Merge pull request #1076 from wiredtiger/txn-sync

Add per-txn sync configuration support. #1074

14 files changed, 291 insertions, 215 deletions

diff --git a/dist/api_config.py b/dist/api_config.py
index 7c37abdfe4f..46a2f94f061 100644
--- a/dist/api_config.py
+++ b/dist/api_config.py
@@ -85,11 +85,12 @@ def getconfcheck(c):
         # Manually re-wrap when there is a check string to avoid ugliness
         # between string and non-string wrapping
         if len(check + ' ' + cstr + ',\n\t    ' + sstr + '},') >= 68:
-            check = check + '\n\t    ' + cstr + ',\n\t    ' + sstr + '},'
+            check = check + '\n\t    ' + cstr + ',\n\t    ' + sstr + ' },'
         else:
-            check = check + ' ' + cstr + ', ' + sstr + '},'
+            check = check + ' ' + cstr + ', ' + sstr + ' },'
     else:
-        check = '\n\t    '.join(w.wrap(check + ' ' + cstr + ', ' + sstr + '},'))
+        check = '\n\t    '.join(
+            w.wrap(check + ' ' + cstr + ', ' + sstr + ' },'))
     return check
 
 skip = False
@@ -122,8 +123,8 @@ for line in open(f, 'r'):
 
     w = textwrap.TextWrapper(width=80-len(prefix.expandtabs()),
             break_on_hyphens=False,
-			replace_whitespace=False,
-			fix_sentence_endings=True)
+            replace_whitespace=False,
+            fix_sentence_endings=True)
     lastname = None
     for c in sorted(api_data.methods[config_name].config):
         name = c.name
@@ -190,7 +191,7 @@ def get_default(c):
         return '(%s)' % (','.join('%s=%s' % (subc.name, get_default(subc))
             for subc in sorted(c.subconfig)))
     elif (c.default or t == 'int') and c.default != 'true':
-	return str(c.default).replace('"', '\\"')
+        return str(c.default).replace('"', '\\"')
     else:
         return ''
 
@@ -206,10 +207,7 @@ static const WT_CONFIG_CHECK confchk_%(name)s_subconfigs[] = {
 };
 ''' % {
     'name' : c.name,
-    'check' : '\n\t'.join('"\n\t    "'.join(
-        w.wrap('{ "%s", "%s", %s, NULL },' %
-        (subc.name, gettype(subc), checkstr(subc))))
-        for subc in sorted(c.subconfig)),
+    'check' : '\n\t'.join(getconfcheck(subc) for subc in sorted(c.subconfig)),
 })
 
 def getsubconfigstr(c):
@@ -249,9 +247,9 @@ for name in sorted(api_data.methods.keys()):
     # Build a list of #defines that reference specific slots in the list (the
     # #defines are used to avoid a list search where we know the correct slot).
     config_defines +=\
-	'#define\tWT_CONFIG_ENTRY_' + name.replace('.', '_') + '\t' * \
-	    max(1, 6 - (len('WT_CONFIG_ENTRY_' + name) / 8)) + \
-	    "%2s" % str(slot) + '\n'
+        '#define\tWT_CONFIG_ENTRY_' + name.replace('.', '_') + '\t' * \
+            max(1, 6 - (len('WT_CONFIG_ENTRY_' + name) / 8)) + \
+            "%2s" % str(slot) + '\n'
 
     # Write the method name and base.
     tfile.write('''
@@ -319,15 +317,15 @@ compare_srcfile(tmp_file, f)
 tfile = open(tmp_file, 'w')
 skip = 0
 for line in open('../src/include/config.h', 'r'):
-	if skip:
-		if 'configuration section: END' in line:
-			tfile.write('/*\n' + line)
-			skip = 0
-	else:
-		tfile.write(line)
-	if 'configuration section: BEGIN' in line:
-		skip = 1
-		tfile.write(' */\n')
-		tfile.write(config_defines)
+    if skip:
+        if 'configuration section: END' in line:
+            tfile.write('/*\n' + line)
+            skip = 0
+    else:
+        tfile.write(line)
+    if 'configuration section: BEGIN' in line:
+        skip = 1
+        tfile.write(' */\n')
+        tfile.write(config_defines)
 tfile.close()
 compare_srcfile(tmp_file, '../src/include/config.h')
diff --git a/dist/api_data.py b/dist/api_data.py
index b38dc7a6ad2..d1b7edd26a8 100644
--- a/dist/api_data.py
+++ b/dist/api_data.py
@@ -596,6 +596,10 @@ methods = {
 	    priority of the transaction for resolving conflicts.
 	    Transactions with higher values are less likely to abort''',
 	    min='-100', max='100'),
+	Config('sync', '', r'''
+	    whether to sync log records when the transaction commits,
+	    inherited from ::wiredtiger_open \c transaction_sync''',
+	    type='boolean'),
 ]),
 
