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SQL: Fix bug regarding histograms usage in scripting (#36866)
Allow scripts to correctly reference grouping functions Fix bug in translation of date/time functions mixed with histograms. Enhance Verifier to prevent histograms being nested inside other functions inside GROUP BY (as it implies double grouping) Extend Histogram docs (cherry picked from commit ac032a0)
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‎docs/reference/sql/functions/grouping.asciidoc‎

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@@ -36,6 +36,8 @@ The histogram function takes all matching values and divides them into buckets w
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bucket_key = Math.floor(value / interval) * interval
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----
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NOTE:: The histogram in SQL does *NOT* return empty buckets for missing intervals as the traditional <<search-aggregations-bucket-histogram-aggregation, histogram>> and <<search-aggregations-bucket-datehistogram-aggregation, date histogram>>. Such behavior does not fit conceptually in SQL which treats all missing values as `NULL`; as such the histogram places all missing values in the `NULL` group.
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`Histogram` can be applied on either numeric fields:
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@@ -51,4 +53,26 @@ or date/time fields:
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include-tagged::{sql-specs}/docs.csv-spec[histogramDate]
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----
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Expressions inside the histogram are also supported as long as the
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return type is numeric:
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs.csv-spec[histogramNumericExpression]
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----
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Do note that histograms (and grouping functions in general) allow custom expressions but cannot have any functions applied to them in the `GROUP BY`. In other words, the following statement is *NOT* allowed:
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs.csv-spec[expressionOnHistogramNotAllowed]
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----
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as it requires two groupings (one for histogram followed by a second for applying the function on top of the histogram groups).
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Instead one can rewrite the query to move the expression on the histogram _inside_ of it:
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs.csv-spec[histogramDateExpression]
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----

‎x-pack/plugin/sql/qa/src/main/resources/agg.csv-spec‎

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Original file line numberDiff line numberDiff line change
@@ -262,9 +262,51 @@ SELECT HISTOGRAM(birth_date, INTERVAL 1 YEAR) AS h, COUNT(*) as c FROM test_emp
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null |10
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;
264264

265-
histogramDateWithDateFunction-Ignore
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SELECT YEAR(HISTOGRAM(birth_date, INTERVAL 1 YEAR)) AS h, COUNT(*) as c FROM test_emp GROUP BY h ORDER BY h DESC;
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histogramDateWithMonthOnTop
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schema::h:i|c:l
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SELECT HISTOGRAM(MONTH(birth_date), 2) AS h, COUNT(*) as c FROM test_emp GROUP BY h ORDER BY h DESC;
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h | c
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---------------+---------------
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12 |7
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10 |17
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8 |16
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6 |16
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4 |18
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2 |10
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0 |6
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null |10
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;
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histogramDateWithYearOnTop
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schema::h:i|c:l
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SELECT HISTOGRAM(YEAR(birth_date), 2) AS h, COUNT(*) as c FROM test_emp GROUP BY h ORDER BY h DESC;
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h | c
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---------------+---------------
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1964 |5
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1962 |13
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1960 |16
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1958 |16
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1956 |9
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1954 |12
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1952 |19
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null |10
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;
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268-
269-
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histogramNumericWithExpression
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schema::h:i|c:l
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SELECT HISTOGRAM(emp_no % 100, 10) AS h, COUNT(*) as c FROM test_emp GROUP BY h ORDER BY h DESC;
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h | c
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---------------+---------------
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90 |10
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80 |10
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70 |10
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60 |10
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50 |10
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40 |10
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30 |10
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20 |10
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10 |10
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0 |10
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;

