The functions, handles and methods applications use to access and manage data with WiredTiger. More...

Classes
struct	WT_ITEM
	A raw item of data to be managed. More...

struct	WT_CURSOR
	A WT_CURSOR handle is the interface to a cursor. More...

struct	WT_SESSION
	All data operations are performed in the context of a WT_SESSION. More...

struct	WT_CONNECTION
	A connection to a WiredTiger database. More...

struct	WT_EVENT_HANDLER
	The interface implemented by applications to handle error, informational and progress messages. More...

Macros
#define	WT_INTPACK64_MAXSIZE
	The maximum packed size of a 64-bit integer. More...

#define	WT_INTPACK32_MAXSIZE
	The maximum packed size of a 32-bit integer. More...

Functions
int	wiredtiger_open (const char home, WT_EVENT_HANDLER errhandler, const char config, WT_CONNECTION *connectionp)
	Open a connection to a database. More...

const char *	wiredtiger_strerror (int err)
	Return information about an error as a string; wiredtiger_strerror is a superset of the ISO C99/POSIX 1003.1-2001 function strerror. More...

const char *	wiredtiger_version (int majorp, int minorp, int *patchp)
	Get version information. More...

Data packing and unpacking
typedef struct __wt_pack_stream	WT_PACK_STREAM
	Streaming interface to packing. More...

int	wiredtiger_struct_pack (WT_SESSION session, void buffer, size_t size, const char *format,...)
	Pack a structure into a buffer. More...

int	wiredtiger_struct_size (WT_SESSION session, size_t sizep, const char *format,...)
	Calculate the size required to pack a structure. More...

int	wiredtiger_struct_unpack (WT_SESSION session, const void buffer, size_t size, const char *format,...)
	Unpack a structure from a buffer. More...

int	wiredtiger_pack_start (WT_SESSION session, const char format, void buffer, size_t size, WT_PACK_STREAM *psp)
	Start a packing operation into a buffer with the given format string. More...

int	wiredtiger_unpack_start (WT_SESSION session, const char format, const void buffer, size_t size, WT_PACK_STREAM *psp)
	Start an unpacking operation from a buffer with the given format string. More...

int	wiredtiger_pack_close (WT_PACK_STREAM ps, size_t usedp)
	Close a packing stream. More...

int	wiredtiger_pack_item (WT_PACK_STREAM ps, WT_ITEM item)
	Pack an item into a packing stream. More...

int	wiredtiger_pack_int (WT_PACK_STREAM *ps, int64_t i)
	Pack a signed integer into a packing stream. More...

int	wiredtiger_pack_str (WT_PACK_STREAM ps, const char s)
	Pack a string into a packing stream. More...

int	wiredtiger_pack_uint (WT_PACK_STREAM *ps, uint64_t u)
	Pack an unsigned integer into a packing stream. More...

int	wiredtiger_unpack_item (WT_PACK_STREAM ps, WT_ITEM item)
	Unpack an item from a packing stream. More...

int	wiredtiger_unpack_int (WT_PACK_STREAM ps, int64_t ip)
	Unpack a signed integer from a packing stream. More...

int	wiredtiger_unpack_str (WT_PACK_STREAM ps, const char *sp)
	Unpack a string from a packing stream. More...

int	wiredtiger_unpack_uint (WT_PACK_STREAM ps, uint64_t up)
	Unpack an unsigned integer from a packing stream. More...

Error returns
Most functions and methods in WiredTiger return an integer code indicating whether the operation succeeded or failed. A return of zero indicates success, all non-zero return values indicate some kind of failure. WiredTiger reserves all values from -31,800 to -31,999 as possible error return values. WiredTiger may also return C99/POSIX error codes such as `ENOMEM`, `EINVAL` and `ENOTSUP`, with the usual meanings. The following are all of the WiredTiger-specific error returns:
#define	WT_DEADLOCK
	Conflict between concurrent operations. More...

#define	WT_DUPLICATE_KEY
	Attempt to insert an existing key. More...

#define	WT_ERROR
	Non-specific WiredTiger error. More...

#define	WT_NOTFOUND
	Item not found. More...

#define	WT_PANIC
	WiredTiger library panic. More...