 'session.commit_transaction' : Method([]),
@@ -748,9 +752,18 @@ methods = {
 	    maximum expected number of sessions (including server
 	    threads)''',
 	    min='1'),
-	Config('transaction_sync', 'fsync', r'''
+	Config('transaction_sync', '', r'''
 	    how to sync log records when the transaction commits''',
-	    choices=['dsync', 'fsync', 'none']),
+	    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''',
+	        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
diff --git a/dist/flags.py b/dist/flags.py
index 8a8641d2187..3a99022a571 100644
--- a/dist/flags.py
+++ b/dist/flags.py
@@ -17,17 +17,18 @@ flags = {
 	'file_types' : [
 		'FILE_TYPE_CHECKPOINT',
 		'FILE_TYPE_DATA',
-		'FILE_TYPE_LOG'
+		'FILE_TYPE_LOG',
 	],
 	'log_scan' : [
 		'LOGSCAN_FIRST',
 		'LOGSCAN_FROM_CKP',
 		'LOGSCAN_ONE',
-		'LOGSCAN_RECOVER'
+		'LOGSCAN_RECOVER',
 	],
 	'log_write' : [
 		'LOG_DSYNC',
-		'LOG_FSYNC'
+		'LOG_FLUSH',
+		'LOG_FSYNC',
 	],
 	'page_read' : [
 		'READ_CACHE',
@@ -43,10 +44,10 @@ flags = {
 	'rec_write' : [
 		'EVICTING',
 		'SKIP_UPDATE_ERR',
-		'SKIP_UPDATE_RESTORE'
+		'SKIP_UPDATE_RESTORE',
 	],
 	'shared_cache' : [
-		'CACHE_POOL_RUN'
+		'CACHE_POOL_RUN',
 	],
 	'txn_log_checkpoint' : [
 		'TXN_LOG_CKPT_FAIL',
@@ -75,7 +76,7 @@ flags = {
 		'VERB_SPLIT',
 		'VERB_VERIFY',
 		'VERB_VERSION',
-		'VERB_WRITE'
+		'VERB_WRITE',
 	],
 
 ###################################################
diff --git a/src/config/config_def.c b/src/config/config_def.c
index b411e674d7e..7baacb0bd8f 100644
--- a/src/config/config_def.c
+++ b/src/config/config_def.c
@@ -3,36 +3,36 @@
 #include "wt_internal.h"
 
 static const WT_CONFIG_CHECK confchk_colgroup_meta[] = {
-	{ "columns", "list", NULL, NULL},
-	{ "source", "string", NULL, NULL},
-	{ "type", "string", NULL, NULL},
+	{ "columns", "list", NULL, NULL },
+	{ "source", "string", NULL, NULL },
+	{ "type", "string", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_connection_async_new_op[] = {
-	{ "append", "boolean", NULL, NULL},
-	{ "overwrite", "boolean", NULL, NULL},
-	{ "raw", "boolean", NULL, NULL},
-	{ "timeout", "int", NULL, NULL},
+	{ "append", "boolean", NULL, NULL },
+	{ "overwrite", "boolean", NULL, NULL },
+	{ "raw", "boolean", NULL, NULL },
+	{ "timeout", "int", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_connection_close[] = {
-	{ "leak_memory", "boolean", NULL, NULL},
+	{ "leak_memory", "boolean", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_connection_load_extension[] = {
-	{ "config", "string", NULL, NULL},
-	{ "entry", "string", NULL, NULL},
-	{ "terminate", "string", NULL, NULL},
+	{ "config", "string", NULL, NULL },
+	{ "entry", "string", NULL, NULL },
+	{ "terminate", "string", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_connection_open_session[] = {
 	{ "isolation", "string",
 	    "choices=[\"read-uncommitted\",\"read-committed\",\"snapshot\"]",
-	    NULL},
+	    NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
@@ -66,97 +66,98 @@ static const WT_CONFIG_CHECK confchk_statistics_log_subconfigs[] = {
 };
 
