path: root/dist/api_data.py

# This file is a python script that describes the WiredTiger API.

class Error:
	def __init__(self, name, desc, long_desc=None, **flags):
		self.name = name
		self.desc = desc
		self.long_desc = long_desc
		self.flags = flags

errors = [
	Error('WT_DEADLOCK', 'conflict between concurrent operations', '''
		This error is generated when an operation cannot be completed
		due to a conflict with concurrent operations.  The operation
		may be retried; if a transaction is in progress, it should be
		rolled back and the operation retried in a new transaction.'''),
	Error('WT_DUPLICATE_KEY', 'attempt to insert an existing key', '''
		This error is generated when the application attempts to insert
		a record with the same key as an existing record without the
		'overwrite' configuration to WT_SESSION::open_cursor.'''),
	Error('WT_ERROR', 'non-specific WiredTiger error', '''
		This error is returned when an error is not covered by a
		specific error return.'''),
	Error('WT_NOTFOUND', 'item not found', '''
		This error indicates an operation did not find a value to
		return.  This includes cursor search and other operations
		where no record matched the cursor's search key such as
		WT_CURSOR::update or WT_CURSOR::remove.'''),
	Error('WT_PANIC', 'WiredTiger library panic', '''
		This error indicates an underlying problem that requires the
		application exit and restart.'''),
	Error('WT_RESTART', 'restart the operation (internal)', undoc=True),
]

class Method:
	def __init__(self, config, **flags):
		self.config = config
		self.flags = flags

class Config:
	def __init__(self, name, default, desc, subconfig=None, **flags):
		self.name = name
		self.default = default
		self.desc = desc
		self.subconfig = subconfig
		self.flags = flags

	def __cmp__(self, other):
		return cmp(self.name, other.name)

# All schema objects can have column names (optional for simple tables).
column_meta = [
	Config('columns', '', r'''
		list of the column names.  Comma-separated list of the form
		<code>(column[,...])</code>.  For tables, the number of entries
		must match the total number of values in \c key_format and \c
		value_format.  For colgroups and indices, all column names must
		appear in the list of columns for the table''',
		type='list'),
]

source_meta = [
	Config('source', '', r'''
		set a custom data source URI for a column group, index or simple
		table.  By default, the data source URI is derived from the \c
		type and the column group or index name.  Applications can
		create tables from existing data sources by supplying a \c
		source configuration''', undoc=True),
	Config('type', 'file', r'''
		set the type of data source used to store a column group, index
		or simple table.  By default, a \c "file:" URI is derived from
		the object name.  The \c type configuration can be used to
		switch to a different data source, such as LSM or an extension
		configured by the application.'''),
]

format_meta = column_meta + [
	Config('key_format', 'u', r'''
		the format of the data packed into key items.  See @ref
		schema_format_types for details.  By default, the key_format is
		\c 'u' and applications use WT_ITEM structures to manipulate
		raw byte arrays. By default, records are stored in row-store
		files: keys of type \c 'r' are record numbers and records
		referenced by record number are stored in column-store files''',
		type='format'),
	Config('value_format', 'u', r'''
		the format of the data packed into value items.  See @ref
		schema_format_types for details.  By default, the value_format
		is \c 'u' and applications use a WT_ITEM structure to
		manipulate raw byte arrays. Value items of type 't' are
		bitfields, and when configured with record number type keys,
		will be stored using a fixed-length store''',
		type='format'),
]

lsm_config = [
	Config('lsm_auto_throttle', 'true', r'''
		Throttle inserts into LSM trees if flushing to disk isn't
		keeping up''',
		type='boolean'),
	Config('lsm_bloom', 'true', r'''
		create bloom filters on LSM tree chunks as they are merged''',
		type='boolean'),
	Config('lsm_bloom_config', '', r'''
		config string used when creating Bloom filter files, passed
		to WT_SESSION::create'''),
	Config('lsm_bloom_bit_count', '8', r'''
		the number of bits used per item for LSM bloom filters''',
		min='2', max='1000'),
	Config('lsm_bloom_hash_count', '4', r'''
		the number of hash values per item used for LSM bloom
		filters''',
		min='2', max='100'),
	Config('lsm_bloom_oldest', 'false', r'''
		create a bloom filter on the oldest LSM tree chunk. Only
		supported if bloom filters are enabled''',
		type='boolean'),
	Config('lsm_chunk_size', '2MB', r'''
		the maximum size of the in-memory chunk of an LSM tree''',
		min='512K', max='500MB'),
	Config('lsm_merge_max', '15', r'''
		the maximum number of chunks to include in a merge operation''',
		min='2', max='100'),
	Config('lsm_merge_threads', '1', r'''
		the number of thread to perform merge operations''',
		min='1', max='10'), # !!! max must match WT_LSM_MAX_WORKERS
]

