ARC_DEFAULT

For example, to set the ARC_DEFAULT environment variable to specify the file /usr/jane/arcdefault.janeroe, enter the following command:

setenv ARC_DEFAULT /usr/jane/arcdefault.janeroe

ARC_KEYPAD

The tctermcap file serves the following purposes for the ON-Archive menu interface:

• It defines the terminal control attributes that allow ON-Archive to manipulate the screen and cursor.
• It defines the mappings between commands and key presses.
• It defines the characters used to draw menus and borders for an API.

  pathname

  is the pathname for a tctermcap file.

setenv ARC_KEYPAD  /usr/jane/tctermcap.janeroe

DBANSIWARN

Setting the DBANSIWARN environment variable for DB-Access is functionally equivalent to including the -ansi flag when invoking the utility from the command line. If you set DBANSIWARN before you run DB-Access, warnings are displayed on the screen within the SQL menu.

Set the DBANSIWARN environment variable before you compile an INFORMIX-ESQL/C program to check for Informix extensions to ANSI standard syntax. When Informix extensions to ANSI-standard syntax are encountered in your program at compile time, warning messages are written to the screen.

At run time, the DBANSIWARN environment variable causes the SQL Communication Area (SQLCA) variable sqlca.sqlwarn.sqlwarn5 to be set to W when a statement that is not ANSI-compliant is executed. (For more information on SQLCA, see the INFORMIX-ESQL/C Programmer's Manual.)

Once you set DBANSIWARN, Informix extension checking is automatic until you log out or unset DBANSIWARN. To turn off Informix extension checking, unset the DBANSIWARN environment variable by entering the following command:

unsetenv DBANSIWARN

If the simple large object is smaller than the default of 10 coagulates or the setting of the DBBLOBBUF environment variable, it is temporarily stored in memory. If the simple large object is larger than the default or the setting of the environment variable, it is written to a temporary file. This environment variable applies to the UNLOAD command only.

For instance, to set a buffer size of 15 kilobytes, set the DBBLOBBUF environment variable as the following example shows:

setenv  DBBLOBBUF 15

DBCENTURY

Previously, if only the decade was provided for a literal DATE or DATETIME value in a table column, the present century was used to expand the year. For example, 12/31/96 would have been expanded to 12/31/1996. With this release, three new algorithms are added to complete the century value of a year: past (P), future (F), and closest (C).

Algorithm	Explanation
P = Past	The past and present centuries are used to expand the year value. These two dates are compared against the current date, and the date that is prior to the current date is chosen. If both dates are prior to the current date, the date that is closest to the current date is chosen.
F = Future	The present and the next centuries are used to expand the year value. These two dates are compared against the current date, and the date that is after the current date is chosen. If both the expansions are after the current date, the date that is closest to the current date is chosen.
C = Closest	The past, present, and next centuries are used to expand the year value, and the date that is closest to the current date is used.
R = Present	The present century is used to expand the year value.

When the DBCENTURY environment variable is not set, the current century is used as the system default.

You can override the default by specifying all four digits.

The following examples illustrate how the DBCENTURY environment variable expands DATE and DATETIME year formats.

Behavior of DBCENTURY = P

Example data type: DATE
Current date: 4/6/1996
User enters: 1-1-1
DBCENTURY = P, Past century algorithm
Previous century expansion : 1/1/1801
Present century expansion: 1/1/1901
Analysis: Both results are prior to the current date, but 1/1/1901 is closer to 
the current date. 1/1/1901 is chosen.

Example data type: DATETIME year to month
Current date: 5/7/2005
User enters: 1/1/1
DBCENTURY = F, Future century algorithm
Present century expansion: 2001-1
Next century expansion: 2101-1
Analysis: Only date 2101-1 is after the current date and it is chosen as the 
expansion of the year value.

Example data type: DATE
Current date: 4/6/1996
User enters: 1-1-1
DBCENTURY = C, Closest century algorithm
Previous century expansion : 1/1/1801
Present century expansion: 1/1/1901
Next century expansion: 1/1/2001
Analysis: Because the next century expansion is the closest to the current date, 
1/1/2001 is chosen.

