Yingyi Bu has uploaded a new change for review.
https://asterix-gerrit.ics.uci.edu/790
Change subject: ASTERIXDB-1382: add examples for SQL++ group-by visitors.
......................................................................
ASTERIXDB-1382: add examples for SQL++ group-by visitors.
Change-Id: I4c125e286bd53126685a0d91a1f4526ebccf9335
---
M
asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/sugar-02/sugar-02.3.query.sqlpp
M
asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupBySugarVisitor.java
M
asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupByVisitor.java
3 files changed, 63 insertions(+), 3 deletions(-)
git pull ssh://asterix-gerrit.ics.uci.edu:29418/asterixdb
refs/changes/90/790/1
diff --git
a/asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/sugar-02/sugar-02.3.query.sqlpp
b/asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/sugar-02/sugar-02.3.query.sqlpp
index e9c3326..e315533 100644
---
a/asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/sugar-02/sugar-02.3.query.sqlpp
+++
b/asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/sugar-02/sugar-02.3.query.sqlpp
@@ -23,5 +23,5 @@
JOIN Incentive i ON e.job_category = i.job_category
JOIN SuperStars s ON e.id = s.id
GROUP BY e.department_id AS deptId
-SELECT deptId as deptId, coll_sum(e.salary + i.bonus) AS star_cost;
+SELECT deptId as deptId, SUM(e.salary + i.bonus) AS star_cost;
diff --git
a/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupBySugarVisitor.java
b/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupBySugarVisitor.java
index ae47264..a2e8a18 100644
---
a/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupBySugarVisitor.java
+++
b/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupBySugarVisitor.java
@@ -50,8 +50,35 @@
import
org.apache.asterix.lang.sqlpp.visitor.base.AbstractSqlppExpressionScopingVisitor;
/**
- * An AST pre-processor to rewrite group-by sugar queries.
+ * An AST pre-processor to rewrite group-by sugar queries, which does the
following transformations:
+ * 1. Rewrite the argument expression of an aggregation function into a
subquery if the argument
+ * expression is not a subquery;
+ * 2. Turn a SQL-92 aggregate function into a SQL++ core aggregate function
when performing 2.
*/
+
+// For example, this visitor turns the following query
+//
+// FROM Employee e
+// JOIN Incentive i ON e.job_category = i.job_category
+// JOIN SuperStars s ON e.id = s.id
+// GROUP BY e.department_id AS deptId
+// GROUP AS eis(e AS e, i AS i, s AS s)
+// SELECT deptId as deptId, SUM(e.salary + i.bonus) AS star_cost;
+//
+// into the following core-version query:
+//
+// FROM Employee e
+// JOIN Incentive i ON e.job_category = i.job_category
+// JOIN SuperStars s ON e.id = s.id
+// GROUP BY e.department_id AS deptId
+// GROUP AS eis(e AS e, i AS i, s AS s)
+// SELECT ELEMENT {
+// 'deptId': deptId,
+// 'star_cost': coll_sum( (FROM eis AS p SELECT ELEMENT p.e.salary +
p.i.bonus) )
+// };
+//
+// where SUM(e.salary + i.bonus) is turned into coll_sum( (FROM eis AS p
SELECT ELEMENT p.e.salary + p.i.bonus) ).
+
public class SqlppGroupBySugarVisitor extends
AbstractSqlppExpressionScopingVisitor {
private final Expression groupVar;
@@ -77,7 +104,8 @@
newExprList.add(newExpr.accept(this, arg));
}
if (rewritten) {
- // Rewrites the SQL-92 function name to core functions.
+ // Rewrites the SQL-92 function name to core functions,
+ // e.g., SUM --> coll_sum
callExpr.setFunctionSignature(FunctionMapUtil.sql92ToCoreAggregateFunction(signature));
}
callExpr.setExprList(newExprList);
diff --git
a/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupByVisitor.java
b/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupByVisitor.java
index c9e7a6e..16e967c 100644
---
a/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupByVisitor.java
+++
b/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupByVisitor.java
@@ -45,6 +45,38 @@
* A pre-processor that adds the group variable as well as its group field
* list into the AST. It will also invoke SQL group-by aggregation sugar
rewritings.
*/
+// This visitor rewrites non-core SQL++ group-by queries into their SQL++ core
version
+// queries. For example, for the non-core query in
+//
asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/sugar-01/sugar-01.3.query.sqlpp,
+//
+// FROM Employee e
+// JOIN Incentive i ON e.job_category = i.job_category
+// JOIN SuperStars s ON e.id = s.id
+// GROUP BY e.department_id AS deptId
+// SELECT deptId as deptId, SUM(e.salary + i.bonus) AS star_cost;
+//
+// this visitor transforms it into the core version in
+//
asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/sugar-01/sugar-01.3.query.sqlpp,
+//
+// FROM Employee e
+// JOIN Incentive i ON e.job_category = i.job_category
+// JOIN SuperStars s ON e.id = s.id
+// GROUP BY e.department_id AS deptId
+// GROUP AS eis(e AS e, i AS i, s AS s)
+// SELECT ELEMENT {
+// 'deptId': deptId,
+// 'star_cost': coll_sum( (FROM eis AS p SELECT ELEMENT p.e.salary +
p.i.bonus) )
+// };
+/**
+ * The transformation include three things:
+ * 1. Add a group variable as well as its definition, e.g., GROUP AS eis(e AS
e, i AS i, s AS s);
+ * 2. Rewrite the argument expression of an aggregation function into a
subquery if the argument
+ * expression is not a subquery;
+ * 3. Turn a SQL-92 aggregate function into a SQL++ core aggregate function
when performing 2, e.g.,
+ * SUM(e.salary + i.bonus) becomes
+ * coll_sum( (FROM eis AS p SELECT ELEMENT p.e.salary + p.i.bonus) ).
+ */
+
public class SqlppGroupByVisitor extends AbstractSqlppExpressionScopingVisitor
{
public SqlppGroupByVisitor(LangRewritingContext context) {
--
To view, visit https://asterix-gerrit.ics.uci.edu/790
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I4c125e286bd53126685a0d91a1f4526ebccf9335
Gerrit-PatchSet: 1
Gerrit-Project: asterixdb
Gerrit-Branch: master
Gerrit-Owner: Yingyi Bu <[email protected]>