# Per-file configuration
file_config = format_meta + [
	Config('allocation_size', '4KB', r'''
		the file unit allocation size, in bytes, must a power-of-two;
		smaller values decrease the file space required by overflow
		items, and the default value of 4KB is a good choice absent
		requirements from the operating system or storage device''',
		min='512B', max='128MB'),
	Config('block_compressor', '', r'''
		configure a compressor for file blocks.  Permitted values are
		empty (off) or \c "bzip2", \c "snappy" or custom compression
		engine \c "name" created with WT_CONNECTION::add_compressor.
		See @ref compression for more information'''),
	Config('cache_resident', 'false', r'''
		do not ever evict the object's pages; see @ref
		tuning_cache_resident for more information''',
		type='boolean'),
	Config('checksum', 'uncompressed', r'''
		configure block checksums; permitted values are <code>on</code>
		(checksum all blocks), <code>off</code> (checksum no blocks) and
		<code>uncompresssed</code> (checksum only blocks which are not
		compressed for any reason).  The \c uncompressed setting is for
		applications which can rely on decompression to fail if a block
		has been corrupted''',
		choices=['on', 'off', 'uncompressed']),
	Config('collator', '', r'''
		configure custom collation for keys.  Value must be a collator
		name created with WT_CONNECTION::add_collator'''),
	Config('dictionary', '0', r'''
		the maximum number of unique values remembered in the Btree
		row-store leaf page value dictionary; see
		@ref file_formats_compression for more information''',
		min='0'),
	Config('format', 'btree', r'''
		the file format''',
		choices=['btree']),
	Config('huffman_key', '', r'''
		configure Huffman encoding for keys.  Permitted values
		are empty (off), \c "english", \c "utf8<file>" or \c
		"utf16<file>".  See @ref huffman for more information'''),
	Config('huffman_value', '', r'''
		configure Huffman encoding for values.  Permitted values
		are empty (off), \c "english", \c "utf8<file>" or \c
		"utf16<file>".  See @ref huffman for more information'''),
	Config('internal_key_truncate', 'true', r'''
		configure internal key truncation, discarding unnecessary
		trailing bytes on internal keys (ignored for custom
		collators)''',
		type='boolean'),
	Config('internal_page_max', '4KB', r'''
		the maximum page size for internal nodes, in bytes; the size
		must be a multiple of the allocation size and is significant
		for applications wanting to avoid excessive L2 cache misses
		while searching the tree.  The page maximum is the bytes of
		uncompressed data, that is, the limit is applied before any
		block compression is done''',
		min='512B', max='512MB'),
	Config('internal_item_max', '0', r'''
		the largest key stored within an internal node, in bytes.  If
		non-zero, any key larger than the specified size will be
		stored as an overflow item (which may require additional I/O
		to access).  If zero, a default size is chosen that permits at
		least 8 keys per internal page''',
		min=0),
	Config('key_gap', '10', r'''
		the maximum gap between instantiated keys in a Btree leaf page,
		constraining the number of keys processed to instantiate a
		random Btree leaf page key''',
		min='0', undoc=True),
	Config('leaf_page_max', '1MB', r'''
		the maximum page size for leaf nodes, in bytes; the size must
		be a multiple of the allocation size, and is significant for
		applications wanting to maximize sequential data transfer from
		a storage device.  The page maximum is the bytes of uncompressed
		data, that is, the limit is applied before any block compression
		is done''',
		min='512B', max='512MB'),
	Config('leaf_item_max', '0', r'''
		the largest key or value stored within a leaf node, in bytes.
		If non-zero, any key or value larger than the specified size
		will be stored as an overflow item (which may require additional
		I/O to access).  If zero, a default size is chosen that permits
		at least 4 key and value pairs per leaf page''',
		min=0),
	Config('memory_page_max', '5MB', r'''
		the maximum size a page can grow to in memory before being
		reconciled to disk.  The specified size will be adjusted to a
		lower bound of <code>50 * leaf_page_max</code>.  This limit is
		soft - it is possible for pages to be temporarily larger than
		this value''',
		min='512B', max='10TB'),
	Config('os_cache_max', '0', r'''
		maximum system buffer cache usage, in bytes.  If non-zero, evict
		object blocks from the system buffer cache after that many bytes
		from this object are read or written into the buffer cache''',
		min=0),
	Config('os_cache_dirty_max', '0', r'''
		maximum dirty system buffer cache usage, in bytes.  If non-zero,
		schedule writes for dirty blocks belonging to this object in the
		system buffer cache after that many bytes from this object are
		written into the buffer cache''',
		min=0),
	Config('prefix_compression', 'true', r'''
		configure prefix compression on row-store leaf pages''',
		type='boolean'),
	Config('prefix_compression_min', '4', r'''
		minimum gain before prefix compression will be used on row-store
		leaf pages''',
		min=0),
	Config('split_pct', '75', r'''
		the Btree page split size as a percentage of the maximum Btree
		page size, that is, when a Btree page is split, it will be
		split into smaller pages, where each page is the specified
		percentage of the maximum Btree page size''',
		min='25', max='100'),
]