Connection statistics
Statistics are accessed through cursors with `"statistics:"` URIs. Individual statistics can be queried through the cursor using the following keys. See Statistics Data for more information.
#define	WT_STAT_CONN_BLOCK_BYTE_MAP_READ
	block manager: mapped bytes read

#define	WT_STAT_CONN_BLOCK_BYTE_READ
	block manager: bytes read

#define	WT_STAT_CONN_BLOCK_BYTE_WRITE
	block manager: bytes written

#define	WT_STAT_CONN_BLOCK_MAP_READ
	block manager: mapped blocks read

#define	WT_STAT_CONN_BLOCK_PRELOAD
	block manager: blocks pre-loaded

#define	WT_STAT_CONN_BLOCK_READ
	block manager: blocks read

#define	WT_STAT_CONN_BLOCK_WRITE
	block manager: blocks written

#define	WT_STAT_CONN_CACHE_BYTES_DIRTY
	cache: tracked dirty bytes in the cache

#define	WT_STAT_CONN_CACHE_BYTES_INUSE
	cache: bytes currently in the cache

#define	WT_STAT_CONN_CACHE_BYTES_MAX
	cache: maximum bytes configured

#define	WT_STAT_CONN_CACHE_BYTES_READ
	cache: bytes read into cache

#define	WT_STAT_CONN_CACHE_BYTES_WRITE
	cache: bytes written from cache

#define	WT_STAT_CONN_CACHE_EVICTION_CHECKPOINT
	cache: checkpoint blocked page eviction

#define	WT_STAT_CONN_CACHE_EVICTION_CLEAN
	cache: unmodified pages evicted

#define	WT_STAT_CONN_CACHE_EVICTION_DIRTY
	cache: modified pages evicted

#define	WT_STAT_CONN_CACHE_EVICTION_FAIL
	cache: pages selected for eviction unable to be evicted

#define	WT_STAT_CONN_CACHE_EVICTION_FORCE
	cache: pages evicted because they exceeded the in-memory maximum

#define	WT_STAT_CONN_CACHE_EVICTION_FORCE_FAIL
	cache: failed eviction of pages that exceeded the in-memory maximum

#define	WT_STAT_CONN_CACHE_EVICTION_HAZARD
	cache: hazard pointer blocked page eviction

#define	WT_STAT_CONN_CACHE_EVICTION_INTERNAL
	cache: internal pages evicted

#define	WT_STAT_CONN_CACHE_EVICTION_MERGE
	cache: internal page merge operations completed

#define	WT_STAT_CONN_CACHE_EVICTION_MERGE_FAIL
	cache: internal page merge attempts that could not complete

#define	WT_STAT_CONN_CACHE_EVICTION_MERGE_LEVELS
	cache: internal levels merged

#define	WT_STAT_CONN_CACHE_EVICTION_SLOW
	cache: eviction server unable to reach eviction goal

#define	WT_STAT_CONN_CACHE_EVICTION_WALK
	cache: pages walked for eviction

#define	WT_STAT_CONN_CACHE_INMEM_SPLIT
	pages split because they were unable to be evicted

#define	WT_STAT_CONN_CACHE_PAGES_DIRTY
	cache: tracked dirty pages in the cache

#define	WT_STAT_CONN_CACHE_PAGES_INUSE
	cache: pages currently held in the cache

#define	WT_STAT_CONN_CACHE_READ
	cache: pages read into cache

#define	WT_STAT_CONN_CACHE_WRITE
	cache: pages written from cache

#define	WT_STAT_CONN_COND_WAIT
	pthread mutex condition wait calls

#define	WT_STAT_CONN_CURSOR_CREATE
	cursor creation

#define	WT_STAT_CONN_CURSOR_INSERT
	Btree cursor insert calls.

#define	WT_STAT_CONN_CURSOR_NEXT
	Btree cursor next calls.

#define	WT_STAT_CONN_CURSOR_PREV
	Btree cursor prev calls.

#define	WT_STAT_CONN_CURSOR_REMOVE
	Btree cursor remove calls.

#define	WT_STAT_CONN_CURSOR_RESET
	Btree cursor reset calls.

#define	WT_STAT_CONN_CURSOR_SEARCH
	Btree cursor search calls.

#define	WT_STAT_CONN_CURSOR_SEARCH_NEAR
	Btree cursor search near calls.

#define	WT_STAT_CONN_CURSOR_UPDATE
	Btree cursor update calls.

