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The following page has been changed by OlgaN:
http://wiki.apache.org/pig/PigSkewedJoinSpec

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     * Skewed join currently works with tow-table inner join.
     * Append 'using "skewed"' construct to the join to force pig to use skewed 
join
-    * pig.skewedjoin.reduce.memusage specifies the fraction of heap available 
for the reducer to perform the join. A low fraction forces pig to use more 
reducers but increases copying cost. For pigmix tests, we have seen good 
performance when we set this value in the range 0.1 - 0.4. However, note that 
this is hardly an accurate range. Its value depends on the amount of heap 
available for the operation, the number of columns in the input and the skew. 
It is best obtained by conducting experiments to achieve a good performance.
+    * pig.skewedjoin.reduce.memusage specifies the fraction of heap available 
for the reducer to perform the join. A low fraction forces pig to use more 
reducers but increases copying cost. For pigmix tests, we have seen good 
performance when we set this value in the range 0.1 - 0.4. However, note that 
this is hardly an accurate range. Its value depends on the amount of heap 
available for the operation, the number of columns in the input and the skew. 
It is best obtained by conducting experiments to achieve a good performance. 
The default value is =0.5=.
  
  
  [[Anchor(Requirements)]]

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