On Optimize performance decreases drastically as the number of conditions increases

[boosterch]

Hi,

I am using Delegate Decompiler for many years in our projects and it's of great help. Recently I found a performance issue when running a query with many conditions.

From odata we run query's with a filter by id's that gets translated to EF. filter=(Id eq d6e5324b-b81a-4715-b8d8-7521a14a82d9) or ((Id eq 6c14fa7b-832b-4c2b-b7b1-d18cabcd0bac)

I tried to create a test that mimics the situation. If you increase the loop count the performance of the optimize step decreases drastically.

        [Test]
        public void TestEveryConditionMutipliesDurationInOptimizer()
        {
            using var env = new MethodEnvironment(classEnv);
            System.Linq.Expressions.Expression<Func<EfItems.Concretes.EfParent, bool>> conditon = x => x.EfParentId == 0;
            var predicate = LinqKit.PredicateBuilder.New<EfParent>();
            for (int i = 0; i < 25; i++)
            {
                var id = i;
                predicate = predicate.Or(x => x.EfParentId == id);
            }
            var expr = env.Db.EfParents.Where(predicate).Expression;
            var compiled = expr.Decompile();
            var optimized = compiled.Optimize();
        }

When debugging I think something goes wrong in the method VisitBinary of class OptimizeExpressionVisitor. When calling into the base method you end up in some kind of loop. I tried to find a solution (commented code) but here is where my knowledge stops :)

        protected override Expression VisitBinary(BinaryExpression node)
        {
......

            //return node.Update(left, VisitAndConvert(node.Conversion, "VisitBinary"), right);
            return base.VisitBinary(node);
        }

Is the Optimize step necessary because EF also caches the query? Do you have any idea what's going on.

Thanks in advance

[NetMastr5]

@boosterch this sounds like the same issue I reported when migrating from 0.31.0 to 0.32.0, which is still open.

[hazzik]

Is the Optimize step necessary because EF also caches the query?

This is needed because EF does not understand expressions if they are simply converted.

[nur-sgaertner]

Possibly solved by #248. Included in 0.34.1.