#define	WT_STAT_CONN_DH_CONN_HANDLES
	dhandle: connection dhandles swept

#define	WT_STAT_CONN_DH_CONN_SWEEPS
	dhandle: connection sweep attempts

#define	WT_STAT_CONN_DH_SESSION_HANDLES
	dhandle: session dhandles swept

#define	WT_STAT_CONN_DH_SESSION_SWEEPS
	dhandle: session sweep attempts

#define	WT_STAT_CONN_DH_SWEEP_EVICT
	dhandle: sweeps conflicting with evict

#define	WT_STAT_CONN_FILE_OPEN
	files currently open

#define	WT_STAT_CONN_LOG_BUFFER_GROW
	log: log buffer size increases

#define	WT_STAT_CONN_LOG_BUFFER_SIZE
	log: total log buffer size

#define	WT_STAT_CONN_LOG_BYTES_USER
	log: user provided log bytes written

#define	WT_STAT_CONN_LOG_BYTES_WRITTEN
	log: log bytes written

#define	WT_STAT_CONN_LOG_MAX_FILESIZE
	log: maximum log file size

#define	WT_STAT_CONN_LOG_READS
	log: log read operations

#define	WT_STAT_CONN_LOG_SCAN_RECORDS
	log: records processed by log scan

#define	WT_STAT_CONN_LOG_SCAN_REREADS
	log: log scan records requiring two reads

#define	WT_STAT_CONN_LOG_SCANS
	log: log scan operations

#define	WT_STAT_CONN_LOG_SLOT_CLOSES
	log: consolidated slot closures

#define	WT_STAT_CONN_LOG_SLOT_CONSOLIDATED
	log: logging bytes consolidated

#define	WT_STAT_CONN_LOG_SLOT_JOINS
	log: consolidated slot joins

#define	WT_STAT_CONN_LOG_SLOT_RACES
	log: consolidated slot join races

#define	WT_STAT_CONN_LOG_SLOT_READY_WAIT_TIMEOUT
	log: log slot ready wait timeouts

#define	WT_STAT_CONN_LOG_SLOT_RELEASE_WAIT_TIMEOUT
	log: log slot release wait timeouts

#define	WT_STAT_CONN_LOG_SLOT_SWITCH_FAILS
	log: slots selected for switching that were unavailable

#define	WT_STAT_CONN_LOG_SLOT_TOOBIG
	log: record size exceeded maximum

#define	WT_STAT_CONN_LOG_SLOT_TOOSMALL
	log: failed to find a slot large enough for record

#define	WT_STAT_CONN_LOG_SLOT_TRANSITIONS
	log: consolidated slot join transitions

#define	WT_STAT_CONN_LOG_SYNC
	log: log sync operations

#define	WT_STAT_CONN_LOG_WRITES
	log: log write operations

#define	WT_STAT_CONN_LSM_ROWS_MERGED
	rows merged in an LSM tree

#define	WT_STAT_CONN_MEMORY_ALLOCATION
	memory allocations

#define	WT_STAT_CONN_MEMORY_FREE
	memory frees

#define	WT_STAT_CONN_MEMORY_GROW
	memory re-allocations

#define	WT_STAT_CONN_READ_IO
	total read I/Os

#define	WT_STAT_CONN_REC_PAGES
	page reconciliation calls

#define	WT_STAT_CONN_REC_PAGES_EVICTION
	page reconciliation calls for eviction

#define	WT_STAT_CONN_REC_SKIPPED_UPDATE
	reconciliation failed because an update could not be included

#define	WT_STAT_CONN_RWLOCK_READ
	pthread mutex shared lock read-lock calls

#define	WT_STAT_CONN_RWLOCK_WRITE
	pthread mutex shared lock write-lock calls

#define	WT_STAT_CONN_SESSION_CURSOR_OPEN
	open cursor count

#define	WT_STAT_CONN_TXN_BEGIN
	transactions

#define	WT_STAT_CONN_TXN_CHECKPOINT
	transaction checkpoints

#define	WT_STAT_CONN_TXN_CHECKPOINT_RUNNING
	transaction checkpoint currently running

#define	WT_STAT_CONN_TXN_COMMIT
	transactions committed

#define	WT_STAT_CONN_TXN_FAIL_CACHE
	transaction failures due to cache overflow

#define	WT_STAT_CONN_TXN_ROLLBACK
	transactions rolled-back

#define	WT_STAT_CONN_WRITE_IO
	total write I/Os

Statistics for data sources

#define	WT_STAT_DSRC_ALLOCATION_SIZE
	block manager: file allocation unit size

#define	WT_STAT_DSRC_BLOCK_ALLOC
	block manager: blocks allocated

#define	WT_STAT_DSRC_BLOCK_CHECKPOINT_SIZE
	block manager: checkpoint size

#define	WT_STAT_DSRC_BLOCK_EXTENSION
	block manager: allocations requiring file extension

#define	WT_STAT_DSRC_BLOCK_FREE
	block manager: blocks freed

#define	WT_STAT_DSRC_BLOCK_MAGIC
	block manager: file magic number

#define	WT_STAT_DSRC_BLOCK_MAJOR
	block manager: file major version number

#define	WT_STAT_DSRC_BLOCK_MINOR
	block manager: minor version number

#define	WT_STAT_DSRC_BLOCK_REUSE_BYTES
	block manager: file bytes available for reuse

