diff --git a/CHANGELOG.md b/CHANGELOG.md
index eba086696..911b009f4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 - Computed columns now only work if they belong to the db-schema - @steve-chavez
 - To use RPC now the `json_to_record/json_to_recordset` functions are needed, these are available starting from PostgreSQL 9.4 - @steve-chavez
+- Overloaded functions now depend on the `dbStructure`, restart/sighup may be needed for their correct functioning - @steve-chavez
 
 ## [0.4.4.0] - 2018-01-08
 
diff --git a/src/PostgREST/ApiRequest.hs b/src/PostgREST/ApiRequest.hs
index 1f8b3ac3e..cec3bfdda 100644
--- a/src/PostgREST/ApiRequest.hs
+++ b/src/PostgREST/ApiRequest.hs
@@ -95,8 +95,6 @@ data ApiRequest = ApiRequest {
   , iHeaders :: [(Text, Text)]
   -- | Request Cookies
   , iCookies :: [(Text, Text)]
-  -- | Rpc query params e.g. /rpc/name?param1=val1, similar to filter but with no operator(eq, lt..)
-  , iRpcQParams :: [(Text, Text)]
   }
 
 -- | Examines HTTP request and translates it into user intent.
@@ -116,7 +114,6 @@ userApiRequest schema req reqBody
       , iPreferSingleObjectParameter = singleObject
       , iPreferCount = hasPrefer "count=exact"
       , iFilters = filters
-      , iRpcQParams = rpcQParams
       , iLogic = [(toS k, toS $ fromJust v) | (k,v) <- qParams, isJust v, endingIn ["and", "or"] k ]
       , iSelect = toS $ fromMaybe "*" $ fromMaybe (Just "*") $ lookup "select" qParams
       , iOrder = [(toS k, toS $ fromJust v) | (k,v) <- qParams, isJust v, endingIn ["order"] k ]
@@ -130,6 +127,7 @@ userApiRequest schema req reqBody
       , iCookies = fromMaybe [] $ parseCookiesText <$> lookupHeader "Cookie"
       }
  where
+  -- rpcQParams = Rpc query params e.g. /rpc/name?param1=val1, similar to filter but with no operator(eq, lt..)
   (filters, rpcQParams) =
     case action of
       ActionInvoke{isReadOnly=True} -> partition (liftM2 (||) (isEmbedPath . fst) (hasOperator . snd)) flts
@@ -141,20 +139,22 @@ userApiRequest schema req reqBody
   isEmbedPath = T.isInfixOf "."
   isTargetingProc = fromMaybe False $ (== "rpc") <$> listToMaybe path
   payload =
-    case decodeContentType . fromMaybe "application/json" $ lookupHeader "content-type" of
-      CTApplicationJSON ->
-        note "All object keys must match" . consPayloadJSON reqBody
+    case (decodeContentType . fromMaybe "application/json" $ lookupHeader "content-type", action) of
+      (_, ActionInvoke{isReadOnly=True}) ->
+        Right $ PayloadJSON (JSON.encode $ M.fromList $ second JSON.toJSON <$> rpcQParams) PJObject (S.fromList $ fst <$> rpcQParams)
+      (CTApplicationJSON, _) ->
+        note "All object keys must match" . payloadAttributes reqBody
           =<< if BL.null reqBody && isTargetingProc
                then Right emptyObject
                else JSON.eitherDecode reqBody
-      CTTextCSV -> do
+      (CTTextCSV, _) -> do
         json <- csvToJson <$> CSV.decodeByName reqBody
-        note "All lines must have same number of fields" $ consPayloadJSON (JSON.encode json) json
-      CTOther "application/x-www-form-urlencoded" ->
+        note "All lines must have same number of fields" $ payloadAttributes (JSON.encode json) json
+      (CTOther "application/x-www-form-urlencoded", _) ->
         let json = M.fromList . map (toS *** JSON.String . toS) . parseSimpleQuery $ toS reqBody
             keys = S.fromList $ M.keys json in
         Right $ PayloadJSON (JSON.encode json) PJObject keys
-      ct ->
+      (ct, _) ->
         Left $ toS $ "Content-Type not acceptable: " <> toMime ct
   topLevelRange = fromMaybe allRange $ M.lookup "limit" ranges
   action =
@@ -177,9 +177,8 @@ userApiRequest schema req reqBody
               ["rpc", proc] -> TargetProc
                               $ QualifiedIdentifier schema proc
               other         -> TargetUnknown other
-  shouldParsePayload = action `elem` [ActionCreate, ActionUpdate, ActionInvoke{isReadOnly=False}]
-  relevantPayload | action == ActionInvoke{isReadOnly=True} = Nothing
-                  | shouldParsePayload = rightToMaybe payload
+  shouldParsePayload = action `elem` [ActionCreate, ActionUpdate, ActionInvoke{isReadOnly=False}, ActionInvoke{isReadOnly=True}]
+  relevantPayload | shouldParsePayload = rightToMaybe payload
                   | otherwise = Nothing
   path            = pathInfo req
   method          = requestMethod req
@@ -274,8 +273,8 @@ csvToJson (_, vals) =
           else JSON.String $ toS str
       )
 
