Berkeley DB: DbEnv::set_lg_max
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++

# DbEnv::set_lg_max |

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    #include <db_cxx.h>

    int
    DbEnv::set_lg_max(u_int32_t lg_max);

# Description

Set the maximum size of a single file in the log, in bytes. By default, or if the lg_max argument is set to 0, a size of 10MB is used. Because DbLsn file offsets are unsigned four-byte values, the set value may not be larger than the maximum unsigned four-byte value. The size of the log file must be at least four times the size of the in-memory log buffer (see DbEnv::set_lg_bsize).

See Log File Limits for more information.

The DbEnv::set_lg_max method configures a database environment, not only operations performed using the specified DbEnv handle.

The DbEnv::set_lg_max interface may be called at any time during the life of the application. If no size is specified by the application, the size last specified for the database region will be used, or if no database region previously existed, the default will be used.

The DbEnv::set_lg_max method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

The database environment's log file size may also be set using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "set_lg_max", one or more whitespace characters, and the size in bytes. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

# Errors

The DbEnv::set_lg_max method may fail and throw an exception or return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

  Called after DbEnv::open was called.

  The size of the log file is less than four times the size of the in-memory log buffer.

  The specified log file size was too large.

The DbEnv::set_lg_max method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the DbEnv::set_lg_max method may fail and either return DB_RUNRECOVERY or throw a DbRunRecoveryException, in which case all subsequent Berkeley DB calls will fail in the same way.

# Class

DbEnv, DbLogc, DbLsn

# See Also

Logging Subsystem and Related Methods`

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