SQL: Plan non-equijoin conditions as cross join followed by filter #15302

abhishekagarwal87 · 2023-11-01T11:28:18Z

This PR revives #14978 with a few more bells and whistles. Instead of an unconditional cross-join, we will now split the join condition such that some conditions are now evaluated post-join. To decide what sub-condition goes where, I have refactored DruidJoinRule class to extract unsupported sub-conditions. We build a postJoinFilter out of these unsupported sub-conditions and push to the join.

Release notes
Druid can support arbitrary join conditions for INNER join. For INNER joins, druid will look at the join condition, and any sub-conditions that cannot be evaluated efficiently as part of the join, will be converted to a post-join filter. With this feature, you can do in-equality joins that were not possible before.

This PR has:

sql/src/test/java/org/apache/druid/sql/calcite/CalciteJoinQueryTest.java

+                                .build()
+                        ),
+                        "j0.",
+                        equalsCondition(makeColumnExpression("m1"), makeColumnExpression("j0.m1")),


sql/src/test/java/org/apache/druid/sql/calcite/CalciteJoinQueryTest.java

+                                .build()
+                        ),
+                        "j0.",
+                        equalsCondition(makeColumnExpression("m1"), makeColumnExpression("j0.m1")),


sql/src/main/java/org/apache/druid/sql/calcite/rule/JoinRules.java

soumyava · 2023-11-14T16:32:30Z

extensions-core/multi-stage-query/src/test/java/org/apache/druid/msq/exec/MSQSelectTest.java

@@ -772,7 +772,7 @@ public void testJoinWithLookup()
                                               DruidExpression.ofColumn(ColumnType.STRING, "dim2"),
                                               DruidExpression.ofColumn(ColumnType.STRING, "j0.k")
                                           ),
-                                           JoinType.LEFT
+                                           JoinType.INNER


The initial query has a left join here and we end up planning it as in inner. Can there be a case where the user does not expect the results which have a pair on both left and right ? Also that seems to be case where the result changed for the not sql compatible mode

soumyava · 2023-11-14T18:48:43Z

sql/src/test/java/org/apache/druid/sql/calcite/CalciteJoinQueryTest.java

@@ -723,7 +723,7 @@ public void testFilterAndGroupByLookupUsingJoinOperatorBackwards(Map<String, Obj
                                ),
                                "j0.",
                                equalsCondition(makeColumnExpression("k"), makeColumnExpression("j0.dim2")),
-                                JoinType.RIGHT
+                                JoinType.INNER


Same comment as before, we are converting a right join to an inner join here and that is changing the expected results

soumyava · 2023-11-14T18:49:08Z

sql/src/test/java/org/apache/druid/sql/calcite/CalciteJoinQueryTest.java

@@ -768,7 +762,7 @@ public void testFilterAndGroupByLookupUsingJoinOperatorWithNotFilter(Map<String,
                                new LookupDataSource("lookyloo"),
                                "j0.",
                                equalsCondition(makeColumnExpression("dim2"), makeColumnExpression("j0.k")),
-                                JoinType.LEFT
+                                JoinType.INNER


Same as before

There is a post-join filter that will reject nulls on the right side. Hence the SQL query is equivalent to INNER join with post-join filter moved into the join condition itself. That's also the same reason why some other join queries have become INNER join queries. I have also now tweaked the rule a bit so that we still reject non-equi conditions for non-sql compatible mode. With that, results in non-sql compatible mode won't change.

soumyava · 2023-11-14T18:49:40Z

sql/src/test/java/org/apache/druid/sql/calcite/CalciteJoinQueryTest.java

@@ -821,7 +809,7 @@ public void testJoinUnionTablesOnLookup(Map<String, Object> queryContext)
                                new LookupDataSource("lookyloo"),
                                "j0.",
                                equalsCondition(makeColumnExpression("dim2"), makeColumnExpression("j0.k")),
-                                JoinType.LEFT
+                                JoinType.INNER


Similar comment as the previous one

sql/src/test/java/org/apache/druid/sql/calcite/DecoupledPlanningCalciteQueryTest.java

sql/src/test/java/org/apache/druid/sql/calcite/CalciteJoinQueryTest.java

-                          "1",
+                          NullHandling.sqlCompatible() ?
+                          equalsCondition(
+                              DruidExpression.fromExpression("CAST(\"j0.k\", 'LONG')"),


This reverts commit 2b5026e.

abhishekagarwal87 · 2023-11-26T15:57:32Z

sql/src/test/java/org/apache/druid/sql/calcite/CalciteJoinQueryTest.java

@@ -740,7 +740,6 @@ public void testFilterAndGroupByLookupUsingJoinOperatorBackwards(Map<String, Obj
            new Object[]{"xabc", 1L}
        )
        : ImmutableList.of(
-            new Object[]{null, 5L},


This result changed because there is a bug in splitting the join filter on leaf nodes. A filter that can reject null cannot be pushed into the left table if the join is right. But that's what https://github.com/apache/druid/blob/master/processing/src/main/java/org/apache/druid/segment/join/filter/JoinFilterAnalyzer.java#L198 will do right now. I will fix this in another PR.