Example data type: DATETIME year to month
Current date: 4/6/1996
User enters: 1/1/1
DBCENTURY = R, Present century algorithm
Present century expansion: 1901-1
Analysis: The present century expansion is used.

• When you input DATE values, Informix products use the DBDATE environment variable to interpret the input. For example, if you specify a literal DATE value in an INSERT statement, Informix database servers expect this literal value to be compatible with the format specified by DBDATE. Similarly, the database server interprets the date you are specifying as input to the DATE( ) function in the format specified by the DBDATE environment variable.
• When you display DATE values, Informix products use the DBDATE environment variable to format the output.

GLS

This section describes standard DBDATE formats. For a description of era-based formats, see the Guide to GLS Functionality.

With standard formats, you can specify the following attributes:

• The order of the month, day, and year in a date
• Whether the year should be printed with two digits (Y2) or four digits (Y4)
• The separator between the month, day, and year

For the U.S. ASCII English locale, the default setting for DBDATE is MDY4/, where M represents the month, D represents the day, Y4 represents a four-digit year, and slash (/) is a separator (for example, 10/08/1994).

Other acceptable characters for the separator are a hyphen (-), a period (.), or a zero (0). Use the zero to indicate no separator.

The slash (/) appears if you attempt to use a character other than a hyphen, period, or zero as a separator, or if you do not include a separator character in the DBDATE definition.

The following table shows a few variations of setting the DBDATE environment variable.

Variation	October 8, 1994 appears as:
MDY4/	10/08/1994
DMY2-	08-10-94
MDY4	10/08/1994
Y2DM.	94.08.10
MDY20	100894
Y4MD*	1994/10/08

Notice that the formats Y4MD* (the asterisk is an unacceptable separator) and MDY4 (no separator is defined) both display the default (slash) as a separator.

Important: If you use the Y2 format, understand that the setting of the DBCENTURY environment variable affects how the DATE values are expanded.

Also, certain routines called by INFORMIX-ESQL/C can use the DBTIME variable, rather than DBDATE, to set DATETIME formats to international specifications. For more information, see the discussion of the DBTIME environment variable on page 3-38 and the "INFORMIX-ESQL/C Programmer's Manual." The setting of the DBDATE variable takes precedence over that of the GL_DATE environment variable, as well as over the default DATE formats as specified by CLIENT_LOCALE. For information about the GL_DATE and CLIENT_LOCALE environment variables, see the "Guide to GLS Functionality".

DBDELIMITER

delimiter

is the field delimiter for unloaded data files.

The delimiter can be any single character, except the characters in the following list:

• Hexadecimal numbers (0 through 9, a through f, A through F)
• NEWLINE or CTRL-J
• The backslash symbol (\)

setenv  DBDELIMITER '+'

For most systems, the default editor is vi. If you use another editor, be sure that it creates flat ASCII files. Some word processors in document mode introduce printer control characters that can interfere with the operation of your Informix product.

To specify the EMACS text editor, set the DBEDIT environment variable by entering the following command:

setenv DBEDIT emacs

To override the default number of decimal digits in the display, you can set the DBFLTMASK environment variable to the number of digits desired.

n	is the number of decimal digits you want the Informix client application to display in the floating-point values.

DBLANG

By default, Informix products put compiled messages in a locale-specific subdirectory of the $INFORMIXDIR/msg directory. These compiled message files have the suffix .iem. If you want to use a message directory other than $INFORMIXDIR/msg, where, for example, you can store message files that you have created, perform the following steps.

To use a non-default message directory

1. Use the mkdir command to create the appropriate directory for the message files. You can make this directory under the directory $INFORMIXDIR or $INFORMIXDIR/msg or you can make it under any other directory.

2. Set the owner and group of the new directory to informix and the access permission for this directory to 755.

3. Set the DBLANG environment variable to the new directory. If this directory is a subdirectory of $INFORMIXDIR or $INFORMIXDIR/msg, you only need to list the relative path to the new directory. Otherwise, you must specify the full pathname of the directory.

