diff --git a/Makefile b/Makefile
index 8db7584..11c701e 100644
--- a/Makefile
+++ b/Makefile
@@ -3,8 +3,11 @@ default:
 
 .PHONY: lint
 lint:
-	luacheck graphql/*.lua test/local/*.lua test/testdata/*.lua \
+	luacheck graphql/*.lua \
+		test/local/*.lua \
+		test/testdata/*.lua \
 		test/common/*.test.lua test/common/lua/*.lua \
+		test/extra/*.test.lua \
 		--no-redefined --no-unused-args
 
 .PHONY: test
diff --git a/README.md b/README.md
index e1f2922..dca5477 100644
--- a/README.md
+++ b/README.md
@@ -95,11 +95,18 @@ make test
 
 ## Requirements
 
-* For use: tarantool, lulpeg, >=tarantool/shard-1.1-91-gfa88bf8 (optional),
-  tarantool/avro-schema.
-* For test (additionally to 'for use'): python 2.7, virtualenv, luacheck,
-  >=tarantool/shard-1.1-92-gec1a27e.
-* For building apidoc (additionally to 'for use'): ldoc.
+* For use:
+  * tarantool,
+  * lulpeg,
+  * >=tarantool/avro-schema-2.0-71-gfea0ead,
+  * >=tarantool/shard-1.1-91-gfa88bf8 (optional).
+* For test (additionally to 'for use'):
+  * python 2.7,
+  * virtualenv,
+  * luacheck,
+  * >=tarantool/shard-1.1-92-gec1a27e.
+* For building apidoc (additionally to 'for use'):
+  * ldoc.
 
 ## License
 
diff --git a/graphql/core/execute.lua b/graphql/core/execute.lua
index 92d5070..53807e2 100644
--- a/graphql/core/execute.lua
+++ b/graphql/core/execute.lua
@@ -2,6 +2,7 @@ local path = (...):gsub('%.[^%.]+$', '')
 local types = require(path .. '.types')
 local util = require(path .. '.util')
 local introspection = require(path .. '.introspection')
+local query_util = require(path .. '.query_util')
 
 local function typeFromAST(node, schema)
   local innerType
@@ -63,89 +64,10 @@ local function doesFragmentApply(fragment, type, context)
   end
 end
 
-local function mergeSelectionSets(fields)
-  local selections = {}
-
-  for i = 1, #fields do
-    local selectionSet = fields[i].selectionSet
-    if selectionSet then
-      for j = 1, #selectionSet.selections do
-        table.insert(selections, selectionSet.selections[j])
-      end
-    end
-  end
-
-  return selections
-end
-
 local function defaultResolver(object, arguments, info)
   return object[info.fieldASTs[1].name.value]
 end
 
-local function buildContext(schema, tree, rootValue, variables, operationName)
-  local context = {
-    schema = schema,
-    rootValue = rootValue,
-    variables = variables,
-    operation = nil,
-    fragmentMap = {},
-    -- The field is passed to resolve function within info attribute.
-    -- Can be used to store any data within one query.
-    qcontext = {}
-  }
-
-  for _, definition in ipairs(tree.definitions) do
-    if definition.kind == 'operation' then
-      if not operationName and context.operation then
-        error('Operation name must be specified if more than one operation exists.')
-      end
-
-      if not operationName or definition.name.value == operationName then
-        context.operation = definition
-      end
-    elseif definition.kind == 'fragmentDefinition' then
-      context.fragmentMap[definition.name.value] = definition
-    end
-  end
-
-  if not context.operation then
-    if operationName then
-      error('Unknown operation "' .. operationName .. '"')
-    else
-      error('Must provide an operation')
-    end
-  end
-
-  return context
-end
-
-local function collectFields(objectType, selections, visitedFragments, result, context)
-  for _, selection in ipairs(selections) do
-    if selection.kind == 'field' then
-      if shouldIncludeNode(selection, context) then
-        local name = getFieldResponseKey(selection)
-        result[name] = result[name] or {}
-        table.insert(result[name], selection)
-      end
-    elseif selection.kind == 'inlineFragment' then
-      if shouldIncludeNode(selection, context) and doesFragmentApply(selection, objectType, context) then
-        collectFields(objectType, selection.selectionSet.selections, visitedFragments, result, context)
-      end
-    elseif selection.kind == 'fragmentSpread' then
-      local fragmentName = selection.name.value
-      if shouldIncludeNode(selection, context) and not visitedFragments[fragmentName] then
-        visitedFragments[fragmentName] = true
-        local fragment = context.fragmentMap[fragmentName]
-        if fragment and shouldIncludeNode(fragment, context) and doesFragmentApply(fragment, objectType, context) then
-          collectFields(objectType, fragment.selectionSet.selections, visitedFragments, result, context)
-        end
-      end
-    end
-  end
-
-  return result
-end
-
 local evaluateSelections
 
 local function completeValue(fieldType, result, subSelections, context)
@@ -230,13 +152,13 @@ local function getFieldEntry(objectType, object, fields, context)
   }
 
   local resolvedObject = (fieldType.resolve or defaultResolver)(object, arguments, info)
-  local subSelections = mergeSelectionSets(fields)
+  local subSelections = query_util.mergeSelectionSets(fields)
 
   return completeValue(fieldType.kind, resolvedObject, subSelections, context)
 end
 
 evaluateSelections = function(objectType, object, selections, context)
-  local groupedFieldSet = collectFields(objectType, selections, {}, {}, context)
+  local groupedFieldSet = query_util.collectFields(objectType, selections, {}, {}, context)
 
   return util.map(groupedFieldSet, function(fields)
     return getFieldEntry(objectType, object, fields, context)
@@ -244,7 +166,10 @@ evaluateSelections = function(objectType, object, selections, context)
 end
 
