Merge pull request #1274 from wiredtiger/basecfg-version

Basecfg version

16 files changed, 673 insertions, 206 deletions

diff --git a/dist/api_data.py b/dist/api_data.py
index 8e42ba72b88..d133c8a082c 100644
--- a/dist/api_data.py
+++ b/dist/api_data.py
@@ -356,6 +356,9 @@ connection_runtime_config = [
 	        merge LSM chunks where possible''',
 	        type='boolean')
 		]),
+	Config('lsm_merge', 'true', r'''
+	    merge LSM chunks where possible (deprecated)''',
+	    type='boolean', undoc=True),
 	Config('eviction', '', r'''
 	    eviction configuration options.''',
 	    type='category', subconfig=[
@@ -462,6 +465,88 @@ session_config = [
 	    choices=['read-uncommitted', 'read-committed', 'snapshot']),
 ]
 
+common_wiredtiger_open = [
+	Config('buffer_alignment', '-1', r'''
+	    in-memory alignment (in bytes) for buffers used for I/O.  The
+	    default value of -1 indicates a platform-specific alignment
+	    value should be used (4KB on Linux systems, zero elsewhere)''',
+	    min='-1', max='1MB'),
+	Config('checkpoint_sync', 'true', r'''
+	    flush files to stable storage when closing or writing
+	    checkpoints''',
+	    type='boolean'),
+	Config('direct_io', '', r'''
+	    Use \c O_DIRECT to access files.  Options are given as a list,
+	    such as <code>"direct_io=[data]"</code>.  Configuring
+	    \c direct_io requires care, see @ref
+	    tuning_system_buffer_cache_direct_io for important warnings.
+		Including \c "data" will cause WiredTiger data files to use
+		\c O_DIRECT, including \c "log" will cause WiredTiger log files
+		to use \c O_DIRECT, and including \c "checkpoint" will cause
+		WiredTiger data files opened at a checkpoint (i.e: read only) to
+		use \c O_DIRECT''',
+	    type='list', choices=['checkpoint', 'data', 'log']),
+	Config('extensions', '', r'''
+	    list of shared library extensions to load (using dlopen).
+	    Any values specified to an library extension are passed to
+	    WT_CONNECTION::load_extension as the \c config parameter
+	    (for example,
+	    <code>extensions=(/path/ext.so={entry=my_entry})</code>)''',
+	    type='list'),
+	Config('file_extend', '', r'''
+	    file extension configuration.  If set, extend files of the set
+	    type in allocations of the set size, instead of a block at a
+	    time as each new block is written.  For example,
+	    <code>file_extend=(data=16MB)</code>''',
+	    type='list', choices=['data', 'log']),
+	Config('hazard_max', '1000', r'''
+	    maximum number of simultaneous hazard pointers per session
+	    handle''',
+	    min='15'),
+	Config('log', '', r'''
+	    enable logging''',
+	    type='category', subconfig=[
+	    Config('archive', 'true', r'''
+	        automatically archive unneeded log files''',
+	        type='boolean'),
+	    Config('enabled', 'false', r'''
+	        enable logging subsystem''',
+	        type='boolean'),
+	    Config('file_max', '100MB', r'''
+	        the maximum size of log files''',
+	        min='100KB', max='2GB'),
+	    Config('path', '""', r'''
+	        the path to a directory into which the log files are written.
+	        If the value is not an absolute path name, the files are created
+	        relative to the database home'''),
+	    ]),
+	Config('mmap', 'true', r'''
+	    Use memory mapping to access files when possible''',
+	    type='boolean'),
+	Config('multiprocess', 'false', r'''
+	    permit sharing between processes (will automatically start an
+	    RPC server for primary processes and use RPC for secondary
+	    processes). <b>Not yet supported in WiredTiger</b>''',
+	    type='boolean'),
+	Config('session_max', '100', r'''
+	    maximum expected number of sessions (including server
+	    threads)''',
+	    min='1'),
+	Config('transaction_sync', '', r'''
+	    how to sync log records when the transaction commits''',
+	    type='category', subconfig=[
+	    Config('enabled', 'false', r'''
+	        whether to sync the log on every commit by default, can
+		be overridden by the \c sync setting to
+		WT_SESSION::begin_transaction''',
+	        type='boolean'),
+	    Config('method', 'fsync', r'''
+	        the method used to ensure log records are stable on disk,
+		see @ref tune_durability for more information''',
+	        choices=['dsync', 'fsync', 'none']),
+	    ]),
+]
+
 methods = {
 'file.meta' : Method(file_meta),
 