#define	WT_STAT_DSRC_BLOCK_SIZE
	block manager: file size in bytes

#define	WT_STAT_DSRC_BLOOM_COUNT
	bloom filters in the LSM tree

#define	WT_STAT_DSRC_BLOOM_FALSE_POSITIVE
	bloom filter false positives

#define	WT_STAT_DSRC_BLOOM_HIT
	bloom filter hits

#define	WT_STAT_DSRC_BLOOM_MISS
	bloom filter misses

#define	WT_STAT_DSRC_BLOOM_PAGE_EVICT
	bloom filter pages evicted from cache

#define	WT_STAT_DSRC_BLOOM_PAGE_READ
	bloom filter pages read into cache

#define	WT_STAT_DSRC_BLOOM_SIZE
	total size of bloom filters

#define	WT_STAT_DSRC_BTREE_COLUMN_DELETED
	column-store variable-size deleted values

#define	WT_STAT_DSRC_BTREE_COLUMN_FIX
	column-store fixed-size leaf pages

#define	WT_STAT_DSRC_BTREE_COLUMN_INTERNAL
	column-store internal pages

#define	WT_STAT_DSRC_BTREE_COLUMN_VARIABLE
	column-store variable-size leaf pages

#define	WT_STAT_DSRC_BTREE_COMPACT_REWRITE
	pages rewritten by compaction

#define	WT_STAT_DSRC_BTREE_ENTRIES
	total LSM, table or file object key/value pairs

#define	WT_STAT_DSRC_BTREE_FIXED_LEN
	fixed-record size

#define	WT_STAT_DSRC_BTREE_MAXIMUM_DEPTH
	maximum tree depth

#define	WT_STAT_DSRC_BTREE_MAXINTLITEM
	maximum internal page item size

#define	WT_STAT_DSRC_BTREE_MAXINTLPAGE
	maximum internal page size

#define	WT_STAT_DSRC_BTREE_MAXLEAFITEM
	maximum leaf page item size

#define	WT_STAT_DSRC_BTREE_MAXLEAFPAGE
	maximum leaf page size

#define	WT_STAT_DSRC_BTREE_OVERFLOW
	overflow pages

#define	WT_STAT_DSRC_BTREE_ROW_INTERNAL
	row-store internal pages

#define	WT_STAT_DSRC_BTREE_ROW_LEAF
	row-store leaf pages

#define	WT_STAT_DSRC_CACHE_BYTES_READ
	bytes read into cache

#define	WT_STAT_DSRC_CACHE_BYTES_WRITE
	bytes written from cache

#define	WT_STAT_DSRC_CACHE_EVICTION_CHECKPOINT
	cache: checkpoint blocked page eviction

#define	WT_STAT_DSRC_CACHE_EVICTION_CLEAN
	unmodified pages evicted

#define	WT_STAT_DSRC_CACHE_EVICTION_DIRTY
	modified pages evicted

#define	WT_STAT_DSRC_CACHE_EVICTION_FAIL
	data source pages selected for eviction unable to be evicted

#define	WT_STAT_DSRC_CACHE_EVICTION_HAZARD
	cache: hazard pointer blocked page eviction

#define	WT_STAT_DSRC_CACHE_EVICTION_INTERNAL
	internal pages evicted

#define	WT_STAT_DSRC_CACHE_EVICTION_MERGE
	cache: internal page merge operations completed

#define	WT_STAT_DSRC_CACHE_EVICTION_MERGE_FAIL
	cache: internal page merge attempts that could not complete

#define	WT_STAT_DSRC_CACHE_EVICTION_MERGE_LEVELS
	cache: internal levels merged

#define	WT_STAT_DSRC_CACHE_INMEM_SPLIT
	pages split because they were unable to be evicted

#define	WT_STAT_DSRC_CACHE_OVERFLOW_VALUE
	overflow values cached in memory

#define	WT_STAT_DSRC_CACHE_READ
	pages read into cache

#define	WT_STAT_DSRC_CACHE_READ_OVERFLOW
	overflow pages read into cache

#define	WT_STAT_DSRC_CACHE_WRITE
	pages written from cache

#define	WT_STAT_DSRC_COMPRESS_RAW_FAIL
	raw compression call failed, no additional data available

#define	WT_STAT_DSRC_COMPRESS_RAW_FAIL_TEMPORARY
	raw compression call failed, additional data available

#define	WT_STAT_DSRC_COMPRESS_RAW_OK
	raw compression call succeeded

#define	WT_STAT_DSRC_COMPRESS_READ
	compressed pages read

#define	WT_STAT_DSRC_COMPRESS_WRITE
	compressed pages written

#define	WT_STAT_DSRC_COMPRESS_WRITE_FAIL
	page written failed to compress

#define	WT_STAT_DSRC_COMPRESS_WRITE_TOO_SMALL
	page written was too small to compress

