[#255] Refactor temporary tables creation

* Separate the logic between Db2 (global temporary tables)
  and the other databases (local temporary tables).
* Remove custom logic to figure out how to run queries
* Rename ReactiveConnection#executeStatement to
  ReactiveConnection#executeUnprepared

Author: DavideD

hibernate-reactive-core/src/main/java/org/hibernate/reactive/bulk/StatementsWithParameters.java

@@ -10,13 +10,10 @@
 import org.hibernate.engine.spi.QueryParameters;
 import org.hibernate.param.ParameterSpecification;
 import org.hibernate.reactive.adaptor.impl.QueryParametersAdaptor;
-import org.hibernate.reactive.pool.ReactiveConnection;
 import org.hibernate.reactive.session.ReactiveQueryExecutor;
-import org.hibernate.reactive.util.impl.CompletionStages;
 
 import static org.hibernate.reactive.util.impl.CompletionStages.total;
 
-
 /**
  * A list of SQL statements to be executed as a single logical unit.
  * May include both DDL and DML statements.
@@ -35,55 +32,17 @@ public interface StatementsWithParameters {
      */
     ParameterSpecification[][] getParameterSpecifications();
 
-    /**
-     * Is the given statement executed inside the current transaction?
-     *
-     * @return true by default
-     */
-    default boolean isTransactionalStatement(String statement) {
-        return true;
-    }
-
-    /**
-     * Should the result of this statement contribute to the running
-     * updated row count?
-     *
-     * @return false for DDL statements by default
-     */
-    default boolean  isSchemaDefinitionStatement(String statement) {
-        return statement.startsWith("create ")
-            || statement.startsWith("drop ");
-    }
-
     /**
      * Execute the statements using the query parameters
      */
     default CompletionStage<Integer> execute(ReactiveQueryExecutor session, QueryParameters queryParameters) {
         return total( 0, getSqlStatements().length, i -> {
-            final String sql = getSqlStatements()[i];
-            ReactiveConnection connection = session.getReactiveConnection();
-            if ( !isSchemaDefinitionStatement( sql ) ) {
-                final Object[] arguments = QueryParametersAdaptor.arguments(
-                        queryParameters,
-                        getParameterSpecifications()[i],
-                        session.getSharedContract()
-                );
-                return connection.update( sql, arguments );
-            }
-            else if ( isTransactionalStatement( sql ) ) {
-                // a DML statement that should be executed within the
-                // transaction (local temporary tables)
-                return connection.execute( sql )
-                        .thenCompose( CompletionStages::zeroFuture );
-            }
-            else {
-                // a DML statement that should be executed outside the
-                // transaction (global temporary tables)
-                return connection.executeOutsideTransaction( sql )
-                        // ignore errors creating tables, since a create
-                        // table fails whenever the table already exists
-                        .handle( (v, x) -> 0 );
-            }
+            final Object[] arguments = QueryParametersAdaptor.arguments(
+                    queryParameters,
+                    getParameterSpecifications()[i],
+                    session.getSharedContract()
+            );
+            return session.getReactiveConnection().update( getSqlStatements()[i], arguments );
         } );
     }
 }