@@ -710,97 +795,68 @@ methods = {
 
 'session.reconfigure' : Method(session_config),
 
-'wiredtiger_open' : Method(connection_runtime_config + [
-	Config('buffer_alignment', '-1', r'''
-	    in-memory alignment (in bytes) for buffers used for I/O.  The
-	    default value of -1 indicates a platform-specific alignment
-	    value should be used (4KB on Linux systems, zero elsewhere)''',
-	    min='-1', max='1MB'),
-	Config('checkpoint_sync', 'true', r'''
-	    flush files to stable storage when closing or writing
-	    checkpoints''',
+# There are 4 variants of the wiredtiger_open configurations.
+# wiredtiger_open:
+#	Configuration values allowed in the application's configuration
+#	argument to the wiredtiger_open call.
+# wiredtiger_open_basecfg:
+#	Configuration values allowed in the WiredTiger.basecfg file (remove
+# creation-specific configuration strings and add a version string).
+# wiredtiger_open_usercfg:
+#	Configuration values allowed in the WiredTiger.config file (remove
+# creation-specific configuration strings).
+# wiredtiger_open_all:
+#	All of the above configuration values combined
+'wiredtiger_open' : Method(
+	connection_runtime_config +
+	common_wiredtiger_open + [
+	Config('config_base', 'true', r'''
+	    write the base configuration file if creating the database,
+	    see @ref config_base for more information''',
 	    type='boolean'),
 	Config('create', 'false', r'''
 	    create the database if it does not exist''',
 	    type='boolean'),
-	Config('direct_io', '', r'''
-	    Use \c O_DIRECT to access files.  Options are given as a list,
-	    such as <code>"direct_io=[data]"</code>.  Configuring
-	    \c direct_io requires care, see @ref
-	    tuning_system_buffer_cache_direct_io for important warnings.
-		Including \c "data" will cause WiredTiger data files to use
-		\c O_DIRECT, including \c "log" will cause WiredTiger log files
-		to use \c O_DIRECT, and including \c "checkpoint" will cause
-		WiredTiger data files opened at a checkpoint (i.e: read only) to
-		use \c O_DIRECT''',
-	    type='list', choices=['checkpoint', 'data', 'log']),
 	Config('exclusive', 'false', r'''
 	    fail if the database already exists, generally used with the
 	    \c create option''',
 	    type='boolean'),
-	Config('extensions', '', r'''
-	    list of shared library extensions to load (using dlopen).
-	    Any values specified to an library extension are passed to
-	    WT_CONNECTION::load_extension as the \c config parameter
-	    (for example,
-	    <code>extensions=(/path/ext.so={entry=my_entry})</code>)''',
-	    type='list'),
-	Config('file_extend', '', r'''
-	    file extension configuration.  If set, extend files of the set
-	    type in allocations of the set size, instead of a block at a
-	    time as each new block is written.  For example,
-	    <code>file_extend=(data=16MB)</code>''',
-	    type='list', choices=['data', 'log']),
-	Config('hazard_max', '1000', r'''
-	    maximum number of simultaneous hazard pointers per session
-	    handle''',
-	    min='15'),
-	Config('log', '', r'''
-	    enable logging''',
-	    type='category', subconfig=[
-	    Config('archive', 'true', r'''
-	        automatically archive unneeded log files''',
-	        type='boolean'),
-	    Config('enabled', 'false', r'''
-	        enable logging subsystem''',
-	        type='boolean'),
-	    Config('file_max', '100MB', r'''
-	        the maximum size of log files''',
-	        min='100KB', max='2GB'),
-	    Config('path', '""', r'''
-	        the path to a directory into which the log files are written.
-	        If the value is not an absolute path name, the files are created
-	        relative to the database home'''),
-	    ]),
-	Config('mmap', 'true', r'''
-	    Use memory mapping to access files when possible''',
+	Config('use_environment_priv', 'false', r'''
+	    use the \c WIREDTIGER_CONFIG and \c WIREDTIGER_HOME environment
+	    variables regardless of whether or not the process is running
+	    with special privileges.  See @ref home for more information''',
 	    type='boolean'),
-	Config('multiprocess', 'false', r'''
-	    permit sharing between processes (will automatically start an
-	    RPC server for primary processes and use RPC for secondary
-	    processes). <b>Not yet supported in WiredTiger</b>''',
+]),
+'wiredtiger_open_basecfg' : Method(
+	connection_runtime_config +
+	common_wiredtiger_open + [
+	Config('version', '(major=0,minor=0)', r'''
+	    the file version'''),
+]),
+'wiredtiger_open_usercfg' : Method(
+	connection_runtime_config +
+	common_wiredtiger_open
+),
+'wiredtiger_open_all' : Method(
+	connection_runtime_config +
+	common_wiredtiger_open + [
+	Config('config_base', 'true', r'''
+	    write the base configuration file if creating the database,
+	    see @ref config_base for more information''',
+	    type='boolean'),
+	Config('create', 'false', r'''
+	    create the database if it does not exist''',
+	    type='boolean'),
+	Config('exclusive', 'false', r'''
+	    fail if the database already exists, generally used with the
+	    \c create option''',
 	    type='boolean'),
-	Config('session_max', '100', r'''
-	    maximum expected number of sessions (including server
-	    threads)''',
-	    min='1'),
-	Config('transaction_sync', '', r'''
-	    how to sync log records when the transaction commits''',
-	    type='category', subconfig=[
-	    Config('enabled', 'false', r'''
-	        whether to sync the log on every commit by default, can
-		be overridden by the \c sync setting to
-		WT_SESSION::begin_transaction''',
-	        type='boolean'),
-	    Config('method', 'fsync', r'''
-	        the method used to ensure log records are stable on disk,
-		see @ref tune_durability for more information''',
-	        choices=['dsync', 'fsync', 'none']),
-	    ]),
 	Config('use_environment_priv', 'false', r'''
 	    use the \c WIREDTIGER_CONFIG and \c WIREDTIGER_HOME environment
 	    variables regardless of whether or not the process is running
 	    with special privileges.  See @ref home for more information''',
 	    type='boolean'),
+	Config('version', '(major=0,minor=0)', r'''
+	    the file version'''),
 ]),
 }
diff --git a/dist/filelist b/dist/filelist
index f7fa0d5dcb7..a69a551ef04 100644
--- a/dist/filelist
+++ b/dist/filelist
@@ -56,6 +56,7 @@ src/config/config_collapse.c
 src/config/config_concat.c
 src/config/config_def.c
 src/config/config_ext.c
+src/config/config_upgrade.c
 src/conn/api_strerror.c
 src/conn/api_version.c
 src/conn/conn_api.c
diff --git a/dist/filelist.win b/dist/filelist.win
index 517af1f4e07..bd8be9728ca 100644
--- a/dist/filelist.win
+++ b/dist/filelist.win
@@ -56,6 +56,7 @@ src/config/config_collapse.c
 src/config/config_concat.c
 src/config/config_def.c
 src/config/config_ext.c
+src/config/config_upgrade.c
 src/conn/api_strerror.c
 src/conn/api_version.c
 src/conn/conn_api.c
diff --git a/dist/s_string.ok b/dist/s_string.ok
index 0cbf72060b0..13d8b7bb696 100644
--- a/dist/s_string.ok
+++ b/dist/s_string.ok
@@ -1088,6 +1088,7 @@ uri
 uri's
 usecs
 usedp
+usercfg
 usr
 utf
 util
diff --git a/src/config/config_def.c b/src/config/config_def.c
index 5a08945d19e..7a8310a1512 100644
--- a/src/config/config_def.c
+++ b/src/config/config_def.c
@@ -92,6 +92,7 @@ static const WT_CONFIG_CHECK confchk_connection_reconfigure[] = {
 	{ "eviction_trigger", "int", "min=10,max=99", NULL },
 	{ "lsm_manager", "category", NULL,
 	     confchk_lsm_manager_subconfigs },
+	{ "lsm_merge", "boolean", NULL, NULL },
 	{ "shared_cache", "category", NULL,
 	     confchk_shared_cache_subconfigs },
 	{ "statistics", "list",
@@ -310,6 +311,7 @@ static const WT_CONFIG_CHECK confchk_wiredtiger_open[] = {
 	{ "checkpoint", "category", NULL,
 	     confchk_checkpoint_subconfigs },
 	{ "checkpoint_sync", "boolean", NULL, NULL },
+	{ "config_base", "boolean", NULL, NULL },
 	{ "create", "boolean", NULL, NULL },
 	{ "direct_io", "list",
 	    "choices=[\"checkpoint\",\"data\",\"log\"]",
@@ -326,6 +328,7 @@ static const WT_CONFIG_CHECK confchk_wiredtiger_open[] = {
 	{ "log", "category", NULL, confchk_log_subconfigs },
 	{ "lsm_manager", "category", NULL,
 	     confchk_lsm_manager_subconfigs },
+	{ "lsm_merge", "boolean", NULL, NULL },
 	{ "mmap", "boolean", NULL, NULL },
 	{ "multiprocess", "boolean", NULL, NULL },
 	{ "session_max", "int", "min=1", NULL },
@@ -349,6 +352,144 @@ static const WT_CONFIG_CHECK confchk_wiredtiger_open[] = {
 	{ NULL, NULL, NULL, NULL }
 };
 
