diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 627c9e28ec..ab56c124f9 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -68,6 +68,7 @@ Yii Framework 2 Change Log
 - Enh #11758: Implemented Dependency Injection Container configuration using Application configuration array (silverfire)
 - Enh: Added constants for specifying `yii\validators\CompareValidator::$type` (cebe)
 - Enh #12854: Added `RangeNotSatisfiableHttpException` to cover HTTP error 416 file request exceptions (zalatov)
+- Enh #13122: Optimized query for information about foreign keys in `yii\db\oci` (zlakomanoff)
 
 2.0.10 October 20, 2016
 -----------------------
diff --git a/framework/db/oci/Schema.php b/framework/db/oci/Schema.php
index 1f47207053..4231ba5518 100644
--- a/framework/db/oci/Schema.php
+++ b/framework/db/oci/Schema.php
@@ -121,17 +121,23 @@ class Schema extends \yii\db\Schema
     protected function findColumns($table)
     {
         $sql = <<<SQL
-SELECT a.column_name, a.data_type, a.data_precision, a.data_scale, a.data_length,
-    a.nullable, a.data_default,
-    com.comments as column_comment
+SELECT 
+    A.COLUMN_NAME, 
+    A.DATA_TYPE, 
+    A.DATA_PRECISION, 
+    A.DATA_SCALE, 
+    A.DATA_LENGTH,
+    A.NULLABLE, 
+    A.DATA_DEFAULT,
+    COM.COMMENTS AS COLUMN_COMMENT
 FROM ALL_TAB_COLUMNS A
-inner join ALL_OBJECTS B ON b.owner = a.owner and ltrim(B.OBJECT_NAME) = ltrim(A.TABLE_NAME)
-LEFT JOIN all_col_comments com ON (A.owner = com.owner AND A.table_name = com.table_name AND A.column_name = com.column_name)
+    INNER JOIN ALL_OBJECTS B ON B.OWNER = A.OWNER AND LTRIM(B.OBJECT_NAME) = LTRIM(A.TABLE_NAME)
+    LEFT JOIN ALL_COL_COMMENTS COM ON (A.OWNER = COM.OWNER AND A.TABLE_NAME = COM.TABLE_NAME AND A.COLUMN_NAME = COM.COLUMN_NAME)
 WHERE
-    a.owner = :schemaName
-    and b.object_type IN ('TABLE', 'VIEW', 'MATERIALIZED VIEW')
-    and b.object_name = :tableName
-ORDER by a.column_id
+    A.OWNER = :schemaName
+    AND B.OBJECT_TYPE IN ('TABLE', 'VIEW', 'MATERIALIZED VIEW')
+    AND B.OBJECT_NAME = :tableName
+ORDER BY A.COLUMN_ID
 SQL;
 
         try {
@@ -167,15 +173,17 @@ SQL;
     protected function getTableSequenceName($tableName)
     {
 
-        $seq_name_sql = <<<SQL
-SELECT ud.referenced_name as sequence_name
-FROM user_dependencies ud
-JOIN user_triggers ut on (ut.trigger_name = ud.name)
-WHERE ut.table_name = :tableName
-AND ud.type='TRIGGER'
-AND ud.referenced_type='SEQUENCE'
+        $sequenceNameSql = <<<SQL
+SELECT 
+    UD.REFERENCED_NAME AS SEQUENCE_NAME
+FROM USER_DEPENDENCIES UD
+    JOIN USER_TRIGGERS UT ON (UT.TRIGGER_NAME = UD.NAME)
+WHERE 
+    UT.TABLE_NAME = :tableName
+    AND UD.TYPE = 'TRIGGER'
+    AND UD.REFERENCED_TYPE = 'SEQUENCE'
 SQL;
-        $sequenceName = $this->db->createCommand($seq_name_sql, [':tableName' => $tableName])->queryScalar();
+        $sequenceName = $this->db->createCommand($sequenceNameSql, [':tableName' => $tableName])->queryScalar();
         return $sequenceName === false ? null : $sequenceName;
     }
 
@@ -251,15 +259,23 @@ SQL;
     protected function findConstraints($table)
     {
         $sql = <<<SQL
-SELECT D.CONSTRAINT_NAME, D.CONSTRAINT_TYPE, C.COLUMN_NAME, C.POSITION, D.R_CONSTRAINT_NAME,
-        E.TABLE_NAME AS TABLE_REF, F.COLUMN_NAME AS COLUMN_REF,
-        C.TABLE_NAME
+SELECT
+    /*+ PUSH_PRED(C) PUSH_PRED(D) PUSH_PRED(E) */
+    D.CONSTRAINT_NAME,