4. Copy the .iem files or the message files that you created to the new message directory specified by $DBLANG. All the files in the message directory should have the owner and group informix and access permission 644.

1. In $DBLANG, if DBLANG is set to a full pathname

2. In $INFORMIXDIR/msg/$DBLANG, if DBLANG is set to a relative pathname

3. In $INFORMIXDIR/$DBLANG, if DBLANG is set to a relative pathname

4. In $INFORMIXDIR/msg/en_us/0333

5. In $INFORMIXDIR/msg/en_us.8859-1

6. In $INFORMIXDIR/msg

7. In $INFORMIXDIR/msg/english

GLS

For more information on access paths for messages, see the description of DBLANG in the Guide to GLS Functionality.

DBMONEY

If you use any character except an alphabetic character for front or back, you must enclose the character in quotes.

When you display MONEY values, Informix products use the DBMONEY environment variable to format the output.

Tip: The setting of DBMONEY does not affect the internal format of the MONEY column in the database.

If you do not set DBMONEY, then MONEY values for the default locale, U.S. ASCII English, are formatted with a dollar sign ($) preceding the MONEY value, a period (.) separating the integral from the fractional part of the MONEY value, and no back symbol. For example, 10050 is formatted as $100.50.

Suppose you want to represent MONEY values in DM (Deutsche Mark), which uses the currency symbol DM and a comma. Set the DBMONEY environment variable by entering the following command:

setenv DBMONEY DM,

GLS

For more information about how the DBMONEY environment variable handles MONEY formats for nondefault locales, see the Guide to GLS Functionality.

DBONPLOAD

For example, to specify load_db as the name of the database, enter the following command:

setenv DBONPLOAD load_db

The CONNECT, DATABASE, START DATABASE, and DROP DATABASE statements use DBPATH to locate the database under two conditions:

• If the location of a database is not explicitly stated
• If the database cannot be located in the default server or
  the default directory

To add a new DBPATH entry to existing entries, see "Modifying the Setting of an Environment Variable".

full_pathname	is a valid full pathname of a directory in which .sql files are stored.
servername	is the name of a Universal Server on which databases are stored. You cannot reference database files with a servername.

DBPATH can contain up to 16 entries. Each entry (full_pathname, servername, or servername and full_pathname) must be less than 128 characters. In addition, the maximum length of DBPATH depends on the hardware platform on which you are setting DBPATH.

When you access a database using the CONNECT, DATABASE, START DATABASE, or DROP DATABASE statement, the search for the database is done first in the directory and/or database server specified in the statement. If no database server is specified, the default database server as set in the INFORMIXSERVER environment variable is used. (The default directory is the current working directory if the database server is on the local computer or your login directory if the database server is on a remote computer.) If a directory is specified but is not a full path, the directory is considered to be relative to the default directory.

If the database is not located during the initial search, and if DBPATH is set, the database servers and/or directories in DBPATH are searched for the indicated database. The entries to DBPATH are considered in order.

Using DBPATH with DB-Access

Searching Local Directories

In the following example, the DBPATH setting causes DB-Access to search for the database files in your current directory and then in the Joachim and Sonja directories on the local computer:

setenv DBPATH /usr/joachim:/usr/sonja

setenv DBPATH //quality/usr/joachim://quality/usr/sonja

setenv DBPATH //marketing/usr/joachim:/usr/sonja

The Universal Server or SE administrator must include each database server mentioned by DBPATH in the $INFORMIXDIR/etc/sqlhosts file. For information on communication-configuration files and dbservernames, see the INFORMIX-Universal Server Administrator's Guide.

For example, if INFORMIXSERVER is set to quality, you can search for a Universal Server database first on the quality database server and then on the marketing database server by setting DBPATH shown in the following example:

setenv DBPATH //marketing

DBPRINT

The default program is found in one of two places:

• For most BSD UNIX systems, the default program is lpr.
• For UNIX System V, the default program is usually lp.

setenv  DBPRINT  myprint

Informix recommends the use of the full pathname syntax on the interactive UNIX platform to avoid problems with similarly named programs in other directories and possible confusion with the restricted shell (/usr/bin/rsh).