+static const WT_CONFIG_CHECK confchk_wiredtiger_open_all[] = {
+	{ "async", "category", NULL, confchk_async_subconfigs },
+	{ "buffer_alignment", "int", "min=-1,max=1MB", NULL },
+	{ "cache_size", "int", "min=1MB,max=10TB", NULL },
+	{ "checkpoint", "category", NULL,
+	     confchk_checkpoint_subconfigs },
+	{ "checkpoint_sync", "boolean", NULL, NULL },
+	{ "config_base", "boolean", NULL, NULL },
+	{ "create", "boolean", NULL, NULL },
+	{ "direct_io", "list",
+	    "choices=[\"checkpoint\",\"data\",\"log\"]",
+	    NULL },
+	{ "error_prefix", "string", NULL, NULL },
+	{ "eviction", "category", NULL, confchk_eviction_subconfigs },
+	{ "eviction_dirty_target", "int", "min=10,max=99", NULL },
+	{ "eviction_target", "int", "min=10,max=99", NULL },
+	{ "eviction_trigger", "int", "min=10,max=99", NULL },
+	{ "exclusive", "boolean", NULL, NULL },
+	{ "extensions", "list", NULL, NULL },
+	{ "file_extend", "list", "choices=[\"data\",\"log\"]", NULL },
+	{ "hazard_max", "int", "min=15", NULL },
+	{ "log", "category", NULL, confchk_log_subconfigs },
+	{ "lsm_manager", "category", NULL,
+	     confchk_lsm_manager_subconfigs },
+	{ "lsm_merge", "boolean", NULL, NULL },
+	{ "mmap", "boolean", NULL, NULL },
+	{ "multiprocess", "boolean", NULL, NULL },
+	{ "session_max", "int", "min=1", NULL },
+	{ "shared_cache", "category", NULL,
+	     confchk_shared_cache_subconfigs },
+	{ "statistics", "list",
+	    "choices=[\"all\",\"fast\",\"none\",\"clear\"]",
+	    NULL },
+	{ "statistics_log", "category", NULL,
+	     confchk_statistics_log_subconfigs },
+	{ "transaction_sync", "category", NULL,
+	     confchk_transaction_sync_subconfigs },
+	{ "use_environment_priv", "boolean", NULL, NULL },
+	{ "verbose", "list",
+	    "choices=[\"api\",\"block\",\"checkpoint\",\"compact\",\"evict\""
+	    ",\"evictserver\",\"fileops\",\"log\",\"lsm\",\"metadata\","
+	    "\"mutex\",\"overflow\",\"read\",\"reconcile\",\"recovery\","
+	    "\"salvage\",\"shared_cache\",\"split\",\"temporary\",\"verify\","
+	    "\"version\",\"write\"]",
+	    NULL },
+	{ "version", "string", NULL, NULL },
+	{ NULL, NULL, NULL, NULL }
+};
+
+static const WT_CONFIG_CHECK confchk_wiredtiger_open_basecfg[] = {
+	{ "async", "category", NULL, confchk_async_subconfigs },
+	{ "buffer_alignment", "int", "min=-1,max=1MB", NULL },
+	{ "cache_size", "int", "min=1MB,max=10TB", NULL },
+	{ "checkpoint", "category", NULL,
+	     confchk_checkpoint_subconfigs },
+	{ "checkpoint_sync", "boolean", NULL, NULL },
+	{ "direct_io", "list",
+	    "choices=[\"checkpoint\",\"data\",\"log\"]",
+	    NULL },
+	{ "error_prefix", "string", NULL, NULL },
+	{ "eviction", "category", NULL, confchk_eviction_subconfigs },
+	{ "eviction_dirty_target", "int", "min=10,max=99", NULL },
+	{ "eviction_target", "int", "min=10,max=99", NULL },
+	{ "eviction_trigger", "int", "min=10,max=99", NULL },
+	{ "extensions", "list", NULL, NULL },
+	{ "file_extend", "list", "choices=[\"data\",\"log\"]", NULL },
+	{ "hazard_max", "int", "min=15", NULL },
+	{ "log", "category", NULL, confchk_log_subconfigs },
+	{ "lsm_manager", "category", NULL,
+	     confchk_lsm_manager_subconfigs },
+	{ "lsm_merge", "boolean", NULL, NULL },
+	{ "mmap", "boolean", NULL, NULL },
+	{ "multiprocess", "boolean", NULL, NULL },
+	{ "session_max", "int", "min=1", NULL },
+	{ "shared_cache", "category", NULL,
+	     confchk_shared_cache_subconfigs },
+	{ "statistics", "list",
+	    "choices=[\"all\",\"fast\",\"none\",\"clear\"]",
+	    NULL },
+	{ "statistics_log", "category", NULL,
+	     confchk_statistics_log_subconfigs },
+	{ "transaction_sync", "category", NULL,
+	     confchk_transaction_sync_subconfigs },
+	{ "verbose", "list",
+	    "choices=[\"api\",\"block\",\"checkpoint\",\"compact\",\"evict\""
+	    ",\"evictserver\",\"fileops\",\"log\",\"lsm\",\"metadata\","
+	    "\"mutex\",\"overflow\",\"read\",\"reconcile\",\"recovery\","
+	    "\"salvage\",\"shared_cache\",\"split\",\"temporary\",\"verify\","
+	    "\"version\",\"write\"]",
+	    NULL },
+	{ "version", "string", NULL, NULL },
+	{ NULL, NULL, NULL, NULL }
+};
+
+static const WT_CONFIG_CHECK confchk_wiredtiger_open_usercfg[] = {
+	{ "async", "category", NULL, confchk_async_subconfigs },
+	{ "buffer_alignment", "int", "min=-1,max=1MB", NULL },
+	{ "cache_size", "int", "min=1MB,max=10TB", NULL },
+	{ "checkpoint", "category", NULL,
+	     confchk_checkpoint_subconfigs },
+	{ "checkpoint_sync", "boolean", NULL, NULL },
+	{ "direct_io", "list",
+	    "choices=[\"checkpoint\",\"data\",\"log\"]",
+	    NULL },
+	{ "error_prefix", "string", NULL, NULL },
+	{ "eviction", "category", NULL, confchk_eviction_subconfigs },
+	{ "eviction_dirty_target", "int", "min=10,max=99", NULL },
+	{ "eviction_target", "int", "min=10,max=99", NULL },
+	{ "eviction_trigger", "int", "min=10,max=99", NULL },
+	{ "extensions", "list", NULL, NULL },
+	{ "file_extend", "list", "choices=[\"data\",\"log\"]", NULL },
+	{ "hazard_max", "int", "min=15", NULL },
+	{ "log", "category", NULL, confchk_log_subconfigs },
+	{ "lsm_manager", "category", NULL,
+	     confchk_lsm_manager_subconfigs },
+	{ "lsm_merge", "boolean", NULL, NULL },
+	{ "mmap", "boolean", NULL, NULL },
+	{ "multiprocess", "boolean", NULL, NULL },
+	{ "session_max", "int", "min=1", NULL },
+	{ "shared_cache", "category", NULL,
+	     confchk_shared_cache_subconfigs },
+	{ "statistics", "list",
+	    "choices=[\"all\",\"fast\",\"none\",\"clear\"]",
+	    NULL },
+	{ "statistics_log", "category", NULL,
+	     confchk_statistics_log_subconfigs },
+	{ "transaction_sync", "category", NULL,
+	     confchk_transaction_sync_subconfigs },
+	{ "verbose", "list",
+	    "choices=[\"api\",\"block\",\"checkpoint\",\"compact\",\"evict\""
+	    ",\"evictserver\",\"fileops\",\"log\",\"lsm\",\"metadata\","
+	    "\"mutex\",\"overflow\",\"read\",\"reconcile\",\"recovery\","
+	    "\"salvage\",\"shared_cache\",\"split\",\"temporary\",\"verify\","
+	    "\"version\",\"write\"]",
+	    NULL },
+	{ NULL, NULL, NULL, NULL }
+};
+
 static const WT_CONFIG_ENTRY config_entries[] = {
 	{ "colgroup.meta",
 	  "app_metadata=,columns=,source=,type=file",
@@ -392,7 +533,7 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	  "checkpoint=(log_size=0,name=\"WiredTigerCheckpoint\",wait=0),"
 	  "error_prefix=,eviction=(threads_max=1,threads_min=1),"
 	  "eviction_dirty_target=80,eviction_target=80,eviction_trigger=95,"
-	  "lsm_manager=(merge=,worker_thread_max=4),"
+	  "lsm_manager=(merge=,worker_thread_max=4),lsm_merge=,"
 	  "shared_cache=(chunk=10MB,name=,reserve=0,size=500MB),"
 	  "statistics=none,statistics_log=(on_close=0,"
 	  "path=\"WiredTigerStat.%d.%H\",sources=,"
@@ -503,12 +644,13 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	{ "wiredtiger_open",
 	  "async=(enabled=0,ops_max=1024,threads=2),buffer_alignment=-1,"
 	  "cache_size=100MB,checkpoint=(log_size=0,"
-	  "name=\"WiredTigerCheckpoint\",wait=0),checkpoint_sync=,create=0,"
-	  "direct_io=,error_prefix=,eviction=(threads_max=1,threads_min=1),"
-	  "eviction_dirty_target=80,eviction_target=80,eviction_trigger=95,"
-	  "exclusive=0,extensions=,file_extend=,hazard_max=1000,"
-	  "log=(archive=,enabled=0,file_max=100MB,path=\"\"),"
-	  "lsm_manager=(merge=,worker_thread_max=4),mmap=,multiprocess=0,"
+	  "name=\"WiredTigerCheckpoint\",wait=0),checkpoint_sync=,"
+	  "config_base=,create=0,direct_io=,error_prefix=,"
+	  "eviction=(threads_max=1,threads_min=1),eviction_dirty_target=80,"
+	  "eviction_target=80,eviction_trigger=95,exclusive=0,extensions=,"
+	  "file_extend=,hazard_max=1000,log=(archive=,enabled=0,"
+	  "file_max=100MB,path=\"\"),lsm_manager=(merge=,"
+	  "worker_thread_max=4),lsm_merge=,mmap=,multiprocess=0,"
 	  "session_max=100,shared_cache=(chunk=10MB,name=,reserve=0,"
 	  "size=500MB),statistics=none,statistics_log=(on_close=0,"
 	  "path=\"WiredTigerStat.%d.%H\",sources=,"
@@ -516,6 +658,56 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	  ",method=fsync),use_environment_priv=0,verbose=",
 	  confchk_wiredtiger_open
 	},
+	{ "wiredtiger_open_all",
+	  "async=(enabled=0,ops_max=1024,threads=2),buffer_alignment=-1,"
+	  "cache_size=100MB,checkpoint=(log_size=0,"
+	  "name=\"WiredTigerCheckpoint\",wait=0),checkpoint_sync=,"
+	  "config_base=,create=0,direct_io=,error_prefix=,"
+	  "eviction=(threads_max=1,threads_min=1),eviction_dirty_target=80,"
+	  "eviction_target=80,eviction_trigger=95,exclusive=0,extensions=,"
+	  "file_extend=,hazard_max=1000,log=(archive=,enabled=0,"
+	  "file_max=100MB,path=\"\"),lsm_manager=(merge=,"
+	  "worker_thread_max=4),lsm_merge=,mmap=,multiprocess=0,"
+	  "session_max=100,shared_cache=(chunk=10MB,name=,reserve=0,"
+	  "size=500MB),statistics=none,statistics_log=(on_close=0,"
+	  "path=\"WiredTigerStat.%d.%H\",sources=,"
+	  "timestamp=\"%b %d %H:%M:%S\",wait=0),transaction_sync=(enabled=0"
+	  ",method=fsync),use_environment_priv=0,verbose=,version=(major=0,"
+	  "minor=0)",
+	  confchk_wiredtiger_open_all
+	},
+	{ "wiredtiger_open_basecfg",
+	  "async=(enabled=0,ops_max=1024,threads=2),buffer_alignment=-1,"
+	  "cache_size=100MB,checkpoint=(log_size=0,"
+	  "name=\"WiredTigerCheckpoint\",wait=0),checkpoint_sync=,"
+	  "direct_io=,error_prefix=,eviction=(threads_max=1,threads_min=1),"
+	  "eviction_dirty_target=80,eviction_target=80,eviction_trigger=95,"
+	  "extensions=,file_extend=,hazard_max=1000,log=(archive=,enabled=0"
+	  ",file_max=100MB,path=\"\"),lsm_manager=(merge=,"
+	  "worker_thread_max=4),lsm_merge=,mmap=,multiprocess=0,"
+	  "session_max=100,shared_cache=(chunk=10MB,name=,reserve=0,"
+	  "size=500MB),statistics=none,statistics_log=(on_close=0,"
+	  "path=\"WiredTigerStat.%d.%H\",sources=,"
+	  "timestamp=\"%b %d %H:%M:%S\",wait=0),transaction_sync=(enabled=0"
+	  ",method=fsync),verbose=,version=(major=0,minor=0)",
+	  confchk_wiredtiger_open_basecfg
+	},
+	{ "wiredtiger_open_usercfg",
+	  "async=(enabled=0,ops_max=1024,threads=2),buffer_alignment=-1,"
+	  "cache_size=100MB,checkpoint=(log_size=0,"
+	  "name=\"WiredTigerCheckpoint\",wait=0),checkpoint_sync=,"
+	  "direct_io=,error_prefix=,eviction=(threads_max=1,threads_min=1),"
+	  "eviction_dirty_target=80,eviction_target=80,eviction_trigger=95,"
+	  "extensions=,file_extend=,hazard_max=1000,log=(archive=,enabled=0"
+	  ",file_max=100MB,path=\"\"),lsm_manager=(merge=,"
+	  "worker_thread_max=4),lsm_merge=,mmap=,multiprocess=0,"
+	  "session_max=100,shared_cache=(chunk=10MB,name=,reserve=0,"
+	  "size=500MB),statistics=none,statistics_log=(on_close=0,"
+	  "path=\"WiredTigerStat.%d.%H\",sources=,"
+	  "timestamp=\"%b %d %H:%M:%S\",wait=0),transaction_sync=(enabled=0"
+	  ",method=fsync),verbose=",
+	  confchk_wiredtiger_open_usercfg
+	},
 	{ NULL, NULL, NULL }
 };
 