 return function(schema, tree, rootValue, variables, operationName)
-  local context = buildContext(schema, tree, rootValue, variables, operationName)
+  local context = query_util.buildContext(schema, tree, rootValue, variables, operationName)
+  -- The field is passed to resolve function within info attribute.
+  -- Can be used to store any data within one query.
+  context.qcontext = {}
   local rootType = schema[context.operation.operation]
 
   if not rootType then
diff --git a/graphql/core/query_util.lua b/graphql/core/query_util.lua
new file mode 100644
index 0000000..7887878
--- /dev/null
+++ b/graphql/core/query_util.lua
@@ -0,0 +1,143 @@
+local path = (...):gsub('%.[^%.]+$', '')
+local types = require(path .. '.types')
+local util = require(path .. '.util')
+
+local query_util = {}
+
+local function typeFromAST(node, schema)
+  local innerType
+  if node.kind == 'listType' then
+    innerType = typeFromAST(node.type)
+    return innerType and types.list(innerType)
+  elseif node.kind == 'nonNullType' then
+    innerType = typeFromAST(node.type)
+    return innerType and types.nonNull(innerType)
+  else
+    assert(node.kind == 'namedType', 'Variable must be a named type')
+    return schema:getType(node.name.value)
+  end
+end
+
+local function getFieldResponseKey(field)
+  return field.alias and field.alias.name.value or field.name.value
+end
+
+local function shouldIncludeNode(selection, context)
+  if selection.directives then
+    local function isDirectiveActive(key, _type)
+      local directive = util.find(selection.directives, function(directive)
+        return directive.name.value == key
+      end)
+
+      if not directive then return end
+
+      local ifArgument = util.find(directive.arguments, function(argument)
+        return argument.name.value == 'if'
+      end)
+
+      if not ifArgument then return end
+
+      return util.coerceValue(ifArgument.value, _type.arguments['if'], context.variables)
+    end
+
+    if isDirectiveActive('skip', types.skip) then return false end
+    if isDirectiveActive('include', types.include) == false then return false end
+  end
+
+  return true
+end
+
+local function doesFragmentApply(fragment, type, context)
+  if not fragment.typeCondition then return true end
+
+  local innerType = typeFromAST(fragment.typeCondition, context.schema)
+
+  if innerType == type then
+    return true
+  elseif innerType.__type == 'Interface' then
+    local implementors = context.schema:getImplementors(innerType.name)
+    return implementors and implementors[type]
+  elseif innerType.__type == 'Union' then
+    return util.find(innerType.types, function(member)
+      return member == type
+    end)
+  end
+end
+
+function query_util.collectFields(objectType, selections, visitedFragments, result, context)
+  for _, selection in ipairs(selections) do
+    if selection.kind == 'field' then
+      if shouldIncludeNode(selection, context) then
+        local name = getFieldResponseKey(selection)
+        result[name] = result[name] or {}
+        table.insert(result[name], selection)
+      end
+    elseif selection.kind == 'inlineFragment' then
+      if shouldIncludeNode(selection, context) and doesFragmentApply(selection, objectType, context) then
+        collectFields(objectType, selection.selectionSet.selections, visitedFragments, result, context)
+      end
+    elseif selection.kind == 'fragmentSpread' then
+      local fragmentName = selection.name.value
+      if shouldIncludeNode(selection, context) and not visitedFragments[fragmentName] then
+        visitedFragments[fragmentName] = true
+        local fragment = context.fragmentMap[fragmentName]
+        if fragment and shouldIncludeNode(fragment, context) and doesFragmentApply(fragment, objectType, context) then
+          collectFields(objectType, fragment.selectionSet.selections, visitedFragments, result, context)
+        end
+      end
+    end
+  end
+
+  return result
+end
+
+function query_util.mergeSelectionSets(fields)
+  local selections = {}
+
+  for i = 1, #fields do
+    local selectionSet = fields[i].selectionSet
+    if selectionSet then
+      for j = 1, #selectionSet.selections do
+        table.insert(selections, selectionSet.selections[j])
+      end
+    end
+  end
+
+  return selections
+end
+
+function query_util.buildContext(schema, tree, rootValue, variables, operationName)
+    local context = {
+        schema = schema,
+        rootValue = rootValue,
+        variables = variables,
+        operation = nil,
+        fragmentMap = {}
+    }
+
+    for _, definition in ipairs(tree.definitions) do
+        if definition.kind == 'operation' then
+            if not operationName and context.operation then
+                error('Operation name must be specified if more than one operation exists.')
+            end
+
+            if not operationName or definition.name.value == operationName then
+                context.operation = definition
+            end
+        elseif definition.kind == 'fragmentDefinition' then
+            context.fragmentMap[definition.name.value] = definition
+        end
+    end
+
+    if not context.operation then
+        if operationName then
+            error('Unknown operation "' .. operationName .. '"')
+        else
+            error('Must provide an operation')
+        end
+    end
+
+    return context
+end
+
+return query_util
diff --git a/graphql/query_to_avro.lua b/graphql/query_to_avro.lua
new file mode 100755
index 0000000..8e9f1a8
--- /dev/null
+++ b/graphql/query_to_avro.lua
@@ -0,0 +1,181 @@
+--- Module for convertion GraphQL query to Avro schema.
+---
+--- Random notes:
+---
+--- * The best way to use this module is to just call `avro_schema` method on
+---   compiled query object.
+local path = "graphql.core"
+local introspection = require(path .. '.introspection')
+local query_util = require(path .. '.query_util')
+
+-- module functions
+local query_to_avro = {}
+
+-- forward declaration
+local object_to_avro
+
+local gql_scalar_to_avro_index = {
+    String = "string",
+    Int = "int",
+    Long = "long",
+    -- GraphQL Float is double precision according to graphql.org.
+    -- More info http://graphql.org/learn/schema/#scalar-types
+    Float = "double",
+    Boolean = "boolean"
+}
