Details
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Bug
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Status: Closed
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Major
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Resolution: Fixed
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1.6.0
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None
Description
Example query:
select '/'||dir0||'/'||dir1||'/'||dir2||'/'||dir3 , count(*) FROM dfs.`/path/to/parquet/files` WHERE ('/'||dir0||'/'||dir1||'/'||dir2||'/'||dir3) IN ( '/2015/11/30', '//2015/09/01', '/2015/09/02', '/2015/09/03', '/2015/09/04', '/2015/09/09', '/2016/03/30' ) group by '/'||dir0||'/'||dir1||'/'||dir2||'/'||dir3 order by 1;
Error:
OOM while trying to prune partitions:
org.apache.drill.exec.exception.OutOfMemoryException: Unable to allocate buffer of size 256 due to memory limit. Current allocation: 5242880 at org.apache.drill.exec.memory.BaseAllocator.buffer(BaseAllocator.java:216) ~[drill-memory-base-1.6.0.jar:1.6.0] at org.apache.drill.exec.ops.BufferManagerImpl.getManagedBuffer(BufferManagerImpl.java:60) ~[drill-java-exec-1.6.0.jar:1.6.0] at org.apache.drill.exec.ops.BufferManagerImpl.getManagedBuffer(BufferManagerImpl.java:56) ~[drill-java-exec-1.6.0.jar:1.6.0] at org.apache.drill.exec.ops.QueryContext.getManagedBuffer(QueryContext.java:241) ~[drill-java-exec-1.6.0.jar:1.6.0] at org.apache.drill.exec.expr.fn.interpreter.InterpreterEvaluator$EvalVisitor.getManagedBufferIfAvailable(InterpreterEvaluator.java:158) ~[drill-java-exec-1.6.0.jar:1.6.0]
Cause:
Interpreter always asks for a new buffer to hold varchar/varbinary or decimal constant values. That's why the memory size required would be proportion to # of constant expressions multiplied by # of input rows (partition). This is different from evaluation from run-time generated where constant expression will be evaluated once and use only one buffer per value.
Fix:
To use one buffer for each unique constant value in query.
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