diff --git a/src/config/config_upgrade.c b/src/config/config_upgrade.c
new file mode 100644
index 00000000000..24297df839b
--- /dev/null
+++ b/src/config/config_upgrade.c
@@ -0,0 +1,32 @@
+/*-
+ * Copyright (c) 2008-2014 WiredTiger, Inc.
+ *	All rights reserved.
+ *
+ * See the file LICENSE for redistribution information.
+ */
+
+#include "wt_internal.h"
+
+/*
+ * __wt_config_upgrade --
+ *	Upgrade a configuration string by appended the replacement version.
+ */
+int
+__wt_config_upgrade(WT_SESSION_IMPL *session, WT_ITEM *buf)
+{
+	WT_CONFIG_ITEM v;
+	const char *config;
+
+	config = buf->data;
+
+	/*
+	 * wiredtiger_open:
+	 *	lsm_merge=boolean -> lsm_manager=(merge=boolean)
+	 */
+	if (__wt_config_getones(
+	    session, config, "lsm_merge", &v) != WT_NOTFOUND)
+		WT_RET(__wt_buf_catfmt(session, buf,
+		    ",lsm_manager=(merge=%s)", v.val ? "true" : "false"));
+
+	return (0);
+}
diff --git a/src/conn/conn_api.c b/src/conn/conn_api.c
index 6c2a536cb92..d33412ba34b 100644
--- a/src/conn/conn_api.c
+++ b/src/conn/conn_api.c
@@ -714,27 +714,66 @@ __conn_config_append(const char *cfg[], const char *config)
 }
 