 static const WT_CONFIG_CHECK confchk_connection_reconfigure[] = {
-	{ "async", "category", NULL, confchk_async_subconfigs},
-	{ "cache_size", "int", "min=1MB,max=10TB", NULL},
-	{ "checkpoint", "category", NULL, confchk_checkpoint_subconfigs}
-	    ,
-	{ "error_prefix", "string", NULL, NULL},
-	{ "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},
-	{ "eviction_workers", "int", "min=0,max=20", NULL},
+	{ "async", "category", NULL, confchk_async_subconfigs },
+	{ "cache_size", "int", "min=1MB,max=10TB", NULL },
+	{ "checkpoint", "category", NULL,
+	     confchk_checkpoint_subconfigs },
+	{ "error_prefix", "string", NULL, NULL },
+	{ "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 },
+	{ "eviction_workers", "int", "min=0,max=20", NULL },
 	{ "shared_cache", "category", NULL,
-	     confchk_shared_cache_subconfigs},
+	     confchk_shared_cache_subconfigs },
 	{ "statistics", "list",
 	    "choices=[\"all\",\"fast\",\"none\",\"clear\"]",
-	    NULL},
+	    NULL },
 	{ "statistics_log", "category", NULL,
-	     confchk_statistics_log_subconfigs},
+	     confchk_statistics_log_subconfigs },
 	{ "verbose", "list",
 	    "choices=[\"api\",\"block\",\"checkpoint\",\"compact\",\"evict\""
 	    ",\"evictserver\",\"fileops\",\"log\",\"lsm\",\"metadata\","
 	    "\"mutex\",\"overflow\",\"read\",\"readserver\",\"reconcile\","
 	    "\"recovery\",\"salvage\",\"shared_cache\",\"split\",\"verify\","
 	    "\"version\",\"write\"]",
-	    NULL},
+	    NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_file_meta[] = {
-	{ "allocation_size", "int", "min=512B,max=128MB", NULL},
+	{ "allocation_size", "int", "min=512B,max=128MB", NULL },
 	{ "block_allocation", "string",
 	    "choices=[\"first\",\"best\"]",
-	    NULL},
-	{ "block_compressor", "string", NULL, NULL},
-	{ "cache_resident", "boolean", NULL, NULL},
-	{ "checkpoint", "string", NULL, NULL},
-	{ "checkpoint_lsn", "string", NULL, NULL},
+	    NULL },
+	{ "block_compressor", "string", NULL, NULL },
+	{ "cache_resident", "boolean", NULL, NULL },
+	{ "checkpoint", "string", NULL, NULL },
+	{ "checkpoint_lsn", "string", NULL, NULL },
 	{ "checksum", "string",
 	    "choices=[\"on\",\"off\",\"uncompressed\"]",
-	    NULL},
-	{ "collator", "string", NULL, NULL},
-	{ "columns", "list", NULL, NULL},
-	{ "dictionary", "int", "min=0", NULL},
-	{ "format", "string", "choices=[\"btree\"]", NULL},
-	{ "huffman_key", "string", NULL, NULL},
-	{ "huffman_value", "string", NULL, NULL},
-	{ "id", "string", NULL, NULL},
-	{ "internal_item_max", "int", "min=0", NULL},
-	{ "internal_key_truncate", "boolean", NULL, NULL},
-	{ "internal_page_max", "int", "min=512B,max=512MB", NULL},
-	{ "key_format", "format", NULL, NULL},
-	{ "key_gap", "int", "min=0", NULL},
-	{ "leaf_item_max", "int", "min=0", NULL},
-	{ "leaf_page_max", "int", "min=512B,max=512MB", NULL},
-	{ "memory_page_max", "int", "min=512B,max=10TB", NULL},
-	{ "os_cache_dirty_max", "int", "min=0", NULL},
-	{ "os_cache_max", "int", "min=0", NULL},
-	{ "prefix_compression", "boolean", NULL, NULL},
-	{ "prefix_compression_min", "int", "min=0", NULL},
-	{ "split_pct", "int", "min=25,max=100", NULL},
-	{ "value_format", "format", NULL, NULL},
-	{ "version", "string", NULL, NULL},
+	    NULL },
+	{ "collator", "string", NULL, NULL },
+	{ "columns", "list", NULL, NULL },
+	{ "dictionary", "int", "min=0", NULL },
+	{ "format", "string", "choices=[\"btree\"]", NULL },
+	{ "huffman_key", "string", NULL, NULL },
+	{ "huffman_value", "string", NULL, NULL },
+	{ "id", "string", NULL, NULL },
+	{ "internal_item_max", "int", "min=0", NULL },
+	{ "internal_key_truncate", "boolean", NULL, NULL },
+	{ "internal_page_max", "int", "min=512B,max=512MB", NULL },
+	{ "key_format", "format", NULL, NULL },
+	{ "key_gap", "int", "min=0", NULL },
+	{ "leaf_item_max", "int", "min=0", NULL },
+	{ "leaf_page_max", "int", "min=512B,max=512MB", NULL },
+	{ "memory_page_max", "int", "min=512B,max=10TB", NULL },
+	{ "os_cache_dirty_max", "int", "min=0", NULL },
+	{ "os_cache_max", "int", "min=0", NULL },
+	{ "prefix_compression", "boolean", NULL, NULL },
+	{ "prefix_compression_min", "int", "min=0", NULL },
+	{ "split_pct", "int", "min=25,max=100", NULL },
+	{ "value_format", "format", NULL, NULL },
+	{ "version", "string", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_index_meta[] = {
-	{ "columns", "list", NULL, NULL},
-	{ "key_format", "format", NULL, NULL},
-	{ "source", "string", NULL, NULL},
-	{ "type", "string", NULL, NULL},
-	{ "value_format", "format", NULL, NULL},
+	{ "columns", "list", NULL, NULL },
+	{ "key_format", "format", NULL, NULL },
+	{ "source", "string", NULL, NULL },
+	{ "type", "string", NULL, NULL },
+	{ "value_format", "format", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_session_begin_transaction[] = {
 	{ "isolation", "string",
 	    "choices=[\"read-uncommitted\",\"read-committed\",\"snapshot\"]",
-	    NULL},
-	{ "name", "string", NULL, NULL},
-	{ "priority", "int", "min=-100,max=100", NULL},
+	    NULL },
+	{ "name", "string", NULL, NULL },
+	{ "priority", "int", "min=-100,max=100", NULL },
+	{ "sync", "boolean", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_session_checkpoint[] = {
-	{ "drop", "list", NULL, NULL},
-	{ "force", "boolean", NULL, NULL},
-	{ "name", "string", NULL, NULL},
-	{ "target", "list", NULL, NULL},
+	{ "drop", "list", NULL, NULL },
+	{ "force", "boolean", NULL, NULL },
+	{ "name", "string", NULL, NULL },
+	{ "target", "list", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_session_compact[] = {
-	{ "timeout", "int", NULL, NULL},
+	{ "timeout", "int", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
@@ -176,92 +177,92 @@ static const WT_CONFIG_CHECK confchk_lsm_subconfigs[] = {
 };
 