clintropolis

👍

docs/querying/datasource.md

sql/src/test/java/org/apache/druid/sql/calcite/rule/DruidJoinRuleTest.java

sql/src/main/java/org/apache/druid/sql/calcite/rule/DruidJoinRule.java

clintropolis · 2023-11-28T10:05:56Z

sql/src/main/java/org/apache/druid/sql/calcite/rule/DruidJoinRule.java

+      // I am not sure in what case, the list of system fields will be not empty. I have just picked up this logic
+      // directly from https://github.com/apache/calcite/blob/calcite-1.35.0/core/src/main/java/org/apache/calcite/rel/rules/AbstractJoinExtractFilterRule.java#L58


what is systemFieldList? i dug around a bit and isnt super obvious to me 🙃

* @param systemFieldList List of system fields that will be prefixed to * output row type; typically empty but must not be * null

or Returns a list of system fields that will be prefixed to output row type. are all that i can find but i don't quite fully understand what it means

I am not sure either. I had asked @kgyrtkirk, and he didn't have any answer either. Maybe @gianm knows since he was exchanging emails with calcite community recently over other kind of system fields (like file names in input format).
In any case, I don't think this list will ever be non-empty based on its usages I found in calcite.

abhishekagarwal87 · 2023-11-29T08:16:23Z

Thank you @clintropolis and @soumyava for review.

…pache#15302) This PR revives apache#14978 with a few more bells and whistles. Instead of an unconditional cross-join, we will now split the join condition such that some conditions are now evaluated post-join. To decide what sub-condition goes where, I have refactored DruidJoinRule class to extract unsupported sub-conditions. We build a postJoinFilter out of these unsupported sub-conditions and push to the join.

…lter rule (#15511) FILTER_INTO_JOIN is mainly run along with the other rules with the Volcano planner; however if the query starts highly underdefined (join conditions in the where clauses) that generic query could give a lot of room for the other rules to play around with only enabled it for when the join uses subqueries for its inputs. PROJECT_FILTER rule is not that useful. and could increase planning times by providing new plans. This problem worsened after we started supporting inner joins with arbitrary join conditions in #15302

maytasm · 2024-05-21T04:28:17Z

@abhishekagarwal87 This doesn't work if we are running in useDefaultValueForNull (Legacy) mode right?

abhishekagarwal87 · 2024-05-21T06:14:17Z

@maytasm Yes

gianm and others added 2 commits November 1, 2023 16:48

Inequality join

f26dc2e

Merge with master

44ff897

github-actions bot added Area - Documentation Area - Batch Ingestion Area - Querying Area - MSQ For multi stage queries - https://github.com/apache/druid/issues/12262 labels Nov 1, 2023

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abhishekagarwal87 added 6 commits November 2, 2023 17:07

fix static rules

808b608

Merge branch 'master' of github.com:apache/druid into inequality_join

f23915f

Merge branch 'master' of github.com:apache/druid into inequality_join

4bd1801

Pull condition handling into DruidJoinRule

d9ca64f

some changes

1aa076f

Some more fixes

259ef9b

abhishekagarwal87 marked this pull request as ready for review November 8, 2023 09:40

abhishekagarwal87 added the Release Notes label Nov 8, 2023

abhishekagarwal87 added 2 commits November 8, 2023 17:57

Fix tests

5e9e33e

try again

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soumyava reviewed Nov 14, 2023

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Fix spelling

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github-advanced-security bot found potential problems Nov 24, 2023

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abhishekagarwal87 added 4 commits November 25, 2023 18:45

Fix other tests

7a29c85

Fix again

d1ede2f

Fix MSQSelectTest

b868756

Fix CalciteSelectQueryMSQTest

2b5026e

github-actions bot added the Area - Segment Format and Ser/De label Nov 26, 2023

abhishekagarwal87 added 2 commits November 26, 2023 22:00

Revert "Fix CalciteSelectQueryMSQTest"

14d5a5e

This reverts commit 2b5026e.

Add the right change

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github-actions bot removed the Area - Segment Format and Ser/De label Nov 26, 2023

abhishekagarwal87 commented Nov 27, 2023

View reviewed changes

clintropolis reviewed Nov 28, 2023

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clintropolis approved these changes Nov 28, 2023

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Minor refactoring

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abhishekagarwal87 merged commit 0a56c87 into apache:master Nov 29, 2023
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LakshSingla added this to the 29.0.0 milestone Jan 29, 2024

LakshSingla mentioned this pull request Feb 13, 2024

[DRAFT] 29.0.0 release notes #15896

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SQL: Plan non-equijoin conditions as cross join followed by filter #15302

SQL: Plan non-equijoin conditions as cross join followed by filter #15302

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maytasm commented May 21, 2024

abhishekagarwal87 commented May 21, 2024

		// I am not sure in what case, the list of system fields will be not empty. I have just picked up this logic
		// directly from https://github.com/apache/calcite/blob/calcite-1.35.0/core/src/main/java/org/apache/calcite/rel/rules/AbstractJoinExtractFilterRule.java#L58

SQL: Plan non-equijoin conditions as cross join followed by filter #15302

SQL: Plan non-equijoin conditions as cross join followed by filter #15302

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