Oracle数据库的SQL ID

大小写、空格、注释会导致不同SQL ID是吗？答案是肯定的。

参考了Ask Tom两篇文章中的实验:

• Getting SQL ids for a a sqltext
• Two identical queries with same parameter values have different execution plans …

以下6个SQL语句：

select /* this */* from dual;  -- 注释不同 select /* that */* from dual;  -- 大写的FROM select /* this */* FROM dual;  -- 大写首字母From select /* that */* From dual;  -- from之前加了多个空间 select /* this */*     from dual;  -- from之前加了一个Tab select /* that */*  from dual; 

查询SQL ID，结果是六个不同的ID：

select sql_id, sql_text from v$sql where  ( sql_text like '%this%' or sql_text like '%that%' );  SQL_ID SQL_TEXT 3n5uv2khs5hrz select /* this */*     from dual gqrwquv0utrb7 select /* this */* from dual cd8h6juhw5wkk select /* that */* from dual dp4qdmznukfmx select /* this */* FROM dual 3q6usz444fzcx select /* that */* From dual 764k7wbm77d1c select /* that */*  from dual