All notable changes to this project are documented in this file. See also TiDB Changelog and PD Changelog.
- Support distributed GC #3179
- Check RocksDB Level 0 files before applying snapshots to avoid Write Stall #3606
- Support reverse
raw_scan
andraw_batch_scan
#3724 - Support using HTTP to obtain monitoring information #3855
- Support DST better #3786
- Support receiving and sending Raft messages in batch #3913
- Introduce a new storage engine Titan #3985
- Upgrade gRPC to v1.17.2 #4023
- Support receiving the client requests and sending replies in batch #4043
- Support multi-thread Apply #4044
- Support multi-thread Raftstore #4066
- Support the configuration format in the unit of
DAY
(d
) and fix the configuration compatibility issue #3931 - Fix the possible panic issue caused by
Approximate Size Split
#3942 - Fix two issues about Region merge #3822, #3873
- Avoid transferring the leader to a newly created peer, to optimize the possible delay #3878
-
Coprocessor
- Add more built-in functions
- Add Coprocessor
ReadPool
to improve the concurrency in processing the requests - Fix the time function parsing issue and the time zone related issues
- Optimize the memory usage for pushdown aggregation computing
-
Transaction
- Optimize the read logic and memory usage of MVCC to improve the performance of the scan operation and the performance of full table scan is 1 time better than that in TiDB 2.0
- Fold the continuous Rollback records to ensure the read performance
- Add the
UnsafeDestroyRange
API to support to collecting space for the dropping table/index - Separate the GC module to reduce the impact on write
- Add the
upper bound
support in thekv_scan
command
-
Raftstore
- Improve the snapshot writing process to avoid RocksDB stall
- Add the
LocalReader
thread to process read requests and reduce the delay for read requests - Support
BatchSplit
to avoid large Region brought by large amounts of write - Support
Region Split
according to statistics to reduce the I/O overhead - Support
Region Split
according to the number of keys to improve the concurrency of index scan - Improve the Raft message process to avoid unnecessary delay brought by
Region Split
- Enable the
PreVote
feature by default to reduce the impact of network isolation on services
-
Storage Engine
- Fix the
CompactFiles
bug in RocksDB and reduce the impact on importing data using Lightning - Upgrade RocksDB to v5.15 to fix the possible issue of snapshot file corruption
- Improve
IngestExternalFile
to avoid the issue that flush could block write
- Fix the
-
tikv-ctl
- Add the
ldb
command to diagnose RocksDB related issues - The
compact
command supports specifying whether to compact data in the bottommost level
- Add the
-
Tools
- Fast full import of large amounts of data: TiDB-Lightning
- Support new TiDB-Binlog
- Improve the error message of
WriteConflict
#3750 - Add the panic mark file #3746
- Downgrade grpcio to avoid the segment fault issue caused by the new version of gRPC #3650
- Add the upper limit to the
kv_scan
interface #3749
- Optimize the RocksDB Write stall issue caused by applying snapshots #3606
- Add raftstore
tick
metrics #3657 - Upgrade RocksDB and fix the Write block issue and that the source file might be damaged by the Write operation when performing
IngestExternalFile
#3661 - Upgrade grpcio and fix the issue that “too many pings” is wrongly reported #3650
- Optimize the concurrency for coprocessor requests #3515
- Add the support for Log functions #3603
- Add the support for the
sha1
function #3612 - Add the support for the
truncate_int
function #3532 - Add the support for the
year
function #3622 - Add the support for the
truncate_real
function #3633
- Fix the reporting error behavior related to time functions #3487, #3615
- Fix the issue that the time parsed from string is inconsistent with that in TiDB #3589
- Support splitting Regions based on statistics estimation to reduce the I/O cost #3511
- Reduce clone in the transaction scheduler #3530
- Add the pushdown support for a large number of built-in functions
- Add the
leader-transfer-max-log-lag
configuration to fix the failure issue of leader scheduling in specific scenarios #3507 - Add the
max-open-engines
configuration to limit the number of engines opened bytikv-importer
simultaneously #3496 - Limit the cleanup speed of garbage data to reduce the impact on
snapshot apply
#3547 - Broadcast the commit message for crucial Raft messages to avoid unnecessary delay #3592
- Fix the leader election issue caused by discarding the
PreVote
message of the newly split Region #3557 - Fix follower related statistics after merging Regions #3573
- Fix the issue that the local reader uses obsolete Region information #3565
- Support UnsafeDestroyRange API to speedup garbage data cleaning after table/index has been truncated/dropped #3560
