HHH-18796 Add JSON aggregate support for DB2

Author: beikov

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/DB2LegacyDialect.java

@@ -439,7 +439,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 				functionFactory.jsonArray_db2();
 				functionFactory.jsonArrayAgg_db2();
 				functionFactory.jsonObjectAgg_db2();
-				functionFactory.jsonTable_db2();
+				functionFactory.jsonTable_db2( getMaximumSeriesSize() );
 			}
 		}
 
@@ -459,7 +459,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 		functionFactory.xmlagg();
 		functionFactory.xmltable_db2();
 
-		functionFactory.unnest_emulated();
+		functionFactory.unnest_db2( getMaximumSeriesSize() );
 		if ( supportsRecursiveCTE() ) {
 			functionFactory.generateSeries_recursive( getMaximumSeriesSize(), false, true );
 		}
@@ -1007,7 +1007,9 @@ public <X> ValueExtractor<X> getExtractor(JavaType<X> javaType) {
 
 	@Override
 	public AggregateSupport getAggregateSupport() {
-		return DB2AggregateSupport.INSTANCE;
+		return getDB2Version().isSameOrAfter( 11 )
+				? DB2AggregateSupport.JSON_INSTANCE
+				: DB2AggregateSupport.INSTANCE;
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java

@@ -410,7 +410,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 			functionFactory.jsonArray_db2();
 			functionFactory.jsonArrayAgg_db2();
 			functionFactory.jsonObjectAgg_db2();
-			functionFactory.jsonTable_db2();
+			functionFactory.jsonTable_db2( getMaximumSeriesSize() );
 		}
 
 		functionFactory.xmlelement();
@@ -429,7 +429,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 		functionFactory.xmlagg();
 		functionFactory.xmltable_db2();
 
-		functionFactory.unnest_emulated();
+		functionFactory.unnest_db2( getMaximumSeriesSize() );
 		functionFactory.generateSeries_recursive( getMaximumSeriesSize(), false, true );
 	}
 
@@ -1066,7 +1066,9 @@ public <X> ValueExtractor<X> getExtractor(JavaType<X> javaType) {
 
 	@Override
 	public AggregateSupport getAggregateSupport() {
-		return DB2AggregateSupport.INSTANCE;
+		return getDB2Version().isSameOrAfter( 11 )
+				? DB2AggregateSupport.JSON_INSTANCE
+				: DB2AggregateSupport.INSTANCE;
 	}
 
 	@Override