A connection to a WiredTiger database. More...

Public Member Functions
synchronized void	delete ()

int	async_flush () throws com.wiredtiger.db.WiredTigerException
	Wait for all outstanding operations to complete. More...

int	close (String config) throws com.wiredtiger.db.WiredTigerException
	Close a connection. More...

int	debug_info (String config) throws com.wiredtiger.db.WiredTigerException

int	reconfigure (String config) throws com.wiredtiger.db.WiredTigerException
	Reconfigure a connection handle. More...

String	get_home ()

int	configure_method (String method, String uri, String config, String type, String check) throws com.wiredtiger.db.WiredTigerException
	Add configuration options for a method. More...

int	is_new ()
	Return if opening this handle created the database. More...

int	query_timestamp (String hex_timestamp, String config) throws com.wiredtiger.db.WiredTigerException
	Query the global transaction timestamp state. More...

int	set_timestamp (String config) throws com.wiredtiger.db.WiredTigerException
	Set a global transaction timestamp. More...

int	rollback_to_stable (String config) throws com.wiredtiger.db.WiredTigerException
	Rollback in-memory non-logged state to an earlier point in time. More...

int	load_extension (String path, String config) throws com.wiredtiger.db.WiredTigerException
	Load an extension. More...

AsyncOp	async_new_op (String uri, String config, Object callbackObject) throws com.wiredtiger.db.WiredTigerException
	Return an async operation handle. More...

Session	open_session (String config) throws com.wiredtiger.db.WiredTigerException
	Open a session. More...

Protected Member Functions
	Connection (long cPtr, boolean cMemoryOwn)

int	_java_init (Object jsess)

Static Protected Member Functions
static long	getCPtr (Connection obj)

Protected Attributes
boolean	swigCMemOwn

Detailed Description

A connection to a WiredTiger database.

The connection may be opened within the same address space as the caller or accessed over a socket connection.

Most applications will open a single connection to a database for each process. The first process to open a connection to a database will access the database in its own address space. Subsequent connections (if allowed) will communicate with the first process over a socket connection to perform their operations.

Thread safety: A WT_CONNECTION handle may be shared between threads, see Multithreading for more information.

Member Function Documentation

◆ async_flush()

int com.wiredtiger.db.Connection.async_flush ( ) throws com.wiredtiger.db.WiredTigerException

Wait for all outstanding operations to complete.

/* Wait for all outstanding operations to complete. */

error_check(conn->async_flush(conn));

Parameters

connection the connection handle

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

◆ async_new_op()

AsyncOp com.wiredtiger.db.Connection.async_new_op	(	String	uri,
		String	config,
		Object	callbackObject
	)		throws com.wiredtiger.db.WiredTigerException

Return an async operation handle.

                while ((ret = conn->async_new_op(conn,
                    "table:async", NULL, &ex_asynckeys.iface, &op)) != 0) {
                        /*
                         * If we used up all the handles, pause and retry to
                         * give the workers a chance to catch up.
                         */
                        fprintf(stderr,
                            "asynchronous operation handle not available\n");
                        if (ret == EBUSY)
                                sleep(1);
                        else
                                return (EXIT_FAILURE);
                }

Parameters

connection the connection handle

uri the connection handle

config

Configuration string, see Configuration Strings. Permitted values:

Name	Effect	Values
`append`	append the value as a new record, creating a new record number key; valid only for operations with record number keys.	a boolean flag; default `false`.
`overwrite`	configures whether the cursor's insert, update and remove methods check the existing state of the record. If `overwrite` is `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.	a boolean flag; default `true`.
`raw`	ignore the encodings for the key and value, manage data as if the formats were `"u"`. See Raw mode for details.	a boolean flag; default `false`.
`timeout`	maximum amount of time to allow for compact in seconds. The actual amount of time spent in compact may exceed the configured value. A value of zero disables the timeout.	an integer; default `1200`.

callback the operation callback

[out] asyncopp the new op handle

Returns: zero on success and a non-zero error code on failure. See Error handling for details. If there are no available handles, EBUSY is returned.