 static const WT_CONFIG_CHECK confchk_session_create[] = {
-	{ "allocation_size", "int", "min=512B,max=128MB", NULL},
+	{ "allocation_size", "int", "min=512B,max=128MB", NULL },
 	{ "block_allocation", "string",
 	    "choices=[\"first\",\"best\"]",
-	    NULL},
-	{ "block_compressor", "string", NULL, NULL},
-	{ "cache_resident", "boolean", NULL, NULL},
+	    NULL },
+	{ "block_compressor", "string", NULL, NULL },
+	{ "cache_resident", "boolean", NULL, NULL },
 	{ "checksum", "string",
 	    "choices=[\"on\",\"off\",\"uncompressed\"]",
-	    NULL},
-	{ "colgroups", "list", NULL, NULL},
-	{ "collator", "string", NULL, NULL},
-	{ "columns", "list", NULL, NULL},
-	{ "dictionary", "int", "min=0", NULL},
-	{ "exclusive", "boolean", NULL, NULL},
-	{ "format", "string", "choices=[\"btree\"]", NULL},
-	{ "huffman_key", "string", NULL, NULL},
-	{ "huffman_value", "string", NULL, NULL},
-	{ "internal_item_max", "int", "min=0", NULL},
-	{ "internal_key_truncate", "boolean", NULL, NULL},
-	{ "internal_page_max", "int", "min=512B,max=512MB", NULL},
-	{ "key_format", "format", NULL, NULL},
-	{ "key_gap", "int", "min=0", NULL},
-	{ "leaf_item_max", "int", "min=0", NULL},
-	{ "leaf_page_max", "int", "min=512B,max=512MB", NULL},
-	{ "lsm", "category", NULL, confchk_lsm_subconfigs},
-	{ "memory_page_max", "int", "min=512B,max=10TB", NULL},
-	{ "os_cache_dirty_max", "int", "min=0", NULL},
-	{ "os_cache_max", "int", "min=0", NULL},
-	{ "prefix_compression", "boolean", NULL, NULL},
-	{ "prefix_compression_min", "int", "min=0", NULL},
-	{ "source", "string", NULL, NULL},
-	{ "split_pct", "int", "min=25,max=100", NULL},
-	{ "type", "string", NULL, NULL},
-	{ "value_format", "format", NULL, NULL},
+	    NULL },
+	{ "colgroups", "list", NULL, NULL },
+	{ "collator", "string", NULL, NULL },
+	{ "columns", "list", NULL, NULL },
+	{ "dictionary", "int", "min=0", NULL },
+	{ "exclusive", "boolean", NULL, NULL },
+	{ "format", "string", "choices=[\"btree\"]", NULL },
+	{ "huffman_key", "string", NULL, NULL },
+	{ "huffman_value", "string", NULL, NULL },
+	{ "internal_item_max", "int", "min=0", NULL },
+	{ "internal_key_truncate", "boolean", NULL, NULL },
+	{ "internal_page_max", "int", "min=512B,max=512MB", NULL },
+	{ "key_format", "format", NULL, NULL },
+	{ "key_gap", "int", "min=0", NULL },
+	{ "leaf_item_max", "int", "min=0", NULL },
+	{ "leaf_page_max", "int", "min=512B,max=512MB", NULL },
+	{ "lsm", "category", NULL, confchk_lsm_subconfigs },
+	{ "memory_page_max", "int", "min=512B,max=10TB", NULL },
+	{ "os_cache_dirty_max", "int", "min=0", NULL },
+	{ "os_cache_max", "int", "min=0", NULL },
+	{ "prefix_compression", "boolean", NULL, NULL },
+	{ "prefix_compression_min", "int", "min=0", NULL },
+	{ "source", "string", NULL, NULL },
+	{ "split_pct", "int", "min=25,max=100", NULL },
+	{ "type", "string", NULL, NULL },
+	{ "value_format", "format", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_session_drop[] = {
-	{ "force", "boolean", NULL, NULL},
-	{ "remove_files", "boolean", NULL, NULL},
+	{ "force", "boolean", NULL, NULL },
+	{ "remove_files", "boolean", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_session_open_cursor[] = {
-	{ "append", "boolean", NULL, NULL},
-	{ "bulk", "string", NULL, NULL},
-	{ "checkpoint", "string", NULL, NULL},
+	{ "append", "boolean", NULL, NULL },
+	{ "bulk", "string", NULL, NULL },
+	{ "checkpoint", "string", NULL, NULL },
 	{ "dump", "string",
 	    "choices=[\"hex\",\"json\",\"print\"]",
-	    NULL},
-	{ "next_random", "boolean", NULL, NULL},
-	{ "overwrite", "boolean", NULL, NULL},
-	{ "raw", "boolean", NULL, NULL},
-	{ "readonly", "boolean", NULL, NULL},
+	    NULL },
+	{ "next_random", "boolean", NULL, NULL },
+	{ "overwrite", "boolean", NULL, NULL },
+	{ "raw", "boolean", NULL, NULL },
+	{ "readonly", "boolean", NULL, NULL },
 	{ "statistics", "list",
 	    "choices=[\"all\",\"fast\",\"clear\"]",
-	    NULL},
-	{ "target", "list", NULL, NULL},
+	    NULL },
+	{ "target", "list", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_session_reconfigure[] = {
 	{ "isolation", "string",
 	    "choices=[\"read-uncommitted\",\"read-committed\",\"snapshot\"]",
-	    NULL},
+	    NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_session_salvage[] = {
-	{ "force", "boolean", NULL, NULL},
+	{ "force", "boolean", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_session_verify[] = {
-	{ "dump_address", "boolean", NULL, NULL},
-	{ "dump_blocks", "boolean", NULL, NULL},
-	{ "dump_offsets", "list", NULL, NULL},
-	{ "dump_pages", "boolean", NULL, NULL},
+	{ "dump_address", "boolean", NULL, NULL },
+	{ "dump_blocks", "boolean", NULL, NULL },
+	{ "dump_offsets", "list", NULL, NULL },
+	{ "dump_pages", "boolean", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
 static const WT_CONFIG_CHECK confchk_table_meta[] = {
-	{ "colgroups", "list", NULL, NULL},
-	{ "columns", "list", NULL, NULL},
-	{ "key_format", "format", NULL, NULL},
-	{ "value_format", "format", NULL, NULL},
+	{ "colgroups", "list", NULL, NULL },
+	{ "columns", "list", NULL, NULL },
+	{ "key_format", "format", NULL, NULL },
+	{ "value_format", "format", NULL, NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
@@ -273,48 +274,55 @@ static const WT_CONFIG_CHECK confchk_log_subconfigs[] = {
 	{ NULL, NULL, NULL, NULL }
 };
 
