All notable changes to this project are documented in this file. See also TiDB Changelog and PD Changelog.
- Make several
INFO
logsDEBUG
and refined some log messages. (tikv#4768)
- Fix the issue that ReadIndex might fail to respond to requests because of duplicate context #5256
- Fix potential scheduling jitters caused by premature
PutStore
#5277 - Fix incorrect timestamps reported from Region heartbeats #5296
- Fix potential TiKV panics during region merge #5291
- Speed up leader change check for the dead lock detector #5317
- Support using
grpc env
to create deadlock clients #5346 - Add
config-check
to check whether the configuration is correct #5349 - Fix the issue that ReadIndex does not return anything when there is no leader #5351
- Exclude shared block cache from core dump #5322
- Fix the bug that TiKV panics if the Raft Log is not written in time #5160
- Fix the bug that the panic information is not written into the log file after TiKV panics #5198
- Fix the bug that the insert operation might be incorrectly performed in the pessimistic transaction #5203
- Lower the output level of some logs that require no manual intervention to INFO #5193
- Improve the accuracy of monitoring the storage engine size #5200
- Improve the accuracy of the Region size in TiKV Control #5195
- Improve the performance of the deadlock detector for pessimistic locks #5192
- Improve the performance of GC in the Titan storage engine #5197
- Add the statistics of the size of blob files in statistics information #5060
- Fix the core dump issue caused by the incorrectly cleaned memory resources when the process exits #5053
- Add all monitoring metrics related to the Titan engine #4772, #4836
- Add the number of open file handles for Titan when counting the number of open file handles to avoid the issue that no file handle is available because of inaccurate statistics of file handles #5026
- Set
blob_run_mode
to decide whether to enable the Titan engine on a specific CF #4991 - Fix the issue that the read operations cannot get the commit information of pessimistic transactions #5067
- Add the
blob-run-mode
configuration parameter to control the running mode of the Titan engine, and its value can benormal
,read-only
orfallback
#4865 Improve the performance of detecting deadlocks #5089
- Engine
- Introduce Titan, a key-value plugin that improves write performance for scenarios with value sizes greater than 1KiB, and relieves write amplification in certain degrees
- Optimize memory management to reduce memory allocation and copying for
Iterator Key Bound Option
- Support
block cache
sharing among different column families
- Server
- Support reversed
raw_scan
andraw_batch_scan
- Support batch receiving and sending Raft messages, improving TPS by 7% for write intensive scenarios
- Support getting monitoring information via HTTP
- Support Local Reader in RawKV to improve performance
- Reduce context switch overhead from
batch commands
- Support reversed
- Raftstore
- Support Multi-thread Raftstore and Multi-thread Apply to improve scalabilities, concurrency capacity, and resource usage within a single node. Performance improves by 70% under the same level of pressure
- Support checking RocksDB Level 0 files before applying snapshots to avoid write stall
- Support Hibernate Regions to optimize CPU consumption from RaftStore (Experimental)
- Remove the local reader thread
- Transaction
- Support distributed GC and concurrent lock resolving for improved GC performance
- Support the pessimistic transaction model (Experimental)
- Modify the semantics of
Insert
to allow Prewrite to succeed only when there is no Key - Remove
txn scheduler
- Add monitoring items related to
read index
andGC worker
- Coprocessor
- Refactor the computation framework to implement vector operators, computation using vector expressions, and vector aggregations to improve performance
- Support providing operator execution status for the
EXPLAIN ANALYZE
statement in TiDB - Switch to the
work-stealing
thread pool model to reduce context switch cost
- Misc
- Develop a unified log format specification with restructured log system to facilitate collection and analysis by tools
- Add performance metrics related to configuration information and key bound crossing.
