diff --git src/main/docbkx/security.xml src/main/docbkx/security.xml index f54f227..c7ea8a4 100644 --- src/main/docbkx/security.xml +++ src/main/docbkx/security.xml @@ -378,7 +378,68 @@ - +
+Tags + + Every cell can have metadata associated with it. Adding metadata in the data part of every cell would make things difficult. + + + The 0.98 version of HBase solves this problem by providing Tags along with the cell format. + Some of the usecases that uses the tags are Visibility labels, Cell level ACLs, etc. + + + HFile V3 version from 0.98 onwards supports tags and this feature can be turned on using the following configuration + + + hfile.format.version + 3 + + ]]> + + Every cell can have zero or more tags. Every tag has a type and the actual tag byte array. + The types 0-31 are reserved for System tags. For example ‘1’ is reserved for ACL and ‘2’ is reserved for Visibility tags. + + + The way rowkeys, column families, qualifiers and values are encoded using different Encoding Algos, similarly the tags can also be encoded. + Tag encoding can be turned on per CF. Default is always turn ON. + To turn on the tag encoding on the HFiles use + + + + Note that encoding of tags takes place only if the DataBlockEncoder is enabled for the CF. + + + As we compress the WAL entries using Dictionary the tags present in the WAL can also be compressed using Dictionary. + Every tag is compressed individually using WAL Dictionary. To turn ON tag compression in WAL dictionary enable the property + + + hbase.regionserver.wal.tags.enablecompression + true + + ]]> + + To add tags to every cell during Puts, the following apis are provided + + + + Some of the feature developed using tags are Cell level ACLs and Visibility labels. + These are some features that use tags framework and allows users to gain better security features on cell level. + + + For details checkout + + + Access Control + Visibility labels + +
Access Control