Using SQLite

Name

sqlite3_set_auxdata() — Set auxiliary data on a function parameter

Definition

void sqlite3_set_auxdata( sqlite3_context* ctx, int pidx,
                                 void* data, mem_callback );

void mem_callback( void* ptr );

ctx

An SQL function context, provided by the SQLite library.

pidx

The parameter index.

data

The auxiliary data value.

mem_callback

A function pointer to a memory deallocation function. This function frees the memory buffer used to hold the value. If the buffer was allocated with sqlite3_malloc(), a reference to sqlite3_free() can be passed directly.

The flags SQLITE_STATIC and SQLITE_TRANSIENT (which are used by sqlite3_bind_xxx() and sqlite3_result_xxx()) are not available in this context.

Description

This function allows an SQL function implementation to attach auxiliary data to specific SQL function parameters. In situations where an SQL statement calls the same function repeatedly with the same parameter values, the auxiliary data will be preserved across calls. This allows a function implementation to cache high-cost value, such as a compiled regular expression.

For more details on how to use auxiliary data, see http://www.sqlite.org/c3ref/get_auxdata.html.

See Also

sqlite3_get_auxdata(), sqlite3_create_function()