- Engine
- Server
- Raftstore
- Fix the issue that local reader cache is not cleared correctly. 4778
- Fix request latency jetter when transferring leader and conf changes. 4734
- Remove invalid empty callbacks. 4682
- Clear stale reads after role change. 4810
- Synchronize all CF files for the received snapshots. 4807
- Fix missing fsync calls for snapshots. 4850
- Coprocessor
- Improve coprocessor batch executor. 4877
- Transaction
- Tikv-ctl
- Improve
bad-regions
andtombstone
subcommands. 4862
- Improve
- Misc
- Add dist_release. 4841
- Engine
- Support multiple column families sharing a block cache #4563
- Server
- Raftstore
- Support hibernate Regions to reduce the consumption of the raftstore CPU #4591
- Fix the issue that the leader does not reply to the
ReadIndex
requests for the learner #4653 - Fix the issue of transferring leader failure in some cases #4684
- Fix the possible dirty read issue in some cases #4688
- Fix the issue that a snapshot lacks data in some cases #4716
- Coprocessor
- Add more RPN functions
LogicalOr
#4691LTReal
#4602LEReal
#4602GTReal
#4602GEReal
#4602NEReal
#4602EQReal
#4602IsNull
#4720IsTrue
#4720IsFalse
#4720- Support comparison arithmetic for
Int
#4625 - Support comparison arithmetic for
Decimal
#4625 - Support comparison arithmetic for
String
#4625 - Support comparison arithmetic for
Time
#4625 - Support comparison arithmetic for
Duration
#4625 - Support comparison arithmetic for
Json
#4625 - Support plus arithmetic for
Int
#4733 - Support plus arithmetic for
Real
#4733 - Support plus arithmetic for
Decimal
#4733 - Support MOD functions for
Int
#4727 - Support MOD functions for
Real
#4727 - Support MOD functions for
Decimal
#4727 - Support minus arithmetic for
Int
#4746 - Support minus arithmetic for
Real
#4746 - Support minus arithmetic for
Decimal
#4746
- Add more RPN functions
- Engine
- Fix the issue that may cause incorrect statistics on read traffic #4436
- Fix the issue that may cause prefix extractor panic when deleting a range #4503
- Optimize memory management to reduce memory allocation and copying for
Iterator Key Bound Option
#4537 - Fix the issue that failing to consider learner log gap may in some cases cause panic #4559
- Support
block cache
sharing among differentcolumn families
#4612
- Server
- RaftStore
- Support configurable
properties index distance
#4517
- Support configurable
- Coprocessor
- Add batch index scan executor #4419
- Add vectorized evaluation framework #4322
- Add execution summary framework for batch executors #4433
- Check the maximum column when constructing the RPN expression to avoid invalid column offset that may cause evaluation panic #4481
- Add
BatchLimitExecutor
#4469 - Replace the original
futures-cpupool
withtokio-threadpool
in ReadPool to reduce context switch #4486 - Add batch aggregation framework #4533
- Add
BatchSelectionExecutor
#4562 - Add batch aggression function
AVG
#4570 - Add RPN function
LogicalAnd
#4575
- Misc
- Support
tcmalloc
as a memory allocator #4370
- Support
- Optimize the Coprocessor calculation execution framework and implement the TableScan section, with the Single TableScan performance improved by 5% ~ 30%
- Implement the definition of the
BatchRows
row and theBatchColumn
column #3660 - Implement
VectorLike
to support accessing encoded and decoded data in the same way #4242 - Define the
BatchExecutor
to interface and implement the way of converting requests toBatchExecutor
#4243 - Implement transforming the expression tree into the RPN format #4329
- Implement the
BatchTableScanExecutor
vectorization calculation operator #4351
- Implement the definition of the
- Unify the log format for easy collection and analysis by tools
- Support using the Local Reader to read in the Raw Read interface #4222
- Add metrics about configuration information #4206
- Add metrics about key exceeding bound #4255
- Add an option to control panic or return an error when encountering the key exceeding bound error #4254
- Add support for the
INSERT
operation, make prewrite succeed only when keys do not exist, and eliminateBatch Get
#4085 - Use more fair batch strategy in the Batch System #4200
- Support Raw scan in tikv-ctl #3825
- Support hibernating regions #4591
- 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
- Fix the incorrect result of counting keys in a Region in some cases #5415
- Add the
config-check
option in TiKV to check whether the TiKV configuration item is valid #5391 - Optimize the starting process to reduce jitters caused by restarting nodes #5277
- Optimize the resolving locking process in some cases to speed up resolving locking for transactions #5339
- Optimize the
get_txn_commit_info
process to speed up committing transactions #5062 - Simplify Raft-related logs #5425
- Resolve the issue that TiKV exits abnormally in some cases #5441
- Unify the log format #5083
- Improve the accuracy of Region's approximate size or keys in extreme cases to improve the accuracy of scheduling #5085
- Optimize processing the empty callback when processing the Raftstore message to avoid sending unnecessary message #4682