-consPayloadJSON :: BL.ByteString -> JSON.Value -> Maybe PayloadJSON
-consPayloadJSON raw json =
+payloadAttributes :: RequestBody -> JSON.Value -> Maybe PayloadJSON
+payloadAttributes raw json =
   -- Test that Array contains only Objects having the same keys
   case json of
     JSON.Array arr ->
diff --git a/src/PostgREST/App.hs b/src/PostgREST/App.hs
index ea449c5a1..2733a37c1 100644
--- a/src/PostgREST/App.hs
+++ b/src/PostgREST/App.hs
@@ -38,7 +38,6 @@ import           PostgREST.Config          (AppConfig (..))
 import           PostgREST.DbStructure
 import           PostgREST.DbRequestBuilder( readRequest
                                            , mutateRequest
-                                           , readRpcRequest
                                            , fieldNames
                                            )
 import           PostgREST.Error           ( simpleError, pgError
@@ -79,35 +78,44 @@ postgrest conf refDbStructure pool worker =
             eClaims <- jwtClaims jwtSecret (configJwtAudience conf) (toS $ iJWT apiRequest)
 
             let authed = containsRole eClaims
-                handleReq = runWithClaims conf eClaims (app dbStructure conf) apiRequest
-                txMode = transactionMode dbStructure
-                  (iTarget apiRequest) (iAction apiRequest)
+                proc = case (iTarget apiRequest, iPayload apiRequest, iPreferSingleObjectParameter apiRequest) of
+                  (TargetProc qi, Just PayloadJSON{pjKeys=pKeys}, s) -> findProc qi pKeys s $ dbProcs dbStructure
+                  _ -> Nothing
+                handleReq = runWithClaims conf eClaims (app dbStructure proc conf) apiRequest
+                txMode = transactionMode proc (iAction apiRequest)
             response <- P.use pool $ HT.transaction HT.ReadCommitted txMode handleReq
             return $ either (pgError authed) identity response
         when (responseStatus response == status503) worker
         respond response
 
-transactionMode :: DbStructure -> Target -> Action -> H.Mode
-transactionMode structure target action =
+findProc :: QualifiedIdentifier -> S.Set Text -> Bool -> M.HashMap Text [ProcDescription] -> Maybe ProcDescription
+findProc qi payloadKeys paramsAsSingleObject allProcs =
+  let procs = M.lookup (qiName qi) allProcs in
+ -- Handle overloaded functions case
+  join $ (case length <$> procs of
+    Just 1 -> headMay -- if it's not an overloaded function then immediatly get the ProcDescription
+    _ -> find (\x ->
+           if paramsAsSingleObject
+             then length (pdArgs x) == 1 -- if the arg is not of json type let the db give the err
+             else payloadKeys `S.isSubsetOf` S.fromList (pgaName <$> pdArgs x))
+  ) <$> procs
+
+transactionMode :: Maybe ProcDescription -> Action -> H.Mode
+transactionMode proc action =
   case action of
     ActionRead -> HT.Read
     ActionInfo -> HT.Read
     ActionInspect -> HT.Read
     ActionInvoke{isReadOnly=False} ->
-      let proc =
-            case target of
-              (TargetProc qi) -> M.lookup (qiName qi) $
-                                   dbProcs structure
-              _               -> Nothing
-          v = fromMaybe Volatile $ pdVolatility <$> proc in
+      let v = fromMaybe Volatile $ pdVolatility <$> proc in
       if v == Stable || v == Immutable
          then HT.Read
          else HT.Write
     ActionInvoke{isReadOnly=True} -> HT.Read
     _ -> HT.Write
 
