Frequently Asked Questions about IBM Informix Database Driver for Perl
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IBM Informix Database Driver for Perl Version 2003.04 (2003-03-05)

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WHAT IS THE DIFFERENCE BETWEEN IBM INFORMIX DATABASE DRIVER FOR PERL AND
DBD::INFORMIX?

Spelling.

The official product name had to be changed from DBD::Informix to IBM
Informix Database Driver for Perl because the acronym DBD is a contested
trademark of two other companies in the USA, so Informix could not release
the product as DBD::Informix without potentially infringing on this
trademark.  Internally, Perl and DBI still uses the name DBD::Informix to
access the driver, and much of the documentation still references
DBD::Informix because that is how Perl references it, and because it is
less of a mouthful than IBM Informix Database Driver for Perl.

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HOW DO I REPORT TECHNICAL PROBLEMS WITH DBD::INFORMIX?

See the information available via "perldoc DBD::Informix::TechSupport".

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WHY IS IBM INFORMIX ESQL/C A PRODUCT PREREQUISITE FOR DBD::INFORMIX?

DBD::Informix is freely available software that is licensed on the same
terms as Perl, under the GNU General Public License or the Perl Artistic
License.

However, to compile or use DBD::Informix, you need some IBM Informix
software on your computer -- specifically, you need either IBM Informix
ESQL/C or IBM Informix Client SDK.  This provides a compiler and the
supporting libraries necessary to connect to Informix databases.  This
software must be licenced from Informix Software Inc.

To purchase any IBM Informix software, look in the the IBM Informix Web
site (http://www.ibm.com/software/data/informix), or contact your local
IBM Sales Office.

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WHERE CAN I FIND DOCUMENTATION FOR IBM INFORMIX PRODUCTS?

You can download PDF files for most IBM Informix product manuals at the
IBM Informix web-site:

	http://www.ibm.com/software/data/informix/pubs
    http://www.informix.com/answers

Electronic manuals are not available for some of the older product
versions.

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WHICH VERSIONS OF ESQL/C AND CLIENT SDK ARE SUPPORTED?

For details on which versions of ESQL/C and Client SDK are supported,
consult the documentation:

	perldoc DBD::Informix::TechSupport

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WHICH OTHER VERSIONS OF IBM INFORMIX ESQL/C EXIST?

Informix ESQL/C exists in versions 5.0x (obsolete), 5.1x, 6.0x (obsolete),
7.0x (obsolete), 7.1x (obsolete), 7.2x, 8.0x (obsolete), 8.1x, and 9.x.
Anything earlier than version 5.00 is very obsolete and cannot be used to
build DBD::Informix.  Within the 9.x family, the 9.0x versions are
obsolete, and the other available versions are mostly part of Client SDK.

    Former Name       Current Name
    -----------       ----------------------
    ESQL/C 9.11     - ESQL/C 9.11 (obsolete)
    ESQL/C 9.12     - DevSDK 9.12 (obsolete)
    ESQL/C 9.13     - Client SDK 2.00 (obsolete)
    ESQL/C 9.14     - Client SDK 2.01 (obsolete)
    ESQL/C 9.15     - Client SDK 2.02 (obsolete)
    ESQL/C 9.16     - Client SDK 2.10 (obsolete)
    ESQL/C 9.20     - Client SDK 2.20 (obsolete)
    ESQL/C 9.21     - Client SDK 2.30 (obsolete)
    ESQL/C 9.30     - Client SDK 2.40
    ESQL/C 9.40     - Client SDK 2.50
    ESQL/C 9.50     - Client SDK 2.60
    ESQL/C 9.51     - Client SDK 2.70
    ESQL/C 9.52     - Client SDK 2.80

With the 7.3x servers, you would normally use Client SDK 2.40 or later.
With the 8.2x or later servers, you would normally use Client SDK 2.40
or later.  With the 9.1x servers, you would normally use some version of
Client SDK, but you are long overdue for an upgrade.  If you have a 9.2x
server, you would normally use Client SDK 2.40 or later.  Finally, note
that Client SDK is available free of charge, so you should use it if at
all possible.  You can make Client SDK talk to the 7.x and even 5.x
servers.

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WILL DBD::INFORMIX WORK WITH ANY OF THESE OTHER VERSIONS?

