To rename a table in HBase, apparently you have to use snapshots. So, you take a snapshot of the table and then clone it as a different name.
How we can alter the table in HBase?
Alter is the command used to make changes to an existing table. Using this command, you can change the maximum number of cells of a column family, set and delete table scope operators, and delete a column family from a table.
How do I rename a namespace in HBase?
- Step1: Create Snapshot of HBase table that you want to rename. You need to create snapshot to migrate or copy that to different namespace.
- Step2: Clone Snapshot to new table name.
- Step3: Use ‘list’ command to check new table.
- Step4: Delete Snapshot.
- Step5: Drop Original Table.
How do I rename a column in HBase?
No, you cannot “rename” a column family in one atomic operation. To “rename”, you must rewrite the data with the new column family. Then, you can simply drop the old column family.
What is snapshot in HBase?
HBase snapshot support enables you to take a snapshot of a table without much impact on RegionServers, because snapshot, clone, and restore operations do not involve data copying. In addition, exporting a snapshot to another cluster has no impact on RegionServers.
What is version in HBase?
A version is a timestamp values is written alongside each value. By default, the timestamp values represent the time on the RegionServer when the data was written, but you can change the default HBase setting and specify a different timestamp value when you put data into the cell.
How do I list tables in HBase namespace?
HBase list_namespace_tables Command The list_namespace_tables command is used to list or display the tables available in given namespace. Below example display the tables available in ‘test’ namespace.
What is an HBase namespace?
HBase automatically assigns a default namespace when you create a table and do not associate it with a namespace. A namespace that is used to contain HBase internal system tables. default. A namespace that contains all other tables when you do not assign a specific user-defined namespace.
How do I Desc a table in HBase?
Use describe command to describe the details and configuration of the HBase table. For example, version, compression, blocksize, replication e.t.c. The syntax to describe the table is as follows. Examples: When table created in a namespace, you need to qualify it on command.
How do I clone a Hbase table?
- make sure you enbale snapshot in hbase-site.xml hbase.snapshot.enabled true
- hbase> snapshot ‘x’ ,’snapshot_x’
- hbase> clone_snapshot ‘snapshot_x’ ,’another_x’
How do I export a table from Hbase?
Using Hbase
- Export $ bin/hbase org.apache.hadoop.hbase.mapreduce.Export \ [ [ []]]
- Copy the output directory in hdfs from the source to destination cluster.
- Import $ bin/hbase org.apache.hadoop.hbase.mapreduce.Import
How do I make changes to a table in HBase?
You can use the HBase Alter shell command used to make changes to an existing table. Using this command, you can change the table properties or attributes such as set version, set and delete table scope operators, and delete a column family from an existing table. HBase Alter Table Syntax Below is the HBase alter table syntax:
How to delete a column family in HBase using alter?
Using alter, you can also delete a column family. Given below is the syntax to delete a column family using alter. hbase> alter ‘ table name ’, ‘delete’ ⇒ ‘ column family ’. Given below is an example to delete a column family from the ‘emp’ table. Assume there is a table named employee in HBase.
What is the HBase-column-mapping parameter used for?
1 When altering a table to add a column to an HBase table, the hbase-column-mapping parameter is required. Specifies the HADOOP or HBase table whose metadata is to be modified. Enables or disables caching on the entire table. When you add data to the table, that data is automatically set to be cached.