+static const WT_CONFIG_CHECK confchk_transaction_sync_subconfigs[] = {
+	{ "enabled", "boolean", NULL, NULL },
+	{ "method", "string",
+	    "choices=[\"dsync\",\"fsync\",\"none\"]",
+	    NULL },
+	{ NULL, NULL, NULL, NULL }
+};
+
 static const WT_CONFIG_CHECK confchk_wiredtiger_open[] = {
-	{ "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},
-	{ "create", "boolean", NULL, NULL},
+	{ "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 },
+	{ "create", "boolean", NULL, NULL },
 	{ "direct_io", "list",
 	    "choices=[\"checkpoint\",\"data\",\"log\"]",
-	    NULL},
-	{ "error_prefix", "string", NULL, NULL},
-	{ "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},
-	{ "eviction_workers", "int", "min=0,max=20", 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_merge", "boolean", NULL, NULL},
-	{ "mmap", "boolean", NULL, NULL},
-	{ "multiprocess", "boolean", NULL, NULL},
-	{ "session_max", "int", "min=1", NULL},
+	    NULL },
+	{ "error_prefix", "string", NULL, NULL },
+	{ "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 },
+	{ "eviction_workers", "int", "min=0,max=20", 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_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},
+	     confchk_shared_cache_subconfigs },
 	{ "statistics", "list",
 	    "choices=[\"all\",\"fast\",\"none\",\"clear\"]",
-	    NULL},
+	    NULL },
 	{ "statistics_log", "category", NULL,
-	     confchk_statistics_log_subconfigs},
-	{ "transaction_sync", "string",
-	    "choices=[\"dsync\",\"fsync\",\"none\"]",
-	    NULL},
-	{ "use_environment_priv", "boolean", NULL, 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\",\"readserver\",\"reconcile\","
 	    "\"recovery\",\"salvage\",\"shared_cache\",\"split\",\"verify\","
 	    "\"version\",\"write\"]",
-	    NULL},
+	    NULL },
 	{ NULL, NULL, NULL, NULL }
 };
 
