Due to concurrent load, there may be duplication in the delete bitmap of historical data and incremental calculations, resulting in duplicate calculations of missed rows.
During concurrent import, the same row location may be marked delete multiple times by different versions of rowset.
Duplicate row location need to be removed.
MoW will mark all duplicate primary key as deleted, so we can add a DCHECK while compaction, if MoW's delete bitmap works incorrectly, we're able to detect this kind of issue ASAP.
In Debug version, DCHECK will make BE crush, in release version, compaction will fail and finally load will fail due to -235
MoW updates the delete bitmap of the imported data during the compaction by rowid conversion. The correctness of rowid conversion is very important to the result of delete bitmap. So I add a rowid conversion result check.
To avoid data irrecoverable due to delete bitmap calculation error，do compaction with merge on read. Through this way ，even if the delete bitmap calculation is wrong, the data can be recovered by full compaction.
1. support row format using codec of jsonb
2. short path optimize for point query
3. support prepared statement for point query
4. support mysql binary format
Tablet::version_for_delete_predicate should travel all rowset metas in tablet meta which complex is O(N), however we can directly judge whether this rowset is a delete rowset by RowsetMeta::has_delete_predicate which complex is O(1).
As we won't call Tablet::version_for_delete_predicate when pick input rowsets for compaction, we can reduce the critical area of Tablet::_meta_lock.
1.add a vertical compaction segment file size config, make it more
flexible to set segment file size
2.add a config to close skip tablet compaction. If current skip logic
has some bug so we can still use old logic
3.delete some useless log
1.remove quick_compaction's rowset pick policy, call cu compaction when trigger
quick compaction
2. skip tablet's compaction task when compaction score is too small
Co-authored-by: yixiutt <yixiu@selectdb.com>
mem tracker can be logically divided into 4 layers: 1)process 2)type 3)query/load/compation task etc. 4)exec node etc.
type includes
enum Type {
GLOBAL = 0, // Life cycle is the same as the process, e.g. Cache and default Orphan
QUERY = 1, // Count the memory consumption of all Query tasks.
LOAD = 2, // Count the memory consumption of all Load tasks.
COMPACTION = 3, // Count the memory consumption of all Base and Cumulative tasks.
SCHEMA_CHANGE = 4, // Count the memory consumption of all SchemaChange tasks.
CLONE = 5, // Count the memory consumption of all EngineCloneTask. Note: Memory that does not contain make/release snapshots.
BATCHLOAD = 6, // Count the memory consumption of all EngineBatchLoadTask.
CONSISTENCY = 7 // Count the memory consumption of all EngineChecksumTask.
}
Object pointers are no longer saved between each layer, and the values of process and each type are periodically aggregated.
other fix:
In [fix](memtracker) Fix transmit_tracker null pointer because phamp is not thread safe #13528, I tried to separate the memory that was manually abandoned in the query from the orphan mem tracker. But in the actual test, the accuracy of this part of the memory cannot be guaranteed, so put it back to the orphan mem tracker again.
## Design
### Trigger
Every time when a rowset writer produces more than N (e.g. 10) segments, we trigger segment compaction. Note that only one segment compaction job for a single rowset at a time to ensure no recursing/queuing nightmare.
### Target Selection
We collect segments during every trigger. We skip big segments whose row num > M (e.g. 10000) coz we get little benefits from compacting them comparing our effort. Hence, we only pick the 'Longest Consecutive Small" segment group to do actual compaction.
### Compaction Process
A new thread pool is introduced to help do the job. We submit the above-mentioned 'Longest Consecutive Small" segment group to the pool. Then the worker thread does the followings:
- build a MergeIterator from the target segments
- create a new segment writer
- for each block readed from MergeIterator, the Writer append it
### SegID handling
SegID must remain consecutive after segment compaction.
If a rowset has small segments named seg_0, seg_1, seg_2, seg_3 and a big segment seg_4:
- we create a segment named "seg_0-3" to save compacted data for seg_0, seg_1, seg_2 and seg_3
- delete seg_0, seg_1, seg_2 and seg_3
- rename seg_0-3 to seg_0
- rename seg_4 to seg_1
It is worth noticing that we should wait inflight segment compaction tasks to finish before building rowset meta and committing this txn.
1.remove quick_compaction's rowset pick policy, call cu compaction when trigger
quick compaction
2. skip tablet's compaction task when compaction score is too small
Co-authored-by: yixiutt <yixiu@selectdb.com>
The mem hook record tracker cannot guarantee that the final consumption is 0, nor can it guarantee that the memory alloc and free are recorded in a one-to-one correspondence.