‎x-pack/plugin/sql/qa/src/main/resources/docs.csv-spec‎

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@@ -725,6 +725,27 @@ SELECT HISTOGRAM(salary, 5000) AS h FROM emp GROUP BY h;
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// end::histogramNumeric
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;
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histogramNumericExpression
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schema::h:i|c:l
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// tag::histogramNumericExpression
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SELECT HISTOGRAM(salary % 100, 10) AS h, COUNT(*) AS c FROM emp GROUP BY h;
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h | c
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---------------+---------------
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0 |10
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10 |15
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20 |10
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30 |14
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40 |9
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50 |9
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60 |8
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70 |13
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80 |3
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90 |9
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// end::histogramNumericExpression
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;
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histogramDate
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schema::h:ts|c:l
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// tag::histogramDate
@@ -752,6 +773,30 @@ null |10
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// end::histogramDate
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;
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expressionOnHistogramNotAllowed-Ignore
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// tag::expressionOnHistogramNotAllowed
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SELECT MONTH(HISTOGRAM(birth_date), 2)) AS h, COUNT(*) as c FROM emp GROUP BY h ORDER BY h DESC;
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// end::expressionOnHistogramNotAllowed
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histogramDateExpression
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schema::h:i|c:l
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// tag::histogramDateExpression
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SELECT HISTOGRAM(MONTH(birth_date), 2) AS h, COUNT(*) as c FROM emp GROUP BY h ORDER BY h DESC;
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h | c
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---------------+---------------
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12 |7
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10 |17
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8 |16
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6 |16
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4 |18
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2 |10
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0 |6
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null |10
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// end::histogramDateExpression
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;
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///////////////////////////////
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//
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// Date/Time

‎x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/analysis/analyzer/Verifier.java‎

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@@ -18,6 +18,8 @@
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import org.elasticsearch.xpack.sql.expression.function.FunctionAttribute;
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import org.elasticsearch.xpack.sql.expression.function.Functions;
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import org.elasticsearch.xpack.sql.expression.function.Score;
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import org.elasticsearch.xpack.sql.expression.function.aggregate.AggregateFunctionAttribute;
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import org.elasticsearch.xpack.sql.expression.function.grouping.GroupingFunctionAttribute;
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import org.elasticsearch.xpack.sql.expression.function.scalar.ScalarFunction;
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import org.elasticsearch.xpack.sql.expression.predicate.conditional.ConditionalFunction;
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import org.elasticsearch.xpack.sql.expression.predicate.operator.comparison.In;
@@ -224,6 +226,7 @@ Collection<Failure> verify(LogicalPlan plan) {
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validateConditional(p, localFailures);
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checkFilterOnAggs(p, localFailures);
229+
checkFilterOnGrouping(p, localFailures);
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if (!groupingFailures.contains(p)) {
229232
checkGroupBy(p, localFailures, resolvedFunctions, groupingFailures);
@@ -419,7 +422,7 @@ private static boolean checkGroupByHavingHasOnlyAggs(Expression e, Node<?> sourc
419422
return true;
420423
}
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// skip aggs (allowed to refer to non-group columns)
422-
if (Functions.isAggregate(e)) {
425+
if (Functions.isAggregate(e) || Functions.isGrouping(e)) {
423426
return true;
424427
}
425428

@@ -448,6 +451,21 @@ private static boolean checkGroupByAgg(LogicalPlan p, Set<Failure> localFailures
448451
}
449452
}));
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454+
a.groupings().forEach(e -> {
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if (Functions.isGrouping(e) == false) {
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e.collectFirstChildren(c -> {
457+
if (Functions.isGrouping(c)) {
458+
localFailures.add(fail(c,
459+
"Cannot combine [%s] grouping function inside GROUP BY, found [%s];"
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+ " consider moving the expression inside the histogram",
461+
Expressions.name(c), Expressions.name(e)));
462+
return true;
463+
}
464+
return false;
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});
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}
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});
468+
451469
if (!localFailures.isEmpty()) {
452470
return false;
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}
@@ -547,19 +565,30 @@ private static void checkFilterOnAggs(LogicalPlan p, Set<Failure> localFailures)
547565
if (p instanceof Filter) {
548566
Filter filter = (Filter) p;
549567
if ((filter.child() instanceof Aggregate) == false) {
550-
filter.condition().forEachDown(f -> {
551-
if (Functions.isAggregate(f) || Functions.isGrouping(f)) {
552-
String type = Functions.isAggregate(f) ? "aggregate" : "grouping";
553-
localFailures.add(fail(f,
554-
"Cannot use WHERE filtering on %s function [%s], use HAVING instead", type, Expressions.name(f)));
568+
filter.condition().forEachDown(e -> {
569+
if (Functions.isAggregate(e) || e instanceof AggregateFunctionAttribute) {
570+
localFailures.add(
571+
fail(e, "Cannot use WHERE filtering on aggregate function [%s], use HAVING instead", Expressions.name(e)));
555572
}
556-
557-
}, Function.class);
573+
}, Expression.class);
558574
}
559575
}
560576
}
561577