# File metadata, including both configurable and non-configurable (internal)
file_meta = file_config + [
	Config('checkpoint', '', r'''
		the file checkpoint entries'''),
	Config('version', '(major=0,minor=0)', r'''
		the file version'''),
]

table_only_meta = [
	Config('colgroups', '', r'''
		comma-separated list of names of column groups.  Each column
		group is stored separately, keyed by the primary key of the
		table.  If no column groups are specified, all columns are
		stored together in a single file.  All value columns in the
		table must appear in at least one column group.  Each column
		group must be created with a separate call to
		WT_SESSION::create''', type='list'),
]

colgroup_meta = column_meta + source_meta

index_meta = format_meta + source_meta

table_meta = format_meta + table_only_meta

# Connection runtime config, shared by conn.reconfigure and wiredtiger_open
connection_runtime_config = [
	Config('shared_cache', '', r'''
		shared cache configuration options. A database should configure
		either a cache_size or a shared_cache not both''',
		type='category', subconfig=[
		Config('enable', 'false', r'''
			whether the connection is using a shared cache''',
			type='boolean'),
		Config('chunk', '10MB', r'''
			the granularity that a shared cache is redistributed''',
			min='1MB', max='10TB'),
		Config('reserve', '0', r'''
			amount of cache this database is guaranteed to have
			available from the shared cache. This setting is per
			database. Defaults to the chunk size''', type='int'),
		Config('name', 'pool', r'''
			name of a cache that is shared between databases'''),
		Config('size', '500MB', r'''
			maximum memory to allocate for the shared cache. Setting
			this will update the value if one is already set''',
			min='1MB', max='10TB')
		]),
	Config('cache_size', '100MB', r'''
		maximum heap memory to allocate for the cache. A database should
		configure either a cache_size or a shared_cache not both''',
		min='1MB', max='10TB'),
	Config('error_prefix', '', r'''
		prefix string for error messages'''),
	Config('eviction_dirty_target', '80', r'''
		continue evicting until the cache has less dirty pages than this
		(as a percentage). Dirty pages will only be evicted if the cache
		is full enough to trigger eviction''',
		min=10, max=99),
	Config('eviction_target', '80', r'''
		continue evicting until the cache becomes less full than this
		(as a percentage).  Must be less than \c eviction_trigger''',
		min=10, max=99),
	Config('eviction_trigger', '95', r'''
		trigger eviction when the cache becomes this full (as a
		percentage)''',
		min=10, max=99),
	Config('statistics', 'false', r'''
		Maintain database statistics that may impact performance''',
		type='boolean'),
	Config('verbose', '', r'''
		enable messages for various events.  Options are given as a
		list, such as <code>"verbose=[evictserver,read]"</code>''',
		type='list', choices=[
		    'block',
		    'ckpt',
		    'evict',
		    'evictserver',
		    'fileops',
		    'hazard',
		    'log',
		    'lsm',
		    'mutex',
		    'overflow',
		    'read',
		    'readserver',
		    'reconcile',
		    'salvage',
		    'shared_cache',
		    'verify',
		    'version',
		    'write']),
]

session_config = [
	Config('isolation', 'read-committed', r'''
		the default isolation level for operations in this session''',
		choices=['read-uncommitted', 'read-committed', 'snapshot']),
]

methods = {
'file.meta' : Method(file_meta),

'colgroup.meta' : Method(colgroup_meta),

'index.meta' : Method(index_meta),

'table.meta' : Method(table_meta),

'cursor.close' : Method([]),

'session.close' : Method([]),

'session.compact' : Method([
	Config('trigger', '30', r'''
		Compaction will not be attempted unless the specified
		percentage of the underlying objects is expected to be
		recovered by compaction''',
		min='10', max='50'),
]),

