Karthik Kumara created HIVE-4247:
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Summary: Filtering on a hbase row key duplicates results across
multiple mappers
Key: HIVE-4247
URL: https://issues.apache.org/jira/browse/HIVE-4247
Project: Hive
Issue Type: Bug
Components: HBase Handler
Affects Versions: 0.9.0
Environment: All Platforms
Reporter: Karthik Kumara
Steps to reproduce
1. Create a Hive external table with HiveHbaseHandler with enough data in the
hbase table to spawn multiple mappers for the hive query.
2. Write a query which has a filter (in the where clause) based on the hbase
row key.
3. Running the map reduce job leads to each mapper querying the entire data
set. duplicating the data for each mapper. Each mapper processes the entire
filtered range and the results get multiplied as the number of mappers run.
Expected behavior:
Each mapper should process a different part of the data and should not
duplicate.
Cause:
The cause seems to be the convertFilter method in HiveHBaseTableInputFormat.
convertFilter has this piece of code which rewrites the start and the stop row
for each split which leads each mapper to process the entire range
if (tableSplit != null) {
tableSplit = new TableSplit(
tableSplit.getTableName(),
startRow,
stopRow,
tableSplit.getRegionLocation());
}
The scan already has the start and stop row set when the splits are created. So
this piece of code is probably redundant.
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