Ejemplo n.º 1
0
        /// <summary>
        /// Provides language specific query translation. Use this to apply language specific rewrites or to make assertions/validations about the query.
        /// </summary>
        /// <param name="expression"> </param>
        /// <returns> </returns>
        public virtual Expression Translate(Expression expression)
        {
            // remove redundant layers again before cross apply rewrite
            expression = UnusedColumnRemover.Remove(expression);
            expression = RedundantColumnRemover.Remove(expression);
            expression = RedundantSubqueryRemover.Remove(expression);

            // convert cross-apply and outer-apply joins into inner & left-outer-joins if possible
            Expression rewritten = CrossApplyRewriter.Rewrite(language, expression);

            // convert cross joins into inner joins
            rewritten = CrossJoinRewriter.Rewrite(rewritten);

            if (rewritten != expression)
            {
                expression = rewritten;
                // do final reduction
                expression = UnusedColumnRemover.Remove(expression);
                expression = RedundantSubqueryRemover.Remove(expression);
                expression = RedundantJoinRemover.Remove(expression);
                expression = RedundantColumnRemover.Remove(expression);
            }

            return(expression);
        }
Ejemplo n.º 2
0
        /// <summary>
        /// Apply mapping translations to this expression
        /// </summary>
        /// <param name="expression"> </param>
        /// <returns> </returns>
        public virtual Expression Translate(Expression expression)
        {
            // convert references to LINQ operators into query specific nodes
            expression = QueryBinder.Bind(this, expression);

            // move aggregate computations so they occur in same select as group-by
            expression = AggregateRewriter.Rewrite(Translator.Linguist.Language, expression);

            // do reduction so duplicate association's are likely to be clumped together
            expression = UnusedColumnRemover.Remove(expression);
            expression = RedundantColumnRemover.Remove(expression);
            expression = RedundantSubqueryRemover.Remove(expression);
            expression = RedundantJoinRemover.Remove(expression);

            // convert references to association properties into correlated queries
            Expression bound = RelationshipBinder.Bind(this, expression);

            if (bound != expression)
            {
                expression = bound;
                // clean up after ourselves! (multiple references to same association property)
                expression = RedundantColumnRemover.Remove(expression);
                expression = RedundantJoinRemover.Remove(expression);
            }

            // rewrite comparision checks between entities and multi-valued constructs
            expression = ComparisonRewriter.Rewrite(Mapping, expression);

            return(expression);
        }
Ejemplo n.º 3
0
        /// <summary>
        /// Provides policy specific query translations. This is where choices about inclusion of related objects and how heirarchies are materialized affect the definition of the queries.
        /// </summary>
        /// <param name="expression"> </param>
        /// <returns> </returns>
        public virtual Expression Translate(Expression expression)
        {
            // add included relationships to client projection
            Expression rewritten = RelationshipIncluder.Include(translator.Mapper, expression);

            if (rewritten != expression)
            {
                expression = rewritten;
                expression = UnusedColumnRemover.Remove(expression);
                expression = RedundantColumnRemover.Remove(expression);
                expression = RedundantSubqueryRemover.Remove(expression);
                expression = RedundantJoinRemover.Remove(expression);
            }

            // convert any singleton (1:1 or n:1) projections into server-side joins (cardinality is preserved)
            rewritten = SingletonProjectionRewriter.Rewrite(translator.Linguist.Language, expression);
            if (rewritten != expression)
            {
                expression = rewritten;
                expression = UnusedColumnRemover.Remove(expression);
                expression = RedundantColumnRemover.Remove(expression);
                expression = RedundantSubqueryRemover.Remove(expression);
                expression = RedundantJoinRemover.Remove(expression);
            }

            // convert projections into client-side joins
            rewritten = ClientJoinedProjectionRewriter.Rewrite(policy, translator.Linguist.Language, expression);
            if (rewritten != expression)
            {
                expression = rewritten;
                expression = UnusedColumnRemover.Remove(expression);
                expression = RedundantColumnRemover.Remove(expression);
                expression = RedundantSubqueryRemover.Remove(expression);
                expression = RedundantJoinRemover.Remove(expression);
            }

            return(expression);
        }