Easy Connect Naming Method这个东西是Oracle 10g推出的东东，我想不用我解释它的好，dba和开发人员都喜欢它，以前一直都用它，从没有关注到它和sqlnet.ora中的NAMES.DIRECTORY_PATH的关系，昨天一朋友和我说到了EZCONNECT，今天查询了一些资料和做了一些实验，使得自己对NAMES.DIRECTORY_PATH和EZCONNECT有了新的认识，也怪自己一致忽略了这个知识点。

1.NAMES.DIRECTORY_PATH= (TNSNAMES)

[oracle@node1 samples]$ more $ORACLE_HOME/network/admin/sqlnet.ora
#NAMES.DIRECTORY_PATH= (EZCONNECT)
NAMES.DIRECTORY_PATH= (TNSNAMES)
[oracle@node1 samples]$ sqlplus hr/xifenfei@127.0.0.1/ecp
SQL*Plus: Release 10.2.0.5.0 - Production on Wed Feb 8 23:12:12 2012
Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.
ERROR:
ORA-12154: TNS:could not resolve the connect identifier specified
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
SP2-0157: unable to CONNECT to ORACLE after 3 attempts, exiting SQL*Plus

证明sqlnet.ora中的NAMES.DIRECTORY_PATH设置为TNSNAMES时，Easy Connect Naming Method不能工作。

2.NAMES.DIRECTORY_PATH= (EZCONNECT)

[oracle@node1 samples]$ more $ORACLE_HOME/network/admin/sqlnet.ora
NAMES.DIRECTORY_PATH= (EZCONNECT)
#NAMES.DIRECTORY_PATH= (TNSNAMES)
[oracle@node1 samples]$ sqlplus hr/xifenfei@127.0.0.1/ecp
SQL*Plus: Release 10.2.0.5.0 - Production on Wed Feb 8 23:13:21 2012
Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>

登录成功，其实这里生效是因为设置了NAMES.DIRECTORY_PATH为EZCONNECT的功效，从EZCONNECT的上面也可以看出是

3.NAMES.DIRECTORY_PATH为默认值

[oracle@node1 samples]$ more $ORACLE_HOME/network/admin/sqlnet.ora
#NAMES.DIRECTORY_PATH= (EZCONNECT)
#NAMES.DIRECTORY_PATH= (TNSNAMES)
[oracle@node1 samples]$ sqlplus hr/xifenfei@127.0.0.1/ecp
SQL*Plus: Release 10.2.0.5.0 - Production on Wed Feb 8 23:13:49 2012
Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>

当NAMES.DIRECTORY_PATH为默认值时，使用Easy Connect Naming Method也可以登录成功(正是因为这个原因，导致我忽略了EZCONNECT的存在).

4.sqlnet.ora中关于NAMES.DIRECTORY_PATH说明

#names.directory_path
#
#Syntax:  <adapter-name>
#Default: TNSNAMES,ONAMES,HOSTNAME
#
# Sets the (ordered) list of naming adaptors to use in resolving a name.
# The default is as shown for 3.0.2 of sqlnet onwards. The default was
# (TNSNAMES, ONAMES) before that. The value can be presented without
# parentheses if only a single entry is being specified. The parameter is
# recognized from version 2.3.2 of sqlnet onward. Acceptable values include:
#  TNSNAMES -- tnsnames.ora lookup
#  ONAMES   -- Oracle Names
#  HOSTNAME -- use the hostname (or an alias of the hostname)
#  NIS      -- NIS (also known as "yp")
#  CDS      -- OSF DCE's Cell Directory Service
#  NDS      -- Novell's Netware Directory Service

5.关于NAMES.DIRECTORY_PATH参数的补充说明

tnsnames:local naming naming method
Set to resolve a net service name through the tnsnames.ora file on the client.
hostname:host naming method
Set to resolve a host name alias through an existing names resolution service or a centrally-maintained set of /etc/hosts files.
onames:Oracle Names method
Set to resolve database objects through a Oracle Names server.
ldap:directory naming naming method
Set to resolve a database service name, net service name, or net service alias through a directory server.
cds:Cell Directory Services (CDS) external naming method
Set to resolve an Oracle database name in a Distributed Computing Environment (DCE) environment.
nis:Network Information Service (NIS) external naming method
Set to resolve service information through an existing NIS.
Ezconnect:The easy connect naming method eliminates the need for service name lookup in the tnsnames.ora files for TCP/IP environments; in fact, no naming or directory system is required if you use this method.