Set the DBREMOTECMD environment variable for a simple command name by entering the following command:

setenv DBREMOTECMD  rcmd

setenv  DBREMOTECMD  /usr/bin/remsh

DBSPACETEMP

The DBSPACETEMP environment variable overrides the default dbspaces specified by the DBSPACETEMP configuration parameter in the Universal Server configuration file.

For example, you might set the DBSPACETEMP environment variable by entering the following command:

setenv DBSPACETEMP sorttmp1:sorttemp2:sorttmp3

The two classes of temporary tables are: explicit temporary tables that are created by the user and implicit temporary tables that are created by Universal Server. You use the DBSPACETEMP environment variable to specify the dbspaces for both types of temporary tables.

If you create an explicit temporary table with the CREATE TEMP TABLE statement and do not specify a dbspace for the table either in the IN dbspace clause or in the FRAGMENT BY clause, Universal Server uses the settings in the DBSPACETEMP environment variable to determine where to create the table. If the DBSPACETEMP environment variable is not set, Universal Server uses the ONCONFIG parameter DBSPACETEMP. If this parameter is not set, Universal Server creates the temporary table in the same dbspace where the database resides.

If you create an explicit temporary table with the SELECT INTO TEMP statement, Universal Server uses the settings in the DBSPACETEMP environment variable to determine where to create the table. If the DBSPACETEMP environment variable is not set, Universal Server uses the ONCONFIG parameter DBSPACETEMP. If this parameter is not set, Universal Server creates the temporary table in the root dbspace.

Universal Server creates implicit temporary tables for its own use while executing join operations, SELECT statements with the GROUP BY clause, SELECT statements with the ORDER BY clause, and index builds. When it creates these implicit temporary tables, Universal Server uses disk space for writing the temporary data, in the following order:

1. The operating system directory or directories specified by the environment variable PSORT_DBTEMP, if it is set

2. The dbspace or dbspaces specified by the environment variable DBSPACETEMP, if it is set

3. The dbspace or dbspaces specified by the ONCONFIG parameter DBSPACETEMP

4. The operating-system file space in /tmp

Set the DBTEMP environment variable to specify the pathname usr/magda/mytemp by entering the following command:

setenv DBTEMP  usr/magda/mytemp

Universal Server uses DBSPACETEMP to specify the location of temporary files.

DBTIME

You can set the DBTIME environment variable to manipulate DATETIME formats so that the formats conform more closely to various international or local TIME conventions. DBTIME takes effect only when you call certain INFORMIX-ESQL/C DATETIME routines; otherwise, use the DBDATE environment variable. (For more information, see the INFORMIX-ESQL/C Programmer's Manual.)

You can set DBTIME to specify the exact format of an input/output (I/O) DATETIME string field by using the formatting directives described in the following list. Otherwise, the behavior of the DATETIME formatting routine is undefined.

(1 of 2)

string	The formatting directives that you can use are described in the following list:
	%b	is replaced by the abbreviated month name.
	%B	is replaced by the full month name.
	%d	is replaced by the day of the month as a decimal number [01,31].
	%Fn	is replaced by the value of the fraction with precision specified by the integer n. The default value of n is 2; the range of n is 0 £ n £ 5.
	%H	is replaced by the hour (24-hour clock).
	%I	is replaced by the hour (12-hour clock).
	%M	is replaced by the minute as a decimal number [00,59].
	%m	is replaced by the month as a decimal number [01,12].
	%p	is replaced by A.M. or P.M. (or the equivalent in the local standards).
	%S	is replaced by the second as a decimal number [00,59].
	%y	is replaced by the year as a four-digit decimal number. If the user enters a two-digit value, the format of this value is affected by the setting of the DBCENTURY environment variable. If DBCENTURY is not set, then the current century is used for the century digits.
	%Y	is replaced by the year as a four-digit decimal number. User must enter a four-digit value.
	%%	is replaced by % (to allow % in the format string).

