jcamachor commented on a change in pull request #1035:
URL: https://github.com/apache/hive/pull/1035#discussion_r433349779
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File path:
ql/src/java/org/apache/hadoop/hive/ql/optimizer/correlation/ReduceSinkDeDuplicationUtils.java
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@@ -197,6 +186,27 @@ public static boolean merge(ReduceSinkOperator cRS,
ReduceSinkOperator pRS, int
return true;
}
+ private static long estimateReducers(HiveConf conf, ReduceSinkOperator rs) {
+ // TODO: Check if we can somehow exploit the logic in SetReducerParallelism
+ if (rs.getConf().getNumReducers() > 0) {
+ return rs.getConf().getNumReducers();
+ }
+ int constantReducers = conf.getIntVar(HiveConf.ConfVars.HADOOPNUMREDUCERS);
+ if (constantReducers > 0) {
+ return constantReducers;
+ }
+ long inputTotalBytes = 0;
+ List<Operator<?>> rsSiblings =
rs.getChildOperators().get(0).getParentOperators();
+ for (Operator<?> sibling : rsSiblings) {
+ if (sibling.getStatistics() != null) {
Review comment:
I am wondering, if you do not have stats available for any of the
siblings, we should probably skip the parallelism check, and thus, fallback to
previous behavior.
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