#define	WT_STAT_DSRC_CURSOR_CREATE
	cursor creation

#define	WT_STAT_DSRC_CURSOR_INSERT
	cursor insert calls

#define	WT_STAT_DSRC_CURSOR_INSERT_BULK
	bulk-loaded cursor-insert calls

#define	WT_STAT_DSRC_CURSOR_INSERT_BYTES
	cursor-insert key and value bytes inserted

#define	WT_STAT_DSRC_CURSOR_NEXT
	cursor next calls

#define	WT_STAT_DSRC_CURSOR_PREV
	cursor prev calls

#define	WT_STAT_DSRC_CURSOR_REMOVE
	cursor remove calls

#define	WT_STAT_DSRC_CURSOR_REMOVE_BYTES
	cursor-remove key bytes removed

#define	WT_STAT_DSRC_CURSOR_RESET
	cursor reset calls

#define	WT_STAT_DSRC_CURSOR_SEARCH
	cursor search calls

#define	WT_STAT_DSRC_CURSOR_SEARCH_NEAR
	cursor search near calls

#define	WT_STAT_DSRC_CURSOR_UPDATE
	cursor update calls

#define	WT_STAT_DSRC_CURSOR_UPDATE_BYTES
	cursor-update value bytes updated

#define	WT_STAT_DSRC_LSM_CHUNK_COUNT
	chunks in the LSM tree

#define	WT_STAT_DSRC_LSM_GENERATION_MAX
	highest merge generation in the LSM tree

#define	WT_STAT_DSRC_LSM_LOOKUP_NO_BLOOM
	queries that could have benefited from a Bloom filter that did not exist

#define	WT_STAT_DSRC_REC_DICTIONARY
	reconciliation dictionary matches

#define	WT_STAT_DSRC_REC_OVERFLOW_KEY_INTERNAL
	reconciliation internal-page overflow keys

#define	WT_STAT_DSRC_REC_OVERFLOW_KEY_LEAF
	reconciliation leaf-page overflow keys

#define	WT_STAT_DSRC_REC_OVERFLOW_VALUE
	reconciliation overflow values written

#define	WT_STAT_DSRC_REC_PAGE_DELETE
	reconciliation pages deleted

#define	WT_STAT_DSRC_REC_PAGE_MERGE
	reconciliation pages merged

#define	WT_STAT_DSRC_REC_PAGES
	page reconciliation calls

#define	WT_STAT_DSRC_REC_PAGES_EVICTION
	page reconciliation calls for eviction

#define	WT_STAT_DSRC_REC_SKIPPED_UPDATE
	reconciliation failed because an update could not be included

#define	WT_STAT_DSRC_REC_SPLIT_INTERNAL
	reconciliation internal pages split

#define	WT_STAT_DSRC_REC_SPLIT_LEAF
	reconciliation leaf pages split

#define	WT_STAT_DSRC_REC_SPLIT_MAX
	reconciliation maximum splits for a page

#define	WT_STAT_DSRC_SESSION_COMPACT
	object compaction

#define	WT_STAT_DSRC_SESSION_CURSOR_OPEN
	open cursor count

#define	WT_STAT_DSRC_TXN_UPDATE_CONFLICT
	update conflicts

Detailed Description

The functions, handles and methods applications use to access and manage data with WiredTiger.

Class Documentation

struct WT_ITEM

A raw item of data to be managed.

Data items have a pointer to the data and a length (limited to 4GB for items stored in tables). WT_ITEM structures do not need to be cleared before use.

Examples:: ex_extending.c, and ex_schema.c.

Class Members
const void *	data	The memory reference of the data item. For items returned by a WT_CURSOR, the pointer is only valid until the next operation on that cursor. Applications that need to keep an item across multiple cursor operations must make a copy.
uint32_t	size	The number of bytes in the data item.

Macro Definition Documentation

#define 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.

#define 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.

#define WT_ERROR

Non-specific WiredTiger error.

This error is returned when an error is not covered by a specific error return.

#define WT_INTPACK32_MAXSIZE

The maximum packed size of a 32-bit integer.

The wiredtiger_struct_pack function will pack single integers into at most this many bytes.

#define WT_INTPACK64_MAXSIZE

The maximum packed size of a 64-bit integer.

The wiredtiger_struct_pack function will pack single long integers into at most this many bytes.

#define 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.

Examples:: ex_stat.c.

#define WT_PANIC

WiredTiger library panic.

This error indicates an underlying problem that requires the application exit and restart.

Typedef Documentation

typedef struct __wt_pack_stream WT_PACK_STREAM

Streaming interface to packing.

