diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 44efb1f4ebc..80935cec7aa 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -67,6 +67,7 @@
 #include "utils/rel.h"
 #include "utils/selfuncs.h"
 #include "utils/syscache.h"
+#include "optimizer/orclauses.h"
 
 /* GUC parameters */
 double		cursor_tuple_fraction = DEFAULT_CURSOR_TUPLE_FRACTION;
@@ -1169,7 +1170,7 @@ preprocess_expression(PlannerInfo *root, Node *expr, int kind)
 	if (kind == EXPRKIND_QUAL)
 	{
 		expr = (Node *) canonicalize_qual((Expr *) expr, false);
-
+expr = transform_ors(root, (Expr *) expr);
 #ifdef OPTIMIZER_DEBUG
 		printf("After canonicalize_qual()\n");
 		pprint(expr);
diff --git a/src/backend/optimizer/util/orclauses.c b/src/backend/optimizer/util/orclauses.c
index 6ef9d14b902..2e30f2bf88a 100644
--- a/src/backend/optimizer/util/orclauses.c
+++ b/src/backend/optimizer/util/orclauses.c
@@ -22,6 +22,10 @@
 #include "optimizer/optimizer.h"
 #include "optimizer/orclauses.h"
 #include "optimizer/restrictinfo.h"
+#include "utils/lsyscache.h"
+#include "parser/parse_expr.h"
+#include "parser/parse_coerce.h"
+#include "parser/parse_oper.h"
 
 
 static bool is_safe_restriction_clause_for(RestrictInfo *rinfo, RelOptInfo *rel);
@@ -29,7 +33,255 @@ static Expr *extract_or_clause(RestrictInfo *or_rinfo, RelOptInfo *rel);
 static void consider_new_or_clause(PlannerInfo *root, RelOptInfo *rel,
 								   Expr *orclause, RestrictInfo *join_or_rinfo);
 