 /*
+ * __conn_config_check_version --
+ *	Check if a configuration version isn't compatible.
+ */
+static int
+__conn_config_check_version(WT_SESSION_IMPL *session, const char *config)
+{
+	WT_CONFIG_ITEM vmajor, vminor;
+
+	/*
+	 * Version numbers aren't included in all configuration strings, but
+	 * we check all of them just in case. Ignore configurations without
+	 * a version.
+	 */
+	 if (__wt_config_getones(
+	     session, config, "version.major", &vmajor) == WT_NOTFOUND)
+		return (0);
+	 WT_RET(__wt_config_getones(session, config, "version.minor", &vminor));
+
+	 if (vmajor.val > WIREDTIGER_VERSION_MAJOR ||
+	     (vmajor.val == WIREDTIGER_VERSION_MAJOR &&
+	     vminor.val > WIREDTIGER_VERSION_MINOR))
+		WT_RET_MSG(session, ENOTSUP,
+		    "WiredTiger configuration is from an incompatible release "
+		    "of the WiredTiger engine");
+
+	return (0);
+}
+
+/*
  * __conn_config_file --
- *	Read in any WiredTiger_config file in the home directory.
+ *	Read WiredTiger config files from the home directory.
  */
 static int
 __conn_config_file(WT_SESSION_IMPL *session,
-    const char *filename, const char **cfg, WT_ITEM *cbuf)
+    const char *filename, int is_user, const char **cfg, WT_ITEM *cbuf)
 {
+	WT_CONNECTION_IMPL *conn;
 	WT_DECL_RET;
 	WT_FH *fh;
 	size_t len;
 	wt_off_t size;
 	int exist, quoted;
-	uint8_t *p, *t;
+	char *p, *t;
 
+	conn = S2C(session);
 	fh = NULL;
 
-	/* Check for an optional configuration file. */
+	/* Configuration files are always optional. */
 	WT_RET(__wt_exist(session, filename, &exist));
 	if (!exist)
 		return (0);
 
+	/*
+	 * The base configuration should not exist if we are creating this
+	 * database.
+	 */
+	if (!is_user && conn->is_new)
+		WT_RET_MSG(session, EINVAL,
+		    "%s exists before database creation", filename);
+
 	/* Open the configuration file. */
 	WT_RET(__wt_open(session, filename, 0, 0, 0, &fh));
 	WT_ERR(__wt_filesize(session, fh, &size));
@@ -831,14 +870,18 @@ __conn_config_file(WT_SESSION_IMPL *session,
 		}
 	}
 	*t = '\0';
+	cbuf->size = WT_PTRDIFF(t, cbuf->data);
 
-#if 0
-	fprintf(stderr, "file config: {%s}\n", (const char *)cbuf->data);
-#endif
+	/* Check any version. */
+	WT_ERR(__conn_config_check_version(session, cbuf->data));
 
-	/* Check the configuration string. */
-	WT_ERR(__wt_config_check(session,
-	    WT_CONFIG_REF(session, wiredtiger_open), cbuf->data, 0));
+	/* Upgrade the configuration string. */
+	WT_ERR(__wt_config_upgrade(session, cbuf));
+
+	/* Check the configuration information. */
+	WT_ERR(__wt_config_check(session, is_user ?
+	    WT_CONFIG_REF(session, wiredtiger_open_usercfg) :
+	    WT_CONFIG_REF(session, wiredtiger_open_basecfg), cbuf->data, 0));
 
 	/* Append it to the stack. */
 	__conn_config_append(cfg, cbuf->data);
@@ -853,14 +896,18 @@ err:	if (fh != NULL)
  *	Read configuration from an environment variable, if set.
  */
 static int
-__conn_config_env(WT_SESSION_IMPL *session, const char *cfg[])
+__conn_config_env(WT_SESSION_IMPL *session, const char *cfg[], WT_ITEM *cbuf)
 {
 	WT_CONFIG_ITEM cval;
 	const char *env_config;
+	size_t len;
 
-	if ((env_config = getenv("WIREDTIGER_CONFIG")) == NULL ||
-	    strlen(env_config) == 0)
+	if ((env_config = getenv("WIREDTIGER_CONFIG")) == NULL)
 		return (0);
+	len = strlen(env_config);
+	if (len == 0)
+		return (0);
+	WT_RET(__wt_buf_set(session, cbuf, env_config, len));
 
 	/*
 	 * Security stuff:
@@ -874,11 +921,19 @@ __conn_config_env(WT_SESSION_IMPL *session, const char *cfg[])
 		    "WIREDTIGER_CONFIG environment variable set but process "
 		    "lacks privileges to use that environment variable");
 
-	/* Check the configuration string. */
+	/* Check any version. */
+	WT_RET(__conn_config_check_version(session, env_config));
+
+	/* Upgrade the configuration string. */
+	WT_RET(__wt_config_upgrade(session, cbuf));
+
+	/* Check the configuration information. */
 	WT_RET(__wt_config_check(session,
 	    WT_CONFIG_REF(session, wiredtiger_open), env_config, 0));
 
+	/* Append it to the stack. */
 	__conn_config_append(cfg, env_config);
+
 	return (0);
 }
 
@@ -1189,16 +1244,32 @@ __wt_verbose_config(WT_SESSION_IMPL *session, const char *cfg[])
  */
 static int
 __conn_write_config(
-    WT_SESSION_IMPL *session, const char *filename, const char *config)
+    WT_SESSION_IMPL *session, const char *filename, const char *cfg[])
 {
 	FILE *fp;
 	WT_CONFIG parser;
-	WT_CONFIG_ITEM ckey, cval;
+	WT_CONFIG_ITEM k, v;
 	WT_DECL_RET;
 	char *path;
 
-	/* If there is no configuration, don't bother creating an empty file. */
-	if (config == NULL)
+	/*
+	 * We were passed an array of configuration strings where slot 0 is all
+	 * all possible values and the second and subsequent slots are changes
+	 * specified by the application during open (using the wiredtiger_open
+	 * configuration string, an environment variable, or user-configuration
+	 * file). The base configuration file contains all changes to default
+	 * settings made at create, and we include the user-configuration file
+	 * in that list, even though we don't expect it to change. Of course,
+	 * an application could leave that file as it is right now and not
+	 * remove a configuration we need, but applications can also guarantee
+	 * all database users specify consistent environment variables and
+	 * wiredtiger_open configuration arguments, and if we protect against
+	 * those problems, might as well include the application's configuration
+	 * file as well.
+	 *
+	 * If there is no configuration, don't bother creating an empty file.
+	 */
+	if (cfg[1] == NULL)
 		return (0);
 
