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한 개의 거짓말을 토한 사람은 이것을 유지하기 위하여 다시 스무 개의 거짓말을 생각해 내지 않을 수 없다. -포우프
2 ini 화일은 뭐죠? #
ODBC가 처음 등장한것은 윈도우즈 3.0에서였습니다. 그당시에는 윈도우즈는 설정정보를 담기위해 .ini 화일을 사용하였습니다. 이는 다음과 같은 형태의 정보를 담고 있는 텍스트화일입니다.
[section1] entry1 = value entry2 = value [section2] entry1 = value entry2 = value ...
윈도우즈 NT에서는 이들 ini화일의 역할이 레지스트리로 대체되었지만, ODBC상에서 접근하는 API는 예전과 똑같이 유지되고 있습니다. 윈도우즈는 odbcinst.dll을 통하여 어플리케이션과 드라이버들이 이 ini 화일들에 질의하고 수정하기위한 두개의 함수를 제공합니다. (SQLGetPrivateProfileString()와 SQLPutPrivateProfileString()) ODBC환경을 윈도우즈 플렛폼이 아닌 다른 플렛폼에서 구현하려는 unixODBC의 목적을 따르기위해서, ini 화일과 libodbcinst 라이브러리는 윈도우즈와 같은 포멧과 기능을 제공하고 있습니다.
3 시스템 vs 사용자 #
ODBC distingushes between two types of ini files. System ini files are designed to be accessable but not modifable by any user, and user files are private to a particular user, and may be modified by that user.
The system files are odbcinst.ini and odbc.ini (note no leading dot), and the user file is ~/.odbc.ini in each user's home directory (note leading dot).
The system file odbcinst.ini contains information about ODBC drivers available to all users, and the odbc.ini file contains information about DSN's available to all users. These "System DSN's" are useful for application such as web servers that may not be running as a real user and so will not have a home directory to contain a .odbc.ini file.
A good example of this is Apache and PHP with ODBC support. When the http server is first started it calls SQLAllocEnv as root. it then at a later time changes to the specified user (in my case nobody) and calls SQLConnect. If the DSN's was not a system DSN then this fails.
4 FILEDSN's #
ODBC 3 also has a third sort of DSN, a file DSN. These store the connection information in a file that may be accessable to anyone. unixODBC does not at this time support FILEDSN's but it will when I get around to it. They are useful things but of less use to UNIX's than NT. Because of the MS view that everyone should have Windows on there desk, each workstation will have it's own registry with it's own set of system and user DSN's that can not be used by other workstations. File DSN's are a fix to allow the information to be stored in a central server that is accessable to all the workstations.
5 Why not vi ? #
All the configuration files needed by unixODBC are plain text files, so there is no reason that you can not use your favorite text editor to setup the files.
However since beta 1.6 the location of the system files odbcinst.ini and odbc.ini are determined by the configure script. The default location is /usr/local/etc, and if a prefix is specified the location is {prefix}/etc. The location of the etc path can be broken out of the normal prefix tree by specifing --sysconfdir=DIR, so the following will expect the system files to be in the same location as pre 1.6 builds.
./configure --sysconfdir=/etcThe upshot of all this is that if you use odbcinst to configure the files you can be sure that the same path to the files will be used as are used by the driver manager, so the modifications will take effect.
6 What goes into them ? #
Ok now we know a bit of the history of ini files and ODBC so now we need to get to the bit that is actually of use. What you put in them.
6.1 odbcinst.ini #
(이 부분은 보통 rpm으로 해당 DB 드라이버를 설치하면 자동으로 설정됩니다)
This contains a section heading that provides a name for the driver, so for the example below PostgreSQL to indicate a Postgres driver. The following lines contain a description and then the important bits. The Driver and Setup paths point to the ODBC driver and setup libs. The setup lib is used when you click on Add in ODBCConfig to add a new DSN, but as this document is about not using the GUI tools, this is not that important for us. Far more important is the Driver entry (vital in fact) This is the library that the driver manager will dynamicaly load when SQLConnect or SQLDriverConnect is called for that DSN. If this points to the wrong place the DSN will not work. If the dlopen() fails the DSN will not work. The fileusage entry is added by the odbcinst program, so if you are using a text editor, you will need to add it yourself.
