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MRS-operation-guide-lts/doc/component-operation-guide-lts/source/using_hbase/using_a_secondary_index.rst
proposalbot d31d5b10fe Changes to mrs_operation-guide-lts from docs/doc-exports#515 (MRS comp-lts 2.0.3 
Reviewed-by: Kacur, Michal <michal.kacur@t-systems.com>
Co-authored-by: proposalbot <proposalbot@otc-service.com>
Co-committed-by: proposalbot <proposalbot@otc-service.com>
2023-01-19 16:53:12 +00:00

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mrs_01_1635.html

Using a Secondary Index

Scenario

HIndex enables HBase indexing based on specific column values, making the retrieval of data highly efficient and fast.

Constraints

  • Column families are separated by semicolons (;).

  • Columns and data types must be contained in square brackets ([]).

  • The column data type is specified by using -> after the column name.

  • If the column data type is not specified, the default data type (string) is used.

  • The number sign (#) is used to separate two index details.

  • The following is an optional parameter:

    -Dscan.caching: number of cached rows when the data table is scanned.

    The default value is set to 1000.

  • Indexes are created for a single region to repair damaged indexes.

    This function is not used to generate new indexes.

Procedure

  1. Install the HBase client. For details, see Using an HBase Client <mrs_01_24041>.

  2. Go to the client installation directory, for example, /opt/client.

    cd /opt/client

  3. Run the following command to configure environment variables:

    source bigdata_env

  4. If the cluster is in security mode, run the following command to authenticate the user. In normal mode, user authentication is not required.

    kinit Component service user

  5. Run the following command to access HIndex:

    hbase org.apache.hadoop.hbase.hindex.mapreduce.TableIndexer

    Table 1 Common HIndex commands
    Description Command
    Add Index TableIndexer-Dtablename.to.index=table1-Dindexspecs.to.add='IDX1=>cf1:[q1->datatype],[q2],[q3];cf2:[q1->datatype],[q2->datatype]#IDX2=>cf1:[q5]'
    Create Index TableIndexer -Dtablename.to.index=table1 -Dindexnames.to.build='IDX1#IDX2'
    Delete Index TableIndexer -Dtablename.to.index=table1 -Dindexnames.to.drop='IDX1#IDX2'
    Disable Index TableIndexer -Dtablename.to.index=table1 -Dindexnames.to.disable='IDX1#IDX2'
    Add and Create Index TableIndexer -Dtablename.to.index=table1 -Dindexspecs.to.add='IDX1=>cf1:[q1->datatype],[q2],[q3];cf2:[q1->datatype],[q2->datatype]#IDX2=>cf1:[q5] -Dindexnames.to.build='IDX1'
    Create Index for a Single Region TableIndexer -Dtablename.to.index=table1 -Dregion.to.index=regionEncodedName -Dindexnames.to.build='IDX1#IDX2'

    Note

    • IDX1: indicates the index name.
    • cf1: indicates the column family name.
    • q1: indicates the column name.
    • datatype: indicates the data type, including String, Integer, Double, Float, Long, Short, Byte and Char.