 	WT_RET(__wt_filename(session, filename, &path));
@@ -1215,23 +1286,41 @@ __conn_write_config(
 	    "# to store persistent database settings.  Instead of changing\n"
 	    "# these settings, set a WIREDTIGER_CONFIG environment variable\n"
 	    "# or create a WiredTiger.config file to override them.");
-	WT_ERR(__wt_config_init(session, &parser, config));
-	while ((ret = __wt_config_next(&parser, &ckey, &cval)) == 0) {
-		/* Skip "create". */
-		if (WT_STRING_MATCH("create", ckey.str, ckey.len))
-			continue;
 
-		/* Fix quoting for non-trivial settings. */
-		if (cval.type == WT_CONFIG_ITEM_STRING) {
-			--cval.str;
-			cval.len += 2;
+	fprintf(fp, "version=(major=%d,minor=%d)\n\n",
+	    WIREDTIGER_VERSION_MAJOR, WIREDTIGER_VERSION_MINOR);
+
+	/*
+	 * We want the list of defaults that have been changed, that is, if the
+	 * application didn't somehow configure a setting, we don't write out a
+	 * default value, so future releases may silently migrate to new default
+	 * values.
+	 */
+	while (*++cfg != NULL) {
+		WT_ERR(__wt_config_init( session,
+		    &parser, WT_CONFIG_BASE(session, wiredtiger_open_basecfg)));
+		while ((ret = __wt_config_next(&parser, &k, &v)) == 0) {
+			if ((ret =
+			    __wt_config_getone(session, *cfg, &k, &v)) == 0) {
+				/* Fix quoting for non-trivial settings. */
+				if (v.type == WT_CONFIG_ITEM_STRING) {
+					--v.str;
+					v.len += 2;
+				}
+				fprintf(fp, "%.*s=%.*s\n",
+				    (int)k.len, k.str, (int)v.len, v.str);
+			}
+			WT_ERR_NOTFOUND_OK(ret);
 		}
-		fprintf(fp, "%.*s=%.*s\n",
-		    (int)ckey.len, ckey.str, (int)cval.len, cval.str);
+		WT_ERR_NOTFOUND_OK(ret);
 	}
-	WT_ERR_NOTFOUND_OK(ret);
 
 err:	WT_TRET(fclose(fp));
+
+	/* Don't leave a damaged file in place. */
+	if (ret != 0)
+		(void)__wt_remove(session, filename);
+
 	return (ret);
 }
 
@@ -1270,10 +1359,9 @@ wiredtiger_open(const char *home, WT_EVENT_HANDLER *event_handler,
 	WT_CONFIG_ITEM cval, sval;
 	WT_CONNECTION_IMPL *conn;
 	WT_DECL_RET;
-	WT_ITEM cbbuf, cubuf;
+	WT_ITEM i1, i2, i3;
 	const WT_NAME_FLAG *ft;
 	WT_SESSION_IMPL *session;
-	int exist;
 
 	/* Leave space for optional additional configuration. */
 	const char *cfg[] = { NULL, NULL, NULL, NULL, NULL, NULL };
@@ -1282,8 +1370,14 @@ wiredtiger_open(const char *home, WT_EVENT_HANDLER *event_handler,
 
 	conn = NULL;
 	session = NULL;
-	WT_CLEAR(cbbuf);
-	WT_CLEAR(cubuf);
+
+	/*
+	 * We could use scratch buffers, but I'd rather the default session
+	 * not tie down chunks of memory past the open call.
+	 */
+	WT_CLEAR(i1);
+	WT_CLEAR(i2);
+	WT_CLEAR(i3);
 
 	WT_RET(__wt_library_init());
 
@@ -1308,13 +1402,13 @@ wiredtiger_open(const char *home, WT_EVENT_HANDLER *event_handler,
 	/* Remaining basic initialization of the connection structure. */
 	WT_ERR(__wt_connection_init(conn));
 
-	/* Check/set the configuration strings. */
+	/* Check/set the application-specified configuration string. */
 	WT_ERR(__wt_config_check(session,
 	    WT_CONFIG_REF(session, wiredtiger_open), config, 0));
 	cfg[0] = WT_CONFIG_BASE(session, wiredtiger_open);
 	cfg[1] = config;
 
-	/* Finish configuring error messages so we get them right early. */
+	/* Configure error messages so we get them right early. */
 	WT_ERR(__wt_config_gets(session, cfg, "error_prefix", &cval));
 	if (cval.len != 0)
 		WT_ERR(__wt_strndup(
@@ -1330,45 +1424,39 @@ wiredtiger_open(const char *home, WT_EVENT_HANDLER *event_handler,
 	 * Build the configuration stack, in the following order (where later
 	 * entries override earlier entries):
 	 *
-	 * 1. default wiredtiger_open configuration
+	 * 1. all possible wiredtiger_open configurations
 	 * 2. base configuration file, created with the database (optional)
 	 * 3. the config passed in by the application.
 	 * 4. user configuration file (optional)
 	 * 5. environment variable settings (optional)
 	 *
-	 * Clear the entry we added to the stack, we're going to build it in
+	 * Clear the entries we added to the stack, we're going to build it in
 	 * order.
 	 */
+	cfg[0] = WT_CONFIG_BASE(session, wiredtiger_open_all);
 	cfg[1] = NULL;
-
-	/*
-	 * The base configuration should not exist if we are creating this
-	 * database.
-	 */
-	exist = 0;
-	if (conn->is_new) {
-		WT_ERR(__wt_exist(session, WT_BASECONFIG, &exist));
-		if (exist)
-			WT_ERR_MSG(session, EINVAL,
-			    "%s exists on creation", WT_BASECONFIG);
-	} else
-		WT_ERR(__conn_config_file(session, WT_BASECONFIG, cfg, &cbbuf));
-
-	/* Add the config string passed in by the application. */
+	WT_ERR(__conn_config_file(session, WT_BASECONFIG, 0, cfg, &i1));
 	__conn_config_append(cfg, config);
-
-	/*
-	 * Read in user's config file and the config environment variable.
-	 */
-	WT_ERR(__conn_config_file(session, WT_USERCONFIG, cfg, &cubuf));
-	WT_ERR(__conn_config_env(session, cfg));
+	WT_ERR(__conn_config_file(session, WT_USERCONFIG, 1, cfg, &i2));
+	WT_ERR(__conn_config_env(session, cfg, &i3));
 
 	/*
 	 * Configuration ...
 	 *
 	 * We can't open sessions yet, so any configurations that cause
 	 * sessions to be opened must be handled inside __wt_connection_open.
+	 *
+	 * The error message configuration might have changed (if set in a
+	 * configuration file, and not in the application's configuration
+	 * string), get it again. Do it first, make error messages correct.
 	 */
+	WT_ERR(__wt_config_gets(session, cfg, "error_prefix", &cval));
+	if (cval.len != 0) {
+		__wt_free(session, conn->error_prefix);
+		WT_ERR(__wt_strndup(
+		    session, cval.str, cval.len, &conn->error_prefix));
+	}
+
 	WT_ERR(__wt_config_gets(session, cfg, "hazard_max", &cval));
 	conn->hazard_max = (uint32_t)cval.val;
 
