private IAsyncEnumerable <KeyValuePair <string, string> > GetFileMappingForColumn(KeyValuePair <string, IAsyncEnumerable <string> > column)
{
var(key, value) = column;
var mapping = value.Select(async val =>
new KeyValuePair <string, string>(val,
await _rootIndexAccess.GetFileNameForColumnAndValue(key, val)))
.Select(t => t.Result);
return(mapping);
}
private async Task <IEnumerable <QueryResult> > GetFilesMatchingCondition(NeedleInHaystackColumnCondition condition)
{
var defaultResult = Enumerable.Empty <QueryResult>();
var indexFileName = await _rootIndexAccess.GetFileNameForColumnAndValue(condition.ColumnName, condition.Value);
if (indexFileName == CommonKeys.END_OF_INDEX_FLAG)
{
return(defaultResult);
}
var downloadedFileName = await this.DownloadIndexFile(indexFileName);//await _amazonAdapter.DownloadObjectAsync(_bucketName, indexFileName);
if (string.IsNullOrEmpty(downloadedFileName))
{
return(Enumerable.Empty <QueryResult>());
}
using var indexFile = File.OpenRead(downloadedFileName);
indexFile.Seek(-(2 * sizeof(long)), SeekOrigin.End);
var metadataOffset = indexFile.ReadBinaryLongFromStream();
var bloomOffset = indexFile.ReadBinaryLongFromStream();
if (!await VerifyConditionWithBloomFilter(condition, indexFile, bloomOffset))
{
return(defaultResult);
}
var(relevantSection, endOffset) = await GetRelevantSectionInIndex(indexFile, condition, metadataOffset, bloomOffset);
if (relevantSection == default(IndexMetadataSectionModel))
{
return(defaultResult);
}
var indexRow = await GetIndexRowForCondition(condition, indexFile, relevantSection, endOffset);
return(indexRow == default(IndexValueModel)
? defaultResult
: indexRow.Files.Select(file =>
new QueryResult {
["FileName"] = file, ["HitValues"] = new[] { condition.Value }
}));
}