'session.create' : Method(table_only_meta + file_config + lsm_config + source_meta + [
	Config('exclusive', 'false', r'''
		fail if the object exists.  When false (the default), if the
		object exists, check that its settings match the specified
		configuration''',
		type='boolean'),
]),

'session.drop' : Method([
	Config('force', 'false', r'''
		return success if the object does not exist''',
		type='boolean'),
	Config('remove_files', 'true', r'''
		should the underlying files be removed?''',
		type='boolean'),
	]),

'session.log_printf' : Method([]),

'session.open_cursor' : Method([
	Config('append', 'false', r'''
		append the value as a new record, creating a new record
		number key; valid only for cursors with record number keys''',
		type='boolean'),
	Config('bulk', 'false', r'''
		configure the cursor for bulk-loading, a fast, initial load
		path (see @ref bulk_load for more information).  Bulk-load
		may only be used for newly created objects and cursors
		configured for bulk-load only support the WT_CURSOR::insert
		and WT_CURSOR::close methods.  When bulk-loading row-store
		objects, keys must be loaded in sorted order.  The value is
		usually a true/false flag; when bulk-loading fixed-length
		column store objects, the special value \c bitmap allows
		chunks of a memory resident bitmap to be loaded directly into
		a file by passing a \c WT_ITEM to WT_CURSOR::set_value where
		the \c size field indicates the number of records in the
		bitmap (as specified by the object's \c value_format
		configuration). Bulk-loaded bitmap values must end on a byte
		boundary relative to the bit count (except for the last set
		of values loaded)'''),
	Config('checkpoint', '', r'''
		the name of a checkpoint to open (the reserved name
		"WiredTigerCheckpoint" opens the most recent internal
		checkpoint taken for the object).  The cursor does not
		support data modification'''),
	Config('dump', '', r'''
		configure the cursor for dump format inputs and outputs:
		"hex" selects a simple hexadecimal format, "print"
		selects a format where only non-printing characters are
		hexadecimal encoded.  The cursor dump format is compatible
		with the @ref util_dump and @ref util_load commands''',
		choices=['hex', 'print']),
	Config('next_random', 'false', r'''
		configure the cursor to return a pseudo-random record from
		the object; valid only for row-store cursors.  Cursors
		configured with \c next_random=true only support the
		WT_CURSOR::next and WT_CURSOR::close methods.  See @ref
		cursor_random for details''',
		type='boolean'),
	Config('overwrite', 'true', r'''
		configures whether the cursor's insert, update and remove
		methods check the existing state of the record.  If \c overwrite
		is \c false, WT_CURSOR::insert fails with ::WT_DUPLICATE_KEY
		if the record exists, WT_CURSOR::update and WT_CURSOR::remove
		fail with ::WT_NOTFOUND if the record does not exist''',
		type='boolean'),
	Config('raw', 'false', r'''
		ignore the encodings for the key and value, manage data as if
		the formats were \c "u".  See @ref cursor_raw for details''',
		type='boolean'),
	Config('statistics_clear', 'false', r'''
		reset statistics counters when the cursor is closed; valid
		only for statistics cursors''',
		type='boolean'),
	Config('statistics_fast', 'true', r'''
		only gather statistics that don't require traversing the tree;
		valid only for statistics cursors''',
		type='boolean'),
	Config('target', '', r'''
		if non-empty, backup the list of objects; valid only for a
		backup data source''',
		type='list'),
]),

'session.rename' : Method([]),
'session.salvage' : Method([
	Config('force', 'false', r'''
		force salvage even of files that do not appear to be WiredTiger
		files''',
		type='boolean'),
]),
'session.truncate' : Method([]),
'session.upgrade' : Method([]),
'session.verify' : Method([
	Config('dump_address', 'false', r'''
	Display addresses and page types as pages are verified, using
	the application's message handler, intended for debugging''',
	type='boolean'),
	Config('dump_blocks', 'false', r'''
	Display the contents of on-disk blocks as they are verified, using
	the application's message handler, intended for debugging''',
	type='boolean'),
	Config('dump_pages', 'false', r'''
	Display the contents of in-memory pages as they are verified, using
	the application's message handler, intended for debugging''',
	type='boolean')
]),