It is believed that DBD::Informix will work with any version of ESQL/C from
version 5.00.UC1 upwards.  However, it has not been tested with every such
version, and many of these versions are obsolete.  For example, all the
5.0x versions are obsolete because they are not officially Y2K-compliant;
ditto for the 6.0x, 7.0x and 7.1x versions.  It has also not been tested on
every platform.

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DO I NEED AN IBM INFORMIX DATABASE SERVER ON MY DEVELOPMENT MACHINE?

You do not need an IBM Informix database server on the computer where you
build or use DBD::Informix.  However, to compile DBD::Informix, or to make
any meaningful use of it after it is compiled, you must have access to a
computer with an IBM Informix database server installed and running on it.
One step of the configuration process for DBD::Informix validates your IBM
Informix ESQL/C and database environments and checks that you have access
to at least one database.  If this step fails, the makefile is not
generated, so DBD::Informix cannot be compiled.

If you do not have the IBM Informix database system set up already, you
need to do so before you try to compile DBD::Informix.  If you do not know
how to do the setup, you must obtain the necessary training.  IBM does
provide training courses in such matters; consult the Web site or your
local sales office as mentioned above.

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WHICH IBM INFORMIX DATABASE SERVERS ARE AVAILABLE?

IBM Informix provides a large family of products, many of which are
available in a number of versions.  Database storage is managed by a
program separate from user applications (such as Perl + DBI +
DBD::Informix).  Such a database management program is called the database
server.  The main Informix database servers are listed below.

Refer to http://www.ibm.com/software/data/informix for additional
product information.

    Informix Standard Engine (SE)                   5.x and up
    Informix OnLine                                 5.x
    Informix OnLine Dynamic Server (ODS)            6.x or 7.x OnLine
    Informix OnLine Workgroup Server (WGS)          7.x versions, UNIX and NT
    Informix OnLine Workstation (OWS)               7.x versions, NT
    Informix OnLine Extended Parallel Server (XPS)  8.x OnLine
    Informix Universal Server (IUS)                 9.x

In 1998, Informix renamed the following products:
    Informix Dynamic Server (IDS)  7.3
    Informix Dynamic Server with Universal Data Option (IDS/UDO) 9.1x
    Informix Dynamic Server with Advanced Decision Support Option 
      (IDS/ADSO) 8.x
    Informix Dynamic Server with Extended Parallel Option (IDS/XPO) 8.x

In July 1999, the new Informix Internet Foundation.2000 products were 
released and included:
    Informix Dynamic Server.2000 (IDS.2000) 9.2x
    Informix Internet Foundation.2000 (IIF.2000) 9.2x

In 2001, the 2000 appellation was dropped.

Version 9.2x merges the 7.x and 9.x code streams.  Basically, Informix
Dynamic Server.2000 is the direct upgrade path if you use Informix Dynamic
Server 7.3x or an earlier version of IDS or OnLine.  IDS.2000 is extensible
but does not come with many extensions.  IIF.2000 is the upgrade for IUS
and comes with standard extensions.  See the Informix Web site for details.
In July 1999, Informix replaced the hyphen with a space in the name
Informix-ESQL/C.  So now the name is Informix ESQL/C.  Older manuals will
not be reissued just because of the spelling change.

The acronym OWS is used only internally and might mean either the OnLine
Workgroup Server or the OnLine Workstation products.  Informix OnLine, ODS,
OWS, and WGS are all known as OnLine.  Although there are major differences
between the various versions, these are not significant if you are not
familiar with the Informix products.

To use DBD::Informix, you need to have access to an Informix database
server, which means that you need either OnLine, SE, or IUS on one of the
computers in your network.  DBD::Informix will probably be of no use to you
unless you have access to a database.  You must know the version number of
the database server to ensure that you compile DBD::Informix with a
compatible version of Informix ESQL/C and run it in a compatible runtime
environment.  Possible versions are 5.0x, (6.0x), 7.1x, 7.2x, (8.0x), 9.0x,
or 9.1x, the x is a string such as '0.UC1' and yields a complete version
string such as 7.22.UC2.  Note that DBD::Informix does not work with
Version 4.1x or earlier versions of the database servers.