This allows applications to pack or unpack records one field at a time. This is an opaque handle returned by wiredtiger_pack_start or wiredtiger_unpack_start. It must be closed with wiredtiger_pack_close.

Function Documentation

int wiredtiger_open	(	const char *	home,
		WT_EVENT_HANDLER *	errhandler,
		const char *	config,
		WT_CONNECTION **	connectionp
	)

Open a connection to a database.

ret = wiredtiger_open(home, NULL, "create,cache_size=500M", &conn);

Parameters

home The path to the database home directory. See Database Home Directory for more information.

errhandler An error handler. If NULL, a builtin error handler is installed that writes error messages to stderr

config

Configuration string, see Configuration Strings. Permitted values:

Name	Effect	Values
`buffer_alignment`	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).	an integer between -1 and 1MB; default `-1`.
`cache_size`	maximum heap memory to allocate for the cache. A database should configure either a cache_size or a shared_cache not both.	an integer between 1MB and 10TB; default `100MB`.
`checkpoint = (`	periodically checkpoint the database.	a set of related configuration options defined below.
`name`	the checkpoint name.	a string; default `"WiredTigerCheckpoint"`.
`wait`	seconds to wait between each checkpoint; setting this value configures periodic checkpoints.	an integer between 1 and 100000; default `0`.
`)`
`checkpoint_sync`	flush files to stable storage when closing or writing checkpoints.	a boolean flag; default `true`.
`create`	create the database if it does not exist.	a boolean flag; default `false`.
`direct_io`	Use `O_DIRECT` to access files. Options are given as a list, such as `"direct_io=[data]"`. Configuring `direct_io` requires care, see Direct I/O for important warnings.	a list, with values chosen from the following options: `"data"`, `"log"`; default empty.
`error_prefix`	prefix string for error messages.	a string; default empty.
`eviction_dirty_target`	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.	an integer between 10 and 99; default `80`.
`eviction_target`	continue evicting until the cache becomes less full than this (as a percentage). Must be less than `eviction_trigger`.	an integer between 10 and 99; default `80`.
`eviction_trigger`	trigger eviction when the cache becomes this full (as a percentage).	an integer between 10 and 99; default `95`.
`extensions`	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 `config` parameter (for example, `extensions=(/path/ext.so={entry=my_entry})`).	a list of strings; default empty.
`file_extend`	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, `file_extend=(data=16MB)`.	a list, with values chosen from the following options: `"data"`, `"log"`; default empty.
`hazard_max`	maximum number of simultaneous hazard pointers per session handle.	an integer greater than or equal to 15; default `1000`.
`log = (`	enable logging.	a set of related configuration options defined below.
`archive`	automatically archive unneeded log files.	a boolean flag; default `true`.
`enabled`	enable logging subsystem.	a boolean flag; default `false`.
`file_max`	the maximum size of log files.	an integer between 100KB and 2GB; default `100MB`.
`path`	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.	a string; default `""`.
`)`
`lsm_merge`	merge LSM chunks where possible.	a boolean flag; default `true`.
`mmap`	Use memory mapping to access files when possible.	a boolean flag; default `true`.
`multiprocess`	permit sharing between processes (will automatically start an RPC server for primary processes and use RPC for secondary processes). Not yet supported in WiredTiger.	a boolean flag; default `false`.
`session_max`	maximum expected number of sessions (including server threads).	an integer greater than or equal to 1; default `50`.
`shared_cache = (`	shared cache configuration options. A database should configure either a cache_size or a shared_cache not both.	a set of related configuration options defined below.
`enable`	whether the connection is using a shared cache.	a boolean flag; default `false`.
`chunk`	the granularity that a shared cache is redistributed.	an integer between 1MB and 10TB; default `10MB`.
`reserve`	amount of cache this database is guaranteed to have available from the shared cache. This setting is per database. Defaults to the chunk size.	an integer; default `0`.
`name`	name of a cache that is shared between databases.	a string; default `pool`.
`size`	maximum memory to allocate for the shared cache. Setting this will update the value if one is already set.	an integer between 1MB and 10TB; default `500MB`.
`)`
`statistics`	Maintain database statistics, which may impact performance. Choosing "all" maintains all statistics regardless of cost, "fast" maintains a subset of statistics that are relatively inexpensive, "none" turns off all statistics. The "clear" configuration resets statistics after they are gathered, where appropriate (for example, a cache size statistic is not cleared, while the count of cursor insert operations will be cleared). When "clear" is configured for the database, gathered statistics are reset each time a statistics cursor is used to gather statistics, as well as each time statistics are logged using the `statistics_log` configuration. See Statistics for more information.	a list, with values chosen from the following options: `"all"`, `"fast"`, `"none"`, `"clear"`; default `none`.
`statistics_log = (`	log any statistics the database is configured to maintain, to a file. See Statistics for more information.	a set of related configuration options defined below.
`path`	the pathname to a file into which the log records are written, may contain ISO C standard strftime conversion specifications. If the value is not an absolute path name, the file is created relative to the database home.	a string; default `"WiredTigerStat.%H"`.
`sources`	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:").	a list of strings; default empty.
`timestamp`	a timestamp prepended to each log record, may contain strftime conversion specifications.	a string; default `"%b %d %H:%M:%S"`.
`wait`	seconds to wait between each write of the log records.	an integer between 1 and 100000; default `0`.
`)`
`transaction_sync`	how to sync log records when the transaction commits.	a string, chosen from the following options: `"dsync"`, `"fsync"`, `"none"`; default `dsync`.
`use_environment_priv`	use the `WIREDTIGER_CONFIG` and `WIREDTIGER_HOME` environment variables regardless of whether or not the process is running with special privileges. See Database Home Directory for more information.	a boolean flag; default `false`.
`verbose`	enable messages for various events. Options are given as a list, such as `"verbose=[evictserver,read]"`.	a list, with values chosen from the following options: `"block"`, `"ckpt"`, `"compact"`, `"evict"`, `"evictserver"`, `"fileops"`, `"hazard"`, `"log"`, `"lsm"`, `"mutex"`, `"overflow"`, `"read"`, `"readserver"`, `"reconcile"`, `"recovery"`, `"salvage"`, `"shared_cache"`, `"verify"`, `"version"`, `"write"`; default empty.

