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Posted to commits@druid.apache.org by GitBox <gi...@apache.org> on 2020/08/07 05:23:07 UTC
[GitHub] [druid] jihoonson opened a new pull request #10253: Allow forceLimitPushDown in SQL
jihoonson opened a new pull request #10253:
URL: https://github.com/apache/druid/pull/10253
Fixes https://github.com/apache/druid/issues/9323.
### Description
`validateAndGetForceLimitPushDown()` can throw an exception while iterating candidate plans in sql planner. This PR postpones validation until it's necessary.
<hr>
This PR has:
- [x] been self-reviewed.
- [ ] using the [concurrency checklist](https://github.com/apache/druid/blob/master/dev/code-review/concurrency.md) (Remove this item if the PR doesn't have any relation to concurrency.)
- [ ] added documentation for new or modified features or behaviors.
- [ ] added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
- [ ] added or updated version, license, or notice information in [licenses.yaml](https://github.com/apache/druid/blob/master/licenses.yaml)
- [ ] added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
- [x] added unit tests or modified existing tests to cover new code paths, ensuring the threshold for [code coverage](https://github.com/apache/druid/blob/master/dev/code-review/code-coverage.md) is met.
- [ ] added integration tests.
- [ ] been tested in a test Druid cluster.
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[GitHub] [druid] clintropolis commented on a change in pull request #10253: Allow forceLimitPushDown in SQL
Posted by GitBox <gi...@apache.org>.
clintropolis commented on a change in pull request #10253:
URL: https://github.com/apache/druid/pull/10253#discussion_r468813252
##########
File path: processing/src/main/java/org/apache/druid/query/groupby/GroupByQuery.java
##########
@@ -409,7 +412,10 @@ public boolean getContextSortByDimsFirst()
@JsonIgnore
public boolean isApplyLimitPushDown()
{
- return applyLimitPushDown;
+ if (forceLimitPushDown == null) {
+ forceLimitPushDown = validateAndGetForceLimitPushDown();
+ }
+ return forceLimitPushDown || canPushDownLimit;
Review comment:
super nit: it seems funny to have `...LimitPushDown` and `...PushDownLimit`, but I'm not really sure what is the best way to square these up. I guess `...LimitPushDown` is more prevalent, so maybe renaming to `canDoLimitPushDown` to be more consistent?
##########
File path: processing/src/main/java/org/apache/druid/query/groupby/GroupByQuery.java
##########
@@ -121,6 +120,10 @@ public static Builder builder()
@Nullable
private final DateTime universalTimestamp;
+ private final boolean canPushDownLimit;
+ @Nullable
+ private Boolean forceLimitPushDown;
Review comment:
I think this would cause extra calls to `validateAndGetForceLimitPushDown` whenever `isApplyLimitPushdown` is called because of being unable to distinguish between an actual `false` and the value not being computed yet. It's probably not especially harmful, but it also seems unnecessary.
##########
File path: processing/src/main/java/org/apache/druid/query/groupby/GroupByQuery.java
##########
@@ -474,14 +480,12 @@ private RowSignature computeResultRowSignature()
.build();
}
- private boolean determineApplyLimitPushDown()
+ private boolean canPushDown()
Review comment:
nit: this method name should probably include `LimitPushDown` or at least `Limit` somehow to make it clearer that it applies to limits, maybe `canDoLimitPushDown()` if you decide to rename the field as well?
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[GitHub] [druid] clintropolis merged pull request #10253: Allow forceLimitPushDown in SQL
Posted by GitBox <gi...@apache.org>.
clintropolis merged pull request #10253:
URL: https://github.com/apache/druid/pull/10253
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[GitHub] [druid] jihoonson commented on a change in pull request #10253: Allow forceLimitPushDown in SQL
Posted by GitBox <gi...@apache.org>.
jihoonson commented on a change in pull request #10253:
URL: https://github.com/apache/druid/pull/10253#discussion_r469693227
##########
File path: processing/src/main/java/org/apache/druid/query/groupby/GroupByQuery.java
##########
@@ -474,14 +480,12 @@ private RowSignature computeResultRowSignature()
.build();
}
- private boolean determineApplyLimitPushDown()
+ private boolean canPushDown()
Review comment:
Added limitSpec, havingSpec, and subtotalsSpec as params and renamed.
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[GitHub] [druid] suneet-s commented on a change in pull request #10253: Allow forceLimitPushDown in SQL
Posted by GitBox <gi...@apache.org>.
suneet-s commented on a change in pull request #10253:
URL: https://github.com/apache/druid/pull/10253#discussion_r467973549
##########
File path: processing/src/main/java/org/apache/druid/query/groupby/GroupByQuery.java
##########
@@ -121,6 +120,10 @@ public static Builder builder()
@Nullable
private final DateTime universalTimestamp;
+ private final boolean canPushDownLimit;
+ @Nullable
+ private Boolean forceLimitPushDown;
Review comment:
Can we default to false instead of making this nullable?
```suggestion
private boolean forceLimitPushDown;
```
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[GitHub] [druid] jihoonson commented on a change in pull request #10253: Allow forceLimitPushDown in SQL
Posted by GitBox <gi...@apache.org>.
jihoonson commented on a change in pull request #10253:
URL: https://github.com/apache/druid/pull/10253#discussion_r469693037
##########
File path: processing/src/main/java/org/apache/druid/query/groupby/GroupByQuery.java
##########
@@ -121,6 +120,10 @@ public static Builder builder()
@Nullable
private final DateTime universalTimestamp;
+ private final boolean canPushDownLimit;
+ @Nullable
+ private Boolean forceLimitPushDown;
Review comment:
Yeah, it's nullable to lazily initialize and cache it. Checking the value of `forceLimitPushDown` is needed a couple of times during a query. Even though it's not very harmful, I don't see any reason to not cache it.
##########
File path: processing/src/main/java/org/apache/druid/query/groupby/GroupByQuery.java
##########
@@ -409,7 +412,10 @@ public boolean getContextSortByDimsFirst()
@JsonIgnore
public boolean isApplyLimitPushDown()
{
- return applyLimitPushDown;
+ if (forceLimitPushDown == null) {
+ forceLimitPushDown = validateAndGetForceLimitPushDown();
+ }
+ return forceLimitPushDown || canPushDownLimit;
Review comment:
Renamed.
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