+local function gql_scalar_to_avro(fieldType)
+    assert(fieldType.__type == "Scalar", "GraphQL scalar field expected")
+    assert(fieldType.name ~= "Map", "Map type is not supported")
+    local result = gql_scalar_to_avro_index[fieldType.name]
+    assert(result ~= nil, "Unexpected scalar type: " .. fieldType.name)
+    return result
+end
+
+--- The function converts avro type to the corresponding nullable type in
+--- place and returns the result.
+---
+--- We make changes in place in case of table input (`avro`) because of
+--- performance reasons, but we returns the result because an input (`avro`)
+--- can be a string. Strings in Lua are immutable.
+---
+--- In the current tarantool/avro-schema implementation we simply add '*' to
+--- the end of a type name.
+---
+--- If the type is already nullable the function leaves it as is.
+---
+--- @tparam table avro avro schema node to be converted to nullable one
+---
+--- @result `result` (string or table) nullable avro type
+local function make_avro_type_nullable(avro)
+    assert(avro ~= nil, "avro must not be nil")
+
+    local value_type = type(avro)
+
+    if value_type == "string" then
+        return avro:endswith("*") and avro or (avro .. '*')
+    elseif value_type == "table" then
+        return make_avro_type_nullable(avro.type)
+    end
+
+    error("avro should be a string or a table, got " .. value_type)
+end
+
+--- Convert GraphQL type to avro-schema with selecting fields.
+---
+--- @tparam table fieldType GraphQL type
+---
+--- @tparam table subSelections fields to select from resulting avro-schema
+--- (internal graphql-lua format)
+---
+--- @tparam table context current traversal context, here it just falls to the
+--- called functions (internal graphql-lua format)
+---
+--- @tresult table `result` is the resulting avro-schema
+local function gql_type_to_avro(fieldType, subSelections, context)
+    local fieldTypeName = fieldType.__type
+    local isNonNull = false
+
+    -- In case the field is NonNull, the real type is in ofType attribute.
+    while fieldTypeName == 'NonNull' do
+        fieldType = fieldType.ofType
+        fieldTypeName = fieldType.__type
+        isNonNull = true
+    end
+
+    local result
+
+    if fieldTypeName == 'List' then
+        local innerType = fieldType.ofType
+        local innerTypeAvro = gql_type_to_avro(innerType, subSelections,
+            context)
+        result = {
+            type = "array",
+            items = innerTypeAvro,
+        }
+    elseif fieldTypeName == 'Scalar' then
+        result = gql_scalar_to_avro(fieldType)
+    elseif fieldTypeName == 'Object' then
+        result = object_to_avro(fieldType, subSelections, context)
+    elseif fieldTypeName == 'Interface' or fieldTypeName == 'Union' then
+        error('Interfaces and Unions are not supported yet')
+    else
+        error(string.format('Unknown type "%s"', tostring(fieldTypeName)))
+    end
+
+    if not isNonNull then
+        result = make_avro_type_nullable(result)
+    end
+    return result
+end
+
+--- The function converts a single Object field to avro format.
+local function field_to_avro(object_type, fields, context)
+    local firstField = fields[1]
+    assert(#fields == 1, "The aliases are not considered yet")
+    local fieldName = firstField.name.value
+    local fieldType = introspection.fieldMap[fieldName] or
+        object_type.fields[fieldName]
+    assert(fieldType ~= nil)
+    local subSelections = query_util.mergeSelectionSets(fields)
+
+    local fieldTypeAvro = gql_type_to_avro(fieldType.kind, subSelections,
+        context)
+    return {
+        name = fieldName,
+        type = fieldTypeAvro,
+    }
+end
+
+--- Convert GraphQL object to avro record.
+---
+--- @tparam table object_type GraphQL type object to be converted to Avro schema
+---
+--- @tparam table selections GraphQL representations of fields which should be
+--- in the output of the query
+---
+--- @tparam table context additional information for Avro schema generation; one
+--- of the fields is `namespace_parts` -- table of names of records from the
+--- root to the current object
+---
+--- @treturn table `result` is the corresponding Avro schema
+object_to_avro = function(object_type, selections, context)
+    local groupedFieldSet = query_util.collectFields(object_type, selections,
+        {}, {}, context)
+    local result = {
+        type = 'record',
+        name = object_type.name,
+        fields = {}
+    }
+    if #context.namespace_parts ~= 0 then
+        result.namespace = table.concat(context.namespace_parts, ".")
+    end
+    table.insert(context.namespace_parts, result.name)
+    for _, fields in pairs(groupedFieldSet) do
+        local avro_field = field_to_avro(object_type, fields, context)
+        table.insert(result.fields, avro_field)
+    end
+    context.namespace_parts[#context.namespace_parts] = nil
+    return result
+end
+
+--- Create an Avro schema for a given query.
+---
+--- @tparam table query object which avro schema should be created for
+---
+--- @treturn table `avro_schema` avro schema for any `query:execute()` result
+function query_to_avro.convert(query)
+    assert(type(query) == "table",
+        ('query should be a table, got: %s; ' ..
+        'hint: use ":" instead of "."'):format(type(table)))
+    local state = query.state
+    local context = query_util.buildContext(state.schema, query.ast, {}, {},
+        query.operation_name)
+    -- The variable is necessary to avoid fullname interferention.
+    -- Each nested Avro record creates it's namespace.
+    context.namespace_parts = {}
+    local rootType = state.schema[context.operation.operation]
+    local selections = context.operation.selectionSet.selections
+    return object_to_avro(rootType, selections, context)
+end
+
+return query_to_avro
diff --git a/graphql/tarantool_graphql.lua b/graphql/tarantool_graphql.lua
index a063c2b..db16799 100644
--- a/graphql/tarantool_graphql.lua
+++ b/graphql/tarantool_graphql.lua
@@ -14,6 +14,7 @@ local schema = require('graphql.core.schema')
 local types = require('graphql.core.types')
 local validate = require('graphql.core.validate')
 local execute = require('graphql.core.execute')
+local query_to_avro = require('graphql.query_to_avro')
 
 local utils = require('graphql.utils')
 