Additionally, if a file named WiredTiger.config appears in the WiredTiger home directory, it is read for configuration values (see WiredTiger.config file for details). Configuration values specified in the config argument to the wiredtiger_open function override configuration values specified in the WiredTiger.config file.

[out] connectionp A pointer to the newly opened connection handle

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

Examples:: ex_access.c, ex_call_center.c, ex_config.c, ex_cursor.c, ex_extending.c, ex_file.c, ex_hello.c, ex_pack.c, ex_schema.c, ex_stat.c, and ex_thread.c.

int wiredtiger_pack_close	(	WT_PACK_STREAM *	ps,
		size_t *	usedp
	)

Close a packing stream.

Parameters

	ps	the packing stream handle
[out]	usedp	the number of bytes in the buffer used by the stream

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

int wiredtiger_pack_int	(	WT_PACK_STREAM *	ps,
		int64_t	i
	)

Pack a signed integer into a packing stream.

Parameters

ps	the packing stream handle
i	a signed integer to pack

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

int wiredtiger_pack_item	(	WT_PACK_STREAM *	ps,
		WT_ITEM *	item
	)

Pack an item into a packing stream.

Parameters

ps	the packing stream handle
item	an item to pack

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

int wiredtiger_pack_start	(	WT_SESSION *	session,
		const char *	format,
		void *	buffer,
		size_t	size,
		WT_PACK_STREAM **	psp
	)

Start a packing operation into a buffer with the given format string.

This should be followed by a series of calls to wiredtiger_pack_item, wiredtiger_pack_int, wiredtiger_pack_str or wiredtiger_pack_uint to fill in the values.

Parameters

	session	the session handle
	format	the data format, see Packing and Unpacking Data
	buffer	a pointer to memory to hold the packed data
	size	the size of the buffer
[out]	psp	the new packing stream handle

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

int wiredtiger_pack_str	(	WT_PACK_STREAM *	ps,
		const char *	s
	)

Pack a string into a packing stream.

Parameters

ps	the packing stream handle
s	a string to pack

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

int wiredtiger_pack_uint	(	WT_PACK_STREAM *	ps,
		uint64_t	u
	)

Pack an unsigned integer into a packing stream.

Parameters

ps	the packing stream handle
u	an unsigned integer to pack

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

const char* wiredtiger_strerror ( int err )

Return information about an error as a string; wiredtiger_strerror is a superset of the ISO C99/POSIX 1003.1-2001 function strerror.

        const char *key = "non-existent key";
        cursor->set_key(cursor, key);
        if ((ret = cursor->remove(cursor)) != 0) {
                fprintf(stderr,
                    "cursor.remove: %s\n", wiredtiger_strerror(ret));
                return (ret);
        }

Parameters

err	a return value from a WiredTiger, C library or POSIX function

Returns: a string representation of the error

Examples:: ex_access.c, ex_call_center.c, ex_config.c, ex_cursor.c, ex_extending.c, ex_file.c, ex_hello.c, ex_pack.c, ex_schema.c, and ex_thread.c.

int wiredtiger_struct_pack	(	WT_SESSION *	session,
		void *	buffer,
		size_t	size,
		const char *	format,
			...
	)

Pack a structure into a buffer.

