+++ /dev/null
-<!--
-$Header: /cvsroot/pgsql/doc/src/sgml/Attic/odbc.sgml,v 1.30 2002/03/22 19:20:16 petere Exp $
--->
-
- <chapter id="odbc">
- <docinfo>
- <authorgroup>
- <author>
- <firstname>Tim</firstname>
- <surname>Goeke</surname>
- </author>
- <author>
- <firstname>Thomas</firstname>
- <surname>Lockhart</surname>
- </author>
- </authorgroup>
- <date>1998-10-21</date>
- </docinfo>
-
- <title>ODBC Interface</title>
-
- <indexterm zone="odbc">
- <primary>ODBC</primary>
- </indexterm>
-
- <sect1 id="odbc-intro">
- <title>Introduction</title>
-
- <note>
- <para>
- Background information originally by Tim Goeke
- (<email>tgoeke@xpressway.com</email>)
- </para>
- </note>
-
- <para>
- <acronym>ODBC</acronym> (Open Database Connectivity) is an abstract
- <acronym>API</acronym>
- that allows you to write applications that can interoperate
- with various <acronym>RDBMS</acronym> servers.
- <acronym>ODBC</acronym> provides a product-neutral interface
- between frontend applications and database servers,
- allowing a user or developer to write applications that are
- portable between servers from different manufacturers..
- </para>
-
- <para>
- The <acronym>ODBC</acronym> <acronym>API</acronym> matches up
- on the backend to an <acronym>ODBC</acronym>-compatible data source.
- This could be anything from a text file to an Oracle or
- <productname>PostgreSQL</productname> <acronym>RDBMS</acronym>.
- </para>
-
- <para>
- The backend access comes from <acronym>ODBC</acronym> drivers,
- or vendor-specific drivers that
- allow data access. <productname>psqlODBC</productname>, which is included in the <productname>PostgreSQL</> distribution, is such a driver,
- along with others that are
- available, such as the <productname>OpenLink</productname> <acronym>ODBC</acronym> drivers.
- </para>
-
- <para>
- Once you write an <acronym>ODBC</acronym> application,
- you <emphasis>should</emphasis> be able to connect to <emphasis>any</emphasis>
- back-end database, regardless of the vendor, as long as the database schema
- is the same.
- </para>
-
- <para>
- For example. you could have <productname>MS SQL Server</productname>
- and <productname>PostgreSQL</productname> servers that have
- exactly the same data. Using <acronym>ODBC</acronym>,
- your Windows application would make exactly the
- same calls and the back-end data source would look the same (to the Windows
- application).
- </para>
- </sect1>
-
- <sect1 id="odbc-install">
- <title>Installation</title>
-
- <para>
- In order to make use of an <acronym>ODBC</> driver there must
- exist a <firstterm>driver manager</> on the system where the
- <acronym>ODBC</> driver is to be used. There are two free
- <acronym>ODBC</> driver managers for Unix-like operating systems
- known to us: <indexterm><primary>iODBC</primary></indexterm>
- <ulink url="http://www.iodbc.org"><productname>iODBC</></ulink>
- and <indexterm><primary>unixODBC</primary></indexterm> <ulink
- url="http://www.unixodbc.org"><productname>unixODBC</></ulink>.
- Instructions for installing these driver managers are to be found
- in the respective distribution. Software that provides database
- access through <acronym>ODBC</acronym> should provide its own
- driver manager (which may well be one of these two). Having said
- that, any driver manager that you can find for your platform
- should support the <productname>PostgreSQL</> <acronym>ODBC</>
- driver, or any other <acronym>ODBC</> driver for that matter.
- </para>
-
- <note>
- <para>
- The <productname>unixODBC</> distribution ships with a
- <productname>PostgreSQL</> <acronym>ODBC</> driver of its own,
- which is similar to the one contained in the
- <productname>PostgreSQL</> distribution. It is up to you which
- one you want to use. We plan to coordinate the development of
- both drivers better in the future.
