Purpose
Provide the MySQL server with position/offset information for
last-read row.
Synopsis
virtual void position
( |
record); |
|
Description
This is the position method.
position() is called after each call to rnd_next() if the data
needs to be ordered. You can do something like the following to
store the position: my_store_ptr(ref, ref_length,
current_position);
The server uses ref to store data. ref_length in the above case
is the size needed to store current_position. ref is just a byte
array that the server will maintain. If you are using offsets to
mark rows, then current_position should be the offset. If it is
a primary key like in BDB, then it needs to
be a primary key.
Called from filesort.cc, sql_select.cc, sql_delete.cc and
sql_update.cc.
Parameters
Return Values
This function has no return values.
Usage
Return offset or retrieval key information for last row.