For example, consider how to convert a DATETIME YEAR TO SECOND to the following ASCII string format:

Mar 21, 1994 at 16 h 30 m 28 s

setenv DBTIME '%b %d, %Y at %H h %M m %S s'

1994-03-21 16:30:28

setenv DBTIME '%Y-%m-%d %H:%M:%S'

When you use field width and precision specifications, the following limitations apply:

• If a conversion specification supplies fewer digits than specified by a precision, it is padded with leading zeros.
• If a conversion specification supplies more characters than specified by a precision, excess characters are truncated on the right.
• If no field width or precision is specified for d, H, I, m, M, S, or y conversions, a default of 0.2 is used. A default of 0.4 is used for Y conversions.

See the discussion of DBDATE on page 3-23 for related information.

DBUPSPACE

For example, to set DBUPSPACE to 2,500 kilobytes, enter the following command:

setenv DBUPSPACE 2500 

If you try to set DBUPSPACE to any value less than 1,024 kilobytes, it is automatically set to 1,024 kilobytes, but no error message is returned. If this value is not large enough to allow more than one distribution to be constructed at a time, at least one distribution is done, even if the amount of disk space required for the one is greater than that specified in DBUPSPACE.

DELIMIDENT

You can use delimited identifiers to specify identifiers that are identical to reserved keywords, such as TABLE or USAGE. You can also use them to specify database identifiers that contain nonalphabetical characters, but you cannot use them to specify storage identifiers that contain nonalphabetical characters. Note that database identifiers are names for database objects such as tables and columns, and storage identifiers are names for storage objects such as dbspaces and blobspaces.

Delimited identifiers are case sensitive. To use delimited identifiers, applications in ESQL/C must set the DELIMIDENT environment variable at compile time and execute time.

ENVIGNORE

For example, to ignore the DBPATH and DBMONEY entries in the environment-configuration files, enter the following command:

setenv  ENVIGNORE  DBPATH:DBMONEY 

ENVIGNORE cannot be set in an environment-configuration file.

FET_BUF_SIZE

When set to a valid value, the environment variable overrides the previously set value. The default setting for the fetch buffer is dependent on row size.

If the buffer size is set to less than the default size or is out of the range of the small integer value, no error is raised. The new buffer size is ignored.

For example, to set a buffer size to 5,000 bytes, set the FET_BUF_SIZE environment variable by entering the following command:

setenv  FET_BUF_SIZE 5000

For example, to specify the GNU C compiler, enter the following command:

setenv  INFORMIXC  gcc

INFORMIXCONCSMCFG

For example, the following command specifies that the concsm.cfg file is in /usr/myfiles.

setenv INFORMIXCONCSMCFG /usr/myfiles

setenv INFORMIXCONCSMCFG /usr/myfiles/csmconfig

INFORMIXCONRETRY

For example, set INFORMIXCONRETRY to three additional connection attempts (after the initial attempt) by entering the following command:

setenv INFORMIXCONRETRY 3 

INFORMIXCONTIME

You might encounter connection difficulties related to system or network load problems. For instance, if the database server is busy establishing new SQL client threads, some clients might fail because the server cannot issue a network function call fast enough. The INFORMIXCONTIME and INFORMIXCONRETRY environment variables let you configure your client-side connection capability to retry the connection instead of returning an error.

value

represents the minimum number of seconds spent in attempts to establish a connection to a server.

For example, set INFORMIXCONTIME to 60 seconds by entering the following command:

setenv INFORMIXCONTIME 60 

If execution of the CONNECT statement involves searching DBPATH, the following rules apply:

• All appropriate servers in the DBPATH setting are accessed at least once, even though the INFORMIXCONTIME value might be exceeded. Thus, the CONNECT statement might take longer than the INFORMIXCONTIME time limit to return an error indicating connection failure or that the database was not found.
• The INFORMIXCONRETRY value specifies the number of additional connections that should be attempted for each server entry in DBPATH.
• The INFORMIXCONTIME value is divided among the number of server entries specified in DBPATH. Thus, if DBPATH contains numerous servers, you should increase the INFORMIXCONTIME value accordingly. For example, if DBPATH contains three entries, to spend at least 30 seconds attempting each connection, set INFORMIXCONTIME to 90.