- </para>
- </note>
-
- <para>
- To install the <acronym>ODBC</> you simply need to supply the
- <option>--enable-odbc</> option to the <filename>configure</>
- script when you are building the entire <productname>PostgreSQL</>
- distribution. The library will then automatically be built and
- installed with the rest of the programs. If you forget that option
- or want to build the ODBC driver later you can change into the
- directory <filename>src/interfaces/odbc</> and do <literal>make</>
- and <literal>make install</> there.
- </para>
-
- <para>
- It is also possible to build the driver to be specifically tuned
- for use with <productname>iODBC</> or <productname>unixODBC</>.
- This means in particular that the driver will use the driver
- manager's routines to process the configuration files, which is
- probably desirable since it creates a more consistent
- <acronym>ODBC</> environment on your system. If you want to do
- that, then supply the <filename>configure</> options
- <option>--with-iodbc</> or <option>--with-unixodbc</> (but not
- both).
- </para>
-
- <para>
- If you build a <quote>stand-alone</quote> driver (not tied to
- <productname>iODBC</> or <productname>unixODBC</>), then you can
- specify where the driver should look for the configuration file
- <filename>odbcinst.ini</>. By default it will be the directory
- <filename>/usr/local/pgsql/etc/</>, or equivalent, depending on
- what <option>--prefix</> and/or <option>--sysconfdir</> options
- you supplied to <filename>configure</>. To select a specific
- location outside the <productname>PostgreSQL</> installation
- layout, use the <option>--with-odbcinst</> option. To be most
- useful, it should be arranged that the driver and the driver
- manager read the same configuration file.
- </para>
-
- <para>
- <indexterm><primary>odbc.sql</></>
- Additionally, you should install the ODBC catalog extensions. That will
- provide a number of functions mandated by the ODBC standard that are not
- supplied by <productname>PostgreSQL</> by default. The file
- <filename>/usr/local/pgsql/share/odbc.sql</> (in the default installation layout)
- contains the appropriate definitions, which you can install as follows:
-<programlisting>
-psql -d template1 -f <replaceable>LOCATION</>/odbc.sql
-</programlisting>
- where specifying <literal>template1</literal> as the target
- database will ensure that all subsequent new databases will have
- these same definitions. If for any reason you want to remove
- these functions again, run the file
- <filename>odbc-drop.sql</filename> through
- <command>psql</command>.
- </para>
- </sect1>
-
- <sect1 id="odbc-config">
- <title>Configuration Files</title>
-
- <indexterm zone="odbc-config"><primary>.odbc.ini</></>
-
- <para>
- <filename>~/.odbc.ini</filename> contains user-specified access information
- for the <productname>psqlODBC</productname> driver.
- The file uses conventions typical for <productname>Windows</productname>
- Registry files.
- </para>
-
- <para>
- The <filename>.odbc.ini</filename> file has three required sections.
- The first is <literal>[ODBC Data Sources]</literal>
- which is a list of arbitrary names and descriptions for each database
- you wish to access. The second required section is the
- Data Source Specification and there will be one of these sections
- for each database.
- Each section must be labeled with the name given in
- <literal>[ODBC Data Sources]</literal> and must contain the following entries:
-
-<programlisting>
-Driver = <replaceable>prefix</replaceable>/lib/libpsqlodbc.so
-Database = <replaceable>DatabaseName</replaceable>
-Servername = localhost
-Port = 5432
-</programlisting>
-
- <tip>
- <para>
- Remember that the <productname>PostgreSQL</productname> database name is
- usually a single word, without path names of any sort.
- The <productname>PostgreSQL</productname> server manages the actual access
- to the database, and you need only specify the name from the client.
- </para>
- </tip>
-
- Other entries may be inserted to control the format of the display.
- The third required section is <literal>[ODBC]</literal>
- which must contain the <literal>InstallDir</literal> keyword
- and which may contain other options.
