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|What are log files?|
files are tables that manage a persistent
set of rows from a table or layer.
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.
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 files are important for applications that need to manage a persistent set of rows from a table or layer. For example, after identifying a set of features, the application can maintain a list of these specific features so that subsequent operations process only the identified 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.