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- INSERT OVERWRITE statements to directories, local directories, and tables (or partitions) can all be used together within the same query.
- INSERT OVERWRITE statements to HDFS filesystem directories are the best way to extract large amounts of data from Hive. Hive can write to HDFS directories in parallel from within a map-reduce job.
- The directory is, as you would expect, OVERWRITten; in other words, if the specified path exists, it is clobbered and replaced with the output.
- As of Hive 0.11.0 the separator used can be specified, in earlier versions it was always the ^A character (\001). However, custom separators are currently only supported for LOCAL writes; this is a bug that will be fixed by HIVE-5672.
- In Hive 0.14, inserts into ACID compliant tables will deactivate vectorization for the duration of the select and insert. This will be done automatically. ACID tables that have data inserted into them can still be queried using vectorization.
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