◆ close()

int com.wiredtiger.db.Connection.close ( String config ) throws com.wiredtiger.db.WiredTigerException

Close a connection.

Any open sessions will be closed.

error_check(conn->close(conn, NULL));

Parameters

connection the connection handle

config

Configuration string, see Configuration Strings. Permitted values:

Name	Effect	Values
`leak_memory`	don't free memory during close.	a boolean flag; default `false`.

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

◆ configure_method()

int com.wiredtiger.db.Connection.configure_method	(	String	method,
		String	uri,
		String	config,
		String	type,
		String	check
	)		throws com.wiredtiger.db.WiredTigerException

Add configuration options for a method.

See Creating data-specific configuration strings for more information.

        /*
         * Applications opening a cursor for the data-source object "my_data"
         * have an additional configuration option "entries", which is an
         * integer type, defaults to 5, and must be an integer between 1 and 10.
         *
         * The method being configured is specified using a concatenation of the
         * handle name, a period and the method name.
         */
        error_check(conn->configure_method(conn,
            "WT_SESSION.open_cursor",
            "my_data:", "entries=5", "int", "min=1,max=10"));
        /*
         * Applications opening a cursor for the data-source object "my_data"
         * have an additional configuration option "devices", which is a list
         * of strings.
         */
        error_check(conn->configure_method(conn,
            "WT_SESSION.open_cursor", "my_data:", "devices", "list", NULL));

Parameters

connection	the connection handle
method	the method being configured
uri	the object type or NULL for all object types
config	the additional configuration's name and default value
type	the additional configuration's type (must be one of `"boolean"\`, `"int"`, `"list"` or `"string"`)
check	the additional configuration check string, or NULL if none

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

◆ debug_info()

int com.wiredtiger.db.Connection.debug_info ( String config ) throws com.wiredtiger.db.WiredTigerException

◆ is_new()

int com.wiredtiger.db.Connection.is_new ( )

Return if opening this handle created the database.

        if (conn->is_new(conn)) {
                /* First time initialization. */
        }

Parameters

connection the connection handle

Returns: false (zero) if the connection existed before the call to wiredtiger_open, true (non-zero) if it was created by opening this handle.

◆ load_extension()

int com.wiredtiger.db.Connection.load_extension	(	String	path,
		String	config
	)		throws com.wiredtiger.db.WiredTigerException

Load an extension.

        error_check(conn->load_extension(conn, "my_extension.dll", NULL));
        error_check(conn->load_extension(conn,
            "datasource/libdatasource.so",
            "config=[device=/dev/sd1,alignment=64]"));

Parameters

connection the connection handle

path the filename of the extension module, or "local" to search the current application binary for the initialization function, see Extending WiredTiger for more details.

config

Configuration string, see Configuration Strings. Permitted values:

Name	Effect	Values
`config`	configuration string passed to the entry point of the extension as its WT_CONFIG_ARG argument.	a string; default empty.
`early_load`	whether this extension should be loaded at the beginning of wiredtiger_open. Only applicable to extensions loaded via the wiredtiger_open configurations string.	a boolean flag; default `false`.
`entry`	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.	a string; default `wiredtiger_extension_init`.
`terminate`	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.	a string; default `wiredtiger_extension_terminate`.

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

◆ open_session()

Session com.wiredtiger.db.Connection.open_session ( String config ) throws com.wiredtiger.db.WiredTigerException

Open a session.

WT_SESSION *session;

error_check(conn->open_session(conn, NULL, NULL, &session));

Parameters

connection the connection handle

errhandler An error handler. If NULL, the connection's error handler is used. See Error handling using the WT_EVENT_HANDLER for more information.

config

Configuration string, see Configuration Strings. Permitted values:

Name	Effect	Values
`ignore_cache_size`	when set, operations performed by this session ignore the cache size and are not blocked when the cache is full. Note that use of this option for operations that create cache pressure can starve ordinary sessions that obey the cache size.	a boolean flag; default `false`.
`isolation`	the default isolation level for operations in this session.	a string, chosen from the following options: `"read-uncommitted"`, `"read-committed"`, `"snapshot"`; default `read-committed`.

