Chapter 4. Building Berkeley DB for Android

Table of Contents

Building the Drop-In Replacement for Android
Migrating from SQLite to Berkeley DB
Building the Android JDBC Driver
Android Configuration Options

Berkeley DB provides support for the Android platform enabling you to develop and deploy a wide range of mobile applications and services. Android provides SQLite as the default database for developing applications that need database support. Berkeley DB SQL API is fully compatible with SQLite and can be used as a replacement. The build_android directory in the Berkeley DB distribution contains a makefile, Android.mk, for building a drop-in replacement for SQLite.

Oracle offers two different solutions for building the BDB SQL API for Android. The first creates a library that can be used as a drop-in replacement for SQLite on Android. The second creates a JDBC driver for Android.

Building the Drop-In Replacement for Android

This section describes how to build a library that can be used as a drop-in replacement for SQLite on Android.

Note

A drop in replacement refers to replacing all instances of SQLite in an Android OS build with Berkeley DB SQL. All databases will be created in the Berkeley DB SQL format including any created with the Java SQLite.* API. This solution requires that users re-compile a custom Android OS image (it is only relevant for platform/device vendors).

  1. Download and compile the Android source tree.

    The compiling process takes time but is a one time activity. For information on downloading and compiling the Android source code, see http://source.android.com/source/download.html.

  2. Copy the Berkeley DB code into the Android build tree.

    $ cd <root>/external/sqlite/dist
    $ tar zxf ${DB_PATH} 

    where <root> is the root of the Android source tree and ${DB_PATH} is the path where you saved the db-xx.tar.gz version of the Berkeley DB distribution.

  3. Update the Android build file to identify Berkeley DB.

    Replace the Android.mk file with the one from the Berkeley DB source tree by doing the following:

    $ cd <root>/external/sqlite/dist
    $ mv Android.mk Android.mk.sqlite
    $ cp ${DB_INSTALL}/build_android/Android.mk ./ 

    where ${DB_INSTALL} is the directory into which you installed the Berkeley DB library.

  4. Tuning parameters.

    The configuration options for performance tuning can be added/edited in the Android.mk file by modifying LOCAL_CFLAGS located in the build libsqlite replacement section. For more information, see Android Configuration Options.

    It is also possible to change these settings using PRAGMA commands or through the DB_CONFIG file.

  5. Build the new Android image.

    To build the Android image with Berkeley DB SQL included, do the following:

    $ cd <root>
    $ . build/envsetup.sh
    $ make clean-libsqlite
    $ mmm -B external/sqlite/dist
    $ make snod
    

    You can locate the new image in <root>/out/target/product/generic.

Migrating from SQLite to Berkeley DB

This section describes how to enable automatic conversion of SQLite format databases to Berkeley DB SQL when they are opened. To do this, you must first make sure that the -DBDBSQL_CONVERT_SQLITE option is added to LOCAL_CFLAGS when you configure your Berkeley DB database build.

  1. Build a static SQLite shell for Android platform.

    Create a script, build_sqlite3_shell.sh, in the <root>/external/sqlite/dist directory.

    #!/bin/bash
    # This script shows how to use built-in toolchain to build
    # sqlite3 shell, which is required by Berkeley DB SQL 
    # on-the-fly migration feature.
    
    # Note: these variables should be set per active Android source tree
    # We assume $PWD=$ROOT/external/sqlite/dist
    ROOT=${PWD}/../../..
    TOOLCHAIN=${ROOT}/prebuilt/linux-x86/toolchain/arm-eabi-4.4.0
    CC=${TOOLCHAIN}/bin/arm-eabi-gcc
    LIB="${ROOT}/out/target/product/generic/obj/lib"
    INCLUDE="${ROOT}/ndk/build/platforms/android-8/arch-arm/usr/include"
    
    # CFLAGS should be set per Android.mk.sqlite (the original 
    # version of SQLite's Android.mk)
    CFLAGS="-DHAVE_USLEEP=1 -DSQLITE_THREADSAFE=1 -DNDEBUG=1 \
     -DSQLITE_DEFAULT_JOURNAL_SIZE_LIMIT=1048576 \
     -DSQLITE_ENABLE_MEMORY_MANAGEMENT=1 \
     -DSQLITE_DEFAULT_AUTOVACUUM=1 \
     -DSQLITE_TEMP_STORE=3 -DSQLITE_ENABLE_FTS3 \
     -DSQLITE_ENABLE_FTS3_BACKWARDS -DTHREADSAFE=1"
    CFLAGS="${CFLAGS} -I${INCLUDE}"
    
    LDFLAGS="-ldl -nostdlib -Wl,--gc-sections -lc -llog -lgcc \
     -Wl,--no-undefined,-z,nocopyreloc ${LIB}/crtend_android.o \
     ${LIB}/crtbegin_dynamic.o -L${LIB} -Wl,-rpath,${LIB}"
    
    ${CC} -DANDROID -DOS_ANDROID --sysroot="${SYSROOT}" -mandroid \
          -fvisibility=hidden -ffunction-sections -fdata-sections \
          -fPIC ${LDFLAGS} ${CFLAGS} \
          sqlite3.c shell.c -o sqlite3orig
    

    Ensure you adjust the variables as per your actual Android environment. This script is suited for Android 2.2.

  2. Execute the build_sqlite3_shell.sh script and to get the static sqlite3 shell utility - sqlite3orig.

  3. Change the system image file.

    Use the xyaffs2 utiltiy to decompress the system.img and get the directory system.

    $ xyaffs2 ./system.img system

    Add static sqlite3 shell utility.

    $ cp <root>/external/sqlite/dist/sqlite3orig \
                          system/xbin/sqlite3orig

    Use the mkyaffs2image utility to rebuild system.img from the changed directory system.

    $ mkyaffs2image -f $PWD/system system.img

    Note

    To open the database in the SQLite format use the sqlite3orig command.