DbEnv::set_mp_mmapsize
DbEnv::set_mp_mmapsize |
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#include <db_cxx.h>int DbEnv::set_mp_mmapsize(size_t mp_mmapsize);
Files that are opened read-only in the pool (and that satisfy a few other criteria) are, by default, mapped into the process address space instead of being copied into the local cache. This can result in better-than-usual performance because available virtual memory is normally much larger than the local cache, and page faults are faster than page copying on many systems. However, it can cause resource starvation in the presence of limited virtual memory, and it can result in immense process sizes in the presence of large databases.
Set the maximum file size, in bytes, for a file to be mapped into the process address space. If no value is specified, it defaults to 10MB.
The DbEnv::set_mp_mmapsize interface may be used only to configure Berkeley DB before the DbEnv::open interface is called.
The DbEnv::set_mp_mmapsize 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 maximum mapped 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_mp_mmapsize", 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.
The DbEnv::set_mp_mmapsize method may fail and throw an exception or return a non-zero error for the following conditions:
Called after DbEnv::open was called.
The DbEnv::set_mp_mmapsize 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_mp_mmapsize method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.
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Copyright Sleepycat Software
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DbEnv::memp_fcreate,
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DbMpoolFile::set_clear_len,
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DbMpoolFile::set_lsn_offset,
DbMpoolFile::set_pgcookie,
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The DbEnv::set_mp_mmapsize method configures operations performed using the specified DbEnv handle, not all operations performed on the underlying database environment.
The DbEnv::set_mp_mmapsize interface may be called at any time during the life of the application. d55 4 a58 4 If a catastrophic error has occurred, the DbEnv::set_mp_mmapsize 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. d60 1 a60 1 DbEnv, DbMpoolFile d62 19 a80 1 Memory Pools and Related Methods @ 1.1.1.4 log @Import: RPM 4.1 @ text @d1 2 a2 2 d4 1 d39 5 a43 2
The DbEnv::set_mp_mmapsize interface may be used only to configure Berkeley DB before the DbEnv::open interface is called. d59 4 a62 4 If a catastrophic error has occurred, the DbEnv::set_mp_mmapsize method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way. d64 1 a64 1 DbEnv, DbMpoolFile d66 1 a66 19 DbEnv::set_cachesize, DbEnv::set_mp_mmapsize, DbEnv::memp_fcreate, DbMpoolFile::close, DbMpoolFile::get, DbMpoolFile::open, DbMpoolFile::put, DbMpoolFile::set, DbMpoolFile::sync, DbEnv::memp_register, DbMpoolFile::set_clear_len, DbMpoolFile::set_fileid, DbMpoolFile::set_ftype, DbMpoolFile::set_lsn_offset, DbMpoolFile::set_pgcookie, DbEnv::memp_stat, DbEnv::memp_sync, and DbEnv::memp_trickle. @ 1.1.1.5 log @Import: RPM 4.1.1 @ text @d1 2 a2 2 a3 1 d38 2 a39 5
The DbEnv::set_mp_mmapsize method configures operations performed using the specified DbEnv handle, not all operations performed on the underlying database environment.
The DbEnv::set_mp_mmapsize interface may be called at any time during the life of the application. d55 4 a58 4 If a catastrophic error has occurred, the DbEnv::set_mp_mmapsize 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. d60 1 a60 1 DbEnv, DbMpoolFile d62 19 a80 1 Memory Pools and Related Methods @