@@ -1423,10 +1511,6 @@ wiredtiger_open(const char *home, WT_EVENT_HANDLER *event_handler,
 	WT_ERR(__wt_lsm_manager_config(session, cfg));
 	WT_ERR(__wt_verbose_config(session, cfg));
 
-	/* Write the base configuration file, if we're creating the database. */
-	if (conn->is_new)
-		WT_ERR(__conn_write_config(session, WT_BASECONFIG, config));
-
 	/* Now that we know if verbose is configured, output the version. */
 	WT_ERR(__wt_verbose(
 	    session, WT_VERB_VERSION, "%s", WIREDTIGER_VERSION_STRING));
@@ -1455,6 +1539,17 @@ wiredtiger_open(const char *home, WT_EVENT_HANDLER *event_handler,
 	WT_ERR(__conn_load_extensions(session, cfg));
 
 	/*
+	 * We've completed configuration, write the base configuration file if
+	 * we're creating the database.
+	 */
+	if (conn->is_new) {
+		WT_ERR(__wt_config_gets(session, cfg, "config_base", &cval));
+		if (cval.val)
+			WT_ERR(
+			    __conn_write_config(session, WT_BASECONFIG, cfg));
+	}
+
+	/*
 	 * Start the worker threads last.
 	 */
 	WT_ERR(__wt_connection_workers(session, cfg));
@@ -1465,8 +1560,10 @@ wiredtiger_open(const char *home, WT_EVENT_HANDLER *event_handler,
 	WT_STATIC_ASSERT(offsetof(WT_CONNECTION_IMPL, iface) == 0);
 	*wt_connp = &conn->iface;
 
-err:	__wt_buf_free(session, &cbbuf);
-	__wt_buf_free(session, &cubuf);
+err:	/* Discard the configuration strings. */
+	__wt_buf_free(session, &i1);
+	__wt_buf_free(session, &i2);
+	__wt_buf_free(session, &i3);
 
 	if (ret != 0 && conn != NULL)
 		WT_TRET(__wt_connection_close(conn));
diff --git a/src/docs/database-config.dox b/src/docs/database-config.dox
index b86971ca450..b8dee0be980 100644
--- a/src/docs/database-config.dox
+++ b/src/docs/database-config.dox
@@ -67,12 +67,27 @@ replaced with commas.
 
 @section config_base WiredTiger.basecfg file
 
-When a WiredTiger database is created, the configuration string passed
-to ::wiredtiger_open is saved to a WiredTiger home directory file named
-\c WiredTiger.basecfg, and that configuration file is read whenever the
-database is subsequently opened.
-
-Users should not edit this file, set the \c WIREDTIGER_CONFIG
-environment variable or create a \c WiredTiger.config file instead.
+When a WiredTiger database is created, non-default configuration
+information specified to ::wiredtiger_open is saved to a WiredTiger home
+directory file named \c WiredTiger.basecfg, and that configuration file
+is read whenever the database is subsequently opened.
+
+For example, if a shared library extensions are required, those settings
+will be saved to the base configuration file so it's easier to write
+general-purpose applications that might not be aware of how a particular
+database was created and configured.
+
+Users should not not edit this file, set the \c WIREDTIGER_CONFIG
+environment variable or create a \c WiredTiger.config file instead, as
+those settings override the settings in the base configuration file.
+
+This file is a potential problem for applications that want to retain
+the ability to downgrade to previous releases. If a new database is
+created after an upgrade, the base configuration file might have
+configuration strings that would cause a previous version of the
+application to fail. For this reason, applications that may want to
+downgrade should configure the ::wiredtiger_open value \c config_base
+to \c false so the base configuration file is not written as part of
+database create.
 
 */
diff --git a/src/docs/programming.dox b/src/docs/programming.dox
index c16fc86657d..cdfb6d336e8 100644
--- a/src/docs/programming.dox
+++ b/src/docs/programming.dox
@@ -33,7 +33,7 @@ each of which is ordered by one or more columns.
 - @subpage signals
 @m_endif
 
-<h2>Advanced features</h2>
+<h2>Advanced topics</h2>
 - @subpage checkpoint
 - @subpage durability
 - @subpage backup
@@ -42,6 +42,7 @@ each of which is ordered by one or more columns.
 - @subpage statistics
 - @subpage shared_cache
 - @subpage cursor_log
+- @subpage upgrade
 