@@ -661,6 +662,7 @@ local function gql_compile(state, query)
     local gql_query = setmetatable(qstate, {
         __index = {
             execute = gql_execute,
+            avro_schema = query_to_avro.convert
         }
     })
     return gql_query
diff --git a/test/common/lua/test_data_user_order.lua b/test/common/lua/test_data_user_order.lua
index 5c6baad..14c8b5d 100644
--- a/test/common/lua/test_data_user_order.lua
+++ b/test/common/lua/test_data_user_order.lua
@@ -1,5 +1,28 @@
 local json = require('json')
 
+-- This module helps to write tests providing simple shop database.
+--
+-- Data layout
+--
+-- models:
+--  - user: Users of the shop.
+--    - id
+--    - first_name
+--    - last_name
+--  - order: Orders (shopping carts) of users. One user can has many orders.
+--    - id
+--    - user_id
+--    - description
+--  - item: Goods of the shop.
+--    - id
+--    - name
+--    - description
+--    - price
+--  - order_item: N:N connection emulation. That is how one order can have many
+--    itema and one item can be in different orders.
+--    - order_id
+--    - item_id
+
 local testdata = {}
 
 testdata.meta = {
@@ -21,6 +44,24 @@ testdata.meta = {
                 { "name": "user_id", "type": "int" },
                 { "name": "description", "type": "string" }
             ]
+        },
+        "item": {
+            "type": "record",
+            "name": "item",
+            "fields": [
+                { "name": "id", "type": "int" },
+                { "name": "description", "type": "string" },
+                { "name": "name", "type": "string" },
+                { "name": "price", "type": "string" }
+            ]
+        },
+        "order_item": {
+            "type": "record",
+            "name": "order_item",
+            "fields": [
+                { "name": "item_id", "type": "int" },
+                { "name": "order_id", "type": "int" }
+            ]
         }
     }]]),
     collections = json.decode([[{
@@ -32,7 +73,10 @@ testdata.meta = {
                     "name": "order_connection",
                     "destination_collection":  "order_collection",
                     "parts": [
-                        { "source_field": "id", "destination_field": "user_id" }
+                        {
+                            "source_field": "id",
+                            "destination_field": "user_id"
+                        }
                     ],
                     "index_name": "user_id_index"
                 }
@@ -41,16 +85,65 @@ testdata.meta = {
         "order_collection": {
             "schema_name": "order",
             "connections": [
+                {
+                    "type": "1:N",
+                    "name": "order__order_item",
+                    "destination_collection":  "order_item_collection",
+                    "parts": [
+                        {
+                            "source_field": "id",
+                            "destination_field": "order_id"
+                        }
+                    ],
+                    "index_name": "order_id_item_id_index"
+                },
                 {
                     "type": "1:1",
                     "name": "user_connection",
                     "destination_collection":  "user_collection",
                     "parts": [
-                        { "source_field": "user_id", "destination_field": "id" }
+                        {
+                            "source_field": "user_id",
+                            "destination_field": "id"
+                        }
                     ],
                     "index_name": "user_id_index"
                 }
             ]
+        },
+        "item_collection": {
+            "schema_name": "item",
+            "connections": [
+            ]
+        },
+        "order_item_collection": {
+            "schema_name": "order_item",
+            "connections": [
+                {
+                    "type": "1:1",
+                    "name": "order_item__order",
+                    "destination_collection":  "order_collection",
+                    "parts": [
+                        {
+                            "source_field": "order_id",
+                            "destination_field": "id"
+                        }
+                    ],
+                    "index_name": "order_id_index"
+                },
+                {
+                    "type": "1:1",
+                    "name": "order_item__item",
+                    "destination_collection":  "item_collection",
+                    "parts": [
+                        {
+                            "source_field": "item_id",
+                            "destination_field": "id"
+                        }
+                    ],
+                    "index_name": "item_id_index"
+                }
+            ]
         }
     }]]),
     service_fields = {
@@ -58,6 +151,8 @@ testdata.meta = {
             {name = 'created', type = 'long', default = 0},
         },
         order = {},
+        item = {},
+        order_item = {},
     },
     indexes = {
         user_collection = {
@@ -85,6 +180,24 @@ testdata.meta = {
                 primary = false,
             },
         },
+        item_collection = {
+            item_id_index = {
+                service_fields = {},
+                fields = {'id'},
+                index_type = 'tree',
+                unique = true,
+                primary = true
+            }
+        },
+        order_item_collection = {
+            order_id_item_id_index = {
+                service_fields = {},
+                fields = {'order_id', 'item_id'},
+                index_type = 'tree',
+                unique = true,
+                primary = true
+            }
+        }
     }
 }
 