-app :: DbStructure -> AppConfig -> ApiRequest -> H.Transaction Response
-app dbStructure conf apiRequest =
+app :: DbStructure -> Maybe ProcDescription -> AppConfig -> ApiRequest -> H.Transaction Response
+app dbStructure proc conf apiRequest =
   case responseContentTypeOrError (iAccepts apiRequest) (iAction apiRequest) of
     Left errorResponse -> return errorResponse
     Right contentType ->
@@ -140,13 +148,13 @@ app dbStructure conf apiRequest =
           case mutateSqlParts of
             Left errorResponse -> return errorResponse
             Right (sq, mq) -> do
-              let (isSingle, rows) = case pType of
-                                       PJArray len -> (len == 1, len)
-                                       PJObject -> (True, 1)
+              let (isSingle, nRows) = case pType of
+                                        PJArray len -> (len == 1, len)
+                                        PJObject -> (True, 1)
               if contentType == CTSingularJSON
                  && not isSingle
                  && iPreferRepresentation apiRequest == Full
-                then return $ singularityError (toInteger rows)
+                then return $ singularityError (toInteger nRows)
                 else do
                   let pKeys = map pkName $ filter (filterPk schema table) allPrKeys -- would it be ok to move primary key detection in the query itself?
                       stm = createWriteStatement sq mq
@@ -163,7 +171,7 @@ app dbStructure conf apiRequest =
                             then Just $ toHeader contentType
                             else Nothing
                         , Just . contentRangeH 1 0 $
-                            toInteger <$> if shouldCount then Just rows else Nothing
+                            toInteger <$> if shouldCount then Just nRows else Nothing
                         ]
 
                   return . responseLBS status201 headers $
@@ -228,31 +236,28 @@ app dbStructure conf apiRequest =
               let acceptH = (hAllow, if tableInsertable table then "GET,POST,PATCH,DELETE" else "GET") in
               return $ responseLBS status200 [allOrigins, acceptH] ""
 
-        (ActionInvoke _isReadOnly, TargetProc qi, payload) ->
-          let proc = M.lookup (qiName qi) allProcs
-              returnsScalar = case proc of
+        (ActionInvoke _, TargetProc qi, Just (PayloadJSON payload pType pKeys)) ->
+          let returnsScalar = case proc of
                 Just ProcDescription{pdReturnType = (Single (Scalar _))} -> True
                 _ -> False
               rpcBinaryField = if returnsScalar
                                  then Right Nothing
                                  else binaryField contentType =<< fldNames
-              parts = (,,) <$> readSqlParts <*> rpcBinaryField <*> rpcQParams in
+              parts = (,) <$> readSqlParts <*> rpcBinaryField in
           case parts of
             Left errorResponse -> return errorResponse
-            Right ((q, cq), bField, params) -> do
-              let (prms, keys, isObject) = case payload of
-                          Just (PayloadJSON p (PJArray _) ks) -> (p, ks, False)
-                          Just (PayloadJSON p PJObject ks)  -> (p, ks, True)
-                          Nothing -> (JSON.encode $ M.fromList $ second JSON.toJSON <$> params, S.fromList $ fst <$> params, True)
+            Right ((q, cq), bField) -> do
+              let isObject = case pType of
+                                PJObject  -> True
+                                PJArray _ -> False
                   singular = contentType == CTSingularJSON
-                  paramsAsSingleObject = iPreferSingleObjectParameter apiRequest
-                  specifiedPgArgs = filter (flip S.member keys . pgaName) $ fromMaybe [] (pdArgs <$> proc)
-              row <- H.query (toS prms) $
+                  specifiedPgArgs = filter ((`S.member` pKeys) . pgaName) $ fromMaybe [] (pdArgs <$> proc)
+              row <- H.query (toS payload) $
                 callProc qi specifiedPgArgs returnsScalar q cq shouldCount
-                         singular paramsAsSingleObject
+                         singular (iPreferSingleObjectParameter apiRequest)
                          (contentType == CTTextCSV)
-                         (contentType == CTOctetStream) _isReadOnly bField
-                         isObject (pgVersion dbStructure)
+                         (contentType == CTOctetStream) bField isObject
+                         (pgVersion dbStructure)
               let (tableTotal, queryTotal, body, jsonHeaders) =
                     fromMaybe (Just 0, 0, "[]", "[]") row
                   (status, contentRange) = rangeHeader queryTotal tableTotal
@@ -273,7 +278,7 @@ app dbStructure conf apiRequest =
               uri Nothing = ("http", host, port, "/")
               uri (Just Proxy { proxyScheme = s, proxyHost = h, proxyPort = p, proxyPath = b }) = (s, h, p, b)
               uri' = uri proxy
-              encodeApi ti sd procs = encodeOpenAPI (M.elems procs) (toTableInfo ti) uri' sd (dbPrimaryKeys dbStructure)
+              encodeApi ti sd procs = encodeOpenAPI (concat $ M.elems procs) (toTableInfo ti) uri' sd (dbPrimaryKeys dbStructure)
           body <- encodeApi <$> H.query schema accessibleTables <*> H.query schema schemaDescription <*> H.query schema accessibleProcs
           return $ responseLBS status200 [toHeader CTOpenAPI] $ toS body
 
