Windows CE/Mobile FAQ
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## Windows CE/Mobile FAQ

1. What if my Windows CE/Mobile device does not support SetFilePointer and/or SetEndOfFile?

   You can manually disable the truncate functionality from the build.

   Do that by opening the `db-X.X.X/build_wince/db_config.h` file, and change the line that reads

       #define HAVE_FTRUCATE 1

   to read

       #undef HAVE_FTRUNCATE

   Making this change disables DB->compact() for btree databases.

2. Why doesn't automatic log archiving work?

   The Windows CE/Mobile platform does not have a concept of a working directory. This means that the DB_ARCH_REMOVE and DB_ARCH_ABS flags do not work properly within Windows CE, since they rely on having a working directory.

   To work around this issue, you can call log_archive with the DB_ARCH_LOG flag, the list of returned file handles will not contain absolute paths. Your application can take this list of files, construct absolute paths, and delete the files.

3. Does Berkeley DB support Windows Mobile?

   Yes.

   Berkeley DB relies on a subset of the Windows API, and some standard C library APIs. These are provided by Windows CE. Windows Mobile is built "on top" of Windows CE.

4. I see a file mapping error when opening a Berkeley DB environment or database. What is wrong?

   The default behavior of Berkeley DB is to use memory mapped files in the environment. It seems that Windows CE does not allow memory mapped files to be created on flash storage.

   There are two workarounds:

   1. Configure the Berkeley DB environment not to use memory mapped files. The options are discussed in detail in the section called “Shared memory regions”.
   2. Create the Berkeley DB environment on non-flash storage. It is possible to store database and log files in a different location to using the DB_ENV->set_data_dir() and DB_ENV->set_lg_dir() APIs.

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