 @m_if{c}
 <h2>Extending WiredTiger</h2>
diff --git a/src/docs/upgrade.dox b/src/docs/upgrade.dox
new file mode 100644
index 00000000000..7952efa0343
--- /dev/null
+++ b/src/docs/upgrade.dox
@@ -0,0 +1,83 @@
+/*! @page upgrade Upgrading and downgrading databases
+
+The upgrade/downgrade process is only necessary for major or minor
+WiredTiger releases (releases where the major or minor version number
+changed). Patch releases (where only the patch number changed), do not
+contain any API or file format changes, and do not require anything
+other than a link step or shared library installation for upgrading or
+downgrading. However, the complete WiredTiger library must be re-built
+from scratch when changing versions, as there is no guarantee modules
+from one version of the library will work with modules from any other
+version.
+
+The rest of this page discusses upgrading and downgrading WiredTiger
+major and minor releases. Specifically, by upgrading, we mean migrating
+an application and its databases to a newer WiredTiger release, and by
+downgrading, we mean reverting to an older version.
+
+When upgrading or downgrading between WiredTiger releases, there are two
+components to consider: the WiredTiger library API and the underlying
+data files used for the database (for example, log files or B+tree
+files).
+
+As part of each WiredTiger release, a new @ref upgrading documentation
+section is created, describing changes in the WiredTiger API and in the
+format of underlying files, if any.  Changes to the format of the
+underlying data files are extremely rare, while changes to WiredTiger
+API are more common.  Generally, when the WiredTiger API changes, the
+changes are backward compatible and applications do not require
+modifications in order to upgrade to the new release.
+
+Note it is not necessary to upgrade (downgrade) to intermediate
+releases, you can ignore intermediate releases and upgrade (downgrade)
+directly to the release you plan to use.
+
+To upgrade to a new release of WiredTiger:
+
+-# Review the information for each release after the WiredTiger release
+you're currently using, up to and including the release you plan to use.
+Changes to the WiredTiger API are normally backward compatible, that is,
+you can continue to use the same WiredTiger configuration values used
+previously. However, it will likely enhance program maintainability to
+switch to newer versions of the configuration strings, as documentation
+for the deprecated values will no longer be available.
+<br><br>
+-# Once you have reviewed the relevant release notes and modified your
+application as necessary, install the new version of the application by
+relinking or installing a new version of the WiredTiger shared library.
+<br><br>
+-# Shut down the old version of the application.
+<br><br>
+-# Start the new version of the application.
+<br><br>
+If the upgrading documentation for any release after the previous
+release and up to and including the release you are using, specifies
+underlying data file formats are no longer backward compatible and will
+not be upgraded at run-time, a data upgrade step is required before the
+data can be accessed. In this case, data files must be upgraded using
+the WT_SESSION::upgrade method.
+
+Applications wanting the ability to downgrade to previous releases of
+WiredTiger are constrained in some important ways:
+
+- The underlying data file formats must not have changed between the
+release currently being run and the release to which you are
+downgrading. In other words, data file format changes are not backward
+compatible, and an upgraded data file cannot be downgraded without being
+dumped and re-loaded.
+<br><br>
+- Applications concerned with downgrading should configure the
+::wiredtiger_open \c config_base value to \c false, so WiredTiger does
+not write the base configuration file file when creating databases.
+Because the base configuration file is written using a current version
+of the WiredTiger API, writing this file could cause applications using
+previous versions of the WiredTiger API to fail. See @ref config_base
+for more information.
+
+To downgrade to a previous release of WiredTiger:
+
+-# Shut down the new version of the application.
+<br><br>
+-# Start the old version of the application.
+
+*/
diff --git a/src/include/config.h b/src/include/config.h
index a32442d25ac..b9c4c97fa00 100644
--- a/src/include/config.h
+++ b/src/include/config.h
@@ -76,6 +76,9 @@ struct __wt_config_parser_impl {
 #define	WT_CONFIG_ENTRY_session_verify			28
 #define	WT_CONFIG_ENTRY_table_meta			29
 #define	WT_CONFIG_ENTRY_wiredtiger_open			30
+#define	WT_CONFIG_ENTRY_wiredtiger_open_all		31
+#define	WT_CONFIG_ENTRY_wiredtiger_open_basecfg		32
+#define	WT_CONFIG_ENTRY_wiredtiger_open_usercfg		33
 /*
  * configuration section: END
  * DO NOT EDIT: automatically built by dist/flags.py.
diff --git a/src/include/extern.h b/src/include/extern.h
index 807092f6060..523529eca02 100644
--- a/src/include/extern.h
+++ b/src/include/extern.h
@@ -219,6 +219,7 @@ extern int __wt_conn_config_init(WT_SESSION_IMPL *session);
 extern void __wt_conn_config_discard(WT_SESSION_IMPL *session);
 extern int __wt_ext_config_parser_open(WT_EXTENSION_API *wt_ext, WT_SESSION *wt_session, const char *config, size_t len, WT_CONFIG_PARSER **config_parserp);
 extern int __wt_ext_config_get(WT_EXTENSION_API *wt_api, WT_SESSION *wt_session, WT_CONFIG_ARG *cfg_arg, const char *key, WT_CONFIG_ITEM *cval);
+extern int __wt_config_upgrade(WT_SESSION_IMPL *session, WT_ITEM *buf);
 extern int __wt_collator_config(WT_SESSION_IMPL *session, const char **cfg, WT_COLLATOR **collatorp, int *ownp);
 extern int __wt_conn_remove_collator(WT_SESSION_IMPL *session);
 extern int __wt_conn_remove_compressor(WT_SESSION_IMPL *session);
diff --git a/src/include/wiredtiger.in b/src/include/wiredtiger.in
index c83c5f49144..de4a04f1d66 100644
--- a/src/include/wiredtiger.in
+++ b/src/include/wiredtiger.in
@@ -1805,6 +1805,9 @@ struct __wt_connection {
  * @config{ ),,}
  * @config{checkpoint_sync, flush files to stable storage when closing or
  * writing checkpoints., a boolean flag; default \c true.}
+ * @config{config_base, write the base configuration file if creating the
+ * database\, see @ref config_base for more information., a boolean flag;
+ * default \c true.}
  * @config{create, create the database if it does not exist., a boolean flag;
  * default \c false.}
  * @config{direct_io, Use \c O_DIRECT to access files.  Options are given as a
diff --git a/src/lsm/lsm_meta.c b/src/lsm/lsm_meta.c
index 6580992ff24..fbb5a9958d5 100644
--- a/src/lsm/lsm_meta.c
+++ b/src/lsm/lsm_meta.c
@@ -147,7 +147,6 @@ __wt_lsm_meta_read(WT_SESSION_IMPL *session, WT_LSM_TREE *lsm_tree)
 		} else if (WT_STRING_MATCH("merge_threads", ck.str, ck.len)) {
 		} else
 			WT_ERR(__wt_illegal_value(session, "LSM metadata"));
-
 	}
 	WT_ERR_NOTFOUND_OK(ret);
 
diff --git a/test/suite/test_gethome.py b/test/suite/test_home.py
index 6f8817f43dc..78310d69079 100644
--- a/test/suite/test_gethome.py
+++ b/test/suite/test_home.py
@@ -28,8 +28,23 @@
 import os
 import wiredtiger, wttest
 
-# test_gethome.py
-#    connection level is-new operation.
+# test_isnew
+#    database is-new method
+class test_isnew(wttest.WiredTigerTestCase):
+
+    # Test is-new of a connection.
+    def test_isnew(self):
+        # We just created a connection, is_new should return True.
+        self.assertEquals(self.conn.is_new(), True)
+
+        # Close and re-open the connection, is_new should return False.
+        self.conn.close()
+        self.conn = self.setUpConnectionOpen(".")
+        self.assertEquals(self.conn.is_new(), False)
+
+
+# test_gethome
+#    database get-home method
 class test_gethome(wttest.WiredTigerTestCase):
 
     # Test gethome of a connection, the initially created one is ".".
@@ -45,5 +60,18 @@ class test_gethome(wttest.WiredTigerTestCase):
         self.assertEquals(self.conn.get_home(), name)
 
 
+# test_base_config
+#       test base configuration file config.
+class test_base_config(wttest.WiredTigerTestCase):
+    def test_base_config(self):
+        # We just created a database, there should be a base configuration file.
+        self.assertTrue(os.path.exists("./WiredTiger.basecfg"))
+
+        # Open up another database, configure without base configuration.
+        os.mkdir("A")
+        conn = wiredtiger.wiredtiger_open("A", "create,config_base=false")
+        self.assertFalse(os.path.exists("A/WiredTiger.basecfg"))
+
+
 if __name__ == '__main__':
     wttest.run()
diff --git a/test/suite/test_isnew.py b/test/suite/test_isnew.py
deleted file mode 100644
index 56a569877d9..00000000000
--- a/test/suite/test_isnew.py
+++ /dev/null
@@ -1,46 +0,0 @@
-#!/usr/bin/env python
-#
-# Public Domain 2008-2014 WiredTiger, Inc.
-#
-# This is free and unencumbered software released into the public domain.
-#
-# Anyone is free to copy, modify, publish, use, compile, sell, or
-# distribute this software, either in source code form or as a compiled
-# binary, for any purpose, commercial or non-commercial, and by any
-# means.
-#
-# In jurisdictions that recognize copyright laws, the author or authors
-# of this software dedicate any and all copyright interest in the
-# software to the public domain. We make this dedication for the benefit
-# of the public at large and to the detriment of our heirs and
-# successors. We intend this dedication to be an overt act of
-# relinquishment in perpetuity of all present and future rights to this
-# software under copyright law.
-#
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
-# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
-# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
-# OTHER DEALINGS IN THE SOFTWARE.
-
-import wiredtiger, wttest
-
-# test_isnew.py
-#    connection level is-new operation.
-class test_isnew(wttest.WiredTigerTestCase):
-
-    # Test is-new of a connection.
-    def test_isnew(self):
-        # We just created a connection, is_new should return True.
-        self.assertEquals(self.conn.is_new(), True)
-
-        # Close and re-open the connection, is_new should return False.
-        self.conn.close()
-        self.conn = self.setUpConnectionOpen(".")
-        self.assertEquals(self.conn.is_new(), False)
-
-
-if __name__ == '__main__':
-    wttest.run()