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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Trivial Update of "Hbase/HbaseShell/HQL" by udanax
Date Sat, 09 Feb 2008 05:22:38 GMT
Dear Wiki user,

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

------------------------------------------------------------------------------
      DataType value = rs.getValue("datatype");
    }
  }}}
+ 
+ == External HQL Query file ==
+ HQL Query file is used for construct schema, table, and column references. It also created
using table dump, and can be fed into Hbase to re-create the tables. 
+ 
+ {{{
+ hql > load query file 'hdfs://hbase/script.hql';
+ }}}
+ 
  == Parallel Execution Features ==
  
  === Parallel Query ===
  Parallel execution can significantly reduce the elapsed time for large queries, but it doesn't
apply to every query. 
  
  {{{
-   hql > alter table tbl_name parallel(map 4 reduce 1);
+ hql > alter table tbl_name parallel(map 4 reduce 1);
-   hql > select count(*) from tbl_name;
+ hql > select count(*) from tbl_name;
-   hql > alter table tbl_name noparallel;
+ hql > alter table tbl_name noparallel;
  }}}
  
  === Parallel Data Loading ===
  HQL Loader utility loads data into Hbase tables from external files. If you have a large
amount of data to load, HQL Loader's parallel support can dramatically reduce the elapsed
time needed to perform that load.
  
  {{{
-   hql > load data file 'hdfs://hbase/big.dat'
+ hql > load data file 'hdfs://hbase/big.dat'
-     --> into table tbl_name
+   --> into table tbl_name
-     --> fields terminated by '\t'
+   --> fields terminated by '\t'
-     --> lines terminated by '\n'
+   --> lines terminated by '\n'
-     --> (column1[, column2, ...]);
+   --> (column1[, column2, ...]);
  }}}
  

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