java - Oracle JDBC刷新共享池不起作用

我有下面的Java代码比较，可以比较这两个SQL查询的性能。
getNamedStatistics()打印v $ session表中的某些列，例如一致的获取，执行计数等。

尽管我无法刷新oracle的内存，所以我可以比较这两个查询的性能。

        clearOracleMemory();
        start = System.nanoTime();
        System.out.println("Named statistics --> " + getNamedStatistic(statistics, conn));
        query1UsingStatement(conn);
        System.out.println("Named statistics --> " + getNamedStatistic(statistics, conn));
        end = System.nanoTime();
        System.out.println("Took: " + ((end - start) / 1000000) + "ms");

        clearOracleMemory();
        start = System.nanoTime();
        System.out.println("Named statistics --> " + getNamedStatistic(statistics, conn));
        query2UsingStatement(conn);
        System.out.println("Named statistics --> " + getNamedStatistic(statistics, conn));
        end = System.nanoTime();
        System.out.println("Took: " + ((end - start) / 1000000) + "ms");

ClearOracleMemory看起来像这样：

    private static void clearOracleMemory() {
        try {
            PreparedStatement stmt = conn.prepareStatement("alter system flush shared_pool");
            ResultSet rs = stmt.executeQuery();
            System.out.println("shared pool flushed");
        }
        catch (SQLException e) {
            System.out.println("error clearing shared pool");
            System.out.println(e.getMessage());
        }
    }

输出示例：

shared pool flushed
Named statistics --> {CPU used by this session=45, consistent gets=5613, parse count (total)=194, parse time elapsed=14, parse time cpu=14, execute count=1544}

Named statistics --> {CPU used by this session=326, consistent gets=936322, parse count (total)=724, parse time elapsed=58, parse time cpu=60, execute count=3651}
Took: 3676ms

shared pool flushed
Named statistics --> {CPU used by this session=344, consistent gets=942088, parse count (total)=851, parse time elapsed=69, parse time cpu=73, execute count=5319}

Named statistics --> {CPU used by this session=2374, consistent gets=1019846, parse count (total)=20975, parse time elapsed=1728, parse time cpu=1732, execute count=26948}
Took: 28038ms

最佳答案

是什么让您认为共享池没有被刷新？

我怀疑您将共享池和会话统计信息混淆了吗？会话统计信息统计会话中不同资源的消耗情况。刷新共享池会影响您的会话消耗多少资源（因为例如它将需要解析语句），但这显然不会重置资源消耗计数器。

我建议您重新审视分配的读数，在此详细说明。

最好的祝福

您友好的老师，您可以设置您要询问的练习

关于java - Oracle JDBC刷新共享池不起作用，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/40886689/