[out] sessionp the new session handle

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

◆ query_timestamp()

int com.wiredtiger.db.Connection.query_timestamp	(	String	hex_timestamp,
		String	config
	)		throws com.wiredtiger.db.WiredTigerException

Query the global transaction timestamp state.

        char timestamp_buf[2 * WT_TIMESTAMP_SIZE + 1];
        error_check(
            session->timestamp_transaction(session, "commit_timestamp=2a"));
        error_check(session->commit_transaction(session, NULL));
        error_check(conn->query_timestamp(
            conn, timestamp_buf, "get=all_committed"));

Parameters

connection the connection handle

[out] hex_timestamp a buffer that will be set to the hexadecimal encoding of the timestamp being queried. Must be large enough to hold a hex-encoded timestamp (i.e., double the timestamp size plus one byte for NUL termination).

config

Configuration string, see Configuration Strings. Permitted values:

Name	Effect	Values
`get`	specify which timestamp to query: `all_committed` returns the largest timestamp such that all earlier timestamps have committed, `oldest` returns the most recent `oldest_timestamp` set with WT_CONNECTION::set_timestamp, `pinned` returns the minimum of the `oldest_timestamp` and the read timestamps of all active readers, and `stable` returns the most recent `stable_timestamp` set with WT_CONNECTION::set_timestamp. See Application-specified Transaction Timestamps.	a string, chosen from the following options: `"all_committed"`, `"oldest"`, `"pinned"`, `"stable"`; default `all_committed`.

Returns: zero on success and a non-zero error code on failure. See Error handling for details. If there is no matching timestamp (e.g., if this method is called before timestamps are used) WT_NOTFOUND will be returned.

◆ reconfigure()

int com.wiredtiger.db.Connection.reconfigure ( String config ) throws com.wiredtiger.db.WiredTigerException

Reconfigure a connection handle.

error_check(conn->reconfigure(conn, "eviction_target=75"));

Parameters

connection the connection handle

config

Configuration string, see Configuration Strings. Permitted values:

