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Version 2.0.1
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Version 2.0.1
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The underlying file format is unchanged in 2.0
In the 2.0 release of WiredTiger the LSM configuration options have been collected into a configuration option subgroup. All configuration options to WT_SESSION::create that previously had a prefix of lsm_ now belong to the lsm configuration group. If you are explicitly configuring any of the following options, you should review the WT_SESSION::create documentation for details of the updated syntax: lsm_auto_throttle, lsm_bloom, lsm_bloom_config, lsm_bloom_bit_count, lsm_bloom_hash_count, lsm_bloom_oldest, lsm_chunk_max, lsm_chunk_size, lsm_merge_max and lsm_merge_threads.
The underlying file formats changed in the 1.6.6 release; tables and files should be dumped and re-loaded into a new database.
In previous releases, the trigger configuration string to the WT_SESSION::compact method specified a requirement to initiate compaction; in the 1.6.6 release, this configuration string has been removed, and compaction will be attempted if it seems likely at least 10% of the file can be recovered. Applications may require modifications to resolve run-time errors.
In previous releases, the wiredtiger_open function took a statistics configuration, which defaulted to false; when set to true, additional, generally performance-expensive statistics were maintained by the database, above and beyond a default set of statistics. In version 1.6.6, the statistics configuration is a list which may be set to "all", "fast" or "none". When set to "none", no statistics are maintained by the database; when set to "fast", only relatively performance-inexpensive statistics are maintained, and when set to "all", all statistics are maintained, regardless of cost.
In previous releases, the wiredtiger_open function took a statistics_log configuration which logged the performance-inexpensive database statistics to a file. In version 1.6.6, the statistics_log configuration logs whatever statistics are configured for the database. If the database is configured with statistics to "none", no statistics will be logged to the file; if the database is configured with "all" or "fast", the corresponding statistics will be logged to the file.
In previous releases, the WT_SESSION::cursor method took statistics_clear and a statistics_fast configurations. The statistics_clear configuration defaulted to false; when set to true, statistics counters were reset after they were gathered by the cursor. The statistics_fast configuration defaulted to true; when set to true, the cursor only gathered performance-inexpensive statistics for the cursor, and when set to false, the cursor gathered all available statistics, regardless of cost.
In version 1.6.6, these two configuration booleans have been replaced with a new configuration list statistics, which may be set from the values "clear", "fast" and "all". When "fast" is configured, only relatively performance-inexpensive statistics are gathered, and when "all" is configured, all statistics are gathered, regardless of cost. When "clear" is configured, statistics counters are reset after they are gathered.
Additionally, in version 1.6.6, statistics cursors must be configured to agree with the database statistics configuration; when the database statistics are configured to "none", attempts to open a statistics cursor will fail; when the database statistics are configured to "fast", a statistics cursor must also be configured to "fast"; when the database statistics are configured to "all", a statistics cursor may be configured to either "fast" or "all". Opening a statistics cursor without configuring either "fast" or "all" will configure the cursor to be the same as the current database configuration.
Applications may require modifications to resolve run-time errors; application statistics configuration and cursors should be reviewed to confirm they are configured for the desired behavior;
Add a new WT_EVENT_HANDLER::handle_close callback that WiredTiger will call any time it automatically closes an application session or cursor handle.
Additionally add a WT_SESSION parameter into the existing WT_EVENT_HANDLER::handle_error, WT_EVENT_HANDLER::handle_message and WT_EVENT_HANDLER::handle_progress callback functions.
In previous releases, the WT_CURSOR::insert ended positioned at the inserted record. To minimize the cursor resources held by applications inserting many records, the WT_CURSOR::insert method has been changed to end without any position. Application insert cursors should be reviewed to confirm they do not attempt to iterate after an insert.
In previous releases, the default statistics_fast configuration to the WT_SESSION::open_cursor method was false; in the 1.6.5 release, the default statistics_fast configuration is true. Applications opening statistics cursors should be reviewed to confirm they have the correct behavior.
The sync configuration key to wiredtiger_open has been renamed checkpoint_sync.
The underlying file formats changed in the 1.6.4 release; tables and files should be dumped and re-loaded into a new database.
The default behavior of the wt utility's load command has been changed to overwrite existing data, by default, and the -o flag to the load command (overwrite existing data) has been replaced with the -n flag (do not overwrite existing data). Applications requiring the previous default behavior of not overwriting existing data should add the -n option to their command line configuration; applications previously using the -o option on their command line configurations should remove it.
