ptupitsyn commented on a change in pull request #8999:
URL: https://github.com/apache/ignite/pull/8999#discussion_r613354601



##########
File path: modules/platforms/dotnet/Apache.Ignite.Linq/Impl/MethodVisitor.cs
##########
@@ -329,6 +331,50 @@ private static void 
AppendAdjustment(CacheQueryExpressionVisitor visitor, int[]
             visitor.Parameters.Add(paramValue);
         }
 
+        /// <summary>
+        /// Get IgnoreCase parameter for string.Compare method
+        /// </summary>
+        /// <param name="expression"></param>
+        /// <returns></returns>
+        private static bool GetStringCompareIgnoreCaseParameter(Expression 
expression)
+        {
+            if (expression is ConstantExpression constant)
+            {
+                if (constant.Value is bool ignoreCase)
+                {
+                    return ignoreCase;
+                }
+            }
+
+            throw new ArgumentException("ignoreCase");            
+        }
+
+        /// <summary>
+        /// Visits string.Compare method
+        /// </summary>
+        /// <param name="expression"></param>
+        /// <param name="visitor"></param>
+        private static void VisitStringCompare(MethodCallExpression 
expression, CacheQueryExpressionVisitor visitor, bool ignoreCase)
+        {
+            visitor.ResultBuilder.Append("casewhen(");
+            if (ignoreCase) visitor.ResultBuilder.Append("lower(");
+            visitor.Visit(expression.Arguments[0]);
+            if (ignoreCase) visitor.ResultBuilder.Append(")");
+            visitor.ResultBuilder.Append(" = ");
+            if (ignoreCase) visitor.ResultBuilder.Append("lower(");
+            visitor.Visit(expression.Arguments[1]);
+            if (ignoreCase) visitor.ResultBuilder.Append(")");
+            visitor.ResultBuilder.Append(", 0, casewhen(");
+            visitor.ResultBuilder.Append("lower(");

Review comment:
       The difference is caused by the fact that this `string.Compare` overload 
is culture-specific (uses `CultureInfo.CurrentCulture`).
   
   I don't think we should try to mimic this behavior when translating to SQL.
   Let's keep it simple, [like EF Core 
does](https://docs.microsoft.com/en-us/ef/core/miscellaneous/collations-and-case-sensitivity#translation-of-built-in-net-string-operations
 for equality `EF Core makes no attempt to translate simple equality to a 
database case-sensitive operation`.
   
   * If `ignoreCase` is set - use `lower`, otherwise don't.
   * Alternatively, drop the support for this overload to avoid confusion, keep 
only `Compare(string, string)`

##########
File path: modules/platforms/dotnet/Apache.Ignite.Linq/Impl/MethodVisitor.cs
##########
@@ -329,6 +331,50 @@ private static void 
AppendAdjustment(CacheQueryExpressionVisitor visitor, int[]
             visitor.Parameters.Add(paramValue);
         }
 
+        /// <summary>
+        /// Get IgnoreCase parameter for string.Compare method
+        /// </summary>
+        /// <param name="expression"></param>
+        /// <returns></returns>
+        private static bool GetStringCompareIgnoreCaseParameter(Expression 
expression)
+        {
+            if (expression is ConstantExpression constant)
+            {
+                if (constant.Value is bool ignoreCase)
+                {
+                    return ignoreCase;
+                }
+            }
+
+            throw new ArgumentException("ignoreCase");            
+        }
+
+        /// <summary>
+        /// Visits string.Compare method
+        /// </summary>
+        /// <param name="expression"></param>
+        /// <param name="visitor"></param>
+        private static void VisitStringCompare(MethodCallExpression 
expression, CacheQueryExpressionVisitor visitor, bool ignoreCase)
+        {
+            visitor.ResultBuilder.Append("casewhen(");
+            if (ignoreCase) visitor.ResultBuilder.Append("lower(");
+            visitor.Visit(expression.Arguments[0]);
+            if (ignoreCase) visitor.ResultBuilder.Append(")");
+            visitor.ResultBuilder.Append(" = ");
+            if (ignoreCase) visitor.ResultBuilder.Append("lower(");
+            visitor.Visit(expression.Arguments[1]);
+            if (ignoreCase) visitor.ResultBuilder.Append(")");
+            visitor.ResultBuilder.Append(", 0, casewhen(");
+            visitor.ResultBuilder.Append("lower(");

Review comment:
       The difference is caused by the fact that this `string.Compare` overload 
is culture-specific (uses `CultureInfo.CurrentCulture`).
   
   I don't think we should try to mimic this behavior when translating to SQL.
   Let's keep it simple, [like EF Core 
does](https://docs.microsoft.com/en-us/ef/core/miscellaneous/collations-and-case-sensitivity#translation-of-built-in-net-string-operations
 for equality `EF Core makes no attempt to translate simple equality to a 
database case-sensitive operation`.
   
   * If `ignoreCase` is `true` - use `lower`, otherwise don't.
   * Alternatively, drop the support for this overload to avoid confusion, keep 
only `Compare(string, string)`




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