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CAN DBD::INFORMIX BE COMPILED WITHOUT IBM INFORMIX ESQL/C?

To compile DBD::Informix, you should have an IBM Informix ESQL/C
compiler.

If you built Perl with the same C compiler as the IBM Informix Classic
4GL c-code compiler uses, then you may be able to build DBD::Informix
with a version 6.00 or later C4GL compiler.  You would configure the
build with the command:

    ESQL=c4gl perl Makefile.PL
    make
    make test

This is not supported by IBM; it is not a good option and it should only
be used as a last resort.  The resulting executable code might be much
larger than if you use a pure ESQL/C version.  You cannot use IBM
Informix 4GL Version 4.1x because it uses the ESQL/C Version 4.1x
compiler, which does not provide the features that DBD::Informix needs.

This compilation technique was shown to work in 1997 using DBD::Informix
Version 0.56 (with Perl 5.004 and DBI Version 0.90) with IBM Informix
4GL 6.05.UC1 on a Sun Sparc 20 running Solaris 2.5.1.  It was also shown
to work in 2002 on a Sun UltraSparc running Solaris 7 with DBD::Informix
1.03.PC1, Perl 5.8.0, DBI 1.30, IBM Informix 4GL 7.31.UC3, with both
Sun's WorkShop 6 update 2 C 5.3 2001/05/15 C compiler and with the GNU C
Compiler (GCC) 3.1.  Note that you should set the environment variable
DBD_INFORMIX_ESQLCC_REMOVE_OPTIONS_REGEX to "^-KPIC$" to avoid warnings
from GCC, and DBD_INFORMIX_ESQLLD_REMOVE_OPTIONS_REGEX to the same value
to prevent linkage warnings.  Note that Solaris is a simple environment
to handle; other environments such as HP-UX are less easy.

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CAN DBD::INFORMIX RUN ON A COMPUTER DIFFERENT FROM WHERE IT WAS COMPILED?

To run DBD::Informix only on the computer where you compiled it, you do not
need any extra software, and you can skip the rest of this subsection.

To run DBD::Informix on a different computer from where you compiled it,
the other computer must have the same architecture as the computer used for
compiling.  However, the computers need not be identical; for example, code
compiled on a Sun Sparc 20 can be run on a Sun Sparc 10.

Every computer where you will use DBD::Informix must have either an IBM
Informix ESQL/C development license, or an IBM Informix runtime license.
Otherwise, you violate the terms of your license agreement with IBM
(Informix).  Either way, the license on the other computer should be the
same version as the development license used to compile the software.
(If you know enough about the compatability requirements for different
versions of Informix products to argue about the finer points ignored by
the "same version" criterion, you probably do not need to read this.)

If you use a 5.x database server (OnLine or SE), you need an Informix
ESQL/C RunTime license.  If you will use a database on a remote
computer, you will also need an Informix Net (or Informix Star) license.
Note that OnLine 5.2x is distributed with Informix Star functionality.

If you are using a 5.0x server, you should upgrade.  In particular,
using OnLine 5.0x is dangerous as the archives might not be restorable,
which is not something you want to find out after the system has crashed
and you need to restore it.

If you use a 6.0x or 7.1x database server, you also need an Informix
ESQL/C RunTime license.  However, you do not need a separate license for
remote database access because the remote database access technology is
part of the basic product.  If you use a 6.0x, 7.0x or 7.1x server, it
is long past time to upgrade.

If you use a 7.2x, 9.0x or 9.1x database server, you need an Informix
Connect license, and you do not need a separate license for remote
database access because the remote database access technology is part of
the basic product.  If you use a 7.2x server earlier than 7.24, you
should upgrade.

If you use an 8.0x or 8.1x database server, you need either an Informix
ESQL/C RunTime license or an Informix Connect license.  The initial 8.00
version was released shortly after the 7.10 version was released, and
the changes made in 7.20 for Informix Connect might not have been
propagated to Version 8.0x.  This has not been tested; you may have to
extemporize to get DBD::Informix to work.  If you are using an 8.0x or
8.1x server, you should upgrade.

Further, both the DBI and DBD::Informix modules will need to be installed
on the second machine, and should go into the same directory on both
machines.  That means that Perl must be installed in the same location on
both machines.  And unless you compiled DBD::Informix with the environment
variable DBD_INFORMIX_RELOCATABLE_INFORMIXDIR set, you will need to have
the Informix software installed in the same place on both machines.