Name	Effect	Values
`async = (`	asynchronous operations configuration options.	a set of related configuration options defined below.
`enabled`	enable asynchronous operation.	a boolean flag; default `false`.
`ops_max`	maximum number of expected simultaneous asynchronous operations.	an integer between 1 and 4096; default `1024`.
`threads`	the number of worker threads to service asynchronous requests. Each worker thread uses a session from the configured session_max.	an integer between 1 and 20; default `2`.
`)`
`cache_overhead`	assume the heap allocator overhead is the specified percentage, and adjust the cache usage by that amount (for example, if there is 10GB of data in cache, a percentage of 10 means WiredTiger treats this as 11GB). This value is configurable because different heap allocators have different overhead and different workloads will have different heap allocation sizes and patterns, therefore applications may need to adjust this value based on allocator choice and behavior in measured workloads.	an integer between 0 and 30; default `8`.
`cache_size`	maximum heap memory to allocate for the cache. A database should configure either `cache_size` or `shared_cache` but not both.	an integer between 1MB and 10TB; default `100MB`.
`checkpoint = (`	periodically checkpoint the database. Enabling the checkpoint server uses a session from the configured session_max.	a set of related configuration options defined below.
`log_size`	wait for this amount of log record bytes to be written to the log between each checkpoint. If non-zero, this value will use a minimum of the log file size. A database can configure both log_size and wait to set an upper bound for checkpoints; setting this value above 0 configures periodic checkpoints.	an integer between 0 and 2GB; default `0`.
`wait`	seconds to wait between each checkpoint; setting this value above 0 configures periodic checkpoints.	an integer between 0 and 100000; default `0`.
`)`
`compatibility = (`	set compatibility version of database. Changing the compatibility version requires that there are no active operations for the duration of the call.	a set of related configuration options defined below.
`release`	compatibility release version string.	a string; default empty.
`)`
`error_prefix`	prefix string for error messages.	a string; default empty.
`eviction = (`	eviction configuration options.	a set of related configuration options defined below.
`threads_max`	maximum number of threads WiredTiger will start to help evict pages from cache. The number of threads started will vary depending on the current eviction load. Each eviction worker thread uses a session from the configured session_max.	an integer between 1 and 20; default `8`.
`threads_min`	minimum number of threads WiredTiger will start to help evict pages from cache. The number of threads currently running will vary depending on the current eviction load.	an integer between 1 and 20; default `1`.
`)`
`eviction_checkpoint_target`	perform eviction at the beginning of checkpoints to bring the dirty content in cache to this level, expressed as a percentage of the total cache size. Ignored if set to zero or `in_memory` is `true`.	an integer between 0 and 99; default `5`.
`eviction_dirty_target`	perform eviction in worker threads when the cache contains at least this much dirty content, expressed as a percentage of the total cache size.	an integer between 1 and 99; default `5`.
`eviction_dirty_trigger`	trigger application threads to perform eviction when the cache contains at least this much dirty content, expressed as a percentage of the total cache size. This setting only alters behavior if it is lower than eviction_trigger.	an integer between 1 and 99; default `20`.
`eviction_target`	perform eviction in worker threads when the cache contains at least this much content, expressed as a percentage of the total cache size. Must be less than `eviction_trigger`.	an integer between 10 and 99; default `80`.
`eviction_trigger`	trigger application threads to perform eviction when the cache contains at least this much content, expressed as a percentage of the total cache size.	an integer between 10 and 99; default `95`.
`file_manager = (`	control how file handles are managed.	a set of related configuration options defined below.
`close_handle_minimum`	number of handles open before the file manager will look for handles to close.	an integer greater than or equal to 0; default `250`.
`close_idle_time`	amount of time in seconds a file handle needs to be idle before attempting to close it. A setting of 0 means that idle handles are not closed.	an integer between 0 and 100000; default `30`.
`close_scan_interval`	interval in seconds at which to check for files that are inactive and close them.	an integer between 1 and 100000; default `10`.
`)`
`log = (`	enable logging. Enabling logging uses three sessions from the configured session_max.	a set of related configuration options defined below.
`archive`	automatically archive unneeded log files.	a boolean flag; default `true`.
`prealloc`	pre-allocate log files.	a boolean flag; default `true`.
`zero_fill`	manually write zeroes into log files.	a boolean flag; default `false`.
`)`
`lsm_manager = (`	configure database wide options for LSM tree management. The LSM manager is started automatically the first time an LSM tree is opened. The LSM manager uses a session from the configured session_max.	a set of related configuration options defined below.
`merge`	merge LSM chunks where possible.	a boolean flag; default `true`.
`worker_thread_max`	Configure a set of threads to manage merging LSM trees in the database. Each worker thread uses a session handle from the configured session_max.	an integer between 3 and 20; default `4`.
`)`
`shared_cache = (`	shared cache configuration options. A database should configure either a cache_size or a shared_cache not both. Enabling a shared cache uses a session from the configured session_max.	a set of related configuration options defined below.
`chunk`	the granularity that a shared cache is redistributed.	an integer between 1MB and 10TB; default `10MB`.
`name`	the name of a cache that is shared between databases or `"none"` when no shared cache is configured.	a string; default `none`.
`quota`	maximum size of cache this database can be allocated from the shared cache. Defaults to the entire shared cache size.	an integer; default `0`.
`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`.
`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"`, `"cache_walk"`, `"fast"`, `"none"`, `"clear"`, `"tree_walk"`; default `none`.
`statistics_log = (`	log any statistics the database is configured to maintain, to a file. See Statistics for more information. Enabling the statistics log server uses a session from the configured session_max.	a set of related configuration options defined below.
`json`	encode statistics in JSON format.	a boolean flag; default `false`.
`on_close`	log statistics on database close.	a boolean flag; default `false`.
`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, when `json` is configured, defaults to `"%FT%Y.000Z"`.	a string; default `"%b %d %H:%M:%S"`.
`wait`	seconds to wait between each write of the log records; setting this value above 0 configures statistics logging.	an integer between 0 and 100000; default `0`.
`)`
`verbose`	enable messages for various events. Only available if WiredTiger is configured with –enable-verbose. Options are given as a list, such as `"verbose=[evictserver,read]"`.	a list, with values chosen from the following options: `"api"`, `"block"`, `"checkpoint"`, `"checkpoint_progress"`, `"compact"`, `"evict"`, `"evict_stuck"`, `"evictserver"`, `"fileops"`, `"handleops"`, `"log"`, `"lookaside"`, `"lookaside_activity"`, `"lsm"`, `"lsm_manager"`, `"metadata"`, `"mutex"`, `"overflow"`, `"read"`, `"rebalance"`, `"reconcile"`, `"recovery"`, `"recovery_progress"`, `"salvage"`, `"shared_cache"`, `"split"`, `"thread_group"`, `"timestamp"`, `"transaction"`, `"verify"`, `"version"`, `"write"`; default empty.