@@ -112,26 +225,244 @@ function testdata.init_spaces()
         {type = 'tree', unique = false, parts = {
             O_USER_ID_FN, 'unsigned'
         }})
+    -- item_collection fields
+    local I_ITEM_ID_FN = 1
+    box.schema.create_space('item_collection')
+    box.space.item_collection:create_index('item_id_index',
+        {type = 'tree', unique = true, parts = {
+            I_ITEM_ID_FN, 'unsigned'
+        }})
+    -- order_item_collection fields
+    local OI_ORDER_ID_FN = 1
+    local OI_USER_ID_FN = 2
+    box.schema.create_space('order_item_collection')
+    box.space.order_item_collection:create_index('order_id_item_id_index',
+        {type = 'tree', unique = true, parts = {
+            OI_ORDER_ID_FN, 'unsigned', OI_USER_ID_FN, 'unsigned'
+        }})
 end
 
 function testdata.drop_spaces()
     box.space.user_collection:drop()
     box.space.order_collection:drop()
+    box.space.item_collection:drop()
+    box.space.order_item_collection:drop()
 end
 
+local items
 
 function testdata.fill_test_data(virtbox)
     local order_id = 1
-    for i = 1, 15 do
+    local item_id_max = #items
+    for _, item in ipairs(items) do
+       virtbox.item_collection:replace({
+           item.id, item.description, item.name, item.price
+       })
+    end
+    local order_item_cnt = 0
+    for user_id = 1, 15 do
         virtbox.user_collection:replace(
-            {1827767717, i, 'user fn ' .. i, 'user ln ' .. i})
+            { 1827767717, user_id, 'user fn ' .. user_id,
+            'user ln ' .. user_id })
         -- Each user has N orders, where `N = user id`
-        for j = 1, i do
-            virtbox.order_collection:replace(
-                {order_id, i, 'order of user ' .. i})
+        for i = 1, user_id do
+            virtbox.order_collection:replace({
+                order_id, user_id, 'order of user ' .. user_id
+            })
             order_id = order_id + 1
+            local items_cnt = 3
+            for k = 1, items_cnt do
+                order_item_cnt = order_item_cnt + 1
+                local item_id = order_item_cnt % item_id_max + 1
+                virtbox.order_item_collection:replace({
+                    order_id, item_id
+                })
+            end
         end
     end
 end
 