@@ -292,7 +297,6 @@ app dbStructure conf apiRequest =
       filterCol :: Schema -> TableName -> Column -> Bool
       filterCol sc tb Column{colTable=Table{tableSchema=s, tableName=t}} = s==sc && t==tb
       allPrKeys = dbPrimaryKeys dbStructure
-      allProcs = dbProcs dbStructure
       allOrigins = ("Access-Control-Allow-Origin", "*") :: Header
       shouldCount = iPreferCount apiRequest
       schema = toS $ configSchema conf
@@ -304,11 +308,10 @@ app dbStructure conf apiRequest =
             status = rangeStatus lower upper (toInteger <$> tableTotal)
         in (status, contentRange)
 
-      readReq = readRequest (configMaxRows conf) (dbRelations dbStructure) allProcs apiRequest
+      readReq = readRequest (configMaxRows conf) (dbRelations dbStructure) proc apiRequest
       fldNames = fieldNames <$> readReq
       readDbRequest = DbRead <$> readReq
       mutateDbRequest = DbMutate <$> (mutateRequest apiRequest =<< fldNames)
-      rpcQParams = readRpcRequest apiRequest
       selectQuery = requestToQuery schema False <$> readDbRequest
       mutateQuery = requestToQuery schema False <$> mutateDbRequest
       countQuery = requestToCountQuery schema <$> readDbRequest
diff --git a/src/PostgREST/DbRequestBuilder.hs b/src/PostgREST/DbRequestBuilder.hs
index 601d70957..be1a53c05 100644
--- a/src/PostgREST/DbRequestBuilder.hs
+++ b/src/PostgREST/DbRequestBuilder.hs
@@ -3,7 +3,6 @@
 module PostgREST.DbRequestBuilder (
   readRequest
 , mutateRequest
-, readRpcRequest
 , fieldNames
 ) where
 
@@ -37,8 +36,8 @@ import           Protolude                hiding (from, dropWhile, drop)
 import           Text.Regex.TDFA         ((=~))
 import           Unsafe                  (unsafeHead)
 
-readRequest :: Maybe Integer -> [Relation] -> M.HashMap Text ProcDescription -> ApiRequest -> Either Response ReadRequest
-readRequest maxRows allRels allProcs apiRequest  =
+readRequest :: Maybe Integer -> [Relation] -> Maybe ProcDescription -> ApiRequest -> Either Response ReadRequest
+readRequest maxRows allRels proc apiRequest  =
   mapLeft apiRequestError $
   treeRestrictRange maxRows =<<
   augumentRequestWithJoin schema relations =<<
@@ -48,13 +47,12 @@ readRequest maxRows allRels allProcs apiRequest  =
       let target = iTarget apiRequest in
       case target of
         (TargetIdent (QualifiedIdentifier s t) ) -> Just (s, t)
-        (TargetProc  (QualifiedIdentifier s proc) ) -> Just (s, tName)
+        (TargetProc  (QualifiedIdentifier s pName) ) -> Just (s, tName)
           where
-            retType = pdReturnType <$> M.lookup proc allProcs
-            tName = case retType of
+            tName = case pdReturnType <$> proc of
               Just (SetOf (Composite qi)) -> qiName qi
               Just (Single (Composite qi)) -> qiName qi
-              _ -> proc
+              _ -> pName
 
