See the full job below. 前言 语法:DROP TABLE [IF EXISTS] table_name [PURGE]; -- (Note: PURGE available in Hive 0.14.0 and later) 删除此表的元数据和数据。如果配置了Trash (没有指定 PURGE)，数据实际上会移动到 .Trash/Current 目录。元数据完全丢失。 The PURGE clause in the Hive DROP TABLE statement causes the underlying data files to be removed immediately, without being transferred into a temporary holding area (such as the HDFS trashcan).. We use PURGE option when we are absolutely sure to delete the data of a table. What is the difference between quit and exit in hive. Syntax: DROP TABLE [IF EXISTS] table_name [PURGE]; Example: DROP TABLE IF EXISTS hql.customer; Underlying data of this internal table will be moved to Trash folder. It can be a normal table (stored in Metastore) or an external table (stored in local file system); Hive treats both in the same manner, irrespective of … While running the same data step again (after deletion), i,e. Load the data into internal table Hive>LOAD DATA INPATH '/user/guru99hive/data.txt' INTO table guruhive_internaltable; 3. 1. creating the same table in the schema - the number of records ingested is incorrect. Drop table in hive with PURGE : Now if we don't use purge the table, it goes to a Trash directory, from there the table can be recovered after drop it. This is needed in certain configurations where moving the files does not work. jdbc:hive2://127.0.0.1:10000 > ALTER TABLE zipcodes DROP IF EXISTS PARTITION ( … Hive Drop Table - The DROP TABLE statement is used to drop an existing table in a database.The SQL DROP TABLE statement allows you to remove or delete a table from the SQL database. In Hive, there is an option to use purge in the drop table command. 1.- A table called "Test" is created by a sqoop import job using "--create-hcatalog-table". When I have a table at my sqoop schema and want to delete it, I go to HIVE editor (through HUE) and key in the following command DROP TABLE IF EXISTS schemaName.tblName PURGE;. Hive drop or delete partition is performed using ALTER TABLE tablename DROP command. PURGE clause: In SAS, when using sql pass through, purge option can be used but what if the user uses proc sql / data step ? This developer built a…. use purge table won't go to Trash directory, so it can't be recovered. For non-Hive tables, as far as I can understand, "PURGE" is the current behavior of Spark. If PURGE is specified, then data is lost completely. With DROP TABLE tableName PURGE statement, table data will not go to trash folder. Something really weird (at least for me) is happening when I drop a table in Hive. What do you roll to sleep in a hidden spot? site design / logo © 2021 Stack Exchange Inc; user contributions licensed under cc by-sa. Deletes the table and removes the directory associated with the table from the file system if the table is not EXTERNAL table. To drop the internal table Hive>DROP TABLE guruhive_internaltable; If you dropped the guruhive_internaltable, including its metadata and its data will be deleted from Hive. In Apache Hive, what is the difference between “ESCAPED BY” and “FIELDS TERMINATED BY”? boolean: functionExists (String db ... Returns the user name which is used as owner for Hive table. Q: How does OVERWRITE clause work in CREATE TABLE statement in Hive. Hive will remove all of its data and metadata from the hive meta-store. How to initialize a qubit with a custom state in Qiskit Composer. A Computer Science portal for geeks. Q: What is the use of TOUCH in ALTER statement? It simply sets the Hive table partition to the new location. Is this a draw despite the Stockfish evaluation of −5? In case of an external table, only the associated metadata information is removed from the metastore database. Do Master Records (in a Master-detail Relationship) Get Locked? Students not answering emails about plagiarism. When you drop a Hive table all the metadata information related to the table is dropped. All rights reserved. Why do we need NMOS transistors for NAND gate? In "By her own quick-wittedness and adroitness she had turned the tables on her would-be destroyer". If the tables is an internal/managed table then the data along with metadata is removed permanently. For non-Hive tables and partitions, Spark already behaves as if the PURGE option was set, so there's no need to do anything. How did James Potter get his Invisibility Cloak? Q: What is the use of Hive in Hadoop eco-system? DROP TABLE [IF EXISTS] table_name [PURGE]; If you don't use purge the table goes to a Trash directory, from there the table can be recovered after drop it. rev 2021.3.12.38768, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide. Is there a good alternative word to “performance” to describe a music team's actions? DROP TABLE in Hive. Drop the specified table. Since the metadata is corrupted for the table Spark can’t drop the table and fails with following exception. So it cannot be retrieved in case of an accidental DROP statement. Drop or Delete Hive Partition. Difficulties in computing the derivatives of the Dirichlet distribution, Effects of time dilation on our observations of the Sun. If you drop a composite-partitioned table, then all the partitions and subpartitions are also dropped. Next steps? We use PURGE option when we are absolutely sure to delete the data of a table. DROP TABLE [IF EXISTS] table_name [PURGE]; -- (Note: PURGE available in Hive 0.14.0 and later) DROP TABLE removes metadata and data for this table. How can I use GDAL installed with QGIS from command line? From the following screenshot, we can observe the output . This chapter describes how to drop a table in Hive. If the client supports it (Hive >= 0.14.0 according to the Hive docs), we should allow that option to be defined. Although the PURGE clause is recognized by the Spark SQL DROP TABLE statement, this clause is currently not passed along to the Hive statement that performs the drop table operation behind the … In fact, I think this is a very handy feature that you can change your table's schema(for instance, you wanna change field name or concat two field to one field) without lose any data. 4. Hive Drop,Truncate&Alter这里主要介绍除create语句外两种常用的语句， Drop,Truncate和Alter。