- Support
batch split
to avoid too large Regions caused by the Write operation on hot Regions - Support splitting Regions based on the number of rows to improve the index scan efficiency
- Use
LocalReader
to separate the Read operation from the raftstore thread to lower the Read latency - Refactor the MVCC framework, optimize the memory usage and improve the scan Read performance
- Support splitting Regions based on statistics estimation to reduce the I/O usage
- Optimize the issue that the Read performance is affected by continuous Write operations on the rollback record
- Reduce the memory usage of pushdown aggregation computing
- Add the pushdown support for a large number of built-in functions and better charset support
- Optimize the GC workflow, improve the GC speed and decrease the impact of GC on the system
- Enable
prevote
to speed up service recovery when the network is abnormal - Add the related configuration items of RocksDB log files
- Adjust the default configuration of
scheduler_latch
- Support setting whether to compact the data in the bottom layer of RocksDB when using tikv-ctl to compact data manually
- Add the check for environment variables when starting TiKV
- Support dynamically configuring the
dynamic_level_bytes
parameter based on the existing data - Support customizing the log format
- Integrate tikv-fail in tikv-ctl
- Add I/O metrics of threads
- Fix decimal related issues
- Fix the issue that
gRPC max_send_message_len
is set mistakenly - Fix the issue caused by misconfiguration of
region_size
- Upgrade Rust to the
nightly-2018-06-14
version - Provide a
Raft PreVote
configuration to avoid leader reelection generated when network recovers after network isolation - Add a metric to display the number of files and
ingest
related information in each layer of RocksDB - Print
key
with too many versions when GC works
- Use
static metric
to optimize multi-label metric performance (YCSBraw get
is improved by 3%) - Remove
box
in multiple modules and use patterns to improve the operating performance (YCSBraw get
is improved by 3%) - Use
asynchronous log
to improve the performance of writing logs - Add a metric to collect the thread status
- Decease memory copy times by decreasing
box
used in the application to improve the performance
- Add the RocksDB
PerfContext
interface for debugging - Add the
region-properties
command fortikv-ctl
- Make GC record the log when GC encounters many versions of data
- Remove the
import-mode
parameter
- Fix the issue that
reverse-seek
is slow when many RocksDB tombstones exist - Fix the crash issue caused by
do_sub
- Correct wrong peer meta for learners
- Report an error instead of getting a result if divisor/dividend is 0 in do_div_mod
- Support configuring more gRPC related parameters
- Support configuring the timeout range of leader election
- Fix the issue that the Raft log is not printed
- Fix the issue that obsolete learner is not deleted
- Fix the issue that the snapshot intermediate file is mistakenly deleted
- Reduced number of
thread_yield
calls - Fix the issue that
SELECT FOR UPDATE
prevents others from reading
- More verbose logs for slow query
- Speed up delete range
- Fix the bug that raftstore is accidentally blocked when generating the snapshot
- Fix the issue that Learner cannot be successfully elected in special conditions
- Fix the issue that split might cause dirty read in extreme conditions
- Correct the default value of the read thread pool configuration
- Protect critical configuration from incorrect modification
- Support
Region Merge
[experimental] - Add the
Raw DeleteRange
API - Add the
GetMetric
API - Add
Raw Batch Put
,Raw Batch Get
,Raw Batch Delete
andRaw Batch Scan
- Add Column Family options for the RawKV API and support executing operation on a specific Column Family
- Support Streaming and Streaming Aggregation in Coprocessor
- Support configuring the request timeout of Coprocessor
- Carry timestamps with Region heartbeats
- Support modifying some RocksDB parameters online, such as
block-cache-size
- Support configuring the behavior of Coprocessor when it encounters some warnings or errors
- Support starting in the importing data mode to reduce write amplification during the data importing process
- Support manually splitting Region in halves
- Improve the data recovery tool
tikv-ctl
- Return more statistics in Coprocessor to guide the behavior of TiDB
- Support the
ImportSST
API to import SST files [experimental] - Add the TiKV Importer binary to integrate with TiDB Lightning to import data quickly [experimental]
- Optimize read performance using
ReadPool
and increase theraw_get/get/batch_get
by 30% - Improve metrics performance
- Inform PD immediately once the Raft snapshot process is completed to speed up balancing