+    D.CONSTRAINT_TYPE,
+    C.COLUMN_NAME,
+    C.POSITION,
+    D.R_CONSTRAINT_NAME,
+    E.TABLE_NAME AS TABLE_REF,
+    F.COLUMN_NAME AS COLUMN_REF,
+    C.TABLE_NAME
 FROM ALL_CONS_COLUMNS C
-INNER JOIN ALL_CONSTRAINTS D ON D.OWNER = C.OWNER AND D.CONSTRAINT_NAME = C.CONSTRAINT_NAME
-LEFT JOIN ALL_CONSTRAINTS E ON E.OWNER = D.R_OWNER AND E.CONSTRAINT_NAME = D.R_CONSTRAINT_NAME
-LEFT JOIN ALL_CONS_COLUMNS F ON F.OWNER = E.OWNER AND F.CONSTRAINT_NAME = E.CONSTRAINT_NAME AND F.POSITION = C.POSITION
-WHERE C.OWNER = :schemaName
-   AND C.TABLE_NAME = :tableName
+    INNER JOIN ALL_CONSTRAINTS D ON D.OWNER = C.OWNER AND D.CONSTRAINT_NAME = C.CONSTRAINT_NAME
+    LEFT JOIN ALL_CONSTRAINTS E ON E.OWNER = D.R_OWNER AND E.CONSTRAINT_NAME = D.R_CONSTRAINT_NAME
+    LEFT JOIN ALL_CONS_COLUMNS F ON F.OWNER = E.OWNER AND F.CONSTRAINT_NAME = E.CONSTRAINT_NAME AND F.POSITION = C.POSITION
+WHERE
+    C.OWNER = :schemaName
+    AND C.TABLE_NAME = :tableName
 ORDER BY D.CONSTRAINT_NAME, C.POSITION
 SQL;
         $command = $this->db->createCommand($sql, [
@@ -306,13 +322,12 @@ SQL;
     protected function findSchemaNames()
     {
         $sql = <<<SQL
-SELECT username
-  FROM dba_users u
- WHERE EXISTS (
-    SELECT 1
-      FROM dba_objects o
-     WHERE o.owner = u.username )
-   AND default_tablespace not in ('SYSTEM','SYSAUX')
+SELECT
+    USERNAME
+FROM DBA_USERS U
+WHERE 
+    EXISTS (SELECT 1 FROM DBA_OBJECTS O WHERE O.OWNER = U.USERNAME)
+    AND DEFAULT_TABLESPACE NOT IN ('SYSTEM','SYSAUX')
 SQL;
         return $this->db->createCommand($sql)->queryColumn();
     }
@@ -324,20 +339,29 @@ SQL;
     {
         if ($schema === '') {
             $sql = <<<SQL
-SELECT table_name FROM user_tables
+SELECT 
+    TABLE_NAME 
+FROM USER_TABLES
 UNION ALL
-SELECT view_name AS table_name FROM user_views
+SELECT 
+    VIEW_NAME AS TABLE_NAME 
+FROM USER_VIEWS
 UNION ALL
-SELECT mview_name AS table_name FROM user_mviews
-ORDER BY table_name
+SELECT 
+    MVIEW_NAME AS TABLE_NAME 
+FROM USER_MVIEWS
+ORDER BY TABLE_NAME
 SQL;
             $command = $this->db->createCommand($sql);
         } else {
             $sql = <<<SQL
-SELECT object_name AS table_name
-FROM all_objects
-WHERE object_type IN ('TABLE', 'VIEW', 'MATERIALIZED VIEW') AND owner=:schema
-ORDER BY object_name
+SELECT 
+    OBJECT_NAME AS TABLE_NAME
+FROM ALL_OBJECTS
+WHERE 
+    OBJECT_TYPE IN ('TABLE', 'VIEW', 'MATERIALIZED VIEW') 
+    AND OWNER = :schema
+ORDER BY OBJECT_NAME
 SQL;
             $command = $this->db->createCommand($sql, [':schema' => $schema]);
         }
@@ -371,13 +395,16 @@ SQL;
     public function findUniqueIndexes($table)
     {
         $query = <<<SQL
-SELECT dic.INDEX_NAME, dic.COLUMN_NAME
-FROM ALL_INDEXES di
-INNER JOIN ALL_IND_COLUMNS dic ON di.TABLE_NAME = dic.TABLE_NAME AND di.INDEX_NAME = dic.INDEX_NAME
-WHERE di.UNIQUENESS = 'UNIQUE'
-AND dic.TABLE_OWNER = :schemaName
-AND dic.TABLE_NAME = :tableName
-ORDER BY dic.TABLE_NAME, dic.INDEX_NAME, dic.COLUMN_POSITION
+SELECT 
+    DIC.INDEX_NAME,
+    DIC.COLUMN_NAME
+FROM ALL_INDEXES DI
+    INNER JOIN ALL_IND_COLUMNS DIC ON DI.TABLE_NAME = DIC.TABLE_NAME AND DI.INDEX_NAME = DIC.INDEX_NAME
+WHERE 
+    DI.UNIQUENESS = 'UNIQUE'
+    AND DIC.TABLE_OWNER = :schemaName
+    AND DIC.TABLE_NAME = :tableName
+ORDER BY DIC.TABLE_NAME, DIC.INDEX_NAME, DIC.COLUMN_POSITION
 SQL;
         $result = [];