- </para>
-
- <para>
- Here is an example <filename>.odbc.ini</filename> file,
- showing access information for three databases:
-
-<programlisting>
-[ODBC Data Sources]
-DataEntry = Read/Write Database
-QueryOnly = Read-only Database
-Test = Debugging Database
-Default = Postgres Stripped
-
-[DataEntry]
-ReadOnly = 0
-Servername = localhost
-Database = Sales
-
-[QueryOnly]
-ReadOnly = 1
-Servername = localhost
-Database = Sales
-
-[Test]
-Debug = 1
-CommLog = 1
-ReadOnly = 0
-Servername = localhost
-Username = tgl
-Password = "no$way"
-Port = 5432
-Database = test
-
-[Default]
-Servername = localhost
-Database = tgl
-Driver = /opt/postgres/current/lib/libpsqlodbc.so
-
-[ODBC]
-InstallDir = /opt/applix/axdata/axshlib
-</programlisting>
- </para>
- </sect1>
-
- <sect1 id="odbc-windows">
- <title><productname>Windows</productname> Applications</title>
-
- <para>
- In the real world, differences in drivers and the level of
- <acronym>ODBC</acronym> support
- lessens the potential of <acronym>ODBC</acronym>:
-
- <itemizedlist spacing="compact" mark="bullet">
- <listitem>
- <para>
- Access, Delphi, and Visual Basic all support <acronym>ODBC</acronym> directly.
- </para>
- </listitem>
- <listitem>
- <para>
- Under C++, such as Visual C++,
- you can use the C++ <acronym>ODBC</acronym> <acronym>API</acronym>.
- </para>
- </listitem>
-
- <listitem>
- <para>
- In Visual C++, you can use the <classname>CRecordSet</classname> class, which wraps the
- <acronym>ODBC</acronym> <acronym>API</acronym>
- set within an <application>MFC</application> 4.2 class. This is the easiest route if you are doing
- Windows C++ development under Windows NT.
- </para>
- </listitem>
- </itemizedlist>
- </para>
-
- <sect2>
- <title>Writing Applications</title>
-
- <para>
- <quote>
- If I write an application for <productname>PostgreSQL</productname>
- can I write it using <acronym>ODBC</acronym> calls
- to the <productname>PostgreSQL</productname> server,
- or is that only when another database program
- like MS SQL Server or Access needs to access the data?
- </quote>
- </para>
- <para>
- The <acronym>ODBC</acronym> <acronym>API</acronym>
- is the way to go.
- For <productname>Visual C++</productname> coding you can find out more at
- Microsoft's web site or in your <productname>Visual C++</productname>
- documentation.
- </para>
-
- <para>
- Visual Basic and the other <acronym>RAD</acronym> tools have <classname>Recordset</classname> objects
- that use <acronym>ODBC</acronym>
- directly to access data. Using the data-aware controls, you can quickly
- link to the <acronym>ODBC</acronym> back-end database
- (<emphasis>very</emphasis> quickly).
- </para>
-
- <para>
- Playing around with <productname>MS Access</> will help you sort this out. Try using
- <menuchoice><guimenu>File</><guimenuitem>Get External Data</></menuchoice>.
- </para>
-
- <tip>
- <para>
- You'll have to set up a <acronym>DSN</acronym> first.
- </para>
- </tip>
-
- </sect2>
- </sect1>
-
- <sect1 id="odbc-applixware">
- <title><application>ApplixWare</application></title>
-
- <indexterm zone="odbc-applixware">
- <primary>Applixware</primary>
- </indexterm>
-
- <para>
- <productname>Applixware</productname> has an
- <acronym>ODBC</acronym> database interface
- supported on at least some platforms.
- <productname>Applixware</productname> 4.4.2 has been
- demonstrated under Linux with <productname>PostgreSQL</productname> 7.0
- using the <productname>psqlODBC</productname>
- driver contained in the <productname>PostgreSQL</productname> distribution.
- </para>
-
- <sect2>
- <title>Configuration</title>
-
- <para>
- <productname>Applixware</productname> must be configured correctly
- in order for it to
- be able to access the <productname>PostgreSQL</productname>
- <acronym>ODBC</acronym> software drivers.
