[jOOQ/jOOQ#13341] Avoid asTable() call when creating scalar subqueries

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

@@ -62,6 +62,7 @@ import org.jooq.Record;
 import org.jooq.RecordMapper;
 import org.jooq.RecordType;
 import org.jooq.Row;
+import org.jooq.Select;
 import org.jooq.SelectField;
 import org.jooq.Table;
 import org.jooq.TableField;
@@ -196,6 +197,14 @@ final class FieldsImpl<R extends Record> extends AbstractQueryPart implements Re
     // RecordType API
     // -------------------------------------------------------------------------
 
+    /**
+     * [#13341] Prevent costly calls to Select.asTable() where not strictly
+     * needed.
+     */
+    static final Row fieldsRow0(FieldsTrait fields) {
+        return fields instanceof Select ? ((Select<?>) fields).asTable("t").fieldsRow() : fields.fieldsRow();
+    }
+
     private static final ThrowingFunction<SelectField<?>, Field<?>, RuntimeException> toField() {
         return f -> f instanceof Row
                   ? new RowAsField<>((Row) f)

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

@@ -37,6 +37,8 @@
  */
 package org.jooq.impl;
 
+import static org.jooq.impl.FieldsImpl.fieldsRow0;
+
 import java.util.stream.Stream;
 
 import org.jooq.DataType;
@@ -174,41 +176,41 @@ interface FieldsTrait extends Fields {
 
     @Override
     default Class<?>[] types() {
-        return fieldsRow().types();
+        return fieldsRow0(this).types();
     }
 
     @Override
     default Class<?> type(int index) {
-        return fieldsRow().type(index);
+        return fieldsRow0(this).type(index);
     }
 
     @Override
     default Class<?> type(String name) {
-        return fieldsRow().type(name);
+        return fieldsRow0(this).type(name);
     }
 
     @Override
     default Class<?> type(Name name) {
-        return fieldsRow().type(name);
+        return fieldsRow0(this).type(name);
     }
 
     @Override
     default DataType<?>[] dataTypes() {
-        return fieldsRow().dataTypes();
+        return fieldsRow0(this).dataTypes();
     }
 
     @Override
     default DataType<?> dataType(int index) {
-        return fieldsRow().dataType(index);
+        return fieldsRow0(this).dataType(index);
     }
 
     @Override
     default DataType<?> dataType(String name) {
-        return fieldsRow().dataType(name);
+        return fieldsRow0(this).dataType(name);
     }
 
     @Override
     default DataType<?> dataType(Name name) {
-        return fieldsRow().dataType(name);
+        return fieldsRow0(this).dataType(name);
     }
 }

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

@@ -3579,7 +3579,7 @@ final class Tools {
 
 
 
-        return map(query.fields(), f -> f.getDataType());
+        return asList(query.dataTypes());
     }
 
     static final DataType<?> scalarType(ResultQuery<?> query) {