SQL性能分析
本文提供了一段SQL查询语句，用于分析数据库性能。该查询通过计算命中率和每次执行的读取次数来评估SQL语句的效率。具体而言，它筛选出执行次数大于0且缓存获取次数大于0的SQL语句，并进一步筛选出命中率低于80%的语句进行性能分析。
SELECT EXECUTIONS,
DISK_READS,
BUFFER_GETS,
ROUND((BUFFER_GETS - DISK_READS) / BUFFER_GETS, 2) Hit_radio,
ROUND(DISK_READS / EXECUTIONS, 2) Reads_per_run,
SQL_TEXT
FROM V$SQLAREA
WHERE EXECUTIONS > 0
AND BUFFER_GETS > 0
AND (BUFFER_GETS - DISK_READS) / BUFFER_GETS < 0.8
ORDER BY 4 DESC;
DISK_READS,
BUFFER_GETS,
ROUND((BUFFER_GETS - DISK_READS) / BUFFER_GETS, 2) Hit_radio,
ROUND(DISK_READS / EXECUTIONS, 2) Reads_per_run,
SQL_TEXT
FROM V$SQLAREA
WHERE EXECUTIONS > 0
AND BUFFER_GETS > 0
AND (BUFFER_GETS - DISK_READS) / BUFFER_GETS < 0.8
ORDER BY 4 DESC;
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