         _ -> Nothing
 
@@ -327,11 +325,6 @@ mutateRequest apiRequest fldNames = mapLeft apiRequestError $
     (mutateFilters, logicFilters) = join (***) onlyRoot (iFilters apiRequest, iLogic apiRequest)
     onlyRoot = filter (not . ( "." `isInfixOf` ) . fst)
 
-readRpcRequest :: ApiRequest -> Either Response [RpcQParam]
-readRpcRequest apiRequest = mapLeft apiRequestError rpcQParams
-  where
-    rpcQParams = mapM pRequestRpcQParam $ iRpcQParams apiRequest
-
 fieldNames :: ReadRequest -> [FieldName]
 fieldNames (Node (sel, _) forest) =
   map (fst . view _1) (select sel) ++ map colName fks
diff --git a/src/PostgREST/DbStructure.hs b/src/PostgREST/DbStructure.hs
index 25b024b75..cec3c7623 100644
--- a/src/PostgREST/DbStructure.hs
+++ b/src/PostgREST/DbStructure.hs
@@ -103,9 +103,10 @@ decodeSynonyms cols =
     <*> HD.value HD.text <*> HD.value HD.text
     <*> HD.value HD.text <*> HD.value HD.text
 
-decodeProcs :: HD.Result (M.HashMap Text ProcDescription)
+decodeProcs :: HD.Result (M.HashMap Text [ProcDescription])
 decodeProcs =
-  M.fromList . map addName <$> HD.rowsList tblRow
+  -- Duplicate rows for a function means they're overloaded, order these by least args according to ProcDescription Ord instance
+  map sort . M.fromListWith (++) . map ((\(x,y) -> (x, [y])) . addName) <$> HD.rowsList tblRow
   where
     tblRow = ProcDescription
               <$> HD.value HD.text
@@ -152,10 +153,10 @@ decodeProcs =
                       | v == 's' = Stable
                       | otherwise = Volatile -- only 'v' can happen here
 
-allProcs :: H.Query Schema (M.HashMap Text ProcDescription)
+allProcs :: H.Query Schema (M.HashMap Text [ProcDescription])
 allProcs = H.statement (toS procsSqlQuery) (HE.value HE.text) decodeProcs True
 
-accessibleProcs :: H.Query Schema (M.HashMap Text ProcDescription)
+accessibleProcs :: H.Query Schema (M.HashMap Text [ProcDescription])
 accessibleProcs = H.statement (toS sql) (HE.value HE.text) decodeProcs True
   where
     sql = procsSqlQuery <> " AND has_function_privilege(p.oid, 'execute')"
diff --git a/src/PostgREST/Parsers.hs b/src/PostgREST/Parsers.hs
index 1b4edf25c..769b0eaa7 100644
--- a/src/PostgREST/Parsers.hs
+++ b/src/PostgREST/Parsers.hs
@@ -47,12 +47,6 @@ pRequestLogicTree (k, v) = mapError $ (,) <$> embedPath <*> logicTree
     -- Concat op and v to make pLogicTree argument regular, in the form of "?and=and(.. , ..)" instead of "?and=(.. , ..)"
     logicTree = join $ parse pLogicTree ("failed to parse logic tree (" ++ toS v ++ ")") . toS <$> ((<>) <$> op <*> pure v)
 
-pRequestRpcQParam :: (Text, Text) -> Either ApiRequestError RpcQParam
-pRequestRpcQParam (k, v) = mapError $ (,) <$> name <*> val
-  where
-    name = parse pFieldName ("failed to parse rpc arg name (" ++ toS k ++ ")") $ toS k
-    val = toS <$> parse (many anyChar) ("failed to parse rpc arg value (" ++ toS v ++ ")") v
-
 ws :: Parser Text
 ws = toS <$> many (oneOf " \t")
 
diff --git a/src/PostgREST/QueryBuilder.hs b/src/PostgREST/QueryBuilder.hs
index 713545d71..d4e625d3d 100644
--- a/src/PostgREST/QueryBuilder.hs
+++ b/src/PostgREST/QueryBuilder.hs
@@ -135,9 +135,9 @@ createWriteStatement selectQuery mutateQuery wantSingle wantHdrs asCsv rep pKeys
 
