From 97d8be10cd97cf997286ed0ca0a5d8b360fa942e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Vr=C3=A1til?= <dvratil@kde.org>
Date: Sat, 1 Dec 2018 17:56:41 +0100
Subject: [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>
---
 src/plugins/sqldrivers/mysql/qsql_mysql.cpp |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/src/plugins/sqldrivers/mysql/qsql_mysql.cpp
+++ b/src/plugins/sqldrivers/mysql/qsql_mysql.cpp
@@ -193,6 +193,7 @@ 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;
@@ -798,6 +799,15 @@ 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);