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 ArcSDE clients

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.