* [feature](planner): push limit to olapscan when meet sort.
* if olap_scan_node's sort_info is set, push sort_limit, read_orderby_key
and read_orderby_key_reverse for olap scanner
* There is a common query pattern to find latest time serials data.
eg. SELECT * from t_log WHERE t>t1 AND t<t2 ORDER BY t DESC LIMIT 100
If the ORDER BY columns is the prefix of the sort key of table, it can
be greatly optimized to read much fewer data instead of read all data
between t1 and t2.
By leveraging the same order of ORDER BY columns and sort key of table,
just read the LIMIT N rows for each related segment and merge N rows.
1. set read_orderby_key to true for read_params and _reader_context
if olap_scan_node's sort info is set.
2. set read_orderby_key_reverse to true for read_params and _reader_context
if is_asc_order is false.
3. rowset reader force merge read segments if read_orderby_key is true.
4. block reader and tablet reader force merge read rowsets if read_orderby_key is true.
5. for ORDER BY DESC, read and compare in reverse order
5.1 segment iterator read backward using a new BackwardBitmapRangeIterator and
reverse the result block before return to caller.
5.2 VCollectIterator::LevelIteratorComparator, VMergeIteratorContext return
opposite result for _is_reverse order in its compare function.
Co-authored-by: jackwener <jakevingoo@gmail.com>
In our origin design, we calc delete bitmap in publish txn, and this operation
will cost too much time as it will load segment data and lookup row key in pre
rowset and segments.And publish version task should run in order, so it'll lead
to timeout in publish_txn.
In this pr, we seperate delete_bitmap calculation to tow part, one of it will be
done in flush mem table, so this work can run parallel. And we calc final
delete_bitmap in publish_txn, get a rowset_id set that should be included and
remove rowsets that has been compacted, the rowset difference between memtable_flush
and publish_txn is really small so publish_txn become very fast.In our test,
publish_txn cost about 10ms.
Co-authored-by: yixiutt <yixiu@selectdb.com>
* not need call delete handler to filter rows since they are filtered in rowset reader
* need not call delete eval in schema change and remove related code
Co-authored-by: yiguolei <yiguolei@gmail.com>
During load process, the same operation are performed on all replicas such as sort and aggregation,
which are resource-intensive.
Concurrent data load would consume much CPU and memory resources.
It's better to perform write process (writing data into MemTable and then data flush) on single replica
and synchronize data files to other replicas before transaction finished.
Analyze schema elements in parquet FileMetaData, and generate the hierarchy of nested fields.
For exmpale:
1. primitive type
```
// thrift:
optional int32 <column-name>;
// sql definition:
<column-name> int32;
```
2. nested type
```
// thrift:
optional group <column-name> (LIST) {
repeated group bag {
optional group array_element (LIST) {
repeated group bag {
optional int32 array_element
}
}
}
}
// sql definition:
<column-name> array<array<int32>>
```
1.make version publish work in version order
2.update delete bitmap while publish version, load current version rowset
primary key and search in pre rowsets
3.speed up publish version task by parallel tablet publish task
Co-authored-by: yixiutt <yixiu@selectdb.com>
When a rowset includes multiple segments, segments rows will be merged in generic_iterator but merged_rows is not maintained. Compaction will failed in check_correctness.
Co-authored-by: yixiutt <yixiu@selectdb.com>
* improvement for dynamic schema
not use schema as lru cache key any more.
load segment just use the rowset's original schema not the current read schema.
generate column reader and column iterator using the original schema, using the read schema if it is a new column.
using column unique id as key instead of column ordinals.
Co-authored-by: yiguolei <yiguolei@gmail.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
