FairCom ISAM for C

Single User Transaction Processing Control

The single user transaction processing logic includes the same robust features found with FairCom Server, including full automatic recovery and log dump utilities. The following information is included for the single user transaction processing developer who has minimal hard drive space available for the log files. The following defines control the quantity and size of the transaction log files. The values listed are the default defines and the minimum recommendations.

Note: If defines are changed, you must rebuild the FairCom DB library, recompile and relink your application.

Define	Location	Default	Minimum
LOGPURGE	cttran.h	4	3
LOGCHUNKX	cttran.h	1100000L	380000L
LOGCHUNKN	cttran.h	550000L	190000L
MINCHKLMT	ctinit.c	75000L	50% of LOGCHUNKN
MINLOGSPACE	ctinit.c	2000000L	750000L

Deviating from the default or minimum recommendations is done so at the user’s own risk. If deviating from the above defines:

• The LOGPURGE define is the number of active transaction log files.
• The MINLOGSPACE is the total space to be used by all active transaction log files.
• LOGCHUNKX is derived by roughly dividing MINLOGSPACE by 2.
• LOGCHUNKN is derived by roughly dividing LOGCHUNKX by 2.
• MINCHKLMT is the smallest number of bytes permitted between checkpoints.

The *.FCS files may be removed if a clean shutdown is performed. A clean shutdown is performed by issuing a CloseISAM() with no active transactions pending.

To modify the number of inactive log files which are maintained (default is zero), add “extern int ct_logkep;” to your application, if not using ctNOGLOBALS. If ctNOGLOBALS is defined, it will already be properly declared. Set ct_logkep to -1 if you wish to keep all inactive logs, or set ct_logkep to the number of inactive log files you wish to keep. Default for ct_logkep is 0, which indicates to use the default transaction log behavior which is to save the most current 4 (including the active) transaction logs.