26.4.4.22 ps_trace_statement_digest()过程
跟踪所有 Performance Schema 检测以获取特定的语句摘要。
如果在 Performance Schema events_statements_summary_by_digesttable 中找到感兴趣的声明，请为此过程指定其DIGEST列 MD5 值，并指示轮询持续时间和间隔。结果是该时间间隔内该摘要的“性能模式”中跟踪的所有统计信息的报告。
该过程还将尝试在该间隔期间为摘要的最长运行示例执行EXPLAIN。该尝试可能会失败，因为性能架构会截断长SQL_TEXT值。因此，EXPLAIN将由于解析错误而失败。
此过程通过操纵sql_log_bin系统变量的会话值来在执行过程中禁用二进制日志记录。那是一个受限的操作，因此该过程需要足以设置受限会话变量的特权。参见第 5.1.8.1 节“系统变量特权”。
Parameters
-
in_digest VARCHAR(32)：要分析的语句摘要标识符。 -
in_runtime INT：以秒为单位运行分析的时间。 -
in_interval DECIMAL(2,2)：尝试拍摄快照的时间间隔(以秒为单位)(可以是分数)。 -
in_start_fresh BOOLEAN：在开始之前是否截断 Performance Schema events_statements_history_long和events_stages_history_longtable。 -
in_auto_enable BOOLEAN：是否自动启用所需的使用者。
Example
mysql> CALL sys.ps_trace_statement_digest('891ec6860f98ba46d89dd20b0c03652c', 10, 0.1, TRUE, TRUE);
+--------------------+
| SUMMARY STATISTICS |
+--------------------+
| SUMMARY STATISTICS |
+--------------------+
1 row in set (9.11 sec)
+------------+-----------+-----------+-----------+---------------+------------+------------+
| executions | exec_time | lock_time | rows_sent | rows_examined | tmp_tables | full_scans |
+------------+-----------+-----------+-----------+---------------+------------+------------+
| 21 | 4.11 ms | 2.00 ms | 0 | 21 | 0 | 0 |
+------------+-----------+-----------+-----------+---------------+------------+------------+
1 row in set (9.11 sec)
+------------------------------------------+-------+-----------+
| event_name | count | latency |
+------------------------------------------+-------+-----------+
| stage/sql/checking query cache for query | 16 | 724.37 us |
| stage/sql/statistics | 16 | 546.92 us |
| stage/sql/freeing items | 18 | 520.11 us |
| stage/sql/init | 51 | 466.80 us |
...
| stage/sql/cleaning up | 18 | 11.92 us |
| stage/sql/executing | 16 | 6.95 us |
+------------------------------------------+-------+-----------+
17 rows in set (9.12 sec)
+---------------------------+
| LONGEST RUNNING STATEMENT |
+---------------------------+
| LONGEST RUNNING STATEMENT |
+---------------------------+
1 row in set (9.16 sec)
+-----------+-----------+-----------+-----------+---------------+------------+-----------+
| thread_id | exec_time | lock_time | rows_sent | rows_examined | tmp_tables | full_scan |
+-----------+-----------+-----------+-----------+---------------+------------+-----------+
| 166646 | 618.43 us | 1.00 ms | 0 | 1 | 0 | 0 |
+-----------+-----------+-----------+-----------+---------------+------------+-----------+
1 row in set (9.16 sec)
# Truncated for clarity...
+-----------------------------------------------------------------+
| sql_text |
+-----------------------------------------------------------------+
| select hibeventhe0_.id as id1382_, hibeventhe0_.createdTime ... |
+-----------------------------------------------------------------+
1 row in set (9.17 sec)
+------------------------------------------+-----------+
| event_name | latency |
+------------------------------------------+-----------+
| stage/sql/init | 8.61 us |
| stage/sql/Waiting for query cache lock | 453.23 us |
| stage/sql/init | 331.07 ns |
| stage/sql/checking query cache for query | 43.04 us |
...
| stage/sql/freeing items | 30.46 us |
| stage/sql/cleaning up | 662.13 ns |
+------------------------------------------+-----------+
18 rows in set (9.23 sec)
+----+-------------+--------------+-------+---------------+-----------+---------+-------------+------+-------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+--------------+-------+---------------+-----------+---------+-------------+------+-------+
| 1 | SIMPLE | hibeventhe0_ | const | fixedTime | fixedTime | 775 | const,const | 1 | NULL |
+----+-------------+--------------+-------+---------------+-----------+---------+-------------+------+-------+
1 row in set (9.27 sec)
Query OK, 0 rows affected (9.28 sec)