 type ProcResults = (Maybe Int64, Int64, ByteString, ByteString)
 callProc :: QualifiedIdentifier -> [PgArg] -> Bool -> SqlQuery -> SqlQuery -> Bool ->
-            Bool -> Bool -> Bool -> Bool -> Bool -> Maybe FieldName -> Bool -> PgVersion ->
+            Bool -> Bool -> Bool -> Bool -> Maybe FieldName -> Bool -> PgVersion ->
             H.Query ByteString (Maybe ProcResults)
-callProc qi pgArgs returnsScalar selectQuery countQuery countTotal isSingle paramsAsSingleObject asCsv asBinary isReadOnly binaryField isObject pgVer =
+callProc qi pgArgs returnsScalar selectQuery countQuery countTotal isSingle paramsAsSingleObject asCsv asBinary binaryField isObject pgVer =
   unicodeStatement sql (HE.value HE.unknown) decodeProc True
   where
     sql =
@@ -164,15 +164,15 @@ callProc qi pgArgs returnsScalar selectQuery countQuery countTotal isSingle para
          {responseHeaders} AS response_headers
        FROM ({selectQuery}) _postgrest_t;|]
 
-    (argsRecord, args) | paramsAsSingleObject && not isReadOnly  = ("_args_record AS (SELECT NULL)", "$1::json")
+    (argsRecord, args) | paramsAsSingleObject = ("_args_record AS (SELECT NULL)", "$1::json")
                        | null pgArgs = (ignoredBody, "")
                        | otherwise = (
-                           "_args_record AS ( "<>
-                             "SELECT * FROM " <> (if isObject then "json_to_record" else "json_to_recordset") <>
-                             "($1) AS _(" <> intercalate ", " ((\a -> pgaName a <> " " <> pgaType a) <$> pgArgs) <> ")" <>
-                           ")"
-                         , intercalate ", " ((\a -> pgaName a <> " := (SELECT " <> pgaName a <> " FROM _args_record)") <$> pgArgs)
-                         )
+                           unwords [
+                           "_args_record AS (",
+                             "SELECT * FROM " <> (if isObject then "json_to_record" else "json_to_recordset") <> "($1)",
+                             "AS _(" <> intercalate ", " ((\a -> pgaName a <> " " <> pgaType a) <$> pgArgs) <> ")",
+                           ")"]
+                         , intercalate ", " ((\a -> pgaName a <> " := (SELECT " <> pgaName a <> " FROM _args_record)") <$> pgArgs))
     countResultF = if countTotal then "( "<> countQuery <> ")" else "null::bigint" :: Text
     _procName = qiName qi
     responseHeaders =
@@ -322,6 +322,7 @@ requestToQuery schema _ (DbMutate (Delete mainTbl logicForest returnings)) =
 -- Due to the use of the `unknown` encoder we need to cast '$1' when the value is not used in the main query
 -- otherwise the query will err with a `could not determine data type of parameter $1`.
 -- This happens because `unknown` relies on the context to determine the value type.
+-- The error also happens on raw libpq used with C.
 ignoredBody :: SqlFragment
 ignoredBody = "ignored_body AS (SELECT $1::text) "
 
diff --git a/src/PostgREST/Types.hs b/src/PostgREST/Types.hs
index 8441a129e..474ee29cb 100644
--- a/src/PostgREST/Types.hs
+++ b/src/PostgREST/Types.hs
@@ -30,7 +30,8 @@ data DbStructure = DbStructure {
 , dbColumns     :: [Column]
 , dbRelations   :: [Relation]
 , dbPrimaryKeys :: [PrimaryKey]
-, dbProcs       :: M.HashMap Text ProcDescription
+-- ProcDescription is a list because a function can be overloaded
+, dbProcs       :: M.HashMap Text [ProcDescription]
 , pgVersion     :: PgVersion
 } deriving (Show, Eq)
 
@@ -38,14 +39,14 @@ data PgArg = PgArg {
   pgaName :: Text
 , pgaType :: Text
 , pgaReq  :: Bool
-} deriving (Show, Eq)
+} deriving (Show, Eq, Ord)
 