[PostgreSQL] Description = PostgreSQL driver for Linux & Win32 Driver = /usr/local/lib/libodbcpsql.so Setup = /usr/local/lib/libodbcpsqlS.so FileUsage = 1
6.2 templates #
odbcinst expects to be supplied with a template file. If you are adding a driver for the above entry the template file would contain the following
[PostgreSQL] Description = PostgreSQL driver for Linux & Win32 Driver = /usr/local/lib/libodbcpsql.so Setup = /usr/local/lib/libodbcpsqlS.so
and you would invoke odbcinst with the following arguments, assuming that you have created a file template_file with the above entries in.
odbcinst -i -d -f template_file
The args to odbcinst are as follows
-i install -d driver -f name of template file
6.3 Threads #
Since 1.6 if the driver manager was built with thread support you may add another entry to each driver entry. For example
[PostgreSQL] Description = PostgreSQL driver for Linux & Win32 Driver = /usr/local/lib/libodbcpsql.so Setup = /usr/local/lib/libodbcpsqlS.so Threading = 2
This entry alters the default thread serialization level. More details can be found in the file DriverManager/__handles.c in the source tree.
6.4 [.]odbc.ini #
The contents of the odbc.ini files are a bit more complicated, but they follow just the same format as the odbcinst.ini entries. These are complicated by each driver requiring different entries. The entries for all the drivers supplied with the distribution are included bellow for reference. The entries may be added in the same way using odbcinst, or a text editor. A sample entry to match the above driver could be
[PostgreSQL] Description = Test to Postgres Driver = PostgreSQL Trace = Yes TraceFile = sql.log Database = nick Servername = localhost UserName = Password = Port = 5432 Protocol = 6.4 ReadOnly = No RowVersioning = No ShowSystemTables = No ShowOidColumn = No FakeOidIndex = No ConnSettings =
And this may be written to a template file, and inserted in the ini file for the current user by
odbcinst -i -s -f template_file
The individual entries of course may vary.
The Driver line is used to match the section entry in the odbcinst.ini file and the the Driver line in the odbcinst file is used to find the path for the driver library, and this loaded and the connection is then established. It's possible to replace the driver entry with a path to the driver itself. This can be used, for example if the user can't get root access to setup anything in /etc (less important now because of the movable etc path). For example
[PostgreSQL] Description = Test to Postgres Driver = /usr/local/lib/libodbcpsql.so Trace = Yes TraceFile = sql.log Database = nick Servername = localhost UserName = Password = Port = 5432 Protocol = 6.4 ReadOnly = No RowVersioning = No ShowSystemTables = No ShowOidColumn = No FakeOidIndex = No ConnSettings =
7.1 Postgress #
[PostgreSQL] Description = Test to Postgres Driver = PostgreSQL Trace = Yes TraceFile = sql.log Database = nick Servername = localhost UserName = Password = Port = 5432 Protocol = 6.4 ReadOnly = No RowVersioning = No ShowSystemTables = No ShowOidColumn = No FakeOidIndex = No ConnSettings =
7.2 Mini SQL #
[Mini SQL] Description = MiniSQL Driver = MiniSQL Trace = No TraceFile = Host = localhost Database = ConfigFile =
7.3 MySQL #
[MySQL-test] Description = MySQL test database Trace = Off TraceFile = stderr Driver = MySQL SERVER = 192.168.1.26 USER = pharvey PASSWORD = PORT = 3306 DATABASE = test
7.4 NNTP driver #
[nntp Data Source] Description = nntp Driver Driver = nntp Driver Trace = No TraceFile = Host = localhost Database = Port =
