Performance tuning for the Informix wrapper

You can use the FOLD_ID and FOLD_PW server options to improve connectivity between the federated server and Informix® data sources.

When the federated server connects to a data source, the server tries to connect using all possible combinations of uppercase and lowercase for the user ID and password. The server might make up to nine connect attempts before successfully connecting to the data source server. These attempts can slow down connect times and might result in the user ID getting locked out.

You can improve performance by specifying the values for the FOLD_ID and FOLD_PW server options.

If all your Informix user IDs and passwords are in lowercase, setting the FOLD_ID and FOLD_PW server options with the value 'L' can improve your connect time.
For example:
```
ALTER SERVER TYPE INFORMIX
   OPTIONS (ADD FOLD_ID 'L');
ALTER SERVER TYPE INFORMIX 
   OPTIONS (ADD FOLD_PW 'L');
```
The federated server attempts each combination of uppercase and lowercase values for the user ID and password. You can reduce the chance of the maximum number of failed login attempts being exceeded by setting these options to 'N' (do not fold the user ID and the password). If you establish these settings, then you need to always specify the user ID and password in the correct case. If an invalid user ID and password are specified, the wrapper will not keep trying the various combinations.
For example:
```
ALTER SERVER TYPE INFORMIX
   OPTIONS (ADD FOLD_ID 'N');
ALTER SERVER TYPE INFORMIX 
   OPTIONS (ADD FOLD_PW 'N');
```