In previous releases, the WT_SESSION::open_cursor overwrite configuration string behaved inconsistently across Btree and LSM data sources. In Btree, overwrite was false by default and was limited to the WT_CURSOR::insert method, changing an insert to succeed regardless of whether or not the record previously existed. In LSM trees, overwrite was true by default, and applied to the WT_CURSOR::insert, WT_CURSOR::remove and WT_CURSOR::update methods, configuring all three methods to ignore the existing state of the record.
In the 1.6.3 release, the overwrite configuration is consistent across both Btree and LSM tree data sources. For performance reasons, the default is the behavior previously described for LSM trees: in other words, overwrite is true by default, causing WT_CURSOR::insert, WT_CURSOR::remove and WT_CURSOR::update to ignore the current state of the record, and these methods will succeed regardless of whether or not the record previously exists. When an application configures overwrite to false, WT_CURSOR::insert will fail with WT_DUPLICATE_KEY if the record previously exists, and WT_CURSOR::update and WT_CURSOR::remove will fail with WT_NOTFOUND if the record does not previously exist.
This is a potentially serious API change that will not be detected by compilation. Application cursors should be reviewed to confirm they are configured for the desired behavior.
transactional configuration The transactional configuration key has been removed from wiredtiger_open. Any application setting it should simply remove it, no change in application behavior is needed.
New functionality was added to the list of WiredTiger extension methods; applications using the extension methods will require recompilation.
The "source" configuration key has been removed from WT_SESSION::create. Normal applications should not have been using it, and there were a number of bugs associated with it.
The default file checksum configuration was changed to uncompressed, which means blocks that are compressed will no longer also include a checksum, by default. Applications using compression insufficient for the purposes of corrupted block identification should change their file checksum configuration to on.
In the 1.6.1 release, the default for the WT_SESSION::create configuration string allocation_size changed from 512B to 4KB, and the default for the configuration string internal_page_max changed from 2KB to 4KB. Applications wanting to create files with smaller allocation or internal page sizes will need to set those configuration values explicitly.
In the 1.6.1 release, an explicit shared_cache=(enable=boolean) option was added to the wiredtiger_open configuration options. Existing applications that use shared cache functionality will need to add the enable option to the configuration string. The default value for the option is false.
In the 1.6.1 release, the split_pct argument to the WT_COMPRESSOR::compress_raw function changed type from u_int to int, applications may require modification to avoid compiler warnings.
The underlying file formats changed in the 1.6.0 release; tables and files should be dumped and re-loaded into a new database.
An undocumented feature where configuration string case was ignored has been removed, and all configuration strings are now case-dependent. Applications may require modifications to resolve run-time errors.
The following changes are only applicable to applications loading extensions and/or using the WiredTiger extension functions described in WT_EXTENSION_API.
The signature of wiredtiger_extension_init has changed from (WT_SESSION *session, WT_EXTENSION_API *api) to (WT_CONNECTION *connection). As no WT_EXTENSION_API handle reference is passed to the function, the WT_CONNECTION::get_extension_api has been added to support retrieval of the extension API. Applications may require modifications.
The type of all configuration arguments to extension methods has changed from "const char *" to "WT_CONFIG_ARG *", and the WT_EXTENSION::config method added to support configuration parsing; applications may require modifications.
The undocumented wiredtiger_XXX defines for WT_EXTENSION_API extension methods have been removed from the wiredtiger_ext.h include file; applications should instead use the method handles referenced by the WT_EXTENSION_API handle to call extension functions.
The extension API methods have all changed to require an additional parameter, the WT_EXTENSION_API method handle; applications may require modifications.
The following changes are only applicable to applications providing new implementations of the WiredTiger WT_DATA_SOURCE class.
The WT_DATA_SOURCE class has three new methods: WT_DATA_SOURCE::compact, WT_DATA_SOURCE::salvage, and WT_DATA_SOURCE::verify; applications may require modifications to resolve compile errors.
The owner argument to the WT_DATA_SOURCE::open_cursor method has been removed; applications may require modifications to resolve compile errors.
exclusive argument to the WT_DATA_SOURCE::create method has been removed; applications may require modifications to resolve compile errors. WiredTiger statistics are no longer maintained by default; to configure statistics, use the statistics configuration string to the wiredtiger_open function.
A new member, WT_COMPRESSOR::compress_raw, was added to the WT_COMPRESSOR extension API. Applications using the WT_COMPRESSOR extension API should add a NULL as the second field of that structure.