+typedef struct OrClauseGroupEntry
+{
+	Node		   *node;
+	List		   *consts;
+	Oid				collation;
+	Oid				opno;
+	RestrictInfo   *rinfo;
+	Expr *expr;
+} OrClauseGroupEntry;
+
+/*
+ * Pass through baserestrictinfo clauses and try to convert OR clauses into IN
+ * Return a modified clause list or just the same baserestrictinfo, if no
+ * changes have made.
+ * XXX: do not change source list of clauses at all.
+ */
+static Expr *
+transform_ors_for_rel(Expr *qual)
+{
+	List	       *modified_clause = NIL;
+	bool		    something_changed = false;
+	List		   *or_list = NIL;
+	ListCell	   *lc_eargs,
+				   *lc_args;
+	List		   *groups_list = NIL;
+	bool			change_apply = false;
+
+	if (!(is_orclause(qual)))
+	{
+		/* Add a clause without changes */
+		return qual;
+	}
+
+	/*
+		* NOTE:
+		* It is an OR-clause. So, rinfo->orclause is a BoolExpr node, contains
+		* a list of sub-restrictinfo args, and rinfo->clause - which is the
+		* same expression, made from bare clauses. To not break selectivity
+		* caches and other optimizations, use both:
+		* - use rinfos from orclause if no transformation needed
+		* - use  bare quals from rinfo->clause in the case of transformation,
+		* to create new RestrictInfo: in this case we have no options to avoid
+		* selectivity estimation procedure.
+		*/
+	foreach(lc_eargs, ((BoolExpr *) qual)->args)
+	{
+		Expr			   *bare_orarg = (Expr *) lfirst(lc_eargs);
+		Node			   *const_expr;
+		Node			   *non_const_expr;
+		ListCell		   *lc_groups;
+		OrClauseGroupEntry *gentry;
+		Oid					opno;
+
+		/* Check: it is an expr of the form 'F(x) oper ConstExpr' */
+		if (!bare_orarg  ||
+			contain_volatile_functions((Node *) bare_orarg))
+		{
+			/* Again, it's not the expr we can transform */
+			or_list = lappend(or_list, (void *) bare_orarg);
+			continue;
+		}
+
+		/* Get pointers to constant and expression sides of the clause */
+		const_expr = get_rightop(bare_orarg);
+		non_const_expr = get_leftop(bare_orarg);
+
+		opno = ((OpExpr *)bare_orarg)->opno;
+		//if (!op_mergejoinable(opno, exprType(non_const_expr)))
+		//{
+			/* And again, filter out non-equality operators */
+		//	or_list = lappend(or_list, (void *) bare_orarg);
+		//	continue;
+		//}
+
+		/*
+			* At this point we definitely have a transformable clause.
+			* Classify it and add into specific group of clauses, or create new
+			* group.
+			* TODO: to manage complexity in the case of many different clauses
+			* (X1=C1) OR (X2=C2 OR) ... (XN = CN) we could invent something
+			* like a hash table (htab key ???).
+			*/
+		foreach(lc_groups, groups_list)
+		{
+			OrClauseGroupEntry *v = (OrClauseGroupEntry *) lfirst(lc_groups);
+
+			Assert(v->node != NULL);
+
+			if (equal(v->node, non_const_expr))
+			{
+				v->consts = lappend(v->consts, const_expr);
+				non_const_expr = NULL;
+				break;
+			}
+		}
+
+		if (non_const_expr == NULL)
+			/*
+				* The clause classified successfully and added into existed
+				* clause group.
+				*/
+			continue;
+
+		/* New clause group needed */
+		gentry = palloc(sizeof(OrClauseGroupEntry));
+		gentry->node = non_const_expr;
+		gentry->consts = list_make1(const_expr);
+		gentry->collation = exprInputCollation((Node *) bare_orarg);
+		gentry->opno = opno;
+		gentry->expr = bare_orarg;
+		groups_list = lappend(groups_list,  (void *) gentry);
+	}
+
+	if (groups_list == NIL)
+	{
+		/*
+			* No any transformations possible with this rinfo, just add itself
+			* to the list and go further.
+			*/
+		modified_clause = lappend(modified_clause, qual);
+	}
+	else
+	{
+		/* Let's convert each group of clauses to an IN operation. */
+
+		/*
+			* Go through the list of groups and convert each, where number of
+			* consts more than 1. trivial groups move to OR-list again
+			*/
+
+		foreach(lc_args, groups_list)
+		{
+			OrClauseGroupEntry *gentry = (OrClauseGroupEntry *) lfirst(lc_args);
+			List			   *allexprs;
+			Oid				    scalar_type;
+			Oid					array_type;
+
+			Assert(list_length(gentry->consts) > 0);
+
+			if (list_length(gentry->consts) == 1)
+			{
+				/*
+				 * Only one element in the class. Return rinfo into the BoolExpr
+				 * args list unchanged.
+				 */
+				list_free(gentry->consts);
+				or_list = lappend(or_list, gentry->expr);
+				continue;
+			}
+
+			/*
+			 * Do the transformation.
+			 *
+			 * First of all, try to select a common type for the array elements.
+			 * Note that since the LHS' type is first in the list, it will be
+			 * preferred when there is doubt (eg, when all the RHS items are
+			 * unknown literals).
+			 *
+			 * Note: use list_concat here not lcons, to avoid damaging rnonvars.
+			 *
+			 * As a source of insides, use make_scalar_array_op()
+			 */
+			allexprs = list_concat(list_make1(gentry->node), gentry->consts);
+			scalar_type = select_common_type(NULL, allexprs, NULL, NULL);
+
+			if (scalar_type != RECORDOID && OidIsValid(scalar_type))
+				array_type = get_array_type(scalar_type);
+			else
+				array_type = InvalidOid;
+
+			if (array_type != InvalidOid)
+			{
+				/*
+				 * OK: coerce all the right-hand non-Var inputs to the common
+				 * type and build an ArrayExpr for them.
+				 */
+				List	   *aexprs;
+				ArrayExpr  *newa;
+				ScalarArrayOpExpr *saopexpr;
+				ListCell *l;
+
+				aexprs = NIL;
+
+				foreach(l, gentry->consts)
+				{
+					Node	   *rexpr = (Node *) lfirst(l);
+
+					rexpr = coerce_to_common_type(NULL, rexpr,
+												scalar_type,
+												"IN");
+					aexprs = lappend(aexprs, rexpr);
+				}
+
+				newa = makeNode(ArrayExpr);
+				/* array_collid will be set by parse_collate.c */
+				newa->element_typeid = scalar_type;
+				newa->array_typeid = array_type;
+				newa->multidims = false;
+				newa->elements = aexprs;
+				newa->location = -1;
+
+				saopexpr =
+					(ScalarArrayOpExpr *)
+						make_scalar_array_op(NULL,
+											 list_make1(makeString((char *) "=")),
+											 true,
+											 gentry->node,
+											 (Node *) newa,
+											 -1);
+
+				or_list = lappend(or_list, (void *) saopexpr);
+			}
+			else
+			{
+				list_free(gentry->consts);
+				or_list = lappend(or_list, gentry->expr);
+				continue;
+			}
+		}
+	}
+
+		/*
+		* Make a new version of the restriction. Remember source restriction
+		* can be used in another path (SeqScan, for example).
+		*/
+	/* One more trick: assemble correct clause */
+	qual = list_length(or_list) > 1 ? make_orclause(or_list) : linitial(or_list);
 
+	//modified_clause = lappend(modified_clause, qual);
+	list_free_deep(groups_list);
+	something_changed = true;
+
+	/*
+	 * Check if transformation has made. If nothing changed - return
+	 * baserestrictinfo as is.
+	 */
+	/* if (something_changed)
+	{
+		return modified_clause;
+	} */
+
+	list_free(modified_clause);
+	return qual;
+}
+Node *
+transform_ors(PlannerInfo *root, Expr *jtnode)
+{
+	return (Node *) transform_ors_for_rel(jtnode);
+}
 /*
  * extract_restriction_or_clauses
  *	  Examine join OR-of-AND clauses to see if any useful restriction OR
diff --git a/src/include/optimizer/orclauses.h b/src/include/optimizer/orclauses.h
index f9dbe6a2972..6a232aeb3ed 100644
--- a/src/include/optimizer/orclauses.h
+++ b/src/include/optimizer/orclauses.h
@@ -17,5 +17,5 @@
 #include "nodes/pathnodes.h"
 
 extern void extract_restriction_or_clauses(PlannerInfo *root);
-
+extern Node * transform_ors(PlannerInfo *root, Expr *jtnode);
 #endif							/* ORCLAUSES_H */