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MY PROGRAM WORKS OK WHEN I RUN IT FROM THE COMMAND LINE BUT FAILS WHEN I
RUN IT VIA A WEB SERVER (CGI, MOD_PERL, ETC), OR FROM A CRON JOB?

The answer is the environment - almost invariably.

You should establish exactly what the environment is when your script is
run, using some surrogate for your real script that uses DBI and
DBD::Informix.  Then you will have to work out how to set the INFORMIXDIR,
INFORMIXSERVER and LD_LIBRARY_PATH environment variables properly.  With
Apache, this is usually the SetEnv directive (possibly PassEnv instead).
Other web servers will have equivalents.  You could also consider trying to
set the environment in a BEGIN block, but it may well set the environment
too late to be useful.

Note that DBD::Informix version 1.00 and later normally build the
DBD::Informix shared library so that it references the Informix shared
libraries with absolute pathnames.  This should mean that the web server
does not need to set LD_LIBRARY_PATH or the local equivalent environment
variable.  The configuration process records a default value for
INFORMIXDIR and INFORMIXSERVER; these may be adequate for your production
environment.

Similar comments apply to jobs run by cron.  Unlike jobs run with the
'at' command, cron jobs get only the most minimal environment set.  You
should ensure that the environment is set correctly by a script before
it attempts to access DBD::Informix.

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IN THE FOLLOWING CODE, I GET ERROR -280 (A QUOTED STRING EXCEEDS 256 BYTES)
WHEN THE VALUE OF $LONGCHARSTRING CONTAINS MORE THAN 256 CHARACTERS.  THIS
IS ODD BECAUSE LONGCHARCOL IS DEFINED TO CONTAIN MANY MORE THAN 256
CHARACTERS (EG CHAR(2500)).

	$sql = "INSERT INTO SomeTable(LongCharCol) VALUES('$longcharstring')";
	my $sth = $dbh->prepare($sql) or die($DBI::errstr);
	$sth->execute() or dir($DBI::errstr)

ESQL/C has an irritating limitation that the longest character string
literal that it allows is 256 characters long.  Furthermore, in most
versions, you cannot embed newlines in string literals.  There's a simple
workaround which always works; use a place-holder in place of the string.
This has the additional advantage of not breaking when the $longcharstring
variable itself contains quote characters, whereas the example code will
break.

	$sql = "INSERT INTO SomeTable(LongCharCol) VALUES(?)";
	my $sth = $dbh->prepare($sql) or die($DBI::errstr);
	$sth->execute($longcharstring) or dir($DBI::errstr)

Using placeholders is also the most reliable way to enter user defined data
into the database (eg from a web page).  If you take arbitrary data typed
by the user, even using the $dbh->quote method, it may be possible for the
user to break your system.  In the original example, if $longcharstring
contains:

	'); DELETE FROM SomeTable; DROP TABLE OtherTable; COMMIT WORK;

and you run the command as written, then your database might be missing two
(presumably important) tables.  Ensure that the web user has the minimum
possible privileges (CONNECT for the database, and no more than the minimum
necessary table-level privileges on any table).

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WHEN I TRY TO BUILD THE SHARED LIBRARY, I GET AN ERROR MESSAGE ABOUT
LOTS OF MISSING SYMBOLS LIKE PERL_NEWAV (REFERENCED IN DBDATTR.O)
AND PERL_NEWSV (REFERENCED IN INFORMIX.O) AND MAIN.  WHAT'S UP?

This most frequently occurs when you need to modify the esql script to
change the default compiler from cc to (typically) gcc, and you don't
respect the INFORMIXC environment variable.  At the start of the original
esql script is a line that reads:

        CC=${INFORMIXC=cc}                  # Original version

If you need to change that to use gcc by default, then modify it to keep
the option of overriding the C compiler with the INFORMIXC environment
variable, because DBD::Informix uses INFORMIXC to ensure that it can build
the shared library on many systems (specifically, this is necessary on
Solaris 2.6, Solaris 7 and Linux; it will be necessary on many SVR4-derived
systems).

