A log file is tied to a specific table or layer, maintains a list of row identifiers, and can be used as a data source for many data retrieval and geoprocessing operations. For example, after identifying a set of features, the application can maintain a list of these specific features so that subsequent operations only process the identified features. Persistent row subsets are managed through log files.

Basic Principles Database Schema API Comparison Samples

Log files can have either a layer or a table as target. Log files with layer targets record the layer feature ID values and are usable only with layers. They can be created using the SE_LOG_FOR_LAYER flag of the SE_loginfo_set_target_object function. They have the limitation that only rows having a non-null feature can be recorded. Log files that have table targets record SDE_ROW_ID values and are usable with any table, not just layers. They can be created by using the SE_LOG_FOR_TABLE flag of the SE_loginfo_set_target_object function.

 Selection threshold for client applications

ArcIMS always uses log files for selections; there is no threshold that must be crossed before log files are used. For ArcGIS, a log file is created the first time a user's selection set contains 100 or more features.

Log file functions use two types of names. Some functions require a simple name that is the log file name only. Functions that allow read/write access by the owner use simple log file names. The second type of name combines a user name and the log file name; for example, user name\file name. Legal delimiters between the user name and file name are the , . \ ; characters. User name\file names are primarily used for read-only log files where other users are allowed access to the log file.

See also