562578

579+
private static void checkFilterOnGrouping(LogicalPlan p, Set<Failure> localFailures) {
580+
if (p instanceof Filter) {
581+
Filter filter = (Filter) p;
582+
filter.condition().forEachDown(e -> {
583+
if (Functions.isGrouping(e) || e instanceof GroupingFunctionAttribute) {
584+
localFailures
585+
.add(fail(e, "Cannot filter on grouping function [%s], use its argument instead", Expressions.name(e)));
586+
}
587+
}, Expression.class);
588+
}
589+
}
590+
591+
563592
private static void checkForScoreInsideFunctions(LogicalPlan p, Set<Failure> localFailures) {
564593
// Make sure that SCORE is only used in "top level" functions
565594
p.forEachExpressions(e ->
@@ -647,4 +676,4 @@ private static boolean areTypesCompatible(DataType left, DataType right) {
647676
(left.isNumeric() && right.isNumeric());
648677
}
649678
}
650-
}
679+
}

‎x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/function/scalar/whitelist/InternalSqlScriptUtils.java‎

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@@ -346,6 +346,9 @@ public static Integer weekOfYear(Object dateTime, String tzId) {
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}
347347

348348
public static ZonedDateTime asDateTime(Object dateTime) {
349+
if (dateTime == null) {
350+
return null;
351+
}
349352
if (dateTime instanceof JodaCompatibleZonedDateTime) {
350353
return ((JodaCompatibleZonedDateTime) dateTime).getZonedDateTime();
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}

‎x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/gen/script/Grouping.java‎

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@@ -0,0 +1,24 @@
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/*
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* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
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* or more contributor license agreements. Licensed under the Elastic License;
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* you may not use this file except in compliance with the Elastic License.
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*/
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package org.elasticsearch.xpack.sql.expression.gen.script;
7+
8+
import org.elasticsearch.xpack.sql.expression.function.grouping.GroupingFunctionAttribute;
9+
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class Grouping extends Param<GroupingFunctionAttribute> {
11+
12+
Grouping(GroupingFunctionAttribute groupRef) {
13+
super(groupRef);
14+
}
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String groupName() {
17+
return value().functionId();
18+
}
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@Override
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public String prefix() {
22+
return "g";
23+
}
24+
}

‎x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/gen/script/Params.java‎

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Original file line numberDiff line numberDiff line change
@@ -85,25 +85,15 @@ Map<String, String> asAggPaths() {
8585
String s = a.aggProperty() != null ? a.aggProperty() : a.aggName();
8686
map.put(p.prefix() + aggs++, s);
8787
}
88-
}
89-
90-
return map;
91-
}
92-
93-
// return the agg refs
94-
List<String> asAggRefs() {
95-
List<String> refs = new ArrayList<>();
96-
97-
for (Param<?> p : params) {
98-
if (p instanceof Agg) {
99-
refs.add(((Agg) p).aggName());
88+
if (p instanceof Grouping) {
89+
Grouping g = (Grouping) p;
90+
map.put(p.prefix() + aggs++, g.groupName());
10091
}
10192
}
10293

103-
return refs;
94+
return map;
10495
}
10596

106-
10797
private static List<Param<?>> flatten(List<Param<?>> params) {
10898
List<Param<?>> flatten = emptyList();
10999