	CC=${INFORMIXC=gcc}                 # Correct change
	CC=${INFORMIXC=/usr/local/bin/gcc}  # Correct change

	CC=gcc                              # Incorrect change
	CC=/usr/local/bin/gcc               # Incorrect change

Why?  On these platforms, the -G option needs to be relayed to the C
compiler or loader, but the esql script thinks that -G is an option
intended for its own benefit.  So, to get the -G option to the C compiler,
it is set in the ESQLLD environment variable, and INFORMIXC is set to run
the esqlld Perl script.  If you modify esql to ignore INFORMIXC, you make
it ignore a lot of hard work -- and cause the build to fail.

See also the information about DBD_INFORMIX_ESQLCC_REMOVE_OPTIONS_REGEX
and DBD_INFORMIX_ESQLLD_REMOVE_OPTIONS_REGEX in the file
Notes/environment.variables.

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HOW CAN I UPDATE BLOBS

You cannot update BYTE and TEXT blobs fully automatically with
DBD::Informix.  You can insert them; you can delete them; you can select
them; all without paying very much attention to the issues.  You cannot
update them without using special measures.

Technically, the DESCRIBE request must give DBD::Informix information
about the types of the paramaters on the RHS of the SET clause in an
UPDATE statement.  Without that type information, DBD::Informix does not
know that it needs to treat the parameter specially.  [This should
change in 2003 when IBM releases IBM Informix ClientSDK 2.81 - ESQL/C
9.53 - and IBM IDS 9.40, but the feature won't be available on older
versions of the servers.]

On the other hand, starting with version 1.03.PC1, you can update them.
See the code in test file t/t73blobupd.t for an illustration of how to
do it using the Informix type support with bind_param (and, one day,
bind_param_inout).  See also 'perldoc DBD::Informix'.

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WHEN I DO "perl makefile.PL" IT FAILS WITH ERROR -369.  IT ALSO FAILS
WITH THAT ERROR IF I TRY TO RUN esqlbasic.  WHAT DOES IT MEAN AND WHAT
MUST I DO TO FIX IT?

Error -369 always means that the ESQL/C you are using is not installed
correctly.  Usually it means that: 1) although you copied off the distribution
media, you did not run the installesql script.  You need to provide a
serial number (eg AAA#A123456) and an activation key (eg ABCDEF).  Until
you do this, the software will not let you use the libraries at runtime,
even if you can compile with it.  Or, 2) if you installed ESQL/C correctly,
something else was subsequently installed incorrectly and wrote over one of
the ESQL/C libraries.  Either way, the corrective action is to reinstall
either the ESQL/C product or the other product which overwrote the ESQL/C
libraries.

The other circumstance under which this can occur with ClientSDK 2.80 or
later is if there is an internal error in the installation process.  The
licence number for such versions should be supplied automatically; if
you get this error, then there is probably a bug in the installation
code.

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HOW DO I CONFIGURE DBD::INFORMIX TO CONNECT TO A REMOTE DATABASE?

How do you connect using DB-Access across the network?  That's how you
connect using DBD::Informix, too.  For example, you will create an entry
in your local sqlhosts file that references the remote system:

    remote_tcp  oltlitcp    remote  service_name

You will then simply do:

    $dbh = DBI->connect("dbi:Informix:dbase\@remote_tcp", "", "")
                or die "A horrible death!";

Note that if you also had a local database, you'd have an entry in the
sqlhosts file such as:

    local_shm   olipcshm    local   service_name

And your connect statement will be:

    $dbh = DBI->connect("dbi:Informix:dbase\@local_shm", "", "")
                or die "A horrible death!";

Or, in other words, there is essentially no difference between the local
and remote connections.  If you need to specify username and password,
do so in place of the empty strings.  If you want to omit the '\@server'
part, you can set $INFORMIXSERVER to the correct value.

NB: The default value of $INFORMIXSQLHOSTS is $INFORMIXDIR/etc/sqlhosts.

NB: On Linux in particular, you often need the FQDN (fully qualified
domain name) of the server in place of 'local' or 'remote'.  Usually,
what 'uname -n' gives is what you need for the local machine.

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Jonathan Leffler
Informix Database Engineering, IBM Data Management Solutions

@(#)$Id: FAQ,v 100.10 2002/11/20 01:41:16 jleffler Exp $