+items = {
+    {
+        id = 1,
+        description = "rhoncus. Nullam velit dui, semper",
+        name = "Salt",
+        price = "7.51"
+    },
+    {
+        id = 2,
+        description = "sit",
+        name = "butter",
+        price = "3.96"
+    },
+    {
+        id = 3,
+        description = "non,",
+        name = "onion",
+        price = "2.83"
+    },
+    {
+        id = 4,
+        description = "mauris",
+        name = "milk",
+        price = "3.53"
+    },
+    {
+        id = 5,
+        description = "Suspendisse tristique neque venenatis",
+        name = "Sausage",
+        price = "1.84"
+    },
+    {
+        id = 6,
+        description = "eget, dictum",
+        name = "Paper",
+        price = "7.83"
+    },
+    {
+        id = 7,
+        description = "lectus quis massa. Mauris",
+        name = "Freezer",
+        price = "5.47"
+    },
+    {
+        id = 8,
+        description = "ac",
+        name = "Stone",
+        price = "8.29"
+    },
+    {
+        id = 9,
+        description = "natoque penatibus et magnis dis",
+        name = "Silk",
+        price = "1.60"
+    },
+    {
+        id = 10,
+        description = "adipiscing",
+        name = "Leather",
+        price = "0.40"
+    },
+    {
+        id = 11,
+        description = "lobortis ultrices. Vivamus rhoncus.",
+        name = "Money",
+        price = "9.74"
+    },
+    {
+        id = 12,
+        description = "montes, nascetur ridiculus",
+        name = "Tree",
+        price = "8.52"
+    },
+    {
+        id = 13,
+        description = "In at pede. Cras vulputate",
+        name = "Garbage",
+        price = "1.88"
+    },
+    {
+        id = 14,
+        description = "dolor quam, elementum at,",
+        name = "Table",
+        price = "2.91"
+    },
+    {
+        id = 15,
+        description = "Donec dignissim",
+        name = "Wire",
+        price = "6.04"
+    },
+    {
+        id = 16,
+        description = "turpis nec mauris blandit",
+        name = "Cup",
+        price = "8.05"
+    },
+    {
+        id = 17,
+        description = "ornare placerat, orci",
+        name = "Blade",
+        price = "2.58"
+    },
+    {
+        id = 18,
+        description = "arcu. Sed",
+        name = "Tea",
+        price = "0.38"
+    },
+    {
+        id = 19,
+        description = "tempus risus. Donec egestas. Duis",
+        name = "Sveater",
+        price = "8.66"
+    },
+    {
+        id = 20,
+        description = "Quisque libero lacus, varius",
+        name = "Keyboard",
+        price = "3.74"
+    },
+    {
+        id = 21,
+        description = "faucibus orci luctus et ultrices",
+        name = "Shoes",
+        price = "2.21"
+    },
+    {
+        id = 22,
+        description = "rhoncus. Nullam velit",
+        name = "Lemon",
+        price = "3.70"
+    },
+    {
+        id = 23,
+        description = "justo sit amet",
+        name = "Orange",
+        price = "9.27"
+    },
+    {
+        id = 24,
+        description = "porttitor tellus non magna.",
+        name = "Pen",
+        price = "3.41"
+    },
+    {
+        id = 25,
+        description = "Suspendisse dui. Fusce diam",
+        name = "Screen",
+        price = "1.22"
+    },
+    {
+        id = 26,
+        description = "eleifend vitae, erat. Vivamus nisi.",
+        name = "Glass",
+        price = "8.59"
+    },
+    {
+        id = 27,
+        description = "tincidunt, nunc",
+        name = "Book",
+        price = "4.24"
+    },
+    {
+        id = 28,
+        description = "orci luctus et ultrices posuere",
+        name = "Mouse",
+        price = "7.73"
+    },
+    {
+        id = 29,
+        description = "in,",
+        name = "Doll",
+        price = "2.13"
+    },
+    {
+        id = 30,
+        description = "lobortis ultrices. Vivamus rhoncus.",
+        name = "Socks",
+        price = "0.91"
+    }
+}
+
 return testdata
diff --git a/test/extra/suite.ini b/test/extra/suite.ini
new file mode 100644
index 0000000..d4d1955
--- /dev/null
+++ b/test/extra/suite.ini
@@ -0,0 +1,8 @@
+[default]
+core = app
+description = tests on features which are not related to specific executor
+lua_libs =
+    ../common/lua/test_data_user_order.lua \
+    ../common/lua/test_data_nested_record.lua \
+    ../testdata/array_and_map_testdata.lua \
+	../testdata/nullable_index_testdata.lua
diff --git a/test/extra/to_avro_arrays.test.lua b/test/extra/to_avro_arrays.test.lua
new file mode 100755
index 0000000..4097a2e
--- /dev/null
+++ b/test/extra/to_avro_arrays.test.lua
@@ -0,0 +1,112 @@
+#!/usr/bin/env tarantool
+local fio = require('fio')
+local yaml = require('yaml')
+local avro = require('avro_schema')
+local testdata = require('array_and_map_testdata')
+local test = require('tap').test('to avro schema')
+-- require in-repo version of graphql/ sources despite current working directory
+package.path = fio.abspath(debug.getinfo(1).source:match("@?(.*/)")
+    :gsub('/./', '/'):gsub('/+$', '')) .. '/../../?.lua' .. ';' ..
+    package.path
+
+local graphql = require('graphql')
+
+box.cfg{wal_mode="none"}
+test:plan(4)
+
+testdata.init_spaces()
+testdata.fill_test_data()
+local meta = testdata.get_test_metadata()
+
+local accessor = graphql.accessor_space.new({
+    schemas = meta.schemas,
+    collections = meta.collections,
+    service_fields = meta.service_fields,
+    indexes = meta.indexes,
+})
+
+local gql_wrapper = graphql.new({
+    schemas = meta.schemas,
+    collections = meta.collections,
+    accessor = accessor,
+})
+
+-- We do not select `customer_balances` and `favorite_holidays` because thay are
+-- is of `Map` type, which is not supported.
+local query = [[
+    query user_holidays($user_id: String) {
+        user_collection(user_id: $user_id) {
+            user_id
+            favorite_food
+            user_balances {
+                value
+            }
+        }
+    }
+]]
+local expected_avro_schema = [[
+type: record
+name: Query
+fields:
+- name: user_collection
+  type:
+    type: array
+    items:
+      type: record
+      fields:
+      - name: user_id
+        type: string
+      - name: user_balances
+        type:
+          type: array
+          items:
+            type: record
+            fields:
+            - name: value
+              type: int
+            name: balance
+            namespace: Query.user_collection
+      - name: favorite_food
+        type:
+          type: array
+          items: string
+      name: user_collection
+      namespace: Query
+]]
+expected_avro_schema = yaml.decode(expected_avro_schema)
+local gql_query = gql_wrapper:compile(query)
+local variables = {
+    user_id = 'user_id_1',
+}
+
+local avros = gql_query:avro_schema()
+
+test:is_deeply(avros, expected_avro_schema, "generated avro schema")
+local result_expected = [[
+user_collection:
+- user_id: user_id_1
+  user_balances:
+  - value: 33
+  - value: 44
+  favorite_food:
+  - meat
+  - potato
+]]
+result_expected = yaml.decode(result_expected)
