該命令返回表的說(shuō)明。它的語(yǔ)法如下:
hbase> describe 'table name'
下面給出的是對(duì)emp表的 describe 命令的輸出。
hbase(main):006:0> describe 'emp' DESCRIPTION ENABLED 'emp', {NAME => 'READONLY', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', COMPRESSION => 'NONE', VERSIONS => '1', TTL true => 'FOREVER', MIN_VERSIONS => '0', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false', BLOCKCACHE => 'true'}, {NAME => 'personal data', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', VERSIONS => '5', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => 'FOREVER', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false', BLOCKCACHE => 'true'}, {NAME => 'professional data', DATA_BLO CK_ENCODING => 'NONE', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', VERSIONS => '1', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => 'FOREVER', K EEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false', BLOCKCACHE => 'true'}, {NAME => 'table_att_unset', DATA_BLOCK_ENCODING => 'NO NE', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', COMPRESSION => 'NONE', VERSIONS => '1', TTL => 'FOREVER', MIN_VERSIONS => '0', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '6
alter用于更改現(xiàn)有表的命令。使用此命令可以更改列族的單元,設(shè)定最大數(shù)量和刪除表范圍運(yùn)算符,并從表中刪除列家族。
下面給出的語(yǔ)法來(lái)改變列家族單元的最大數(shù)目。
hbase> alter 't1', NAME => 'f1', VERSIONS => 5
在下面的例子中,單元的最大數(shù)目設(shè)置為5。
hbase(main):003:0> alter 'emp', NAME => 'personal data', VERSIONS => 5 Updating all regions with the new schema... 0/1 regions updated. 1/1 regions updated. Done. 0 row(s) in 2.3050 seconds
使用alter,可以設(shè)置和刪除表范圍,運(yùn)算符,如MAX_FILESIZE,READONLY,MEMSTORE_FLUSHSIZE,DEFERRED_LOG_FLUSH等。
下面給出的是語(yǔ)法,是用以設(shè)置表為只讀。
hbase>alter 't1', READONLY(option)
在下面的例子中,我們已經(jīng)設(shè)置表emp為只讀。
hbase(main):006:0> alter 'emp', READONLY Updating all regions with上一篇:HBase Shell