Drop,TruncateDROP TABLE [IF EXISTS] table_name [PURGE];DROP TABLE命令将会删除这个表的元数据和数据，如果是内部表且配置了Trash并且PURGE没有指定数据将会被移动到当前目录 Q: What is the purpose of USE command in Hive? Posted by Knowledge Powerhouse. So it cannot be retrieved in case of an accidental DROP statement. What is the difference between partitioning and bucketing a table in Hive ? You can use ALTER TABLE with DROP PARTITION option to drop a partition for a table. The usage of SCHEMA and DATABASE are same. Join Stack Overflow to learn, share knowledge, and build your career. When using proc sql - drop table / proc delete / proc dataset - delete, the hive metadata is deleted i.e. But if you do use purge table won't go to Trash directory, so it can't be recovered. So it cannot be retrieved in case of an accidental DROP statement. Hi Please describe the difference between both in hive with example. For non-Hive tables and partitions, Spark already behaves as if the PURGE option was set, so there's no need to do anything. Can a Lan Adapter cause a whole home network to crash? To drop the internal table Hive>DROP TABLE guruhive_internaltable; When I have a table at my sqoop schema and want to delete it, I go to HIVE editor (through HUE) and key in the following command DROP TABLE IF EXISTS schemaName.tblName PURGE;. But if you do . Q: What is the use of ORC format tables in Hive? With DROP TABLE tableName PURGE statement, table data will not go to trash folder. table structure is dropped from the schema but the underlying HDFS file is not. So it cannot be retrieved in case of an accidental DROP statement. Hive is very much capable such that it can query petabytes of records stored inside the hive table. What is the use of PURGE in DROP statement of Hive? Drop an external table along with data When you run DROP TABLE on an external table, by default Hive drops only the metadata (schema). DROP TABLE. 1. Could we carve a large radio dish in the Antarctic ice? Hello guys! If you want the DROP TABLE command to also remove the actual data in the external table, as DROP TABLE does on a managed table, you need to configure the table properties accordingly. Here is a common approach to delete a hive table: If you are deleting a hive table using Spark, it is very much possible that the table gets deleted but the data in the format of files is still there. Display the content of the table Hive>select * from guruhive_internaltable; 4. After that the table disappeared form the gui of HUE (sqoop table list, metastore list) but the actual files of the table were not deleted from the HDFS. Hive support for PURGE was added in 0.14 (for tables) and 1.2 (for partitions), so the code reflects that: trying to use the option with older versions of Hive will … Asking for help, clarification, or responding to other answers. But if you do use purge table won't go to Trash directory, so it can't be recovered. When you run Drop table command, Spark checks whether table exists or not before dropping the table. cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL, State of the Stack: a new quarterly update on community and product, Podcast 320: Covid vaccine websites are frustrating. To learn more, see our tips on writing great answers. With DROP TABLE tableName PURGE statement, table data will not go to trash folder. The metadata (table schema) stored in the metastore is corrupted. Cause. When you drop a range-, hash-, or list-partitioned table, then the database drops all the table partitions. When you drop a table from Hive Metastore, it removes the table/column data and their metadata. Translation of lucis mortiat / reginae gloriae. If PURGE is not specified then the data is actually moved to the .Trash/current directory. You can use PURGE option to delete data file as well along with partition metadata but it works only in Internal/ Managed tables. The drop partition will actually move data to the .Trash/Current directory if Trash is configured, unless PURGE is specified, but the metadata is completely lost. That flag is necessary in certain situations where the table data cannot be moved to the trash (which will be tried unless "PURGE" is requested). If you want the DROP TABLE command to also remove the actual data in the external table, as DROP TABLE does on a managed table, you need to configure the table properties accordingly. What is the difference between Apache Pig and Apache Hive? An external table describes the metadata / schema on external files. Dropping a partition from a table removes the data from HDFS and from Hive Metastore. Use the PURGE clause of DROP TABLE when dropping internal (managed) tables. In above code and from screen shot we do following things, Related Articles Hadoop Hive Table Dynamic Partition and Examples Q: What is the use of CLUSTERED BY clause during table creation in Hive? Making statements based on opinion; back them up with references or personal experience. In SAS, when using sql pass through, purge option can be used but what if the user uses proc sql / data step ? We use PURGE option when we are absolutely sure to delete the data of a table. This chapter describes how to drop a database in Hive. Drop Database Statement. DROP TABLE command in the hive is used to drop a table inside the hive. When you run DROP TABLE on an external table, by default Hive drops only the metadata (schema). Q: What is the use of strict mode in Hive? For non-Hive tables, as far as I