+local result = gql_query:execute(variables)
+test:is_deeply(result, result_expected, 'graphql qury exec result')
+local ok, ash, r, fs, _
+ok, ash = avro.create(avros)
+assert(ok)
+ok, _ = avro.validate(ash, result)
+assert(ok)
+test:is(ok, true, 'gql result validation by avro')
+ok, fs = avro.compile(ash)
+assert(ok)
+ok, r = fs.flatten(result)
+assert(ok)
+ok, r = fs.unflatten(r)
+assert(ok)
+test:is_deeply(r, result_expected, 'res = unflatten(flatten(res))')
+
+os.exit(test:check() == true and 0 or 1)
diff --git a/test/extra/to_avro_huge.test.lua b/test/extra/to_avro_huge.test.lua
new file mode 100755
index 0000000..072efef
--- /dev/null
+++ b/test/extra/to_avro_huge.test.lua
@@ -0,0 +1,267 @@
+#!/usr/bin/env tarantool
+local fio = require('fio')
+local yaml = require('yaml')
+local avro = require('avro_schema')
+local data = require('test_data_user_order')
+local test = require('tap').test('to avro schema')
+-- require in-repo version of graphql/ sources despite current working directory
+package.path = fio.abspath(debug.getinfo(1).source:match("@?(.*/)")
+    :gsub('/./', '/'):gsub('/+$', '')) .. '/../../?.lua' .. ';' ..
+    package.path
+
+local graphql = require('graphql')
+
+box.cfg{wal_mode="none"}
+test:plan(4)
+
+data.init_spaces()
+data.fill_test_data(box.space)
+
+local accessor = graphql.accessor_space.new({
+    schemas = data.meta.schemas,
+    collections = data.meta.collections,
+    service_fields = data.meta.service_fields,
+    indexes = data.meta.indexes,
+})
+
+local gql_wrapper = graphql.new({
+    schemas = data.meta.schemas,
+    collections = data.meta.collections,
+    accessor = accessor,
+})
+
+local query = [[
+    query object_result_max($user_id: Int, $order_id: Int) {
+        user_collection(id: $user_id) {
+            id
+            last_name
+            first_name
+            order_connection(limit: 1) {
+                id
+                user_id
+                description
+                order__order_item {
+                    order_id
+                    item_id
+                    order_item__item{
+                        id
+                        name
+                        description
+                        price
+                    }
+                }
+            }
+        },
+        order_collection(id: $order_id) {
+            id
+            description
+            user_connection {
+                id
+                first_name
+                last_name
+                order_connection(limit: 1) {
+                    id
+                    order__order_item {
+                        order_item__item {
+                            name
+                            price
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+]]
+local expected_avro_schema = [[
+type: record
+name: Query
+fields:
+- name: user_collection
+  type:
+    type: array
+    items:
+      type: record
+      fields:
+      - name: order_connection
+        type:
+          type: array
+          items:
+            type: record
+            fields:
+            - name: user_id
+              type: int
+            - name: order__order_item
+              type:
+                type: array
+                items:
+                  type: record
+                  fields:
+                  - name: order_id
+                    type: int
+                  - name: item_id
+                    type: int
+                  - name: order_item__item
+                    type:
+                      type: record
+                      fields:
+                      - name: description
+                        type: string
+                      - name: price
+                        type: string
+                      - name: name
+                        type: string
+                      - name: id
+                        type: int
+                      name: item_collection
+                      namespace: Query.user_collection.order_collection.order_item_collection
+                  name: order_item_collection
+                  namespace: Query.user_collection.order_collection
+            - name: description
+              type: string
+            - name: id
+              type: int
+            name: order_collection
+            namespace: Query.user_collection
+      - name: last_name
+        type: string
+      - name: first_name
+        type: string
+      - name: id
+        type: int
+      name: user_collection
+      namespace: Query
+- name: order_collection
+  type:
+    type: array
+    items:
+      type: record
+      fields:
+      - name: user_connection
+        type:
+          type: record
+          fields:
+          - name: order_connection
+            type:
+              type: array
+              items:
+                type: record
+                fields:
+                - name: order__order_item
+                  type:
+                    type: array
+                    items:
+                      type: record
+                      fields:
+                      - name: order_item__item
+                        type:
+                          type: record
+                          fields:
+                          - name: name
+                            type: string
+                          - name: price
+                            type: string
+                          name: item_collection
+                          namespace: Query.order_collection.user_collection.order_collection.order_item_collection
+                      name: order_item_collection
+                      namespace: Query.order_collection.user_collection.order_collection
+                - name: id
+                  type: int
+                name: order_collection
+                namespace: Query.order_collection.user_collection
+          - name: last_name
+            type: string
+          - name: first_name
+            type: string
+          - name: id
+            type: int
+          name: user_collection
+          namespace: Query.order_collection
+      - name: id
+        type: int
+      - name: description
+        type: string
+      name: order_collection
+      namespace: Query
+
+]]
+expected_avro_schema = yaml.decode(expected_avro_schema)
+local gql_query = gql_wrapper:compile(query)
+local variables = {
+    user_id = 5,
+    order_id = 20
+}
+
+local avros = gql_query:avro_schema()
+test:is_deeply(avros, expected_avro_schema, "generated avro schema")
+local result_expected = [[
+user_collection:
+- order_connection:
+  - user_id: 5
+    id: 11
+    description: order of user 5
+    order__order_item:
+    - order_id: 1
+      item_id: 11
+      order_item__item:
+        id: 11
+        price: '9.74'
+        name: Money
+        description: lobortis ultrices. Vivamus rhoncus.
+    - order_id: 29
+      item_id: 11
+      order_item__item:
+        id: 11
+        price: '9.74'
+        name: Money
+        description: lobortis ultrices. Vivamus rhoncus.
+    - order_id: 30
+      item_id: 11
