The C API code is distributed with MySQL. It is included in the
mysqlclient library and allows C programs to
access a database.
Many of the clients in the MySQL source distribution are written in
C. If you are looking for examples that demonstrate how to use the C
API, take a look at these clients. You can find these in the
client directory in the MySQL source
Most of the other client APIs (all except Connector/J and
Connector/NET) use the
mysqlclient library to
communicate with the MySQL server. This means that, for example, you
can take advantage of many of the same environment variables that
are used by other client programs, because they are referenced from
the library. See Chapter 4, MySQL Programs, for a list of these
The client has a maximum communication buffer size. The size of the buffer that is allocated initially (16KB) is automatically increased up to the maximum size (the maximum is 16MB). Because buffer sizes are increased only as demand warrants, simply increasing the default maximum limit does not in itself cause more resources to be used. This size check is mostly a check for erroneous statements and communication packets.
The communication buffer must be large enough to contain a single
SQL statement (for client-to-server traffic) and one row of returned
data (for server-to-client traffic). Each thread's communication
buffer is dynamically enlarged to handle any query or row up to the
maximum limit. For example, if you have
BLOB values that contain up to 16MB
of data, you must have a communication buffer limit of at least 16MB
(in both server and client). The client's default maximum is 16MB,
but the default maximum in the server is 1MB. You can increase this
by changing the value of the
max_allowed_packet parameter when
the server is started. See Section 7.5.3, “Tuning Server Parameters”.
The MySQL server shrinks each communication buffer to
net_buffer_length bytes after each
query. For clients, the size of the buffer associated with a
connection is not decreased until the connection is closed, at which
time client memory is reclaimed.
For programming with threads, see Section 188.8.131.52, “How to Make a Threaded Client”. For creating a standalone application which includes the "server" and "client" in the same program (and does not communicate with an external MySQL server), see Section 17.5, “libmysqld, the Embedded MySQL Server Library”.
MySQL Enterprise. MySQL Enterprise subscribers will find more information about using the C API in the Knowledge Base articles, The C API. Access to the MySQL Knowledge Base collection of articles is one of the advantages of subscribing to MySQL Enterprise. For more information, see http://www.mysql.com/products/enterprise/advisors.html.