The WT_SESSION::create method's checksum configuration string has been changed from a boolean type to a string type. Applications using the checksum configuration string should change a value of true to the string on, and a value of false to the string off or the string uncompressed.
The underlying file formats changed in the 1.3.9 release; tables and files should be dumped and re-loaded into a new database.
The statistics key constants have been renamed to use all capitals, and use consistent prefixes to distinguish between connection statistics and statistics for data sources.
The installed WiredTiger extension library names changed to limit namespace pollution:
| Library | Previous Name | New Name |
|---|---|---|
| Bzip2 compression | bzip2_compress.a | libwiredtiger_bzip2.a |
| bzip2_compress.la | libwiredtiger_bzip2.la | |
| bzip2_compress.so | libwiredtiger_bzip2.so | |
| Snappy compression | snappy_compress.a | libwiredtiger_snappy.a |
| snappy_compress.la | libwiredtiger_snappy.la | |
| snappy_compress.so | libwiredtiger_snappy.so | |
| No-op compression | nop_compress.a | No longer installed |
| nop_compress.la | No longer installed | |
| nop_compress.so | No longer installed | |
| Reverse order collator | reverse_collator.a | No longer installed |
| reverse_collator.la | No longer installed | |
| reverse_collator.so | No longer installed |
The built-in compression name arguments to the WT_SESSION:create block_compressor configuration string changed for consistency:
| Extension | Previous Name | New Name |
|---|---|---|
| Bzip2 compression | "bzip2_compress" | "bzip2" |
| Snappy compression | "snappy_compress" | "snappy" |
The underlying file formats changed in the 1.3.5 release; tables and files should be dumped and re-loaded into a new database.
The checkpoint functionality supported by WT_SESSION::checkpoint and the snapshot functionality supported by WT_SESSION::sync have been merged into a single piece of functionality.
WT_SESSION.checkpoint
The WT_SESSION::checkpoint method's snapshot configuration string has been renamed to name. The name assigned to checkpoints without a specified name configuration is now "WiredTigerCheckpoint".
WT_SESSION.drop
In releases before 1.3, the WT_SESSION::drop method was used to delete snapshots. In 1.3, the functionality of deleting snapshots has been moved to the WT_SESSION::checkpoint method, specifically, snapshots are discarded using the WT_SESSION::checkpoint method's drop configuration string.
WT_SESSION.sync
The WT_SESSION::sync method has been removed from the 1.3 release; the functionality of creating an object snapshot has moved to the WT_SESSION::checkpoint method, specifically, creating a snapshot of a one or more objects is done using the WT_SESSION::checkpoint method's target configuration string.
wt drop -s
The -s option to the drop command for the wt command line utility has been removed, and object snapshots may no longer be removed from the command line.
-s options to the dump and list commands for the wt command line utility have been renamed to be -c. In releases before 1.3, the WT_SESSION::open_cursor method could duplicate cursors that were not positioned in an object; in 1.3, a cursor must be positioned in order to be duplicated.
In releases before 1.3, ending a transaction by calling the WT_SESSION::commit_transaction or WT_SESSION::rollback_transaction methods implicitly closed all open cursors; in 1.3, the cursors remain open, but are reset (discarding their positions and cursor values). This means applications must change to either close cursors explicitly, or rely on an eventual WT_SESSION::close or WT_CONNECTION::close methods to implicitly close open cursors.
In releases before 1.3, the default isolation level for transaction was snapshot, and the default isolation level for non-transaction operations was read-uncommitted; in 1.3, the default isolation level for all operations is read-committed.
The default can be overridden for a session using the isolation setting in WT_CONNECTION::open_cursor.
In releases before 1.3, the WT_SESSION::truncate method required cursors used for truncation of a cursor range to reference existing keys in the object; in 1.3, the WT_SESSION::truncate method has been changed to allow cursors to reference any valid key in the object's name space so applications may discard portions of the object name space without knowing exactly what records the object contains.
In releases before 1.3, the WT_CURSOR::equals method returned zero/non-zero to indicate cursor equality; in 1.3, the WT_CURSOR::equals method has been replaced with WT_CURSOR::compare, which compares two cursors and returns a cursor comparison status (less than 0, equal to 0, or greater than 0) depending on the cursors' key order.
The underlying file formats changed in the 1.3 release; tables and files should be dumped and re-loaded into a new database.