Prepare the runtime environment - connecting to the database

In order to connect to Oracle®, you must have a database driver "dbmora" in $FGLDIR/dbdrivers.
If you want to connect to a remote Oracle server from an application server, you must install the Oracle Client Software on your application server and configure this.
Make sure that the ORACLE client environment variables are properly set.
Check Oracle client configuration envrionment variables such as TNS_ADMIN. See the Oracle documentation for more details.

Verify the environment variable defining the search path for database client shared libraries (libclntsh.so on UNIX™, OCI.DLL on Windows®)


Oracle version	Shared library environment setting
Oracle 19c and higher	UNIX: Define LD_LIBRARY_PATH (or its equivalent): Database Server: Add `$ORACLE_HOME/lib` Instant Client: Add `install-directory` Windows: Define PATH: Database Server: Add `%ORACLE_HOME%\bin` Instant Client: Add `install-directory`

Check the database client locale settings (NLS_LANG, NLS_DATE_FORMAT, etc).
The database client locale must match the locale used by the runtime system (LC_ALL, LANG).
If you are using the TNS protocol, verify if the Oracle listener is started on the server.
To test the client environment settings, you can try to connect to the Oracle server with the SQL*Plus tool:
```
$ sqlplus username/password@service
```
Disable installation by Oracle client of SIGINT signal handler.

By default, the OCI client library installs a signal handlers for the SIGINT signal. Normally this should not be done by a database client library: It's in the hands of the main code (fglrun / DEFER INTERRUPT) to install SIGINT signal handlers and call appropriate DB client APIs to cancel an SQL query (OCIBreak()).

To workaround this problem, the ODI driver for Oracle resets the fglrun signal handler for SIGINT, after each connectiong to Oracle.

Additionally, you can disable OCI client library SIGINT signal handler installation, by defining the DISABLE_INTERRUPT sqlnet.ora file:
```
DISABLE_INTERRUPT=ON
```
For more details, search the Oracle bug database for Bug 12877221.
Disable installation by Oracle client of various signal handlers for the OCI diagnostic framework.

By default, the OCI client library installs signal handlers for the OCI diagnostic framework. These signal handlers are registered when connecting to the database, and can conflict with the signal handlers installed by the fglrun runtime system.

Unless you are explicitly asked to use OCI diagnostic framework, there is no need to let OCI use these signals.

To disable OCI client library signal handlers installations, define the following parameters in the sqlnet.ora file:
```
DIAG_ADR_ENABLED=FALSE
DIAG_DDE_ENABLED=FALSE
DIAG_SIGHANDLER_ENABLED=FALSE
```
For more details, search Oracle OCI documentation about "Fault Diagnosability in OCI".
Set up the FGLPROFILE entries for database connections.
1. Set up FGLPROFILE for the serial emulation method.
  The following entry defines the serial emulation method. You can use the sequence-based trigger or the serialreg-based trigger method:
```
dbi.database.dbname.ifxemul.datatype.serial.emulation = "(native|regtable)" 
```
  The value 'native' selects the sequence-based method, and the value 'regtable' selects the serialreg-based method. This entry has no effect if dbi.database.dbname.ifxemul.datatype.serial is set to 'false'.
  The default is serial emulation enabled with native method (sequence-based). See issue SERIAL and BIGSERIAL data types for more details.
2. The "source" parameter defines the TNS name of the Oracle database.
```
dbi.database.dbname.source = "stock"
```
3. Define the database schema selection if needed.
  The following entry defines the database schema to be used by the application. The database interface automatically executes an "ALTER SESSION SET CURRENT_SCHEMA owner" instruction to switch to a specific schema:
```
dbi.database.dbname.ora.schema = "name"
```
  Here dbname identifies the database name used in the BDL program (DATABASE dbname) and name is the schema name to be used in the ALTER SESSION instruction. If this entry is not defined, no ALTER SESSION instruction is executed and the current schema defaults to the user's name.
4. Define pre-fetch parameters.
  Oracle offers high performance by pre-fetching rows in memory. The pre-fetching parameters can be tuned with the following entries:
```
dbi.database.dbname.ora.prefetch.rows = integer
dbi.database.dbname.ora.prefetch.memory = integer # in bytes
```
  These values will be applied to all application cursors.
  
  The interface pre-fetches rows up to the prefetch.rows limit unless the prefetch.memory limit is reached, in which case the interface returns as many rows as will fit in a buffer of size prefetch.memory. By default, pre-fetching is on and defaults to 10 rows; the memory parameter is set to zero, so the memory size is not included in computing the number of rows to prefetch.
5. If needed, define a specific command to generate session identifiers with this FGLPROFILE setting:
```
dbi.database.dbname.ora.sid.command = "SELECT ..." 
```
  This unique session identifier will be used to create table names for temporary table emulation.
  
  By default, the database driver will use "SELECT USERENV('SESSIONID') FROM DUAL".
6. If needed, define a specific command to generate session identifiers with this FGLPROFILE setting:
```
dbi.database.dbname.ora.sid.command = "SELECT ..." 
```
  This unique session identifier will be used to create table names for temporary table emulation.
  
  By default, the database driver will use "SELECT USERENV('SESSIONID') FROM DUAL".
7. The default temporary table emulation uses regular permanent tables.
  If this does not fit your needs, you can use global temporary tables with this FGLPROFILE setting:
```
dbi.database.dbname.ifxemul.temptables.emulation = "global"
```
8. By default, the tablespace for the default temporary table emulation is TEMPTABS. For global temporary table emulation, there is no tablespace used by default.
  If required, define the tablespace to be used for temporary table emulations (note that this parameter applies to all temporary table emulation methods):
```
dbi.database.dbname.ora.temptables.tablespace = "mytemptabs"
```
9. By default, no schema is used for the default temporary table emulation. For global temporary table emulation, the schema TEMPTABS is used by default.
  If required, define the schema to be used for temporary table emulations (note that these parameters applies to all temporary table emulation methods). Define the "source" parameter to use the current user login, or a SELECT command to produce the schema name:
```
# Get the schema from the current user name specified in connection command:
dbi.database.dbname.ora.temptables.schema.source = "login"
# or, get the schema from a SELECT statement:
dbi.database.dbname.ora.temptables.schema.source = "command"
dbi.database.dbname.ora.temptables.schema.command =
    "SELECT SYS_CONTEXT('USERENV','SESSION_USER') FROM DUAL"
```