DB2 10.1中DB2_EVALUNCOMMITTED这个参数是不是没有作用了。

没有抛弃，只是优先使用CC了。

DB2_EVALUNCOMMITTED is only applicable when currently committed semantics will not help avoid lock contentions. When this variable is set and currently committed is applicable to a scan, deleted rows will not be skipped and predicate evaluate will not occur on uncommitted data; the currently committed version of the rows and data will be processed instead.

As well, DB2_EVALUNCOMMITTED is applicable only to statements using either Cursor Stability or Read Stability isolation levels. Furthermore, deleted rows are skipped unconditionally on table scan access while deleted keys are not skipped for index scans unless the registry variable DB2_SKIPDELETED is also set.收起

回复 9# masaly


    非常感谢您的答复，谢谢。

     我觉得DB2也是多此一举，有了CC还搞这3个参数干嘛？会引起误会的。收起

这个参数默认是OFF的，需要通过db2set设置，实例还需重启才生效。

e95fp7@suse1:~/sqllib> db2set DB2_SKIPDELETED=ON
e95fp7@suse1:~/sqllib> db2set
DB2_SKIPDELETED=ON
DB2COMM=tcpip

e95fp7@suse1:~/sqllib> cat profile.env
DB2_SKIPDELETED='ON'
DB2COMM='tcpip'收起

回复 7# masaly


     谢谢，看了您的回复，收益匪浅。

    我能否这么理解，就参数DB2_SKIPINSERTED为例，如果我没有吧这个参数加入到profile中，那么对这些事例来说，这个参数就没有发生作用。收起

1) Display all supported registry variables:   

db2set -lr

2) Display all defined values for the current instance:   

db2set -all

The environment, denoted by [e]
The node level registry, denoted by [n]
The instance level registry, denoted by [i]
The global level registry, denoted by [g].

例如：
e95fp7@suse1:~/sqllib> db2set -all
[i] DB2COMM=tcpip
[g] DB2FCMCOMM=TCPIP4
[g] DB2SYSTEM=suse1

3) Display all defined global variables which are visible by all instances pertaining to a particular installation:   

db2set -g

4) Display all defined variables for the current instance:   

db2set

5) On Linux and UNIX operating systems, the instance-level profile registry is stored in the profile.env text file.收起

回复 5# masaly


      谢谢，但是我发现这2个参数无法使用db2set -all看。

      另外，参数写入profile.env和不写出有什么区别？收起

db2inst1@suse1:~> db2level
DB21085I  This instance or install (instance name, where applicable:
"db2inst1") uses "64" bits and DB2 code release "SQL10055" with level
identifier "0606010E".
Informational tokens are "DB2 v10.5.0.5", "s141128", "IP23633", and Fix Pack
"5".
Product is installed at "/opt/IBM/db2/v105_fp5".

db2inst1@suse1:~> db2set -lr|grep -Ei "DB2_SKIPDELETED|DB2_SKIPINSERTED"
DB2_SKIPDELETED
DB2_SKIPINSERTED收起

回复 3# masaly


    DB2_SKIPDELETED，DB2_SKIPINSERTED

这2个参数在DB2中已经看不到了。收起

发现不光DB2_EVALUNCOMMITTED没有用，而且DB2_SKIPDELETED，DB2_SKIPINSERTED也没有什么用，这3个参数感觉已经被IBM给抛弃了。收起