- </para>
-
- <procedure>
- <title>Enabling <application>Applixware</application> Database Access</title>
-
- <para>
- These instructions are for the 4.4.2 release of
- <productname>Applixware</productname> on <productname>Linux</productname>.
- Refer to the <citetitle>Linux Sys Admin</citetitle> on-line book
- for more detailed information.
- </para>
-
- <step performance="required">
- <para>
- You must modify <filename>axnet.cnf</filename> so that
- <filename>elfodbc</filename> can
- find <filename>libodbc.so</filename>
- (the <acronym>ODBC</acronym> driver manager) shared library.
- This library is included with the <application>Applixware</application> distribution,
- but <filename>axnet.cnf</filename> needs to be modified to point to the
- correct location.
- </para>
-
- <para>
- As root, edit the file
- <filename><replaceable>applixroot</replaceable>/applix/axdata/axnet.cnf</filename>.
- </para>
-
- <substeps>
-
- <step performance="required">
- <para>
- At the bottom of <filename>axnet.cnf</filename>,
- find the line that starts with
-
-<programlisting>
-#libFor elfodbc /ax/<replaceable>...</replaceable>
-</programlisting>
- </para>
- </step>
- <step performance="required">
- <para>
- Change line to read
-
-<programlisting>
-libFor elfodbc <replaceable>applixroot</replaceable>/applix/axdata/axshlib/lib
-</programlisting>
-
- which will tell <literal>elfodbc</literal> to look in this directory
- for the <acronym>ODBC</acronym> support library.
- Typically <productname>Applix</productname> is installed in
- <filename>/opt</filename> so the full path would be
- <filename>/opt/applix/axdata/axshlib/lib</filename>,
- but if you have installed <productname>Applix</productname>
- somewhere else then change the path accordingly.
- </para>
- </step>
- </substeps>
- </step>
-
- <step performance="required">
- <para>
- Create <filename>.odbc.ini</filename> as
- described in <xref linkend="odbc-config">. You may also want to add the flag
-
-<programlisting>
-TextAsLongVarchar=0
-</programlisting>
-
- to the database-specific portion of <filename>.odbc.ini</filename>
- so that text fields will not be shown as <literal>**BLOB**</literal>.
- </para>
- </step>
- </procedure>
-
- <procedure>
- <title>Testing <application>Applixware</application> ODBC Connections</title>
-
- <step performance="required">
- <para>
- Bring up <application>Applix Data</application>
- </para>
- </step>
-
- <step performance="required">
- <para>
- Select the <productname>PostgreSQL</productname> database of interest.
- </para>
-
- <substeps>
-
- <step performance="required">
- <para>
- Select <menuchoice><guimenu>Query</guimenu><guimenuitem>Choose Server</guimenuitem></menuchoice>.
- </para>
- </step>
- <step performance="required">
- <para>
- Select <guimenuitem>ODBC</guimenuitem>, and click <guibutton>Browse</guibutton>.
- The database you configured in <filename>.odbc.ini</filename>
- should be shown. Make sure that the <guilabel>Host:</guilabel> field
- is empty (if it is not, <literal>axnet</> will try to contact <literal>axnet</> on another machine
- to look for the database).
- </para>
- </step>
- <step performance="required">
- <para>
- Select the database in the box that was launched by <guibutton>Browse</guibutton>,
- then click <guibutton>OK</guibutton>.
- </para>
- </step>
- <step performance="required">
- <para>
- Enter user name and password in the login identification dialog,
- and click <guibutton>OK</guibutton>.
- </para>
- </step>
- </substeps>
-
- <para>
- You should see <guilabel>Starting elfodbc server</guilabel>
- in the lower left corner of the
- data window. If you get an error dialog box, see the debugging section
- below.
- </para>
- </step>
- <step performance="required">
- <para>
- The <quote>Ready</quote> message will appear in the lower left corner of the data
- window. This indicates that you can now enter queries.