         $command = $this->db->createCommand($query, [
diff --git a/tests/data/config.php b/tests/data/config.php
index 8ba7b26ae0..107258621f 100644
--- a/tests/data/config.php
+++ b/tests/data/config.php
@@ -43,6 +43,12 @@ $config = [
             'password' => 'postgres',
             'fixture' => __DIR__ . '/postgres.sql',
         ],
+        'oci' => [
+            'dsn' => 'oci:dbname=LOCAL_XE;charset=AL32UTF8;',
+            'username' => '',
+            'password' => '',
+            'fixture' => __DIR__ . '/oci.sql',
+        ],
     ],
 ];
 
diff --git a/tests/framework/db/QueryBuilderTest.php b/tests/framework/db/QueryBuilderTest.php
index 719f3b15d8..a498ed35af 100644
--- a/tests/framework/db/QueryBuilderTest.php
+++ b/tests/framework/db/QueryBuilderTest.php
@@ -167,7 +167,6 @@ abstract class QueryBuilderTest extends DatabaseTestCase
                 [
                     'mysql' => 'char(1) CHECK (value LIKE "test%")',
                     'sqlite' => 'char(1) CHECK (value LIKE "test%")',
-                    'oci' => 'CHAR(1) CHECK (value LIKE "test%")',
                     'cubrid' => 'char(1) CHECK (value LIKE "test%")',
                 ],
             ],
@@ -188,7 +187,6 @@ abstract class QueryBuilderTest extends DatabaseTestCase
                 [
                     'mysql' => 'char(6) CHECK (value LIKE "test%")',
                     'sqlite' => 'char(6) CHECK (value LIKE "test%")',
-                    'oci' => 'CHAR(6) CHECK (value LIKE "test%")',
                     'cubrid' => 'char(6) CHECK (value LIKE "test%")',
                 ],
             ],
@@ -883,7 +881,6 @@ abstract class QueryBuilderTest extends DatabaseTestCase
                     'mysql' => 'timestamp NULL DEFAULT NULL',
                     'postgres' => 'timestamp(0) NULL DEFAULT NULL',
                     'sqlite' => 'timestamp NULL DEFAULT NULL',
-                    'oci' => 'TIMESTAMP NULL DEFAULT NULL',
                     'sqlsrv' => 'timestamp NULL DEFAULT NULL',
                     'cubrid' => 'timestamp NULL DEFAULT NULL',
                 ],
@@ -912,7 +909,6 @@ abstract class QueryBuilderTest extends DatabaseTestCase
                 [
                     'mysql' => "int(11) COMMENT 'test comment'",
                     'postgres' => 'integer',
-                    'oci' => "NUMBER(10)",
                     'sqlsrv' => 'int',
                     'cubrid' => "int COMMENT 'test comment'",
                 ],
@@ -923,7 +919,6 @@ abstract class QueryBuilderTest extends DatabaseTestCase
                 [
                     'mysql' => "int(11) NOT NULL AUTO_INCREMENT PRIMARY KEY COMMENT 'test comment'",
                     'postgres' => 'serial NOT NULL PRIMARY KEY',
-                    'oci' => 'NUMBER(10) NOT NULL PRIMARY KEY',
                     'sqlsrv' => 'int IDENTITY PRIMARY KEY',
                     'cubrid' => "int NOT NULL AUTO_INCREMENT PRIMARY KEY COMMENT 'test comment'",
                 ],
diff --git a/tests/framework/db/oci/ConnectionTest.php b/tests/framework/db/oci/ConnectionTest.php
index d65b000fb3..b78c6c1789 100644
--- a/tests/framework/db/oci/ConnectionTest.php
+++ b/tests/framework/db/oci/ConnectionTest.php
@@ -9,4 +9,62 @@ namespace yiiunit\framework\db\oci;
 class ConnectionTest extends \yiiunit\framework\db\ConnectionTest
 {
     protected $driverName = 'oci';
+
+    public function testSerialize()
+    {
