/// <summary>
/// Get many by multiple indexes
/// </summary>
/// <param name="binaryExpressions">a string formatted like "key operator value" </param>
/// <returns></returns>
public OrQuery GetMany(params string[] binaryExpressions)
{
var query = new OrQuery(_typeDescription.FullTypeName);
var andQuery = new AndQuery();
query.Elements.Add(andQuery);
foreach (var expression in binaryExpressions)
{
var q = StringToQuery(expression);
andQuery.Elements.Add(q);
}
QueryHelper.OptimizeQuery(query);
return(query);
}
public static void OptimizeQuery(OrQuery rootExpression)
{
// convert < and > into BETWEEN operator. Much more afficient
foreach (var andQuery in rootExpression.Elements)
{
var multipleTests = andQuery.Elements.GroupBy(q => q.IndexName).Where(g => g.Count() > 1).ToList();
if (multipleTests.Count > 0)
{
// these ones will not be changed
var atomicQueries = andQuery.Elements.Where(q => multipleTests.All(mt => mt.Key != q.IndexName))
.ToList();
foreach (var multipleTest in multipleTests)
{
if (multipleTest.Count() != 2)
{
throw new CacheException($"Inconsistent query on index {multipleTest.Key}");
}
var q1 = multipleTest.First();
var q2 = multipleTest.Last();
// multiple atomic queries for the same index do not make sense
if (q1.Operator == QueryOperator.Eq)
{
throw new CacheException($"Inconsistent query on index {multipleTest.Key}");
}
if (q2.Operator == QueryOperator.Eq)
{
throw new CacheException($"Inconsistent query on index {multipleTest.Key}");
}
var optimized = false;
// a >= x && a <=y will be concverted to "a BETWEEN x, y"
if (q1.Operator != QueryOperator.In && q1.Operator != QueryOperator.In)
{
if (q1.Value < q2.Value)
{
if (q1.Operator == QueryOperator.Ge)
{
if (q2.Operator == QueryOperator.Le)
{
var between = new AtomicQuery(q1.Value, q2.Value);
atomicQueries.Add(between);
optimized = true;
}
}
}
else if (q1.Value > q2.Value)
{
if (q1.Operator == QueryOperator.Le)
{
if (q2.Operator == QueryOperator.Ge)
{
var between = new AtomicQuery(q2.Value, q1.Value);
atomicQueries.Add(between);
optimized = true;
}
}
}
}
if (!optimized)
{
// keep the original expressions
atomicQueries.Add(q1);
atomicQueries.Add(q2);
}
}
andQuery.Elements.Clear();
andQuery.Elements.AddRange(atomicQueries);
}
}
}