@@ -116,6 +106,9 @@ private static List<Param<?>> flatten(List<Param<?>> params) {
116106
else if (p instanceof Agg) {
117107
flatten.add(p);
118108
}
109+
else if (p instanceof Grouping) {
110+
flatten.add(p);
111+
}
119112
else if (p instanceof Var) {
120113
flatten.add(p);
121114
}
@@ -131,4 +124,4 @@ else if (p instanceof Var) {
131124
public String toString() {
132125
return params.toString();
133126
}
134-
}
127+
}

‎x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/gen/script/ParamsBuilder.java‎

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Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@
66
package org.elasticsearch.xpack.sql.expression.gen.script;
77

88
import org.elasticsearch.xpack.sql.expression.function.aggregate.AggregateFunctionAttribute;
9+
import org.elasticsearch.xpack.sql.expression.function.grouping.GroupingFunctionAttribute;
910

1011
import java.util.ArrayList;
1112
import java.util.List;
@@ -28,6 +29,11 @@ public ParamsBuilder agg(AggregateFunctionAttribute agg) {
2829
return this;
2930
}
3031

32+
public ParamsBuilder grouping(GroupingFunctionAttribute grouping) {
33+
params.add(new Grouping(grouping));
34+
return this;
35+
}
36+
3137
public ParamsBuilder script(Params ps) {
3238
params.add(new Script(ps));
3339
return this;

‎x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/gen/script/ScriptTemplate.java‎

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Original file line numberDiff line numberDiff line change
@@ -44,10 +44,6 @@ public Params params() {
4444
return params;
4545
}
4646

47-
public List<String> aggRefs() {
48-
return params.asAggRefs();
49-
}
50-
5147
public Map<String, String> aggPaths() {
5248
return params.asAggPaths();
5349
}

‎x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/gen/script/ScriptWeaver.java‎

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Original file line numberDiff line numberDiff line change
@@ -12,6 +12,7 @@
1212
import org.elasticsearch.xpack.sql.expression.Expressions;
1313
import org.elasticsearch.xpack.sql.expression.FieldAttribute;
1414
import org.elasticsearch.xpack.sql.expression.function.aggregate.AggregateFunctionAttribute;
15+
import org.elasticsearch.xpack.sql.expression.function.grouping.GroupingFunctionAttribute;
1516
import org.elasticsearch.xpack.sql.expression.function.scalar.ScalarFunctionAttribute;
1617
import org.elasticsearch.xpack.sql.expression.literal.IntervalDayTime;
1718
import org.elasticsearch.xpack.sql.expression.literal.IntervalYearMonth;
@@ -37,6 +38,9 @@ default ScriptTemplate asScript(Expression exp) {
3738
if (attr instanceof AggregateFunctionAttribute) {
3839
return scriptWithAggregate((AggregateFunctionAttribute) attr);
3940
}
41+
if (attr instanceof GroupingFunctionAttribute) {
42+
return scriptWithGrouping((GroupingFunctionAttribute) attr);
43+
}
4044
if (attr instanceof FieldAttribute) {
4145
return scriptWithField((FieldAttribute) attr);
4246
}
@@ -83,6 +87,16 @@ default ScriptTemplate scriptWithAggregate(AggregateFunctionAttribute aggregate)
8387
dataType());
8488
}
8589

90+
default ScriptTemplate scriptWithGrouping(GroupingFunctionAttribute grouping) {
91+
String template = "{}";
92+
if (grouping.dataType() == DataType.DATE) {
93+
template = "{sql}.asDateTime({})";
94+
}
95+
return new ScriptTemplate(processScript(template),
96+
paramsBuilder().grouping(grouping).build(),
97+
dataType());
98+
}
99+
86100
default ScriptTemplate scriptWithField(FieldAttribute field) {
87101
return new ScriptTemplate(processScript("doc[{}].value"),
88102
paramsBuilder().variable(field.name()).build(),

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