estimate-OR-similar-to-IN-clauses.patch

diff --git a/src/backend/statistics/dependencies.c b/src/backend/statistics/dependencies.c
index 72dc1cd1bd..5f9b43bf7f 100644
--- a/src/backend/statistics/dependencies.c
+++ b/src/backend/statistics/dependencies.c
@@ -753,24 +753,27 @@ pg_dependencies_send(PG_FUNCTION_ARGS)
 static bool
 dependency_is_compatible_clause(Node *clause, Index relid, AttrNumber *attnum)
 {
-	RestrictInfo *rinfo = (RestrictInfo *) clause;
 	Var		   *var;
 
-	if (!IsA(rinfo, RestrictInfo))
-		return false;
+	if (IsA(clause, RestrictInfo))
+	{
+		RestrictInfo *rinfo = (RestrictInfo *) clause;
 
-	/* Pseudoconstants are not interesting (they couldn't contain a Var) */
-	if (rinfo->pseudoconstant)
-		return false;
+		/* Pseudoconstants are not interesting (they couldn't contain a Var) */
+		if (rinfo->pseudoconstant)
+			return false;
 
-	/* Clauses referencing multiple, or no, varnos are incompatible */
-	if (bms_membership(rinfo->clause_relids) != BMS_SINGLETON)
-		return false;
+		/* Clauses referencing multiple, or no, varnos are incompatible */
+		if (bms_membership(rinfo->clause_relids) != BMS_SINGLETON)
+			return false;
 
-	if (is_opclause(rinfo->clause))
+		clause = (Node *) rinfo->clause;
+	}
+
+	if (is_opclause(clause))
 	{
 		/* If it's an opclause, check for Var = Const or Const = Var. */
-		OpExpr	   *expr = (OpExpr *) rinfo->clause;
+		OpExpr	   *expr = (OpExpr *) clause;
 
 		/* Only expressions with two arguments are candidates. */
 		if (list_length(expr->args) != 2)
@@ -801,10 +804,10 @@ dependency_is_compatible_clause(Node *clause, Index relid, AttrNumber *attnum)
 
 		/* OK to proceed with checking "var" */
 	}
-	else if (IsA(rinfo->clause, ScalarArrayOpExpr))
+	else if (IsA(clause, ScalarArrayOpExpr))
 	{
 		/* If it's an scalar array operator, check for Var IN Const. */
-		ScalarArrayOpExpr	   *expr = (ScalarArrayOpExpr *) rinfo->clause;
+		ScalarArrayOpExpr	   *expr = (ScalarArrayOpExpr *) clause;
 
 		/*
 		 * Reject ALL() variant, we only care about ANY/IN.
@@ -839,13 +842,43 @@ dependency_is_compatible_clause(Node *clause, Index relid, AttrNumber *attnum)
 
 		/* OK to proceed with checking "var" */
 	}
-	else if (is_notclause(rinfo->clause))
+	else if (is_orclause(clause))
+	{
+		BoolExpr   *expr = (BoolExpr *) clause;
+		ListCell   *lc;
+
+		/* start with no attribute number */
+		*attnum = InvalidAttrNumber;
+
+		foreach(lc, expr->args)
+		{
+			AttrNumber	clause_attnum;
+
+			/*
+			 * Had we found incompatible clause in the arguments, treat the
+			 * whole clause as incompatible.
+			 */
+			if (!dependency_is_compatible_clause((Node *) lfirst(lc),
+												 relid, &clause_attnum))
+				return false;
+
+			if (*attnum == InvalidAttrNumber)
+				*attnum = clause_attnum;
+
+			if (*attnum != clause_attnum)
+				return false;
+		}
+
+		/* the Var is already checked by the recursive call */
+		return true;
+	}
+	else if (is_notclause(clause))
 	{
 		/*
 		 * "NOT x" can be interpreted as "x = false", so get the argument and
 		 * proceed with seeing if it's a suitable Var.
 		 */
-		var = (Var *) get_notclausearg(rinfo->clause);
+		var = (Var *) get_notclausearg(clause);
 	}
 	else
 	{
@@ -853,7 +886,7 @@ dependency_is_compatible_clause(Node *clause, Index relid, AttrNumber *attnum)
 		 * A boolean expression "x" can be interpreted as "x = true", so
 		 * proceed with seeing if it's a suitable Var.
 		 */
-		var = (Var *) rinfo->clause;
+		var = (Var *) clause;
 	}
 