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

◆ rollback_to_stable()

int com.wiredtiger.db.Connection.rollback_to_stable ( String config ) throws com.wiredtiger.db.WiredTigerException

Rollback in-memory non-logged state to an earlier point in time.

This method uses a timestamp to define the rollback point, and thus requires that the application uses timestamps and that the stable_timestamp must have been set via a call to WT_CONNECTION::set_timestamp. Any updates to checkpoint durable tables that are more recent than the stable timestamp are removed.

This method requires that there are no active operations for the duration of the call.

Any updates made to logged tables will not be rolled back. Any updates made without an associated timestamp will not be rolled back. See Application-specified Transaction Timestamps.

error_check(conn->rollback_to_stable(conn, NULL));

Parameters

connection	the connection handle
config	Configuration string, see Configuration Strings. No values currently permitted.

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

◆ set_timestamp()

int com.wiredtiger.db.Connection.set_timestamp ( String config ) throws com.wiredtiger.db.WiredTigerException

Set a global transaction timestamp.

error_check(conn->set_timestamp(conn, "commit_timestamp=2a"));

error_check(conn->set_timestamp(conn, "oldest_timestamp=2a"));

error_check(conn->set_timestamp(conn, "stable_timestamp=2a"));

Parameters

connection the connection handle

config

Configuration string, see Configuration Strings. Permitted values:

Name	Effect	Values
`commit_timestamp`	reset the maximum commit timestamp tracked by WiredTiger. This will cause future calls to WT_CONNECTION::query_timestamp to ignore commit timestamps greater than the specified value until the next commit moves the tracked commit timestamp forwards. This is only intended for use where the application is rolling back locally committed transactions. The supplied value should not be older than the current oldest and stable timestamps. See Application-specified Transaction Timestamps.	a string; default empty.
`force`	set timestamps even if they violate normal ordering requirements. For example allow the `oldest_timestamp` to move backwards.	a boolean flag; default `false`.
`oldest_timestamp`	future commits and queries will be no earlier than the specified timestamp. Supplied values must be monotonically increasing, any attempt to set the value to older than the current is silently ignored. The supplied value should not be newer than the current stable timestamp. See Application-specified Transaction Timestamps.	a string; default empty.
`stable_timestamp`	checkpoints will not include commits that are newer than the specified timestamp in tables configured with `log=`(enabled=false). Supplied values must be monotonically increasing, any attempt to set the value to older than the current is silently ignored. The supplied value should not be older than the current oldest timestamp. See Application-specified Transaction Timestamps.	a string; default empty.

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

Public Member Functions

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Detailed Description

Member Function Documentation

◆ async_flush()

◆ async_new_op()

◆ close()

◆ configure_method()

◆ debug_info()

◆ is_new()

◆ load_extension()

◆ open_session()

◆ query_timestamp()

◆ reconfigure()

◆ rollback_to_stable()

◆ set_timestamp()