In the life cycle of a memtable from insert to flush, the memory free of hook is more than that of alloc, resulting in tracker consumption less than 0.
In order to avoid the cumulative error of the upper load channel tracker, the memtable tracker consumption is reset to zero on destructor.
In VCollectIterator&VGenericIterator, use insert_range_from to copy rows
in a block which is continuous to save cpu cost.
If rows in rowset and segment are non overlapping, this whill improve 30%
throughput of compaction.If rows are completely overlapping such as load two
same files, the throughput goes nearly same as before.
Co-authored-by: yixiutt <yixiu@selectdb.com>
1. use rlock in most logic instead of wrlock
2. filter stale rowset's delete bitmap in save meta
3. add a delete_bitmap lock to handle compaction and publish_txn confict
Co-authored-by: yixiutt <yixiu@selectdb.com>
* remove alpha_rowset_meta
* remove alpha rowset related codes in compaction
* remove alpha rowset related codes in RowsetMeta
* fix be ut because some ut use alpha rowsetmeta
* [Schema Change] support fast add/drop column (#49)
* [feature](schema-change) support fast schema change. coauthor: yixiutt
* [schema change] Using columns desc from fe to read data. coauthor: Lchangliang
* [feature](schema change) schema change optimize for add/drop columns.
1.add uniqueId field for class column.
2.schema change for add/drop columns directly update schema meta
Co-authored-by: yixiutt <yixiu@selectdb.com>
Co-authored-by: SWJTU-ZhangLei <1091517373@qq.com>
[Feature](schema change) fix write and add regression test (#69)
Co-authored-by: yixiutt <yixiu@selectdb.com>
[schema change] be ssupport that delete use newest schema
add delete regression test
fix regression case (#107)
tmp
[feature](schema change) light schema change exclude rollup and agg/uniq/dup key type.
[feature](schema change) fe olapTable maxUniqueId write in disk.
[feature](schema change) add rpc iface for sc add column.
[feature](schema change) add columnsDesc to TPushReq for ligtht sc.
resolve the deadlock when schema change (#124)
fix columns from fe don't has bitmap_index flag (#134)
add update/delete case
construct MATERIALIZED schema from origin schema when insert
fix not vectorized compaction coredump
use segment cache
choose newest schema by schema version when compaction (#182)
[bugfix](schema change) fix ligth schema change problem.
[feature](schema change) light schema change add alter job. (#1)
fix be ut
[bug] (schema change) unique drop key column should not light schema
change
[feature](schema change) add schema change regression-test.
fix regression test
[bugfix](schema change) fix multi alter clauses for light schema change. (#2)
[bugfix](schema change) fix multi clauses calculate column unique id (#3)
modify PushTask process (#217)
[Bugfix](schema change) fix jobId replay cause bdbje exception.
[bug](schema change) fix max col unique id repeatitive. (#232)
[optimize](schema change) modify pendingMaxColUniqueId generate rule.
fix compaction error
* fix be ut
* fix snapshot load core
fix unique_id error (#278)
[refact](fe) remove redundant code for light schema change. (#4)
[refact](fe) remove redundant code for light schema change. (#4)
format fe core
format be core
fix be ut
modify fe meta version
fix rebase error
flush schema into rowset_meta in old table
[refactor](schema change) refact fe light schema change. (#5)
delete the change of schemahash and support get max version schema
* modify for review
* fix be ut
* fix schema change test
This PR supports rowset level data upload on the BE side, so that there can be both cold data and hot data in a tablet,
and there is no necessary to prohibit loading new data to cooled tablets.
Each rowset is bound to a `FileSystem`, so that the storage layer can read and write rowsets without
perceiving the underlying filesystem.
The abstracted `RemoteFileSystem` can try local caching strategies with different granularity,
instead of caching segment files as before.
To avoid conflicts with the code in be/src/io, we temporarily put the file system related code in the be/src/io/fs directory.
In the future, `FileReader`s and `FileWriter`s should be unified.
* compaction quickly for small data import #9791
1.merge small versions of rowset as soon as possible to increase the import frequency of small version data
2.small version means that the number of rows is less than config::small_compaction_rowset_rows default 1000
As in issue, the combination and schema change at the same time may lead to version intersection.
Describe the overview of changes.
1. Do not do compaction before schema change is actually executed.
2. Set tablet as bad when it has version intersection.
3. Do not do schema change when it can not find appropriate versions to delete in new tablet.
4. Do not change rowsets after compaction if the rowsets of the tablet has changed.
1. Fix Lru Cache MemTracker consumption value is negative.
2. Fix compaction Cache MemTracker has no track.
3. Add USE_MEM_TRACKER compile option.
4. Make sure the malloc/free hook is not stopped at any time.
