Can we update the records in the hive?
Hive doesn’t support updates (or deletes), but it does support INSERT INTO, so it’s possible to add new rows to an existing table.
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How will I update the data in the hive files?
Use the UPDATE statement to modify data already written to Apache Hive. Depending on the condition specified in the optional WHERE clause, an UPDATE statement can affect all rows in a table. You must have SELECT and UPDATE privileges to use this statement.
How are records updated in Hadoop?
It consists of the following steps:
- Maintain a current copy of master data: A complete copy of your dimension data must reside on HDFS.
- Load delta data – Load the newly updated data into HDFS.
- Merge data – Merge master and delta data on key business fields.
How do I enable update and delete in Hive?
Below is the sequence of steps required to update and delete records/rows in Hive table.
- Enable ACID Transaction Manager (DbTxnManager) on the Hive session.
- Enable concurrency.
- Create table enabling transactional (TBLPROPERTIES (‘transactional’=’true’))
- Create table with storage type ORC.
How do I delete records from the Hive external table?
Drop an external table along with the data
- Create a CSV file of data that you want to query in Hive.
- Start hive.
- Run DROP TABLE on the external table. DROP TABLE text_names;
- Prevent the external table data from being deleted using a DROP TABLE statement. ALTER TABLE text_addresses SET TBLPROPERTIES (‘external.table.purge’=’false’);
How do I check my version of Hive?
- in the linux shell: “hive –version”
- on the hive shell: ” ! hive –version;”
How do I drop an external table in Hive?
Can an existing file be modified in HDFS?
You can’t UPDATE any existing records in HDFS, but yes, you can surely make another copy of the data (with the modifications/updates) in HDFS and you can delete the old original copy.
Is it possible to update data in a file stored in HDFS?
HDFS only writes data, it does not update. In Hadoop you can only write and delete files. You can’t update them. The system is built to be resilient and fail-safe because when each data node writes its memory to disk data blocks, it also writes that memory to another server through replication.
How do I check my hive version?
Can we update the hive external table?
You cannot have the most recent data in the query output. Another is the external table where Hive will not copy your data to the internal store. So every time you fire a query on the table, it retrieves data from the file. So you can even have the most recent data in the query output.
How to update or delete a hive partition?
The Hive ALTER TABLE command is used to update or remove a partition from a Hive Metastore and HDFS (managed table) location. You can also manually update or delete a Hive partition directly on HDFS using Hadoop commands; if it does, you must run the MSCK command to sync the HDFS files with the Hive Metastore.
Is it possible to delete a record in Hive?
If a table is to be used in ACID (insert, update, delete) writes, then the “transactional” table property must be set on that table, starting with Hive 0.14.0. Without this value, inserts will be done in the old style; Updates and removals will be prohibited. Yes, well said. Hive does not support the UPDATE option.
Is there a way to update the main table in hive?
Hive does not support the UPDATE option. But the following alternative could be used to achieve the result: the main table is supposed to be split by some key. Load the incremental data (the data to be updated) into a partitioned staging table with the same keys as the main table.
How does Hive partition work in HDFS?
Hive partitioning partitions the table into multiple tables (in multiple HDFS subdirectories) based on the partition key. The partition key can be one or more columns.