presto-main/src/main/java/io/prestosql/operator/TableScanWorkProcessorOperator.java/TableScanWorkProcessorOperator/TableScanWorkProcessorOperator
class TableScanWorkProcessorOperator:    public TableScanWorkProcessorOperator(
            Session session,
            MemoryTrackingContext memoryTrackingContext,
            WorkProcessor<Split> splits,
            PageSourceProvider pageSourceProvider,
            TableHandle table,
            Iterable<ColumnHandle> columns)
    {
        this.splitToPages = new SplitToPages(
                session,
                pageSourceProvider,
                table,
                columns,
                memoryTrackingContext.aggregateSystemMemoryContext());
        this.pages = splits.flatTransform(splitToPages);
    }