 	/*
diff --git a/src/test/regress/expected/stats_ext.out b/src/test/regress/expected/stats_ext.out
index 9fa659c71d..74da75c3c6 100644
--- a/src/test/regress/expected/stats_ext.out
+++ b/src/test/regress/expected/stats_ext.out
@@ -458,6 +458,32 @@ SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE
          3 |    400
 (1 row)
 
+-- OR clauses referencing the same attribute
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 51) AND b = ''1''');
+ estimated | actual 
+-----------+--------
+         2 |    100
+(1 row)
+
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 51) AND (b = ''1'' OR b = ''2'')');
+ estimated | actual 
+-----------+--------
+         4 |    100
+(1 row)
+
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 2 OR a = 51 OR a = 52) AND (b = ''1'' OR b = ''2'')');
+ estimated | actual 
+-----------+--------
+         8 |    200
+(1 row)
+
+-- OR clauses referencing different attributes
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR b = ''1'') AND b = ''1''');
+ estimated | actual 
+-----------+--------
+         3 |    100
+(1 row)
+
 -- ANY
 SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE a = ANY (ARRAY[1, 51]) AND b = ''1''');
  estimated | actual 
@@ -585,6 +611,32 @@ SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE
        400 |    400
 (1 row)
 
+-- OR clauses referencing the same attribute
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 51) AND b = ''1''');
+ estimated | actual 
+-----------+--------
+        99 |    100
+(1 row)
+
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 51) AND (b = ''1'' OR b = ''2'')');
+ estimated | actual 
+-----------+--------
+        99 |    100
+(1 row)
+
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 2 OR a = 51 OR a = 52) AND (b = ''1'' OR b = ''2'')');
+ estimated | actual 
+-----------+--------
+       197 |    200
+(1 row)
+
+-- OR clauses referencing different attributes are incompatible
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR b = ''1'') AND b = ''1''');
+ estimated | actual 
+-----------+--------
+         3 |    100
+(1 row)
+
 -- ANY
 SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE a = ANY (ARRAY[1, 51]) AND b = ''1''');
  estimated | actual 
diff --git a/src/test/regress/sql/stats_ext.sql b/src/test/regress/sql/stats_ext.sql
index 0ece39a279..d9c935896b 100644
--- a/src/test/regress/sql/stats_ext.sql
+++ b/src/test/regress/sql/stats_ext.sql
@@ -286,6 +286,16 @@ SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE
 
 SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE a IN (1, 2, 26, 27, 51, 52, 76, 77) AND b IN (''1'', ''2'', ''26'', ''27'') AND c IN (1, 2)');
 
+-- OR clauses referencing the same attribute
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 51) AND b = ''1''');
+
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 51) AND (b = ''1'' OR b = ''2'')');
+
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 2 OR a = 51 OR a = 52) AND (b = ''1'' OR b = ''2'')');
+
+-- OR clauses referencing different attributes
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR b = ''1'') AND b = ''1''');
+
 -- ANY
 SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE a = ANY (ARRAY[1, 51]) AND b = ''1''');
 
@@ -335,6 +345,16 @@ SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE
 
 SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE a IN (1, 2, 26, 27, 51, 52, 76, 77) AND b IN (''1'', ''2'', ''26'', ''27'') AND c IN (1, 2)');
 
+-- OR clauses referencing the same attribute
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 51) AND b = ''1''');
+
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 51) AND (b = ''1'' OR b = ''2'')');
+
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR a = 2 OR a = 51 OR a = 52) AND (b = ''1'' OR b = ''2'')');
+
+-- OR clauses referencing different attributes are incompatible
+SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE (a = 1 OR b = ''1'') AND b = ''1''');
+
 -- ANY
 SELECT * FROM check_estimated_rows('SELECT * FROM functional_dependencies WHERE a = ANY (ARRAY[1, 51]) AND b = ''1''');