- </para>
- </step>
- <step performance="required">
- <para>
- Select a table from
- <menuchoice><guimenu>Query</><guimenuitem>Choose
- tables</></menuchoice>, and then select
- <menuchoice><guimenu>Query</><guimenuitem>Query</></menuchoice>
- to access the database. The first 50 or so rows from the table
- should appear.
- </para>
- </step>
- </procedure>
- </sect2>
-
- <sect2>
- <title>Common Problems</title>
-
- <para>
- The following messages can appear while trying to make an
- <acronym>ODBC</acronym> connection through
- <productname>Applix Data</productname>:
-
- <variablelist>
- <varlistentry>
- <term>
- <computeroutput>Cannot launch gateway on server</computeroutput>
- </term>
- <listitem>
- <para>
- <literal>elfodbc</literal> can't find <filename>libodbc.so</filename>.
- Check your <filename>axnet.cnf</filename>.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><computeroutput>
- Error from ODBC Gateway:
- IM003::[iODBC][Driver Manager]Specified driver could not be loaded</computeroutput>
- </term>
- <listitem>
- <para>
- <filename>libodbc.so</filename> cannot find the driver listed in
- <filename>.odbc.ini</filename>. Verify the settings.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term>
- <computeroutput>Server: Broken Pipe</computeroutput>
- </term>
-
- <listitem>
- <para>
- The driver process has terminated due to some other
- problem. You might not have an up-to-date version
- of the <productname>PostgreSQL</productname>
- <acronym>ODBC</acronym> package.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term>
- <computeroutput>setuid to 256: failed to launch gateway</computeroutput>
- </term>
-
- <listitem>
- <para>
- The September release of <application>Applixware</application> 4.4.1 (the first release with official
- <acronym>ODBC</acronym> support under Linux) shows problems when user names
- exceed eight (8) characters in length.
- Problem description contributed by Steve Campbell
- (<email>scampbell@lear.com</email>).
- </para>
- </listitem>
- </varlistentry>
-
- </variablelist>
- </para>
-
- <para>
- <note>
- <title>Author</title>
-
- <para>
- Contributed by Steve Campbell (<email>scampbell@lear.com</email>),
- 1998-10-20
- </para>
- </note>
-
- The <application>axnet</application> program's security system
- seems a little suspect. <application>axnet</application> does things
- on behalf of the user and on a true
- multiuser system it really should be run with root security
- (so it can read/write in each user's directory).
- I would hesitate to recommend this, however, since we have no idea what
- security holes this creates.
- </para>
- </sect2>
-
- <sect2>
- <title>Debugging <application>Applixware</application> ODBC Connections</title>
-
- <para>
- One good tool for debugging connection problems uses the Unix system
- utility <application>strace</application>.
- </para>
- <procedure>
- <title>Debugging with <command>strace</command></title>
-
- <step performance="required">
- <para>
- Start <application>Applixware</application>.
- </para>
- </step>
- <step performance="required">
- <para>
- Start an <application>strace</application> on
- the <literal>axnet</literal> process. For example, if
-
-<screen>
-<prompt>$</prompt> <userinput>ps -aucx | grep ax</userinput>
-</screen>
-
- shows
-
-<screen>
-cary 10432 0.0 2.6 1740 392 ? S Oct 9 0:00 axnet
-cary 27883 0.9 31.0 12692 4596 ? S 10:24 0:04 axmain
-</screen>
- </para>
-
- <para>
- Then run
-
-<screen>
-<prompt>$</prompt> <userinput>strace -f -s 1024 -p 10432</userinput>
-</screen>
- </para>
- </step>
-
- <step performance="required">
- <para>
- Check the <command>strace</command> output.
- </para>
- <note>
- <title>Note from Cary</title>
-
- <para>
- Many of the error messages from <productname>Applixware</productname>
- go to <filename>stderr</filename>,
- but I'm not sure where <filename>stderr</filename>
- is sent, so <command>strace</command> is the way to find out.
