dengzhhu653 commented on a change in pull request #2473:
URL: https://github.com/apache/hive/pull/2473#discussion_r677261197
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File path: ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java
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@@ -2680,9 +2683,9 @@ public void run() {
total += estimator.estimate(jobConf, scanOp,
-1).getTotalLength();
}
recordSummary(path, new ContentSummary(total, -1, -1));
- } else {
- // todo: should nullify summary for non-native tables,
- // not to be selected as a mapjoin target
+ } else if (handler == null) {
Review comment:
Last two months, in our cluster we found that join a kudu table(mr
engine) cloud make the hiveserver2 oom.
[HMSHandler](https://github.com/apache/hive/blob/master/standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/HMSHandler.java#L2385-L2407)
seems create a path for the non-native table, so `fs.getContentSummary(path)`
returns the file length with 0(if data does not store under the table dir like
kudu, hbase), the optimizer will
[collect](https://github.com/apache/hive/blob/7b3ecf617a6d46f48a3b6f77e0339fd4ad95a420/ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/AbstractJoinTaskDispatcher.java#L118)
the sizes of join tables before converting the join to mapjoin(by default), if
the non-native table is able to be a stream table(like inner join) and the
length of `his data` is 0, the non-native will be tagged as small table and a
local task will be started to build the hashtable. If the non-native table has
millions of records, the jvm
may not be able to hold all these records in memory.
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