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new b89ad49 disable group by config applyLimitPushDownToSegment by
default (#9711)
b89ad49 is described below
commit b89ad49396387bfb931ea936a65986700ca1ff9e
Author: Clint Wylie <[email protected]>
AuthorDate: Thu Apr 16 03:03:35 2020 -0700
disable group by config applyLimitPushDownToSegment by default (#9711)
* disable group by config applyLimitPushDownToSegment by default
* document
---
docs/querying/groupbyquery.md | 2 +-
.../java/org/apache/druid/query/groupby/GroupByQueryConfig.java | 2 +-
.../java/org/apache/druid/query/groupby/GroupByQueryConfigTest.java | 6 ++++--
3 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/docs/querying/groupbyquery.md b/docs/querying/groupbyquery.md
index a9ff9b2..27323e4 100644
--- a/docs/querying/groupbyquery.md
+++ b/docs/querying/groupbyquery.md
@@ -414,7 +414,7 @@ Supported runtime properties:
|`druid.query.groupBy.forceHashAggregation`|Force to use hash-based
aggregation.|false|
|`druid.query.groupBy.intermediateCombineDegree`|Number of intermediate nodes
combined together in the combining tree. Higher degrees will need less threads
which might be helpful to improve the query performance by reducing the
overhead of too many threads if the server has sufficiently powerful cpu
cores.|8|
|`druid.query.groupBy.numParallelCombineThreads`|Hint for the number of
parallel combining threads. This should be larger than 1 to turn on the
parallel combining feature. The actual number of threads used for parallel
combining is min(`druid.query.groupBy.numParallelCombineThreads`,
`druid.processing.numThreads`).|1 (disabled)|
-|`druid.query.groupBy.applyLimitPushDownToSegment`|If Broker pushes limit down
to queryable nodes (historicals, peons) then limit results during segment
scan.|true (enabled)|
+|`druid.query.groupBy.applyLimitPushDownToSegment`|If Broker pushes limit down
to queryable data server (historicals, peons) then limit results during segment
scan. If typically there are a large number of segments taking part in a query
on a data server, this setting may counterintuitively reduce performance if
enabled.|false (disabled)|
Supported query contexts:
diff --git
a/processing/src/main/java/org/apache/druid/query/groupby/GroupByQueryConfig.java
b/processing/src/main/java/org/apache/druid/query/groupby/GroupByQueryConfig.java
index 17ca929..c31ec26 100644
---
a/processing/src/main/java/org/apache/druid/query/groupby/GroupByQueryConfig.java
+++
b/processing/src/main/java/org/apache/druid/query/groupby/GroupByQueryConfig.java
@@ -80,7 +80,7 @@ public class GroupByQueryConfig
private boolean forcePushDownLimit = false;
@JsonProperty
- private boolean applyLimitPushDownToSegment = true;
+ private boolean applyLimitPushDownToSegment = false;
@JsonProperty
private boolean forcePushDownNestedQuery = false;
diff --git
a/processing/src/test/java/org/apache/druid/query/groupby/GroupByQueryConfigTest.java
b/processing/src/test/java/org/apache/druid/query/groupby/GroupByQueryConfigTest.java
index 4cb5e80..fb0090f 100644
---
a/processing/src/test/java/org/apache/druid/query/groupby/GroupByQueryConfigTest.java
+++
b/processing/src/test/java/org/apache/druid/query/groupby/GroupByQueryConfigTest.java
@@ -56,6 +56,7 @@ public class GroupByQueryConfigTest
Assert.assertEquals(4, config.getMaxOnDiskStorage());
Assert.assertEquals(5, config.getMaxMergingDictionarySize());
Assert.assertEquals(6.0, config.getBufferGrouperMaxLoadFactor(), 0.0);
+ Assert.assertFalse(config.isApplyLimitPushDownToSegment());
}
@Test
@@ -78,6 +79,7 @@ public class GroupByQueryConfigTest
Assert.assertEquals(4, config2.getMaxOnDiskStorage());
Assert.assertEquals(5, config2.getMaxMergingDictionarySize());
Assert.assertEquals(6.0, config2.getBufferGrouperMaxLoadFactor(), 0.0);
+ Assert.assertFalse(config2.isApplyLimitPushDownToSegment());
}
@Test
@@ -95,7 +97,7 @@ public class GroupByQueryConfigTest
"maxOnDiskStorage", 0,
"maxResults", 2,
"maxMergingDictionarySize", 3,
- "applyLimitPushDownToSegment", false
+ "applyLimitPushDownToSegment", true
)
)
.build()
@@ -109,6 +111,6 @@ public class GroupByQueryConfigTest
Assert.assertEquals(0, config2.getMaxOnDiskStorage());
Assert.assertEquals(3, config2.getMaxMergingDictionarySize());
Assert.assertEquals(6.0, config2.getBufferGrouperMaxLoadFactor(), 0.0);
- Assert.assertFalse(config2.isApplyLimitPushDownToSegment());
+ Assert.assertTrue(config2.isApplyLimitPushDownToSegment());
}
}
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