- </para>
- </note>
- </step>
- </procedure>
-
- <para>
- For example, after getting
- a <errorname>Cannot launch gateway on server</errorname>,
- I ran <command>strace</command> on <literal>axnet</literal> and got
-
-<screen>
-[pid 27947] open("/usr/lib/libodbc.so", O_RDONLY) = -1 ENOENT (No such file or directory)
-[pid 27947] open("/lib/libodbc.so", O_RDONLY) = -1 ENOENT (No such file or directory)
-[pid 27947] write(2, "/usr2/applix/axdata/elfodbc: can't load library 'libodbc.so'\n", 61) = -1 EIO (I/O error)
-</screen>
- So what is happening is that <literal>applix elfodbc</literal> is searching for <filename>libodbc.so</filename>, but it
- cannot find it. That is why <filename>axnet.cnf</filename> needed to be changed.
- </para>
- </sect2>
-
- <sect2>
- <title>Running the <application>Applixware</application> Demo</title>
-
- <comment>I think the condition this refers to is gone. -- petere 2002-01-07</comment>
-
- <para>
- In order to go through the
- <citetitle>Applixware Data Tutorial</citetitle>, you need to create
- the sample tables that the Tutorial refers to. The ELF Macro used to
- create the tables tries to use a NULL condition
- on many of the database columns,
- and <productname>PostgreSQL</productname> does not currently allow this option.
- </para>
-
- <para>
- To get around this problem, you can do the following:
- </para>
-
- <procedure>
- <title>Modifying the <application>Applixware</application> Demo</title>
-
- <step performance="required">
- <para>
- Copy <filename>/opt/applix/axdata/eng/Demos/sqldemo.am</filename>
- to a local directory.
- </para>
- </step>
-
- <step performance="required">
- <para>
- Edit this local copy of <filename>sqldemo.am</filename>:
- </para>
-
- <substeps>
-
- <step performance="required">
- <para>
- Search for <literal>null_clause = "NULL"</literal>.
- </para>
- </step>
-
- <step performance="required">
- <para>
- Change this to <literal>null_clause = ""</literal>.
- </para>
- </step>
-
- </substeps>
- </step>
- <step performance="required">
- <para>
- Start <application>Applix Macro Editor</application>.
- </para>
- </step>
-
- <step performance="required">
- <para>
- Open the <filename>sqldemo.am</filename> file from the <application>Macro Editor</application>.
- </para>
- </step>
-
- <step performance="required">
- <para>
- Select <menuchoice><guimenu>File</><guimenuitem>Compile and Save</></menuchoice>.
- </para>
- </step>
-
- <step performance="required">
- <para>
- Exit <application>Macro Editor</application>.
- </para>
- </step>
-
- <step performance="required">
- <para>
- Start <application>Applix Data</application>.
- </para>
- </step>
-
- <step performance="required">
- <para>
- Select <menuchoice><guimenu>*</><guimenuitem>Run Macro</guimenuitem></menuchoice>.
- </para>
- </step>
-
- <step performance="required">
- <para>
- Enter the value <literal>sqldemo</literal>, then click <guibutton>OK</guibutton>.
- </para>
-
- <para>
- You should see the progress in the status line of the data window
- (in the lower left corner).
- </para>
- </step>
-
- <step performance="required">
- <para>
- You should now be able to access the demo tables.
- </para>
- </step>
- </procedure>
- </sect2>
-
- <sect2>
- <title>Useful Macros</title>
-
- <para>
- You can add information about your
- database login and password to the standard <application>Applix</application> start-up
- macro file. This is an example
- <filename>~/axhome/macros/login.am</filename> file:
-
-<programlisting>
-macro login
-set_set_system_var@("sql_username@","tgl")
-set_system_var@("sql_passwd@","no$way")
-endmacro
-</programlisting>
-
- <caution>
- <para>
- You should be careful about the file protections on any file containing
- user name and password information.
- </para>
- </caution>
- </para>
- </sect2>
-
- </sect1>
- </chapter>
-
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