Library Version 18.1.40

DB_ENV->set_memory_max()
Prev | Chapter 5. The DB_ENV Handle | Next

## DB_ENV->set_memory_max()

    #include <db.h>

    int
    DB_ENV->set_memory_max(DB_ENV *dbenv, u_int32_t gbytes, u_int32_t bytes);

This method sets the maximum amount of memory to be used by shared structures in the main environment region. These are the structures used to coordinate access to the environment other than mutexes and those in the page cache (memory pool). If the region files are in memory mapped files, or if `DB_PRIVATE` is specified, the memory specified by this method is not allocated completely at startup. As memory is needed, the shared region will be extended or, in the case of `DB_PRIVATE`, more memory will be allocated using the system malloc call. For memory mapped files, a mapped region will be allocated to this size but the underlying file will only be allocated sufficient memory to hold the initial allocation of shared memory structures as set by DB_ENV->set_memory_init() .

If no memory maximum is specified then it is calculated from defaults, initial settings or (deprecated) maximum settings of the various shared structures. In the case of environments created with `DB_PRIVATE`, no maximum need be set and the shared structure allocation will grow as needed until the process memory limit is exhausted.

The database environment's maximum memory may also be configured using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "set_memory_max", one or more whitespace characters, followed by the maximum to be allocated. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

The `DB_ENV->set_memory_max()` method must be called prior to opening the database environment.

### Parameters

#### gbytes

The maximum memory is set to gbytes gigabytes plus bytes.

#### bytes

The maximum memory is set to gbytes gigabytes plus bytes.

### Errors

The `DB_ENV->set_memory_max()` method may fail and return one of the following non-zero errors:

#### EINVAL

If the method was called after DB_ENV->open() was called; or if an invalid flag value or parameter was specified.

### Class

DB_ENV

### See Also

Database Environments and Related Methods

Prev | Up | Next
DB_ENV->set_memory_init() | Home | DB_ENV->set_metadata_dir()