See Packing and Unpacking Data for a description of the permitted format strings.

Packing Examples

For example, the string "iSh" will pack a 32-bit integer followed by a NUL-terminated string, followed by a 16-bit integer. The default, big-endian encoding will be used, with no alignment. This could be used in C as follows:

        char buf[100];
        ret = wiredtiger_struct_pack(
            session, buf, sizeof(buf), "iSh", 42, "hello", -3);

Then later, the values can be unpacked as follows:

        int i;
        char *s;
        short h;
        ret = wiredtiger_struct_unpack(
            session, buf, sizeof(buf), "iSh", &i, &s, &h);

Parameters

session	the session handle
buffer	a pointer to a packed byte array
size	the number of valid bytes in the buffer
format	the data format, see Packing and Unpacking Data

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

Examples:: ex_pack.c.

int wiredtiger_struct_size	(	WT_SESSION *	session,
		size_t *	sizep,
		const char *	format,
			...
	)

Calculate the size required to pack a structure.

Note that for variable-sized fields including variable-sized strings and integers, the calculated sized merely reflects the expected sizes specified in the format string itself.

size_t size;

ret = wiredtiger_struct_size(session, &size, "iSh", 42, "hello", -3);

Parameters

session	the session handle
sizep	a location where the number of bytes needed for the matching call to wiredtiger_struct_pack is returned
format	the data format, see Packing and Unpacking Data

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

Examples:: ex_pack.c.

int wiredtiger_struct_unpack	(	WT_SESSION *	session,
		const void *	buffer,
		size_t	size,
		const char *	format,
			...
	)

Unpack a structure from a buffer.

Reverse of wiredtiger_struct_pack: gets values out of a packed byte string.

        int i;
        char *s;
        short h;
        ret = wiredtiger_struct_unpack(
            session, buf, sizeof(buf), "iSh", &i, &s, &h);

Parameters

session	the session handle
buffer	a pointer to a packed byte array
size	the number of valid bytes in the buffer
format	the data format, see Packing and Unpacking Data

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

Examples:: ex_pack.c, and ex_schema.c.

int wiredtiger_unpack_int	(	WT_PACK_STREAM *	ps,
		int64_t *	ip
	)

Unpack a signed integer from a packing stream.

Parameters

	ps	the packing stream handle
[out]	ip	the unpacked signed integer

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

int wiredtiger_unpack_item	(	WT_PACK_STREAM *	ps,
		WT_ITEM *	item
	)

Unpack an item from a packing stream.

Parameters

ps	the packing stream handle
item	an item to unpack

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

int wiredtiger_unpack_start	(	WT_SESSION *	session,
		const char *	format,
		const void *	buffer,
		size_t	size,
		WT_PACK_STREAM **	psp
	)

Start an unpacking operation from a buffer with the given format string.

This should be followed by a series of calls to wiredtiger_unpack_item, wiredtiger_unpack_int, wiredtiger_unpack_str or wiredtiger_unpack_uint to retrieve the packed values.

Parameters

	session	the session handle
	format	the data format, see Packing and Unpacking Data
	buffer	a pointer to memory holding the packed data
	size	the size of the buffer
[out]	psp	the new packing stream handle

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

int wiredtiger_unpack_str	(	WT_PACK_STREAM *	ps,
		const char **	sp
	)

Unpack a string from a packing stream.

Parameters

	ps	the packing stream handle
[out]	sp	the unpacked string

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

int wiredtiger_unpack_uint	(	WT_PACK_STREAM *	ps,
		uint64_t *	up
	)

Unpack an unsigned integer from a packing stream.

Parameters

	ps	the packing stream handle
[out]	up	the unpacked unsigned integer

Returns: zero on success and a non-zero error code on failure. See Error Returns for details.

const char* wiredtiger_version	(	int *	majorp,
		int *	minorp,
		int *	patchp
	)

Get version information.

printf("WiredTiger version %s\n", wiredtiger_version(NULL, NULL, NULL));

        int major, minor, patch;
        (void)wiredtiger_version(&major, &minor, &patch);
        printf("WiredTiger version is %d, %d (patch %d)\n",
            major, minor, patch);

Parameters

majorp	a location where the major version number is returned
minorp	a location where the minor version number is returned
patchp	a location where the patch version number is returned

Returns: a string representation of the version

Classes

Macros

Functions

Data packing and unpacking

Error returns

Connection statistics

Statistics for data sources

Detailed Description

Class Documentation

Macro Definition Documentation

Typedef Documentation

Function Documentation

Packing Examples