import org.apache.spark.sql.catalyst.optimizer.PushDownPredicate
val q = visits
.groupBy("city")
.pivot("year")
.count()
.where($"city" === "Boston")
val pivotPlanAnalyzed = q.queryExecution.analyzed
scala> println(pivotPlanAnalyzed.numberedTreeString)
00 Filter (city#8 = Boston)
01 +- Project [city#8, __pivot_count(1) AS `count` AS `count(1) AS ``count```#142[0] AS 2015#143L, __pivot_count(1) AS `count` AS `count(1) AS ``count```#142[1] AS 2016#144L, __pivot_count(1) AS `count` AS `count(1) AS ``count```#142[2] AS 2017#145L]
02 +- Aggregate [city#8], [city#8, pivotfirst(year#9, count(1) AS `count`#134L, 2015, 2016, 2017, 0, 0) AS __pivot_count(1) AS `count` AS `count(1) AS ``count```#142]
03 +- Aggregate [city#8, year#9], [city#8, year#9, count(1) AS count(1) AS `count`#134L]
04 +- Project [_1#3 AS id#7, _2#4 AS city#8, _3#5 AS year#9]
05 +- LocalRelation [_1#3, _2#4, _3#5]
val afterPushDown = PushDownPredicate(pivotPlanAnalyzed)
scala> println(afterPushDown.numberedTreeString)
00 Project [city#8, __pivot_count(1) AS `count` AS `count(1) AS ``count```#142[0] AS 2015#143L, __pivot_count(1) AS `count` AS `count(1) AS ``count```#142[1] AS 2016#144L, __pivot_count(1) AS `count` AS `count(1) AS ``count```#142[2] AS 2017#145L]
01 +- Aggregate [city#8], [city#8, pivotfirst(year#9, count(1) AS `count`#134L, 2015, 2016, 2017, 0, 0) AS __pivot_count(1) AS `count` AS `count(1) AS ``count```#142]
02 +- Aggregate [city#8, year#9], [city#8, year#9, count(1) AS count(1) AS `count`#134L]
03 +- Project [_1#3 AS id#7, _2#4 AS city#8, _3#5 AS year#9]
04 +- Filter (_2#4 = Boston)
05 +- LocalRelation [_1#3, _2#4, _3#5]Aggregate Unary Logical Operator
Aggregate is a unary logical operator that holds the following:
-
Grouping expressions
-
Aggregate named expressions
-
Child logical plan
Aggregate is created to represent the following after a logical plan is analyzed:
-
SQL’s GROUP BY clause (possibly with
WITH CUBEorWITH ROLLUP) inAstBuilder -
RelationalGroupedDataset aggregations (e.g. pivot)
-
KeyValueGroupedDataset aggregations
-
AnalyzeColumnCommand
|
Note
|
Aggregate logical operator is translated to one of HashAggregateExec, ObjectHashAggregateExec or SortAggregateExec physical operators in Aggregation execution planning strategy.
|
| Name | Description | ||
|---|---|---|---|
|
Child logical plan's
|
||
|
Attributes of aggregate named expressions
|
||
|
Enabled when:
|
||
|
The (expression) constraints of child logical plan and non-aggregate aggregate named expressions.
|
computeStats Method
|
Caution
|
FIXME |
|
Note
|
computeStats is a part of LogicalPlan Contract to calculating statistics estimates (for cost-based optimizer).
|
Rule-Based Logical Optimization Phase
PushDownPredicate logical plan optimization applies so-called filter pushdown to a Pivot operator when under Filter operator and with all expressions deterministic.