@@ -387,7 +395,7 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	  confchk_index_meta
 	},
 	{ "session.begin_transaction",
-	  "isolation=,name=,priority=0",
+	  "isolation=,name=,priority=0,sync=",
 	  confchk_session_begin_transaction
 	},
 	{ "session.checkpoint",
@@ -475,8 +483,8 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	  "mmap=,multiprocess=0,session_max=100,shared_cache=(chunk=10MB,"
 	  "name=,reserve=0,size=500MB),statistics=none,"
 	  "statistics_log=(path=\"WiredTigerStat.%d.%H\",sources=,"
-	  "timestamp=\"%b %d %H:%M:%S\",wait=0),transaction_sync=fsync,"
-	  "use_environment_priv=0,verbose=",
+	  "timestamp=\"%b %d %H:%M:%S\",wait=0),transaction_sync=(enabled=0"
+	  ",method=fsync),use_environment_priv=0,verbose=",
 	  confchk_wiredtiger_open
 	},
 	{ NULL, NULL, NULL }
diff --git a/src/conn/conn_log.c b/src/conn/conn_log.c
index be35a99d8aa..a9085f15029 100644
--- a/src/conn/conn_log.c
+++ b/src/conn/conn_log.c
@@ -8,24 +8,43 @@
 #include "wt_internal.h"
 
 /*
+ * __logmgr_sync_cfg --
+ *	Interpret the transaction_sync config.
+ */
+static int
+__logmgr_sync_cfg(WT_SESSION_IMPL *session, const char **cfg)
+{
+	WT_CONFIG_ITEM cval;
+	WT_CONNECTION_IMPL *conn;
+
+	conn = S2C(session);
+
+	WT_RET(
+	    __wt_config_gets(session, cfg, "transaction_sync.enabled", &cval));
+	if (cval.val)
+		FLD_SET(conn->txn_logsync, WT_LOG_FLUSH);
+	else
+		FLD_CLR(conn->txn_logsync, WT_LOG_FLUSH);
+
+	WT_RET(
+	    __wt_config_gets(session, cfg, "transaction_sync.method", &cval));
+	FLD_CLR(conn->txn_logsync, WT_LOG_DSYNC | WT_LOG_FSYNC);
+	if (WT_STRING_MATCH("dsync", cval.str, cval.len))
+		FLD_SET(conn->txn_logsync, WT_LOG_DSYNC);
+	else if (WT_STRING_MATCH("fsync", cval.str, cval.len))
+		FLD_SET(conn->txn_logsync, WT_LOG_FSYNC);
+	return (0);
+}
+
+/*
  * __logmgr_config --
  *	Parse and setup the logging server options.
  */
 static int
 __logmgr_config(WT_SESSION_IMPL *session, const char **cfg, int *runp)
 {
-	static const struct {
-		const char *name;
-		uint32_t flag;
-	} *st, sync_types[] = {
-		{ "dsync",	WT_LOG_DSYNC},
-		{ "fsync",	WT_LOG_FSYNC},
-		{ "none",	0 },
-		{ NULL, 0 }
-	};
-	WT_CONFIG_ITEM cval, sval;
+	WT_CONFIG_ITEM cval;
 	WT_CONNECTION_IMPL *conn;
-	WT_DECL_RET;
 
 	conn = S2C(session);
 