'session.begin_transaction' : Method([
	Config('isolation', '', r'''
		the isolation level for this transaction; defaults to the
		session's isolation level''',
		choices=['read-uncommitted', 'read-committed', 'snapshot']),
	Config('name', '', r'''
		name of the transaction for tracing and debugging'''),
	Config('priority', 0, r'''
		priority of the transaction for resolving conflicts.
		Transactions with higher values are less likely to abort''',
		min='-100', max='100'),
]),

'session.commit_transaction' : Method([]),
'session.rollback_transaction' : Method([]),

'session.checkpoint' : Method([
	Config('drop', '', r'''
		specify a list of checkpoints to drop.
		The list may additionally contain one of the following keys:
		\c "from=all" to drop all checkpoints,
		\c "from=<checkpoint>" to drop all checkpoints after and
		including the named checkpoint, or
		\c "to=<checkpoint>" to drop all checkpoints before and
		including the named checkpoint.  Checkpoints cannot be
		dropped while a hot backup is in progress or if open in
		a cursor''', type='list'),
	Config('force', 'false', r'''
		by default, checkpoints may be skipped if the underlying object
		has not been modified, this option forces the checkpoint''',
		type='boolean'),
	Config('name', '', r'''
		if non-empty, specify a name for the checkpoint (note that
		checkpoints including LSM trees may not be named)'''),
	Config('target', '', r'''
		if non-empty, checkpoint the list of objects''', type='list'),
]),

'connection.add_collator' : Method([]),
'connection.add_compressor' : Method([]),
'connection.add_data_source' : Method([]),
'connection.add_extractor' : Method([]),
'connection.close' : Method([]),
'connection.reconfigure' : Method(connection_runtime_config),

'connection.load_extension' : Method([
	Config('config', '', r'''
		configuration string passed to the entry point of the
		extension as its WT_CONFIG_ARG argument'''),
	Config('entry', 'wiredtiger_extension_init', r'''
		the entry point of the extension, called to initialize the
		extension when it is loaded.  The signature of the function
		must match ::wiredtiger_extension_init'''),
	Config('terminate', 'wiredtiger_extension_terminate', r'''
		an optional function in the extension that is called before
		the extension is unloaded during WT_CONNECTION::close.  The
		signature of the function must match
		::wiredtiger_extension_terminate'''),
]),

'connection.open_session' : Method(session_config),

'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', '', r'''
		periodically checkpoint the database''',
		type='category', subconfig=[
		Config('name', '"WiredTigerCheckpoint"', r'''
		the checkpoint name'''),
		Config('wait', '0', r'''
		seconds to wait between each checkpoint; setting this value
		configures periodic checkpoints''',
		min='1', max='100000'),
		]),
	Config('checkpoint_sync', 'true', r'''
		flush files to stable storage when closing or writing
		checkpoints''',
		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''',
		type='list', choices=['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 the log file''',
		min='1MB', 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('lsm_merge', 'true', r'''
		merge LSM chunks where possible''',
		type='boolean'),
	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', '50', r'''
		maximum expected number of sessions (including server
		threads)''',
		min='1'),
	Config('statistics_log', '', r'''
		log database connection statistics to a file (implies
		setting the \c statistics configuration value to true).
		See @ref statistics_log for more information''',
		type='category', subconfig=[
		Config('clear', 'true', r'''
		reset statistics counters after each set of log records are
		written''', type='boolean'),
		Config('path', '"WiredTigerStat.%H"', r'''
		the pathname to a file into which the log records are written,
		may contain strftime conversion specifications.  If the value
		is not an absolute path name, the file is created relative to
		the database home'''),
		Config('sources', '', r'''
		if non-empty, include statistics for the list of data source
		URIs, if they are open at the time of the statistics logging.
		The list may include URIs matching a single data source
		("table:mytable"), or a URI matching all data sources of a
		particular type ("table:").  No statistics that require the 
		traversal of a tree are reported, as if the \c statistics_fast
		configuration string were set''',
		type='list'),
		Config('timestamp', '"%b %d %H:%M:%S"', r'''
		a timestamp prepended to each log record, may contain strftime
		conversion specifications'''),
		Config('wait', '0', r'''
		seconds to wait between each write of the log records; setting
		this value configures \c statistics and statistics logging''',
		min='1', max='100000'),
		]),
	Config('transaction_sync', 'dsync', r'''
		how to sync log records when the transaction commits''',
		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'),
]),
}