public int Next(int desiredCount, CancellationToken cancellationToken)
{
// If this is the first call, walk all rows once to find best rows
if (!_isDictionaryBuilt)
{
_isDictionaryBuilt = true;
BuildChooseDictionary(cancellationToken);
_source.Reset();
}
int outerCount;
while ((outerCount = _source.Next(desiredCount, cancellationToken)) > 0)
{
// Ask for the indices of rows which were chosen in this page
XArray chosenRows = _dictionary.GetChosenRows(_totalRowsRead, _totalRowsRead + outerCount, _totalRowsRead);
// Track the total row count (so we know which rows to ask for chosens each time)
_totalRowsRead += outerCount;
// Tell the remapper to filter to chosen rows
_chosenRowsFilter.SetMatches((int[])chosenRows.Array, chosenRows.Count);
if (chosenRows.Count > 0)
{
CurrentRowCount = chosenRows.Count;
return(CurrentRowCount);
}
}
return(0);
}
public int Next(int desiredCount, CancellationToken cancellationToken)
{
// If this is the first call, fully cache the JoinToSource and build a lookup Dictionary
if (_joinDictionary == null)
{
BuildJoinDictionary(cancellationToken);
}
BitVector matchedRows = null;
while (true)
{
// Get the next rows from the source
int count = _source.Next(desiredCount, cancellationToken);
if (count == 0)
{
CurrentRowCount = 0;
return(0);
}
// Get values to join from
XArray joinFromValues = _joinFromColumnGetter();
// Find which rows matched and to what right-side row indices
matchedRows = _joinDictionary.TryGetValues(joinFromValues, out _currentRightSideSelector);
if (_currentRightSideSelector.Count > 0)
{
break;
}
}
// Filter left-side rows to the matches (inner join)
_sourceJoinedRowsFilter.SetMatches(matchedRows);
// Seek right-side rows to the matches
for (int i = 0; i < _rightSideColumns.Length; ++i)
{
_rightSideColumns[i].Set(_currentRightSideSelector);
}
CurrentRowCount = _currentRightSideSelector.Count;
return(_currentRightSideSelector.Count);
}
public override int Next(int desiredCount, CancellationToken cancellationToken)
{
_currentMatchesReturned += _nextCountToReturn;
// If we previously retrieved extra rows, return more of those
if (_currentMatchesTotal > _currentMatchesReturned)
{
_nextCountToReturn = Math.Min(desiredCount, _currentMatchesTotal - _currentMatchesReturned);
_mapper.NextMatchPage(_nextCountToReturn);
return(_nextCountToReturn);
}
// Otherwise, retrieve more rows
int countToRequest = CountToRequest(desiredCount);
_currentMatchesReturned = 0;
int outerCount;
while ((outerCount = _source.Next(countToRequest, cancellationToken)) > 0)
{
// Track the total retrieved from the source
_totalRowsRetrieved += outerCount;
Allocator.AllocateToSize(ref _vector, outerCount);
_vector.None();
// Match the query expression and count all matches
_expression.Evaluate(_vector);
_currentMatchesTotal = _vector.Count;
_totalRowsMatched += _currentMatchesTotal;
// If we got matches, return the first set requested, otherwise ask for more
if (_currentMatchesTotal > 0)
{
_nextCountToReturn = Math.Min(desiredCount, _currentMatchesTotal - _currentMatchesReturned);
_mapper.SetMatches(_vector, _nextCountToReturn);
return(_nextCountToReturn);
}
// Reconsider how many rows to request if no matches
countToRequest = CountToRequest(desiredCount);
}
// Tell the mapper there are no more matches
Allocator.AllocateToSize(ref _vector, desiredCount);
_vector.None();
_mapper.SetMatches(_vector, 0);
return(0);
// Where.Next implementation which doesn't request excess results and page through them.
// Use instead to diagnose "wrong row count" problems which might be due to paging problems.
//int outerCount;
//while ((outerCount = _source.Next(desiredCount)) > 0)
//{
// // Track the total retrieved from the source
// _totalRowsRetrieved += outerCount;
// Allocator.AllocateToSize(ref _vector, outerCount);
// _vector.None();
// // Match the query expression and count all matches
// _expression.Evaluate(_vector);
// _currentMatchesTotal = _vector.Count;
// _totalRowsMatched += _currentMatchesTotal;
// _mapper.SetMatches(_vector);
// if (_currentMatchesTotal > 0) return _currentMatchesTotal;
//}
//return 0;
}