can understand, "PURGE" is the current behavior of Spark. When you drop an Internal table, it drops the table from Metastore, metadata and it’s data files from the data warehouse HDFS location. The hive DROP TABLE statement comes with … After that the table disappeared form the gui of HUE (sqoop table list, metastore list) but the actual files of the table were not deleted from the HDFS. What is the use of PURGE in DROP statement of Hive? ... , boolean purge, boolean retainData) Drop one or many partitions in the given table, assuming they exist. This operation is expensive for tables that reside on the Amazon S3 object store. By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy. By default, when you drop an internal (managed) table, the data files are moved to the HDFS trashcan. This option is used by Hive to directly delete the files instead of moving them to the trash. org.apache.spark.sql.hive.client.HiveVersion: version Returns the Hive Version of this client. How worried should I be about this cough? When you drop a partitioned table with the PURGE keyword, the statement executes as a series of subtransactions, each of which drops a subset of partitions or subpartitions and their metadata. 2. The data is actually moved to the .Trash/Current directory if Trash is configured (and PURGE is not specified). It can be a normal table (stored in Metastore) or an external table (stored in local file system); Hive treats both in the same manner, irrespective of their types. We use PURGE option when we are absolutely sure to delete the data of a table. Hive support for PURGE was added in 0.14 (for tables) and 1.2 (for partitions), so the code reflects that: trying to use the option with older versions of Hive will … Drop table. Have any kings ever been serving admirals? Q: What does the overwrite keyword denote in Hive load statement? Developed by Madanswer. Hive has a Internal and External tables. An exception is thrown if the table does not exist. DROP TABLE IF EXISTS hql.customer PURGE; Underlying data in HDFS will be purged directly and table cannot be restored. Click here to read more about Loan/Mortgage. ALTER TABLE table_name DROP [IF EXISTS] PARTITION partition_spec PURGE; -- (Note: Hive 1.2.0 and later) PURGE选项也可以用表属性中auto.purge指定（见上文的TBLPROPERTIES）。 从Hive0.7.0到更高版本，DROP的分区如果不存在，返回一个错误，除非指定IF EXISTS或设置变量hive.exec.drop.ignorenonexistent为true。 If u wanna use the table name for other use, then drop the table and remove the directory in hdfs. Why might radios not be effective in a post-apocalyptic world? Former PI lists a non-contributor as first author on a manuscript for which I did all the work. Connect and share knowledge within a single location that is structured and easy to search. When you drop a table from Hive Metastore, it removes the table/column data and their metadata. Click here to read more about Loan/Mortgage, Many hands make light work, Share it here, Q: Which of the following is true about drop command in Hive. If the client supports it (Hive >= 0.14.0 according to the Hive docs), we should allow that option to be defined. DROP TABLE [IF EXISTS] table_name [PURGE]; If you don't use purge the table goes to a Trash directory, from there the table can be recovered after drop it. That flag is necessary in certain situations where the table data cannot be moved to the trash (which will be tried unless "PURGE" is requested). It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview … Q: What is the use of .hiverc file in Hive? Drop or Delete Hive Partition. The DROP TABLE statement in Hive deletes the data for a particular table and remove all metadata associated with it from Hive metastore. I hope your day is going well. External table files can be accessed and managed by processes outside of Hive. Drop Database is a statement that … In case of external table as well, Drop table command removes metadata and data of a table, but from only Hive table, data will be still present in HDFS location, as external table’s data is completely managed by HDFS itself, so only the linkage between Hive … In Hive, there is an option to use purge in the drop table command. ALTER TABLE some_table DROP IF EXISTS PARTITION(year = 2012); This command will remove the data and metadata for this partition. For non-Hive tables and partitions, Spark already behaves as if the PURGE option was set, so there's no need to do anything. Why couldn't Foaly tell that Artemis had planned more than what he let on under the effect of the Mesmer while he was editing Artemis's memories? ALTER TABLE table_name DROP [IF EXISTS] PARTITION partition_spec PURGE; But for External tables have a two-step process to alter table drop partition + … How do a transform simple object to have a concave shape, Which step response matches the system transfer function. When dropping an external table with its data located in an encryption zone, hive should not throw out MetaException(message:Unable to drop table because it is in an encryption zone and trash is enabled. If the table is external table then only the metadata is dropped. What is the use of PURGE in DROP statement of Hive? With DROP TABLE tableName PURGE statement, table data will not go to trash folder. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Using %sql or spark.sql to drop table doesn’t work either. Thanks for contributing an answer to Stack Overflow! © Copyright 2018-2020 www.madanswer.com. Dropping an External table drops just the table from Metastore and the actual data in HDFS will not be removed. In case of Internal Table, Drop table command removes the metadata and data of a table, means both the structure of the table and data inside a table is removed, as internal tables are completely managed by Hive.
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