wikitechy.com/interview-questions/hive/what-is-the-best-way-to-take-the-back-up-of-hive-partitioned-table-into-a-disk/ https://www.wikitechy.com/interview-questions/hive/what-is-the-best-way-to-take-the-back-up-of-hive-partitioned-table-into-a-disk/#respond Tue, 13 Jul 2021 21:51:10 +0000 https://www.wikitechy.com/interview-questions/?p=585

Best way to take the back up of hive partitioned table into a disk

  • Partitioning is the optimization technique in Hive which improves the performance significantly.
  • Apache Hive is the data warehouse on the top of Hadoop, which enables ad-hoc analysis over structured and semi-structured data
  • Apache Hive organizes tables into partitions.Partitioning is dividing a table into connected components based on the values of specific columns like date, city, and department.
  • Each table in hive can have one or additional partition keys to identify a particular partition. using partition it is easy to do queries on slices of the data.
hive-partitioned-table-into-a-disk
The Hadoop Distributed File System considered reliable from a technical failure purpose of view, but to archive data you need to copy it offline, with copyToLocal, or copy the data to another cluster or another location on the cluster.

For copyToLocal the command syntax is:

hadoop fs -copyToLocal [-ignorecrc] [-crc] URI <localdst>

Additionally, you can use Hive to copy data from a table to local directory.

INSERT OVERWRITE LOCAL DIRECTORY '/tmp/local_out' SELECT a.* FROM wikitechy  where year=2018
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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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