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In the Oracle database, the optimizer needs to rely on the collection of statistical information of related objects in order to generate the optimal execution plan. The database can automatically collect the execution plan or use the package DBMS_STATS is collected manually. This article does not explain the collection of general statistics. It ...

---------------------------------------------------------------Table building----------------Determine whether the student table exists declare num number; --Declare parameters num type number begin --start select count(1) into num from user_tables where table_name='student'; if num>0 then execute immediate 'drop table st ...

In Oracle and SQL Server databases, you can set up some complex account password policies, such as locking an account more than N times after a failed login, so can you do the same in MySQL?The answer is that MySQL has similar capabilities, except in MySQL it delays the response time when its login fails beyond the threshold, instead of locking ...

Modifying and listening IP address of oracle Reference and combine these two blogs Modifying and listening IP address of oracle Oracle modify listening IP address In a very simple way, the problem of monitoring is solved. Now let's combine and rearrange it 1. In cmd, enter hostname discovery hostname 2. Modify the ...

In the previous section, we talked about the configuration of haproxy's access control ACL. For a review, please refer to https://www.cnblogs.com/qiuhom-1874/p/12817773.html ; Today let's talk about the configuration of haproxy's https, tcp-based four-tier load balancing, and access control. First let's look at the configuration of haproxy's ht ...

topN query select * from emp where rownum=1 or rownum=2; select * from (select * from emp order by sal desc) where rownum<5; 1 2 Paging query select * from (select rownum no,e.* from(select * from emp order by sal desc) e where rownum<=5) where no>=3; select * from (select rownum no,e.* from(select * from emp order by ...

Environment related: OS: CentOS release 6.6 RAC: 11.2.0.4.0 dual node ASM Library 1. Cause of failure Today, four data files are added in batches. add datafile '+ DATADG' in the second to fourth data file add SQL misses' + '. After oracle successfully adds the first data file, it is found that the second data fil ...

1. Find the most ordered SQL SQL> SELECT HASH_VALUE, SQL_TEXT, SORTS, EXECUTIONS FROM V$SQLAREA ORDER BY SORTS DESC; 2. Find the SQL with the most reads and writes on the disk SQL> SELECT * FROM (SELECT sql_text,disk_reads "total disk" , executions "total exec",disk_reads/executions "disk/exec" FROM v$sql WHERE executions>0 and is_o ...

To facilitate the test, the Demo code is given first: mybatis-oracle-config.xml 1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" 3 "http://mybatis.org/dtd/mybatis-3-config.dtd"> 4 5 <configuration> 6 <properties> 7 <property nam ...

 Classification: Oracle(67) Author's similar articles X This is an Oracle column conversion function: listag() Oracle after version 11.2 can be used, but t ...