INFORMIXDIR

Set the INFORMIXDIR environment variable to the desired installation directory by entering the following command:

setenv  INFORMIXDIR /usr/informix 

For example, the following command specifies that the name and location of the keytab file is /usr/myfiles/mykeytab.

setenv INFORMIXKEYTAB /usr/myfiles/keytab

INFORMIXOPCACHE

You set the INFORMIXOPCACHE environment variable by specifying the size of the memory cache in kilobytes. The specified size must be equal to or smaller than the size of the system-wide configuration parameter, OPCACHEMAX. If you do not set the INFORMIXOPCACHE environment variable, the default cache size is 128 kilobytes or the size specified in the configuration parameter OPCACHEMAX. The default for OPCACHEMAX is 128 kilobytes. If you set INFORMIXOPCACHE to a value of 0, INFORMIX-OnLine/Optical does not use the cache.

INFORMIXSERVER

The value of INFORMIXSERVER must correspond to a valid dbservername entry in the $INFORMIXDIR/etc/sqlhosts file on the computer running the application. The dbservername must be specified using lowercase characters and cannot exceed 18 characters for Universal Server. For example, specify the coral database server as the default for connection by entering the following command:

setenv  INFORMIXSERVER  coral 

Important: INFORMIXSERVER must be set even if the application or DB-Access does not use implicit or explicit default connections.

INFORMIXSHMBASE

Important: Resetting INFORMIXSHMBASE requires a thorough understanding of how the application uses memory. Normally you do not reset INFORMIXSHMBASE.

You use INFORMIXSHMBASE to specify where shared-memory communication segments are attached to the client process so that client applications can avoid collisions with other memory segments used by the application. If you do not set INFORMIXSHMBASE, the memory address of the communication segments defaults to an implementation-specific value such as 0x800000.

value

is used to calculate the memory address.

Universal Server calculates the memory address where segments are attached by multiplying the value of INFORMIXSHMBASE by 1,024. For example, to set the memory address to the value 0x800000, set the INFORMIXSHMBASE environment variable by entering the following command:

setenv  INFORMIXSHMBASE  8192 

INFORMIXSQLHOSTS

The file specified in the INFORMIXSQLHOSTS environment variable has the same format as the $INFORMIXDIR/etc/sqlhosts file. For a description of the $INFORMIXDIR/etc/sqlhosts file, see the INFORMIX-Universal Server Administrator's Guide.

pathname

specifies the full pathname and filename of the file that contains connectivity information.

For example, to specify that the client or database server will look for connectivity information in the mysqlhosts file in the /work/envt directory, enter the following command:

setenv INFORMIXSQLHOSTS /work/envt/mysqlhosts

INFORMIXSTACKSIZE

For example, to decrease the INFORMIXSTACKSIZE to 20 kilobytes, enter the following command:

setenv  INFORMIXSTACKSIZE  20 

Warning: For specific instructions for setting this value, see the "INFORMIX-Universal Server Administrator's Guide." If you incorrectly set the value of INFORMIXSTACKSIZE, it can cause Universal Server to crash.

INFORMIXTERM

If INFORMIXTERM is not set, the default setting is termcap. When DB-Access is installed on your system, a termcap file is placed in the etc subdirectory of $INFORMIXDIR. This file is a superset of an operating-system termcap file.

You can use the termcap file supplied by Informix, the system termcap file, or a termcap file that you create. You must set the TERMCAP environment variable if you do not use the default termcap file. For information on setting the TERMCAP environment variable, see page 3-63.