- Solve performance jitter caused by RocksDB flushing
- Optimize the space reclaiming mechanism after deleting data
- Speed up garbage cleaning while starting the server
- Reduce the I/O overhead during replica migration using
DeleteFilesInRanges
- Fix the issue that gRPC call does not returned when the PD leader switches
- Fix the issue that it is slow to offline nodes caused by snapshots
- Limit the temporary space usage consumed by migrating replicas
- Report the Regions that cannot elect a leader for a long time
- Update the Region size information in time according to compaction events
- Limit the size of scan lock to avoid request timeout
- Limit the memory usage when receiving snapshots to avoid OOM
- Increase the speed of CI test
- Fix the OOM issue caused by too many snapshots
- Configure
keepalive
of gRPC - Fix the OOM issue caused by an increase of the Region number
- Reduce lock contention in Worker
- Add metrics to the FuturePool
- Fix misused metrics in Coprocessor
- Support compacting Regions in
tikv-ctl
- Add raw batch put/get/delete/scan API for TiKV service
- Add ImportKV service
- Support eval error in Coprocessor
- Support dynamic adjustment of RocksDB cache size by
tikv-ctl
- Collect number of rows scanned for each range in Coprocessor
- Support treating overflow as warning in Coprocessor
- Support learner in raftstore
- Increase snap GC timeout
- Limit the memory usage during receiving snapshots, to avoid OOM in extreme conditions
- Support configuring the behavior of Coprocessor when it encounters warnings
- Support importing the data pattern in TiKV
- Support splitting Region in the middle
- Fix the issue that too many logs are output caused by leader missing when TiKV is isolated
- Use crossbeam channel in worker
- Support Region Merge
- Add the Raw DeleteRange API
- Add the GetMetric API
- Support streaming in Coprocessor
- Support modifying RocksDB parameters online
- Inform PD immediately once the Raft snapshot process is completed, to speed up balancing
- Reduce the I/O fluctuation caused by RocksDB sync files
- Optimize the space reclaiming mechanism after deleting data
- Improve the data recovery tool
tikv-ctl
- Fix the issue that it is slow to make nodes down caused by snapshot
- Increase the raw_get/get/batch_get by 30% with ReadPool
- Support configuring the request timeout of Coprocessor
- Carry time information in Region heartbeats
- Limit the space usage of snapshot files to avoid consuming too much disk space
- Record and report the Regions that cannot elect a leader for a long time
- Speed up garbage cleaning when starting the server
- Update the size information about the corresponding Region according to compaction events
- Limit the size of scan lock to avoid request timeout
- Use DeleteRange to speed up Region deletion
- Implement IngestSST API
tikv-ctl
now can send consistency-check requests to TiKV- Support dumping stats of RocksDB and malloc in
tikv-ctl
- Reclaim disk space after data have been deleted
- Protect important configuration which cannot be changed after initial configuration
- Check whether SSD is used when you start the cluster
- Fix the issue that gRPC call is not cancelled when PD leaders switch
- Optimize the read performance using ReadPool, and improve the performance by 30% for raw get
- Improve metrics and optimize the usage of metrics
- Traverse locks using offset + limit to avoid potential GC problems
- Support resolving locks in batches to improve GC speed
- Support GC concurrency to improve GC speed
- Update the Region size using the RocksDB compaction listener for more accurate PD scheduling
- Delete the outdated data in batches using DeleteFilesInRanges, to make TiKV start faster
- Configure the Raft snapshot max size to avoid the retained files taking up too much space
- Support more recovery operations in tikv-ctl
- Optimize the ordered flow aggregation operation
- Use DeleteFilesInRanges to clear stale data and improve the TiKV starting speed
- Sync the metadata of the received Snapshot compulsorily to ensure its safety
- Use Decimal in Coprocessor sum
- Support key-only option in Table Scan executor
- Support the remote mode in tikv-ctl
- Fix the loss of scheduling command from PD
- Fix the format compatibility issue of tikv-ctl proto
- Add timeout in Push metric
- Support Raft learner
- Support TLS
- Optimize Raft Snapshot and reduce the I/O overhead
- Optimize the RocksDB configuration to improve performance
- Optimize count (*) and query performance of unique index in Coprocessor
- Solve the reconnection issue between PD and TiKV
- Enhance the features of the data recovery tool
tikv-ctl
- Support the Delete Range feature
- Support splitting according to table in Regions
- Support setting the I/O limit caused by snapshot
- Improve the flow control mechanism