[jOOQ/jOOQ#11767] ROWNUM transformation should avoid creating derived tables if possible

jOOQ/src/main/java/org/jooq/impl/Finder.java

@@ -0,0 +1,90 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Other licenses:
+ * -----------------------------------------------------------------------------
+ * Commercial licenses for this work are available. These replace the above
+ * ASL 2.0 and offer limited warranties, support, maintenance, and commercial
+ * database integrations.
+ *
+ * For more information, please visit: http://www.jooq.org/licenses
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ */
+package org.jooq.impl;
+
+import java.sql.SQLException;
+import java.util.function.Predicate;
+
+import org.jooq.BindContext;
+import org.jooq.Configuration;
+import org.jooq.Field;
+import org.jooq.Param;
+import org.jooq.QueryPart;
+import org.jooq.QueryPartInternal;
+
+/**
+ * A stub {@link BindContext} that acts as a collector of {@link Param}
+ * {@link QueryPart}'s
+ *
+ * @author Lukas Eder
+ */
+final class Finder extends AbstractBindContext {
+
+    private final Predicate<? super QueryPart> find;
+    private final Predicate<? super QueryPart> enter;
+    private boolean                            found;
+
+    Finder(
+        Configuration configuration,
+        Predicate<? super QueryPart> find,
+        Predicate<? super QueryPart> enter
+    ) {
+        super(configuration, null);
+
+        this.find = find;
+        this.enter = enter;
+    }
+
+    @Override
+    protected final void bindInternal(QueryPartInternal internal) {
+        if (found |= find.test(internal))
+            return;
+
+        if (enter.test(internal))
+            super.bindInternal(internal);
+    }
+
+    final boolean found() {
+        return found;
+    }
+
+    @Override
+    protected final BindContext bindValue0(Object value, Field<?> field) throws SQLException {
+        throw new UnsupportedOperationException();
+    }
+}

jOOQ/src/main/java/org/jooq/impl/SelectQueryImpl.java

@@ -495,18 +495,38 @@ final class SelectQueryImpl<R extends Record> extends AbstractResultQuery<R> imp
 
 
 
-    private final SelectQueryImpl<R> copyTo(CopyClause clause, SelectQueryImpl<R> result) {
-        return copyBetween(CopyClause.START, clause, result);
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+    private final SelectQueryImpl<R> copyTo(CopyClause clause, boolean scalarSelect, SelectQueryImpl<R> result) {
+        return copyBetween(CopyClause.START, clause, scalarSelect, result);
     }
 
-    private final SelectQueryImpl<R> copyAfter(CopyClause clause, SelectQueryImpl<R> result) {
-        return copyBetween(clause, CopyClause.END, result);
+    private final SelectQueryImpl<R> copyAfter(CopyClause clause, boolean scalarSelect, SelectQueryImpl<R> result) {
+        return copyBetween(clause, CopyClause.END, scalarSelect, result);
     }
 
-    private final SelectQueryImpl<R> copyBetween(CopyClause start, CopyClause end, SelectQueryImpl<R> result) {
+    private final SelectQueryImpl<R> copyBetween(CopyClause start, CopyClause end, boolean scalarSelect, SelectQueryImpl<R> result) {
         if (CopyClause.START.between(start, end)) {
             result.from.addAll(from);
             result.condition.setWhere(condition.getWhere());
+
+            if (scalarSelect)
+                result.select.addAll(select);
         }
 
         if (CopyClause.WHERE.between(start, end)) {
@@ -525,7 +545,9 @@ final class SelectQueryImpl<R extends Record> extends AbstractResultQuery<R> imp
         }
 
         if (CopyClause.QUALIFY.between(start, end)) {
-            result.select.addAll(select);
+            if (!scalarSelect)
+                result.select.addAll(select);
+
             result.hint = hint;
             result.distinct = distinct;
             result.distinctOn = distinctOn;
@@ -561,7 +583,7 @@ final class SelectQueryImpl<R extends Record> extends AbstractResultQuery<R> imp
     }
 
     private final SelectQueryImpl<R> copy(Function<? super SelectQueryImpl<R>, ? extends SelectQueryImpl<R>> finisher) {
-        return finisher.apply(copyTo(CopyClause.END, new SelectQueryImpl<>(configuration(), with)));
+        return finisher.apply(copyTo(CopyClause.END, false, new SelectQueryImpl<>(configuration(), with)));
     }
 
 
@@ -598,6 +620,11 @@ final class SelectQueryImpl<R extends Record> extends AbstractResultQuery<R> imp
 
 
 
+
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+