The terminfo directory contains a file for each terminal name that has been defined. The terminfo setting for INFORMIXTERM is supported only on computers that provide full support for the UNIX System V terminfo library. For details, see the Version 9.1 machine notes file for your product.

INF_ROLE_SEP

If INF_ROLE_SEP is set, role separation is implemented and a separate group is specified to serve each of the following responsibilities: the database system security officer (DBSSO), the audit analysis officer (AAO), and the standard user. If INF_ROLE_SEP is not set, user informix (the default) can perform all administrative tasks.

n	is any positive integer.

See the INFORMIX-Universal Server Trusted Facility Manual to learn more about the security feature of role separation. See the INFORMIX-Universal Server Installation Guide to learn how to configure role separation when you install Universal Server.

IFX_AUTOFREE

When the cursor is automatically freed, its associated PREPARE statement is also freed and cannot be used to declare any new cursor thereafter.

1	IFX_AUTOFREE is enabled.
0	IFX_AUTOFREE is disabled.

If the environment variable is not set to any value, the feature is not enabled.

The SET AUTOFREE SQL syntax has the same functionality as the IFX_AUTOFREE environment variable. The IFX_AUTOFREE environment variable should be set before an application starts. The SET AUTOFREE syntax can be specified for a single cursor and overrides the setting of the environment variable for that cursor.

Important: The environment variable needs to be set before the application starts for the setting to take effect.

The SQL statement SET DEFERRED_PREPARE has the same functionality as the on (1) setting of this environment variable. The SQL statement overrides the setting of this environment variable.

Tip: If PREPARE/EXECUTE statements are used or if a DESCRIBE statement is executed before the first OPEN statement in the ESQL/C code when deferred prepare functionality is turned on, error is returned.

IFX_DEFERRED_PREPARE

If the IFX_DEFERRED_PREPARE variable is set to 1, the PREPARE statement in an ESQL/C code is not executed until the cursor has been declared on it and opened, thus optimizing the number of round-trip messages to the server. Setting of the variable to 1 enables every PREPARE statement in every thread in the application to be optimized.

Setting the value of the IFX_DEFERRED_PREPARE environment variable to 0 disables the optimization feature. If IFX_DEFERRED_PREPARE is not set, the optimization feature is not turned on.

Important: The environment variable needs to be set before the application starts for the setting to take effect.

The SQL statement SET DEFERRED_PREPARE has the same functionality as the `on' (1) setting of this environment variable. The SQL statement overrides the setting of this environment variable.

Tip: If PREPARE/EXECUTE statements are used or if a DESCRIBE statement is executed before the first OPEN statement in the ESQL/C code when deferred prepare functionality is turned on, an error is returned.

NODEFDAC

ONCONFIG

Prepare the ONCONFIG file by making a copy of the onconfig.std file and modifying the copy. Informix recommends that you name the ONCONFIG file so it can easily be related to a specific Universal Server database server. If you have multiple instances of Universal Server, each instance must have its own uniquely named ONCONFIG file.

If you do not set the ONCONFIG environment variable, the default filename is onconfig.

For more information, see the INFORMIX-Universal Server Administrator's Guide.

OPTCOMPIND

When the OPTCOMPIND environment variable is not set, Universal Server uses the value specified for the ONCONFIG configuration parameter OPTCOMPIND. When neither the environment variable nor the configuration parameter is set, the default value is 2.

For more information on the ONCONFIG configuration parameter OPTCOMPIND, see the INFORMIX-Universal Server Administrator's Guide. For more information on the different join methods used by the optimizer, see the INFORMIX-Universal Server Performance Guide.

PATH

You can specify the correct search path in various ways. Be sure to include a colon between the directory names.

For additional information about how to modify your path, see "Modifying the Setting of an Environment Variable".

PDQPRIORITY

When the PDQPRIORITY environment variable is not set, the default value is OFF.

When the environment variable is set to HIGH, the database server determines an appropriate value to use for PDQPRIORITY based on several criteria, including the number of available processors, the fragmentation of tables queried, the complexity of the query, and so on.

