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From Apache Wiki <wikidi...@apache.org>
Subject [Lucene-hadoop Wiki] Trivial Update of "Hbase/HbaseShell/HQL" by InchulSong
Date Mon, 27 Aug 2007 15:09:02 GMT
Dear Wiki user,

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The following page has been changed by InchulSong:
http://wiki.apache.org/lucene-hadoop/Hbase/HbaseShell/HQL

The comment on the change is:
Changes on bloom filter options in the CREATE TABLE syntax.

------------------------------------------------------------------------------
  [[TableOfContents(4)]]
  
  ----
- == Hbase Query Language (HQL) Introduction ==
+ == Hbase Query Language (HQL) ==
  HQL is an SQL-like query language for Hbase. You can use it to query and modify tables in
Hbase. 
  HQL is not intended to fully support the SQL syntax and semantics. 
  HQL, instead, is developed to help easy manipulation of tables in Hbase through the Hbase
Shell command line without using programming APIs. 
@@ -29, +29 @@

      [MAX_LENGTH=n]
      [COMPRESSION=NONE|BLOCK|RECORD]
      [IN_MEMORY]
-     [BLOOMFILTER=NONE|BLOOM|COUNTING|RETOUCHED]
+     [BLOOMFILTER=NONE|BLOOM|COUNTING|RETOUCHED VECTOR_SIZE=n NUM_HASH=n]
  }}}
  
  CREATE TABLE enables you to create a new table with various options for each column family.
  
   * MAX_VERSIONS makes a table keep only the recent n versions in a cell. Its default value
is 3, i.e., only the most recent 3 versions of values are stored in a cell. 
+ 
   * MAX_LENGTH specifies the maximum size of a column value. By default, the maximum size
is unlimited. It is limited only by Integer.MAX_VALUE.
+ 
   * COMPRESSION specifies which compression technique to use for the column family. By default,
Hbase does not compress any data.
+ 
   * IN_MEMORY specifies whether to keep the values in the column family in-memory, or not.
By default, values are not kept in-memory.
-  * BLOOMFILTER specifies which bloom filter to use for the column family. By default, none
of the bloom filters is used.
+ 
+  * BLOOMFILTER specifies which bloom filter to use for the column family. By default, none
of the bloom filters is used. You can specify the options in two ways: with VECTOR_SIZE and
NUM_HASH, or with NUM_ENTRIES. VECTOR_SIZE specifies the number of elements in the vector,
and NUM_HASH specifies the number of hash functions to use; With NUM_ENTRIES, you  specify
only the approximated number of entries in the column, and VECTOR_SIZE and NUM_HASH are automatically
determined. Currently, the NUM_ENTRIES option is not supported.
+ 
   * See [http://lucene.zones.apache.org:8080/hudson/job/Hadoop-Nightly/javadoc/org/apache/hadoop/hbase/HColumnDescriptor.html
   HColumnDescriptor API] for more information.
  
  === DROP TABLE Syntax ===
@@ -60, +65 @@

    | CHANGE column_family_name column_family_spec
  }}}
  
- ALTER TABLE changes the structure of an existing table. You can 
+ ALTER TABLE changes the structure of the specified table. You can 
  add, delete, or change column families. 
  
  == Data Manipulation Statements ==
@@ -128, +133 @@

  {{{
  LOAD FROM FILE 'file_name'
    INTO TABLE table_name
-   [options]
  }}}
  
  LOAD FROM FILE reads rows from the specified file and inserts these rows into the specified
table. LOAD FROM FILE is complement of SELECT INTO FILE.

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