For an vectorized expression which meets the condition vexpr->is_constant(), a const column is expected to return.
But now we still don't cover all predicates for const expression.
For example, for query SELECT col FROM tbl WHERE 'PROMOTION' LIKE 'AAA%', predicate like will return a ColumnVector which contains a single value.
This PR want to cover all const predicates in scan node whether it returns a constcolumn or not
Refactor the scanners for hms external catalog, work in progress.
Use VFileScanner, will remove NewFileParquetScanner, NewFileOrcScanner and NewFileTextScanner after fully tested.
Query for parquet file has been tested, still need to add readers for orc file, text file and load logic as well.
This PR introduce a new enum type `PushDownType`:
```
enum class PushDownType {
// The predicate can not be pushed down to data source
UNACCEPTABLE,
// The predicate can be pushed down to data source
// and the data source can fully evaludate it
ACCEPTABLE,
// The predicate can be pushed down to data source
// but the data source can not fully evaluate it.
PARTIAL_ACCEPTABLE
};
```
And derived class of VScanNode can override following method to determine whether to accept
a bianry/in/bloom filter/is null predicate:
```
PushDownType _should_push_down_binary_predicate();
PushDownType _should_push_down_in_predicate();
PushDownType _should_push_down_function_filter();
PushDownType _should_push_down_bloom_filter();
PushDownType _should_push_down_is_null_predicate();
```
When ExecNode's projections is not empty, it use output row descriptor to initialize the block before doing projection. But we should use original row descriptor. This PR fix it.
Copy most of profiles from VOlapScanNode and VOlapScanner to NewOlapScanNode and NewOlapScanner.
Fix some blocking bug of new scan framework.
TODO:
Memtracker
Opentelemetry spen
The new framework is still disabled by default, so it will not effect other feature.
There are currently many types of ScanNodes in Doris. And most of the logic of these ScanNodes is the same, including:
Runtime filter
Predicate pushdown
Scanner generation and scheduling
So I intend to unify the common logic of all ScanNodes.
Different data sources only need to implement different Scanners for data access.
So that the future optimization for scan can be applied to the scan of all data sources,
while also reducing the code duplication.
This PR mainly adds 4 new class:
VScanner
All Scanners' parent class. The subclasses can inherit this class to implement specific data access methods.
VScanNode
The unified ScanNode, and is responsible for common logic including RuntimeFilter, predicate pushdown, Scanner generation and scheduling.
ScannerContext
ScannerContext is responsible for recording the execution status
of a group of Scanners corresponding to a ScanNode.
Including how many scanners are being scheduled, and maintaining
a producer-consumer blocks queue between scanners and scan nodes.
ScannerContext is also the scheduling unit of ScannerScheduler.
ScannerScheduler schedules a ScannerContext at a time,
and submits the Scanners to the scanner thread pool for data scanning.
ScannerScheduler
Unified responsible for all Scanner scheduling tasks
Test:
This work is still in progress and default is disabled.
I tested it with jmeter with 50 concurrency, but currently the scanner is just return without data.
The QPS can reach about 9000.
I can't compare it to origin implement because no data is read for now. I will test it when new olap scanner is ready.
Co-authored-by: morningman <morningman@apache.org>