@@ -47,19 +66,8 @@ __logmgr_config(WT_SESSION_IMPL *session, const char **cfg, int *runp)
 	WT_RET(__wt_config_gets(session, cfg, "log.path", &cval));
 	WT_RET(__wt_strndup(session, cval.str, cval.len, &conn->log_path));
 
-	conn->txn_logsync = WT_LOG_DSYNC;
-	WT_RET(__wt_config_gets(session, cfg, "transaction_sync", &cval));
-	for (st = sync_types; st->name != NULL; st++) {
-		ret = __wt_config_subgets(session, &cval, st->name, &sval);
-		if (ret == 0) {
-			if (sval.val)
-				conn->txn_logsync = st->flag;
-		} else if (ret != WT_NOTFOUND)
-			goto err;
-	}
-	ret = 0;
-err:
-	return (ret);
+	WT_RET(__logmgr_sync_cfg(session, cfg));
+	return (0);
 }
 
 /*
diff --git a/src/docs/upgrading.dox b/src/docs/upgrading.dox
index 908da65188d..c5a24279d4c 100644
--- a/src/docs/upgrading.dox
+++ b/src/docs/upgrading.dox
@@ -33,6 +33,17 @@ configured \c os_cache_dirty_max, causing additional system calls that slowed
 some workloads.  Applications that benefit from this setting should set it
 explicitly in WT_SESSION::create.
 </dd>
+
+<dt>\c transaction_sync setting change</dt>
+<dd>
+In the 2.2.1 release of WiredTiger the ::wiredtiger_open \c transaction_sync
+configuration setting has changed from a string value to a structure with two
+fields: \c method, which corresponds to the previous value (\c dsync, \c fsync
+or \c none), and \c enabled, which determines whether there is a sync on
+every transaction commit by default.  Applications can enable or disable sync
+for a specific transaction with the \c sync setting to
+WT_SESSION::begin_transaction.
+</dd>
 </dl>
 
 @section version_220 Upgrading to Version 2.2.0
diff --git a/src/include/flags.h b/src/include/flags.h
index 5f23c9b38db..80f2a1079e9 100644
--- a/src/include/flags.h
+++ b/src/include/flags.h
@@ -23,7 +23,8 @@
 #define	WT_LOGSCAN_FROM_CKP				0x00000004
 #define	WT_LOGSCAN_ONE					0x00000002
 #define	WT_LOGSCAN_RECOVER				0x00000001
-#define	WT_LOG_DSYNC					0x00000002
+#define	WT_LOG_DSYNC					0x00000004
+#define	WT_LOG_FLUSH					0x00000002
 #define	WT_LOG_FSYNC					0x00000001
 #define	WT_READ_CACHE					0x00000100
 #define	WT_READ_COMPACT					0x00000080
diff --git a/src/include/txn.h b/src/include/txn.h
index 99851d4eca7..bbd24362c16 100644
--- a/src/include/txn.h
+++ b/src/include/txn.h
@@ -108,6 +108,7 @@ struct __wt_txn {
 	uint64_t snap_min, snap_max;
 	uint64_t *snapshot;
 	uint32_t snapshot_count;
+	uint32_t txn_logsync;	/* Log sync configuration */
 
 	/* Array of modifications by this transaction. */
 	WT_TXN_OP      *mod;
diff --git a/src/include/wiredtiger.in b/src/include/wiredtiger.in
index 4dd77db15e9..e1a400913ff 100644
--- a/src/include/wiredtiger.in
+++ b/src/include/wiredtiger.in
@@ -1400,6 +1400,9 @@ struct __wt_session {
 	 * @config{priority, priority of the transaction for resolving
 	 * conflicts.  Transactions with higher values are less likely to
 	 * abort., an integer between -100 and 100; default \c 0.}
+	 * @config{sync, whether to sync log records when the transaction
+	 * commits\, inherited from ::wiredtiger_open \c transaction_sync., a
+	 * boolean flag; default empty.}
 	 * @configend
 	 * @errors
 	 */
@@ -1986,9 +1989,15 @@ struct __wt_connection {
  * between each write of the log records., an integer between 0 and 100000;
  * default \c 0.}
  * @config{ ),,}
- * @config{transaction_sync, how to sync log records when the transaction
- * commits., a string\, chosen from the following options: \c "dsync"\, \c
- * "fsync"\, \c "none"; default \c fsync.}
+ * @config{transaction_sync = (, how to sync log records when the transaction
+ * commits., a set of related configuration options defined below.}
+ * @config{&nbsp;&nbsp;&nbsp;&nbsp;enabled, whether to sync the log on every
+ * commit by default\, can be overridden by the \c sync setting to
+ * WT_SESSION::begin_transaction., a boolean flag; default \c false.}
+ * @config{&nbsp;&nbsp;&nbsp;&nbsp;method, the method used to ensure log records
+ * are stable on disk., a string\, chosen from the following options: \c
+ * "dsync"\, \c "fsync"\, \c "none"; default \c fsync.}
+ * @config{ ),,}
  * @config{use_environment_priv, 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
diff --git a/src/txn/txn.c b/src/txn/txn.c
index ab1a77fb5e5..2edf45c34cc 100644
--- a/src/txn/txn.c
+++ b/src/txn/txn.c
@@ -252,6 +252,16 @@ __wt_txn_begin(WT_SESSION_IMPL *session, const char *cfg[])
 		    WT_STRING_MATCH("read-committed", cval.str, cval.len) ?
 		    TXN_ISO_READ_COMMITTED : TXN_ISO_READ_UNCOMMITTED;
 