+      order_item__item:
+        id: 11
+        price: '9.74'
+        name: Money
+        description: lobortis ultrices. Vivamus rhoncus.
+  last_name: user ln 5
+  first_name: user fn 5
+  id: 5
+order_collection:
+- description: order of user 6
+  user_connection:
+    order_connection:
+    - id: 16
+      order__order_item:
+      - order_item__item:
+          name: Cup
+          price: '8.05'
+      - order_item__item:
+          name: Cup
+          price: '8.05'
+      - order_item__item:
+          name: Cup
+          price: '8.05'
+    last_name: user ln 6
+    first_name: user fn 6
+    id: 6
+  id: 20
+]]
+result_expected = yaml.decode(result_expected)
+local result = gql_query:execute(variables)
+test:is_deeply(result, result_expected, 'graphql qury exec result')
+local ok, ash, r, fs, _
+ok, ash = avro.create(avros)
+assert(ok)
+ok, _ = avro.validate(ash, result)
+assert(ok)
+test:is(ok, true, 'gql result validation by avro')
+ok, fs = avro.compile(ash)
+assert(ok)
+ok, r = fs.flatten(result)
+assert(ok)
+ok, r = fs.unflatten(r)
+-- The test can fail if wrong avro-schema version is installed.
+-- Please install avro-schema >= fea0ead9d1.
+assert(ok)
+test:is_deeply(r, result_expected, 'res = unflatten(flatten(res))')
+
+os.exit(test:check() == true and 0 or 1)
diff --git a/test/extra/to_avro_nested.test.lua b/test/extra/to_avro_nested.test.lua
new file mode 100755
index 0000000..3335bca
--- /dev/null
+++ b/test/extra/to_avro_nested.test.lua
@@ -0,0 +1,110 @@
+#!/usr/bin/env tarantool
+local fio = require('fio')
+local yaml = require('yaml')
+local avro = require('avro_schema')
+local data = require('test_data_nested_record')
+local test = require('tap').test('to avro schema')
+-- require in-repo version of graphql/ sources despite current working directory
+package.path = fio.abspath(debug.getinfo(1).source:match("@?(.*/)")
+    :gsub('/./', '/'):gsub('/+$', '')) .. '/../../?.lua' .. ';' ..
+    package.path
+
+local graphql = require('graphql')
+
+box.cfg{wal_mode="none"}
+test:plan(4)
+
+data.init_spaces()
+data.fill_test_data(box.space)
+
+local accessor = graphql.accessor_space.new({
+    schemas = data.meta.schemas,
+    collections = data.meta.collections,
+    service_fields = data.meta.service_fields,
+    indexes = data.meta.indexes,
+})
+
+local gql_wrapper = graphql.new({
+    schemas = data.meta.schemas,
+    collections = data.meta.collections,
+    accessor = accessor,
+})
+
+local query = [[
+    query getUserByUid($uid: Long) {
+        user(uid: $uid) {
+            uid
+            p1
+            p2
+            nested {
+                x
+                y
+            }
+        }
+    }
+]]
+local expected_avro_schema = [[
+type: record
+name: Query
+fields:
+- name: user
+  type:
+    type: array
+    items:
+      type: record
+      fields:
+      - name: p2
+        type: string
+      - name: p1
+        type: string
+      - name: uid
+        type: long
+      - name: nested
+        type:
+          type: record
+          fields:
+          - name: y
+            type: long
+          - name: x
+            type: long
+          name: nested
+          namespace: Query.user
+      name: user
+      namespace: Query
+]]
+expected_avro_schema = yaml.decode(expected_avro_schema)
+local gql_query = gql_wrapper:compile(query)
+local variables = {
+    uid = 1,
+}
+
+local avros = gql_query:avro_schema()
+
+test:is_deeply(avros, expected_avro_schema, "generated avro schema")
+local result_expected = [[
+user:
+- p2: p2 1
+  p1: p1 1
+  uid: 1
+  nested:
+    y: 2001
+    x: 1001
+]]
+result_expected = yaml.decode(result_expected)
+local result = gql_query:execute(variables)
+test:is_deeply(result, result_expected, 'graphql qury exec result')
+local ok, ash, r, fs, _
+ok, ash = avro.create(avros)
+assert(ok)
+ok, _ = avro.validate(ash, result)
+assert(ok)
+test:is(ok, true, 'gql result validation by avro')
+ok, fs = avro.compile(ash)
+assert(ok)
+ok, r = fs.flatten(result)
+assert(ok)
+ok, r = fs.unflatten(r)
+assert(ok)
+test:is_deeply(r, result_expected, 'res = unflatten(flatten(res))')
+
+os.exit(test:check() == true and 0 or 1)
diff --git a/test/extra/to_avro_nullable.test.lua b/test/extra/to_avro_nullable.test.lua
new file mode 100755
index 0000000..d54ce11
--- /dev/null
+++ b/test/extra/to_avro_nullable.test.lua
@@ -0,0 +1,98 @@
+#!/usr/bin/env tarantool
+local fio = require('fio')
+local yaml = require('yaml')
+local avro = require('avro_schema')
+local testdata = require('nullable_index_testdata')
+local test = require('tap').test('to avro schema')
+-- require in-repo version of graphql/ sources despite current working directory
+package.path = fio.abspath(debug.getinfo(1).source:match("@?(.*/)")
+    :gsub('/./', '/'):gsub('/+$', '')) .. '/../../?.lua' .. ';' ..
+    package.path
+
+local graphql = require('graphql')
+
+box.cfg{wal_mode="none"}
+test:plan(4)
+
+testdata.init_spaces()
+testdata.fill_test_data()
+local meta = testdata.get_test_metadata()
+
+local accessor = graphql.accessor_space.new({
+    schemas = meta.schemas,
+    collections = meta.collections,
+    service_fields = meta.service_fields,
+    indexes = meta.indexes,
+})
+
+local gql_wrapper = graphql.new({
+    schemas = meta.schemas,
+    collections = meta.collections,
+    accessor = accessor,
+})
+
+-- We do not select `customer_balances` and `favorite_holidays` because thay are
+-- is of `Map` type, which is not supported.
+local query = [[
+   query get_foo($id: String) {
+        bar(id: $id) {
+            id
+            id_or_null_1
+            id_or_null_2
+            id_or_null_3
+        }
+    }
+]]
+local expected_avro_schema = [[
+type: record
+name: Query
+fields:
+- name: bar
+  type:
+    type: array
+    items:
+      type: record
+      fields:
+      - name: id_or_null_1
+        type: string*
+      - name: id_or_null_3
+        type: string*
+      - name: id_or_null_2
+        type: string*
+      - name: id
+        type: string
+      name: bar
+      namespace: Query
+]]
+expected_avro_schema = yaml.decode(expected_avro_schema)
+local gql_query = gql_wrapper:compile(query)
+local variables = {
+    id = '101',
+}
+
+local avros = gql_query:avro_schema()
+
+test:is_deeply(avros, expected_avro_schema, "generated avro schema")
+local result_expected = [[
+bar:
+- id_or_null_3: '101'
+  id_or_null_2: '101'
+  id: '101'
+]]
+result_expected = yaml.decode(result_expected)
+local result = gql_query:execute(variables)
+test:is_deeply(result, result_expected, 'graphql query exec result')
+local ok, ash = avro.create(avros)
+assert(ok, tostring(ash))
+local ok, err = avro.validate(ash, result)
+assert(ok, tostring(err))
+test:is(ok, true, 'gql result validation by avro')
+local ok, fs = avro.compile(ash)
+assert(ok, tostring(fs))
+local ok, r = fs.flatten(result)
+assert(ok, tostring(r))
+local ok, r = fs.unflatten(r)
+assert(ok, tostring(r))
+test:is_deeply(r, result_expected, 'res = unflatten(flatten(res))')
+
+os.exit(test:check() == true and 0 or 1)