[PATCH] MySQL: Free the results when QSqlQuery::finished() is called

Calling mysql_stmt_free_result() frees the results of the last
executed query while keeping the prepared statement valid. This
allows one to keep around prepared QSqlQueries without the overhead
of keeping all the results in memory.

Change-Id: I4589e90857cc4e9a6f9612799bfca967a67e2ab2
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Andy Shaw <andy.shaw@qt.io>
Gbp-Pq: Name mysql_free_results_when_qsqlquery_finished_is_called.patch

diff --git a/src/plugins/sqldrivers/mysql/qsql_mysql.cpp b/src/plugins/sqldrivers/mysql/qsql_mysql.cpp
index f2ae3fbc470da911aa6bc76537b2b5350f184b0c..80c0c9c522bd0e89a7e81a6b123c28fa6d574407 100644 (file)
--- a/src/plugins/sqldrivers/mysql/qsql_mysql.cpp
+++ b/src/plugins/sqldrivers/mysql/qsql_mysql.cpp
@@ -197,6 +197,7 @@ protected:
     QSqlRecord record() const override;
     void virtual_hook(int id, void *data) override;
     bool nextResult() override;
+    void detachFromResultSet() override;
 
 #if MYSQL_VERSION_ID >= 40108
     bool prepare(const QString &stmt) override;
@@ -804,6 +805,15 @@ int QMYSQLResult::numRowsAffected()
     return d->rowsAffected;
 }
 
+void QMYSQLResult::detachFromResultSet()
+{
+    Q_D(QMYSQLResult);
+
+    if (d->preparedQuery) {
+        mysql_stmt_free_result(d->stmt);
+    }
+}
+
 QVariant QMYSQLResult::lastInsertId() const
 {
     Q_D(const QMYSQLResult);