Wiredtiger

See the upgrading documentation for details of API and behavior changes.

Significant changes:
* WT-3968 Use compression ratio to tune page sizes
* WT-4156 Add a new salvage API option to wiredtiger_open
* WT-4192 Remove support for raw compression in WiredTiger
* WT-4426 Change WiredTiger data format to optionally include timestamps in cells
* WT-4447 Add a quota like system to manage I/O per subsystem
* WT-4494 Support import of of standalone WiredTiger files
* WT-4670 Remove support for LevelDB APIs in WiredTiger
* WT-4765 Remove support for Helium/Levyx data sources in WiredTiger
* WT-4803 Implement file_max configuration for Cache Overflow mechanism
* WT-4913 Fix the Windows CRC32 on blocks that aren't 8B aligned and/or multiples of 8B

See JIRA changelog for a full listing:
https://jira.mongodb.org/projects/WT/versions/21117
https://jira.mongodb.org/projects/WT/versions/22515

See the upgrading documentation for details of API and behavior changes.

Significant changes:
* WT-3968 Use compression ratio to tune page sizes
* WT-4156 Add a new salvage API option to wiredtiger_open
* WT-4192 Remove support for raw compression in WiredTiger
* WT-4426 Change WiredTiger data format to optionally include timestamps in cells
* WT-4447 Add a quota like system to manage I/O per subsystem
* WT-4670 Remove support for LevelDB APIs in WiredTiger
* WT-4765 Remove support for Helium/Levyx data sources in WiredTiger

See JIRA changelog for a full listing:
https://jira.mongodb.org/projects/WT/versions/21117

See the upgrading documentation for details of API and behavior changes.

See JIRA changelog for a full listing:
https://jira.mongodb.org/projects/WT/versions/19708

See the upgrading documentation for details of API and behavior changes.

Significant changes:

JIRA reference | Brief description
------------ | -------------
WT-3039 | Change the log file format to record a previous LSN record
WT-3181 | Add support for application defined transaction IDs via a mechanism called timestamps.
WT-3310 | Add support to WT_SESSION::alter to change table log setting
WT-3389 | Restructure page split code to hold a split generation for the entire operation.
WT-3406 | Fix a bug in reconciliation so that it ignores concurrent updates.
WT-3418 | Fix a block manager race in tree close/open
WT-3435 | Improvements to the cache overflow mechanism aka lookaside
WT-3437 | Improvements to auto tuning of number of eviction workers
WT-3440 | Add a log record when starting a checkpoint.
WT-3461 | Avoid hangs when system clocks move backwards by using CLOCK_MONOTONIC for pthread_cond_timedwait if possible.
WT-3490 | Fix a bug in WT_CURSOR.modify unaligned size_t access.
WT-3495 | Fix a bug so we don't ftruncate if log cursors are open
WT-3497 | Improve logging message when hitting the configured session limits
WT-3537 | Split pages in memory when nothing can be written
WT-3556 | Remove wtstats support
WT-3681 | Change recovery so that it doesn't truncate the last log file
WT-3683 | Allow eviction of clean pages with history when cache is stuck
WT-3710 | Get a page-level lock to ensure page splits are single threaded
WT-3752 | Allow trimming of obsolete modify updates.

See JIRA changelog for a full listing:
https://jira.mongodb.org/projects/WT/versions/18401

See the upgrading documentation for details of API and behavior changes.

Significant changes:

JIRA reference | Brief description
------------ | -------------
WT-2972 | Add an interface allowing partial updates to existing values
WT-3063 | Add an interface allowing reservation of records for read-modify-write
WT-3142 | Add a workload generator application
WT-3160 | Improve eviction of internal pages from idle trees
WT-3245 | Avoid hangs on shutdown when a utility thread encounters an error
WT-3258 | Improve visibility into thread wait time due to pages exceeding memory_page_max
WT-3263 | Allow archive on restart/recovery if clean shutdown
WT-3287 | Review WiredTiger internal panic checks
WT-3292 | Review/cleanup full-barrier calls in WiredTiger
WT-3296 | LAS table fixes/improvements
WT-3327 | Checkpoints can hang if time runs backward
WT-3345 | Improve rwlock scaling
WT-3373 | Access violation due to a bug in internal page splitting
WT-3379 | Change when pages can be split to avoid excessively slowing some operations

See JIRA changelog for a full listing:
https://jira.mongodb.org/browse/WT/fixforversion/18291

See the upgrading documentation for details of API and behavior changes.

Significant changes:

JIRA reference | Brief description
------------ | -------------
SERVER-16796 | Increase logging activity for journal recovery operations
SERVER-28168 | Cannot start or repair MongoDB after unexpected shutdown
SERVER-28194 | Fix a bug where a missing WiredTiger.turtle file can result in data loss
WT-98 | Update the current cursor value without a search
WT-2439 | Enhance reconciliation page layout
WT-2898 | Improve performance of eviction-heavy workloads by dynamically controlling the number of eviction threads
WT-3097 | Race on reconfigure or shutdown can lead to waiting for statistics log server
WT-3106 | Add truncate support to command line wt utility
WT-3114 | Avoid archiving log files immediately after recovery
WT-3115 | Change the dhandle lock to a read/write lock
WT-3127 | Fix a bug with CPU yield calls don't necessarily imply memory barriers
WT-3135 | Fix a bug with search_near() for index with custom collator
WT-3137 | Fix a hang in __log_slot_join/__log_slot_switch_internal
WT-3144 | Fix a bug where random cursor returns not-found when descending to an empty page
WT-3148 | Improve eviction efficiency with many small trees
WT-3149 | Change eviction to start new walks from a random place in the tree
WT-3150 | Reduce impact of checkpoints on eviction server
WT-3152 | Convert table lock from a spinlock to a read write lock
WT-3157 | Fix a bug in checkpoint/transaction integrity issue when writes fail.
WT-3158 | Fix structure packing on Windows.
WT-3188 | Fix error handling in logging where fatal errors could lead to a hang
WT-3193 | Close a race between verify opening a handle and eviction visiting it
WT-3206 | Fix a bug where core dump happened on NULL page index
WT-3218 | Fix a bug that could lead to unexpected checkpoint ordering failures
WT-3243 | Reorder log slot release so joins don't wait on IO
WT-3262 | Stop making schema operations wait for cache

See JIRA changelog for a full listing:
https://jira.mongodb.org/browse/WT/fixforversion/17874

NOTE: The tag for the release is one commit behind the actual release package. The package contains a single document formatting change in addition.