Usually the more resources Universal Server uses, the better its performance for a given query, but using too many resources can cause contention among the resources and also take away resources from other queries, resulting in degraded performance.

An application can override the setting of the environment variable when it issues the SQL statement SET PDQPRIORITY, which is described in the Informix Guide to SQL: Syntax.

PLCONFIG

For example, to specify the $INFORMIXDIR/etc/custom.cfg file as the configuration file for the High-Performance Loader, enter the following command:

setenv PLCONFIG custom.cfg

Universal Server uses the directory specified by PSORT_DBTEMP even if the environment variable PSORT_NPROCS is not set.

pathname

is the name of the UNIX directory used for intermediate writes during a sort.

Set the PSORT_DBTEMP environment variable to specify the directory (for example, /usr/leif/tempsort) by entering the following command:

setenv PSORT_DBTEMP /usr/leif/tempsort

You also might want to consider setting the environment variable DBSPACETEMP to place temporary files used in sorting in dbspaces rather than operating-system files. See the discussion of the DBSPACETEMP environment variable on page 3-36.

For additional information about the PSORT_DBTEMP environment variable, see the INFORMIX-Universal Server Administrator's Guide as well as the INFORMIX-Universal Server Performance Guide.

PSORT_NPROCS

Use the following command to set the PSORT_NPROCS environment variable to 4:

setenv PSORT_NPROCS  4

You can disable parallel sorting by entering the following command:

unsetenv PSORT_NPROCS 

Tip: If the PDQPRIORITY environment variable is not set, Universal Server allocates the minimum amount of memory to sorts. This minimum memory is insufficient to start even two sort threads. If you have not set the PDQPRIORITY environment variable, check the available memory before you perform a large-scale sort (such as an index build) and make sure that you have enough memory.

If PSORT_NPROCS is not set, parallel sorting does not take place. Universal Server uses one thread for the sort.

If PSORT_NPROCS is set to 0, Universal Server uses three threads for the sort.

Default Values for Attached Indexes

If the PSORT_NPROCS environment variable is set, you get the specified number of sort threads for each fragment of the index that is being built.

If the PSORT_NPROCS environment variable is not set, or if it is set to 0, you get two sort threads for each fragment of the index unless you have a single-CPU virtual processor. If you have a single-CPU virtual processor, you get one sort thread for each fragment of the index.

For additional information about the PSORT_NPROCS environment variable, see the INFORMIX-Universal Server Administrator's Guide as well as the INFORMIX-Universal Server Performance Guide.

TERM

The terminal type specified in the TERM setting must correspond to an entry in the termcap file or terminfo directory. Before you can set the TERM environment variable, you must obtain the code for your terminal from the DBA.

For example, to specify the vt100 terminal, set the TERM environment variable by entering the following command:

setenv TERM vt100 

The termcap file contains a list of various types of terminals and their characteristics. For example, you can provide DB-Access terminal-handling information, which is specified in the /usr/informix/etc/termcap file, by entering the following command:

setenv  TERMCAP  /usr/informix/etc/termcap

1. The termcap file that you create

2. The termcap file supplied by Informix (that is, $INFORMIXDIR/etc/termcap)

3. The operating-system termcap file (that is, /etc/termcap)

If you do not set the TERMCAP environment variable, the system file (that is, /etc/termcap) is used by default.

TERMINFO

TERMINFO tells DB-Access to communicate with the terminfo directory instead of the termcap file. The terminfo directory has subdirectories that contain files that pertain to terminals and their characteristics.

Set TERMINFO by entering the following command:

setenvTERMINFO/usr/lib/terminfo

THREADLIB

The THREADLIB environment variable indicates which thread package to use when you compile an application. Currently only the Distributed Computing Environment (DCE) is supported.

The THREADLIB environment variable is checked when the -thread option is passed to the ESQL/C script when you compile a multithreaded ESQL/C application. When you use the -thread option while compiling, the ESQL/C script generates an error if the THREADLIB environment variable is not set or if the variable is set to an unsupported thread package.