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The aspects of logging that may be configured are the size of the -logging subsystem's region, the size of the log files on disk and the -size of the log buffer in memory. The DB_ENV->set_lg_regionmax() method -specifies the size of the logging subsystem's region, in bytes. The -logging subsystem's default size is approximately 60KB. This value may -need to be increased if a large number of files are registered with the -Berkeley DB log manager, for example, by opening a large number of Berkeley DB -database files in a transactional application.

The DB_ENV->set_lg_max() method specifies the individual log file size for -all the applications sharing the Berkeley DB environment. Setting the log -file size is largely a matter of convenience and a reflection of the -application's preferences in backup media and frequency. However, -setting the log file size too low can potentially cause problems because -it would be possible to run out of log sequence numbers, which requires -a full archival and application restart to reset. See -Log file limits for more -information.

The DB_ENV->set_lg_bsize() method specifies the size of the in-memory log -buffer, in bytes. Log information is stored in memory until the buffer -fills up or transaction commit forces the buffer to be written to disk. -Larger buffer sizes can significantly increase throughput in the -presence of long-running transactions, highly concurrent applications, -or transactions producing large amounts of data. By default, the buffer -is approximately 32KB.

The DB_ENV->set_lg_dir() method specifies the directory in which -log files will be placed. By default, log files are placed in -the environment home directory.

The DB_ENV->set_lg_filemode() method specifies the absolute file mode for -created log files. This method is only useful for the rare Berkeley DB -application that does not control its umask value.

The DB_ENV->log_set_config() method configures several boolean parameters -that control the use of file system controls such as O_DIRECT and O_DSYNC, -automatic removal of log files, in-memory logging, and pre-zeroing of logfiles.

+ The aspects of logging that may be configured are the size + of the logging subsystem's region, the size of the log files + on disk, the size of the log buffer in memory, and several + operating system settings affecting the behavior of log files. +

+ The DB_ENV->set_lg_regionmax() method specifies the size of the logging + subsystem's region, in bytes. The logging subsystem's default size + is approximately 60KB. This value may need to be increased if a + large number of files are registered with the Berkeley DB log + manager, for example, by opening a large number of Berkeley DB + database files in a transactional application. +

+ The DB_ENV->set_lg_max() method specifies the individual log file + size for all the applications sharing the Berkeley DB + environment. Setting the log file size is largely a matter of + convenience and a reflection of the application's preferences + in backup media and frequency. However, setting the log file + size too low can potentially cause problems because it would + be possible to run out of log sequence numbers, which requires + a full archival and application restart to reset. See Log file limits for more + information. +

+ The DB_ENV->set_lg_bsize() method specifies the size of the + in-memory log buffer, in bytes. Log information is stored in + memory until the buffer fills up or transaction commit forces + the buffer to be written to disk. Larger buffer sizes can + significantly increase throughput in the presence of + long-running transactions, highly concurrent applications, or + transactions producing large amounts of data. By default, the + buffer is approximately 32KB. +

+ The DB_ENV->set_lg_dir() method specifies the directory in which + log files will be placed. By default, log files are placed in + the environment home directory. +

+ The DB_ENV->set_lg_filemode() method specifies the absolute file + mode for created log files. This method is only useful for the + rare Berkeley DB application that does not control its umask + value. +

+ The DB_ENV->log_set_config() method configures several boolean + parameters that control the use of file system controls such + as O_DIRECT and O_DSYNC, automatic removal of log files, + in-memory logging, and pre-zeroing of logfiles. +

@@ -83,9 +100,7 @@ automatic removal of log files, in-memory logging, and pre-zeroing of logfiles.< Next - Chapter 17. - The Logging Subsystem - + Chapter 17. The Logging Subsystem Home -- cgit v1.2.1