+	/*
+	 * The default sync setting is inherited from the connection, but can
+	 * be overridden by an explicit "sync" setting for this transaction.
+	 */
+	txn->txn_logsync = S2C(session)->txn_logsync;
+	WT_RET(__wt_config_gets_def(session, cfg, "sync",
+	    FLD_ISSET(txn->txn_logsync, WT_LOG_FLUSH), &cval));
+	if (!cval.val)
+		txn->txn_logsync = 0;
+
 	F_SET(txn, TXN_RUNNING);
 	if (txn->isolation == TXN_ISO_SNAPSHOT)
 		__wt_txn_refresh(session, WT_TXN_NONE, 1);
diff --git a/src/txn/txn_log.c b/src/txn/txn_log.c
index 01a49e9c583..3ad36fa118f 100644
--- a/src/txn/txn_log.c
+++ b/src/txn/txn_log.c
@@ -189,7 +189,7 @@ __wt_txn_log_commit(WT_SESSION_IMPL *session, const char *cfg[])
 
 	/* Write updates to the log. */
 	return (__wt_log_write(session,
-	    txn->logrec, NULL, S2C(session)->txn_logsync));
+	    txn->logrec, NULL, txn->txn_logsync));
 }
 
 /*
diff --git a/test/suite/test_txn02.py b/test/suite/test_txn02.py
index c3e8e51d8df..3eb35de8691 100644
--- a/test/suite/test_txn02.py
+++ b/test/suite/test_txn02.py
@@ -41,7 +41,12 @@ class test_txn02(wttest.WiredTigerTestCase, suite_subprocess):
     uri = 'table:' + tablename
     archive_list = ['true', 'false']
     conn_list = ['reopen', 'stay_open']
-    sync_list = ['dsync', 'fsync', 'none']
+    sync_list = [
+        '(method=dsync,enabled)',
+        '(method=fsync,enabled)',
+        '(method=none,enabled)',
+        '(enabled=false)'
+    ]
 
     types = [
         ('row', dict(tabletype='row',
@@ -210,7 +215,8 @@ class test_txn02(wttest.WiredTigerTestCase, suite_subprocess):
                 self.reopen_conn()
                 c = self.session.open_cursor(self.uri, None, 'overwrite')
 
-            self.session.begin_transaction()
+            self.session.begin_transaction(
+                (self.scenario_number % 2) and 'sync' or None)
             # Test multiple operations per transaction by always
             # doing the same operation on key k + 1.
             k1 = k + 1
diff --git a/test/suite/test_txn04.py b/test/suite/test_txn04.py
index 66f41903592..7e8b448856b 100644
--- a/test/suite/test_txn04.py
+++ b/test/suite/test_txn04.py
@@ -39,7 +39,12 @@ class test_txn04(wttest.WiredTigerTestCase, suite_subprocess):
     logmax = "100K"
     tablename = 'test_txn04'
     uri = 'table:' + tablename
-    sync_list = ['dsync', 'fsync', 'none']
+    sync_list = [
+        '(method=dsync,enabled)',
+        '(method=fsync,enabled)',
+        '(method=none,enabled)',
+        '(enabled=false)'
+    ]
 
     types = [
         ('row', dict(tabletype='row',
diff --git a/test/suite/test_txn05.py b/test/suite/test_txn05.py
index 37f240bec73..83218dba27b 100644
--- a/test/suite/test_txn05.py
+++ b/test/suite/test_txn05.py
@@ -40,7 +40,12 @@ class test_txn05(wttest.WiredTigerTestCase, suite_subprocess):
     tablename = 'test_txn05'
     uri = 'table:' + tablename
     archive_list = ['true', 'false']
-    sync_list = ['dsync', 'fsync', 'none']
+    sync_list = [
+        '(method=dsync,enabled)',
+        '(method=fsync,enabled)',
+        '(method=none,enabled)',
+        '(enabled=false)'
+    ]
 
     types = [
         ('row', dict(tabletype='row',