| # |
| # |
| # Licensed to the Apache Software Foundation (ASF) under one |
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| # to you under the Apache License, Version 2.0 (the |
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| # http://www.apache.org/licenses/LICENSE-2.0 |
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| # distributed under the License is distributed on an "AS IS" BASIS, |
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| # |
| |
| module Shell |
| module Commands |
| class Alter < Command |
| def help |
| <<-EOF |
| Alter a table. Tables can be altered without disabling them first. |
| Altering enabled tables has caused problems |
| in the past, so use caution and test it before using in production. |
| |
| You can use the alter command to add, |
| modify or delete column families or change table configuration options. |
| Column families work in a similar way as the 'create' command. The column family |
| specification can either be a name string, or a dictionary with the NAME attribute. |
| Dictionaries are described in the output of the 'help' command, with no arguments. |
| |
| For example, to change or add the 'f1' column family in table 't1' from |
| current value to keep a maximum of 5 cell VERSIONS, do: |
| |
| hbase> alter 't1', NAME => 'f1', VERSIONS => 5 |
| |
| You can operate on several column families: |
| |
| hbase> alter 't1', 'f1', {NAME => 'f2', IN_MEMORY => true}, {NAME => 'f3', VERSIONS => 5} |
| |
| To delete the 'f1' column family in table 'ns1:t1', use one of: |
| |
| hbase> alter 'ns1:t1', NAME => 'f1', METHOD => 'delete' |
| hbase> alter 'ns1:t1', 'delete' => 'f1' |
| |
| You can also change table-scope attributes like MAX_FILESIZE, READONLY, |
| MEMSTORE_FLUSHSIZE, NORMALIZATION_ENABLED, NORMALIZER_TARGET_REGION_COUNT, |
| NORMALIZER_TARGET_REGION_SIZE(MB), DURABILITY, etc. These can be put at the end; |
| for example, to change the max size of a region to 128MB, do: |
| |
| hbase> alter 't1', MAX_FILESIZE => '134217728' |
| |
| You can add a table coprocessor by setting a table coprocessor attribute. Only the CLASSNAME is |
| required in the coprocessor specification. |
| |
| hbase> alter 't1', COPROCESSOR => { |
| CLASSNAME => 'org.apache.hadoop.hbase.coprocessor.SimpleRegionObserver', |
| JAR_PATH => 'hdfs:///foo.jar', |
| PRIORITY => 12, |
| PROPERTIES => {'a' => '17' } |
| } |
| |
| Since you can have multiple coprocessors configured for a table, a |
| sequence number will be automatically appended to the attribute name |
| to uniquely identify it. For example, the attribute name might be "coprocessor$1". |
| |
| You can also set configuration settings specific to this table or column family: |
| |
| hbase> alter 't1', CONFIGURATION => {'hbase.hregion.scan.loadColumnFamiliesOnDemand' => 'true'} |
| hbase> alter 't1', {NAME => 'f2', CONFIGURATION => {'hbase.hstore.blockingStoreFiles' => '10'}} |
| |
| You can also unset configuration settings specific to this table: |
| |
| hbase> alter 't1', METHOD => 'table_conf_unset', NAME => 'hbase.hregion.majorcompaction' |
| |
| You can also remove a table-scope attribute: |
| |
| hbase> alter 't1', METHOD => 'table_att_unset', NAME => 'MAX_FILESIZE' |
| |
| hbase> alter 't1', METHOD => 'table_att_unset', NAME => 'coprocessor$1' |
| |
| You can also set REGION_REPLICATION: |
| |
| hbase> alter 't1', {REGION_REPLICATION => 2} |
| |
| You can disable/enable table split and/or merge: |
| |
| hbase> alter 't1', {SPLIT_ENABLED => false} |
| hbase> alter 't1', {MERGE_ENABLED => false} |
| |
| There could be more than one alteration in one command: |
| |
| hbase> alter 't1', { NAME => 'f1', VERSIONS => 3 }, |
| { MAX_FILESIZE => '134217728' }, { METHOD => 'delete', NAME => 'f2' }, |
| METADATA => { 'mykey' => 'myvalue' } |
| EOF |
| end |
| |
| def command(table, *args) |
| admin.alter(table, true, *args) |
| end |
| end |
| end |
| end |