+        $connection = $this->getConnection(false, false);
+        $connection->open();
+        $serialized = serialize($connection);
+        $unserialized = unserialize($serialized);
+        $this->assertInstanceOf('yii\db\Connection', $unserialized);
+
+        $this->assertEquals(123, $unserialized->createCommand("SELECT 123 FROM DUAL")->queryScalar());
+    }
+
+    public function testQuoteTableName()
+    {
+        $connection = $this->getConnection(false);
+        $this->assertEquals('"table"', $connection->quoteTableName('table'));
+        $this->assertEquals('"table"', $connection->quoteTableName('"table"'));
+        $this->assertEquals('"schema"."table"', $connection->quoteTableName('schema.table'));
+        $this->assertEquals('"schema"."table"', $connection->quoteTableName('schema."table"'));
+        $this->assertEquals('"schema"."table"', $connection->quoteTableName('"schema"."table"'));
+        $this->assertEquals('{{table}}', $connection->quoteTableName('{{table}}'));
+        $this->assertEquals('(table)', $connection->quoteTableName('(table)'));
+    }
+
+    public function testQuoteColumnName()
+    {
+        $connection = $this->getConnection(false);
+        $this->assertEquals('"column"', $connection->quoteColumnName('column'));
+        $this->assertEquals('"column"', $connection->quoteColumnName('"column"'));
+        $this->assertEquals('[[column]]', $connection->quoteColumnName('[[column]]'));
+        $this->assertEquals('{{column}}', $connection->quoteColumnName('{{column}}'));
+        $this->assertEquals('(column)', $connection->quoteColumnName('(column)'));
+
+        $this->assertEquals('"column"', $connection->quoteSql('[[column]]'));
+        $this->assertEquals('"column"', $connection->quoteSql('{{column}}'));
+    }
+
+    public function testQuoteFullColumnName()
+    {
+        $connection = $this->getConnection(false, false);
+        $this->assertEquals('"table"."column"', $connection->quoteColumnName('table.column'));
+        $this->assertEquals('"table"."column"', $connection->quoteColumnName('table."column"'));
+        $this->assertEquals('"table"."column"', $connection->quoteColumnName('"table".column'));
+        $this->assertEquals('"table"."column"', $connection->quoteColumnName('"table"."column"'));
+
+        $this->assertEquals('[[table.column]]', $connection->quoteColumnName('[[table.column]]'));
+        $this->assertEquals('{{table}}."column"', $connection->quoteColumnName('{{table}}.column'));
+        $this->assertEquals('{{table}}."column"', $connection->quoteColumnName('{{table}}."column"'));
+        $this->assertEquals('{{table}}.[[column]]', $connection->quoteColumnName('{{table}}.[[column]]'));
+        $this->assertEquals('{{%table}}."column"', $connection->quoteColumnName('{{%table}}.column'));
+        $this->assertEquals('{{%table}}."column"', $connection->quoteColumnName('{{%table}}."column"'));
+
+        $this->assertEquals('"table"."column"', $connection->quoteSql('[[table.column]]'));
+        $this->assertEquals('"table"."column"', $connection->quoteSql('{{table}}.[[column]]'));
+        $this->assertEquals('"table"."column"', $connection->quoteSql('{{table}}."column"'));
+        $this->assertEquals('"table"."column"', $connection->quoteSql('{{%table}}.[[column]]'));
+        $this->assertEquals('"table"."column"', $connection->quoteSql('{{%table}}."column"'));
+    }
 }