- Fix the issue that incomplete snapshots are generated in the system caused by the iterator not checking the status #4940
- Add a feature to check the validity for the
block-size
configuration #4930
- Fix the issue that Regions are not available during the leader transfer process in extreme conditions #4799
- Fix the issue that TiKV loses data when the power of the machine fails abnormally, caused by delayed data flush to the disk when receiving snapshots #4850
- Fix the issue that the learner reads an empty index when there is only one leader and one learner #4751
- Process
ScanLock
andResolveLock
in the thread pool with a high priority to reduce their impacts on commands with a normal priority #4791 - Synchronize all CF files for received snapshots #4811
- Reject transfer leader when the region recently changed config #4684
- Add priority label to coprocessor metrics #4643
- Fix the issue that read index may read stale data during transfering leader #4724
- Fix the issue that
CommitMerge
may cause TiKV unable to restart #4615 - Fix unknown logs #4730
- Fix potential quorum changes when transferring leader (tikv/raft-rs#221)
- Fix the Importer bug that some SST files fail to be imported but it still returns successful import result #4566
- Support setting a speed limit in Importer when uploading SST files to TiKV #4607
- Change Importer RocksDB SST default compression method to
lz4
to reduce CPU consumption #4624
- Fix the issue of wrong statistics of the read traffic #4441
- Fix the raftstore performance issue when checking to decide whether to process pending snapshots when many Regions exist #4484
- Do not ingest files when the number of level 0 SST files exceeds
level_zero_slowdown_writes_trigger/2
#4464
- Fix the
StoreNotMatch
issue caused by decoding protobuf error in some cases #4303 - Improve import speed by increasing default region-split-size to 512 MiB #4347
- Fix OOM issue by storing the intermediate SST files on disk instead of memory #4348
- Restrict memory usage by RocksDB #4350
- Fix the issue that scattering Region doesn't take effect #4352
- Fix the panic issue caused by Region merge in some cases #4235
- Fix the issue that Importer fails to import data in some cases #4223
- Fix the
KeyNotInRegion
error in some cases #4125 - Add the detailed
StoreNotMatch
error message #3885
- Fix the abnormal result issue of the event listener in some cases #4126
- Fix the duplicate write issue when closing TiKV #4146
- Support obtaining the monitoring information using the HTTP method #3855
- Fix the NULL issue of data_format #4075
- Add verifying the range for scan requests #4124
- 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
- Fix two issues about Region merge #4003 and #4004
- Avoid transferring the leader to a newly created peer, to optimize the possible delay #3929
- Fix redundant Region heartbeats #3930
- Add the end-key limit to the kv_scan interface #3749
- Abandon the max-tasks-xxx configuration and add max-tasks-per-worker-xxx #3093
- Fix the CompactFiles issue in RocksDB #3789
- Fix the issue that the memory consumed by Raftstore EntryCache keeps increasing when a node goes down 3529
- Enable dynamic-level-bytes by default to reduce space amplification
- Update Region's approximate size and approximate keys count after Region merge
- Enlarge scheduler’s default slots to reduce false conflicts
- Reduce continuous records of rollback transactions, to improve the Read
- performance when conflicts are extremely severe
- Limit the size and number of RocksDB log files, to reduce unnecessary
- disk usage in long-running condition
- Fix the crash issue when converting the data type from string to decimal
- Fix the potential overflow issue in decimal operations
- Fix the dirty read issue that might occur in the process of merge
- 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
- 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
- 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
- Fix the issue that it is slow to get the CPU ID using the get_cpuid function.
- Support the dynamic-level-bytes parameter to improve the space collection situation.
- Fix a possible performance issue when a snapshot is applied
- Fix the performance issue for reverse scan after removing a lot of data
- Fix the wrong encoded result for the Decimal type under special circumstances
- Support splitting table to ensure one region does not contain data from multiple tables.
- Limit the length of a key to be no more than 4 KB.
- More accurate read traffic statistics.
- Implement deep protection on the coprocessor stack.
- Fix the LIKE behavior and the do_div_mod bug.
- Support flow control with write bytes.
- Reduce Raft allocation.
- Increase coprocessor stack size to 10MB.
- Remove the useless log from coprocessor.
- Coprocessor now supports more pushdown functions
- Support pushing down the sampling operation
- Support manually triggering data compact to collect space quickly
- Improve the performance and stability
- Add a Debug API for debugging