When using the BDB SQL interface, you configure your database page size in
                exactly the same way as you do when using 
                SQLite. That is, use PRAGMA page_size
                to report and set the page size. This PRAGMA must be called
                before you create your first SQLite table. See the
     PRAGMA page_size
                documentation for more information. 
            
                When you use
                PRAGMA cache_size to size your in-memory
                cache, you provide the cache size in terms of a number of
                pages. Therefore, your database page size influences how large your
                cache is, and so determines how much of your
                database will fit into memory. If you adjust the database
                page size, you may also want to adjust the in-memory cache
                size, as described in 
                Configuring the In-Memory Cache.
            
The size of your pages can also affect how efficient your application is at performing disk I/O. It will also determine just how fine-grained the fine-grained locking actually is. This is because Berkeley DB locks database pages when it acquires a lock.
Note that the default value for your page size is probably correct for the physical hardware that you are using. In almost all situations, the default page size value will give your application the best possible I/O performance. For this reason, tuning the page size should rarely, if ever, be attempted.
That said, when using the BDB SQL interface, the page size affects how much of your tables are locked when read and/or write locks are acquired. (See Internal Database Usage for more information.) Increasing your page size will typically improve the bandwidth you get accessing the disk, but it also may increase contention if too many key data pairs are on the same page. Decreasing your page size frequently improves concurrency, but may increase the number of locks you need to acquire and may decrease your disk bandwidth.
                    When changing your page size, make sure the value you
                    select is a power of 2 that is greater than 512 and
                    less than or equal to 64KB. (Note that the standard
                    SQLite MAX_PAGE_SIZE limit is not
                    examined for this upper bound.)
                
Beyond that, there are some additional things that you need to consider when selecting your page size. For a thorough treatment of selecting your page size, see the section on Selecting a page size in the Berkeley DB Programmer's Reference Guide.