-data PgType = Scalar QualifiedIdentifier | Composite QualifiedIdentifier deriving (Eq, Show)
+data PgType = Scalar QualifiedIdentifier | Composite QualifiedIdentifier deriving (Eq, Show, Ord)
 
-data RetType = Single PgType | SetOf PgType deriving (Eq, Show)
+data RetType = Single PgType | SetOf PgType deriving (Eq, Show, Ord)
 
 data ProcVolatility = Volatile | Stable | Immutable
-  deriving (Eq, Show)
+  deriving (Eq, Show, Ord)
 
 data ProcDescription = ProcDescription {
   pdName        :: Text
@@ -55,6 +56,13 @@ data ProcDescription = ProcDescription {
 , pdVolatility  :: ProcVolatility
 } deriving (Show, Eq)
 
+-- Order by least number of args in the case of overloaded functions
+instance Ord ProcDescription where
+  ProcDescription name1 des1 args1 rt1 vol1 `compare` ProcDescription name2 des2 args2 rt2 vol2
+    | name1 == name2 && length args1 < length args2  = LT
+    | name1 == name2 && length args1 > length args2  = GT
+    | otherwise = (name1, des1, args1, rt1, vol1) `compare` (name2, des2, args2, rt2, vol2)
+
 type Schema = Text
 type TableName = Text
 type SqlQuery = Text
@@ -111,7 +119,7 @@ data OrderTerm = OrderTerm {
 data QualifiedIdentifier = QualifiedIdentifier {
   qiSchema :: Schema
 , qiName   :: TableName
-} deriving (Show, Eq)
+} deriving (Show, Eq, Ord)
 
 
 data RelationType = Child | Parent | Many | Root deriving (Show, Eq)
diff --git a/test/Feature/InsertSpec.hs b/test/Feature/InsertSpec.hs
index 68853d871..3fef1119f 100644
--- a/test/Feature/InsertSpec.hs
+++ b/test/Feature/InsertSpec.hs
@@ -416,13 +416,21 @@ spec = do
         -- put value back for other tests
         void $ request methodPatch "/items?id=eq.99" [] [json| { "id":1 } |]
 
-      it "makes no updates and returns 204, when patching with an empty json object" $ do
+      it "makes no updates and returns 204, when patching with an empty json object/array" $ do
         request methodPatch "/items" [] [json| {} |]
           `shouldRespondWith` ""
           {
             matchStatus  = 204,
             matchHeaders = ["Content-Range" <:> "*/*"]
           }
+
+        request methodPatch "/items" [] [json| [] |]
+          `shouldRespondWith` ""
+          {
+            matchStatus  = 204,
+            matchHeaders = ["Content-Range" <:> "*/*"]
+          }
+
         get "/items" `shouldRespondWith`
           [json|[{"id":3},{"id":4},{"id":5},{"id":6},{"id":7},{"id":8},{"id":9},{"id":10},{"id":11},{"id":12},{"id":13},{"id":14},{"id":15},{id:16},{"id":2},{"id":1}]|]
           { matchHeaders = [matchContentTypeJson] }
diff --git a/test/Feature/RpcSpec.hs b/test/Feature/RpcSpec.hs
index 02e60e07e..48da43e09 100644
--- a/test/Feature/RpcSpec.hs
+++ b/test/Feature/RpcSpec.hs
@@ -275,8 +275,14 @@ spec =
           [json|[{"my_json":{"a": 1, "b": "two"},"num":3,"str":"four"}]|] { matchHeaders = [matchContentTypeJson] }
 
       it "returns a row result when there are many INOUT params" $
-        get "/rpc/many_inout_params?num=1&str=two" `shouldRespondWith`
-          [json| [{"num":1,"str":"two","b":true}]|] { matchHeaders = [matchContentTypeJson] }
+        get "/rpc/many_inout_params?num=1&str=two&b=false" `shouldRespondWith`
+          [json| [{"num":1,"str":"two","b":false}]|] { matchHeaders = [matchContentTypeJson] }
+
+    it "can handle procs with args that have a DEFAULT value" $ do
+      get "/rpc/many_inout_params?num=1&str=two" `shouldRespondWith`
+        [json| [{"num":1,"str":"two","b":true}]|] { matchHeaders = [matchContentTypeJson] }
+      get "/rpc/three_defaults?b=4" `shouldRespondWith`
+        [json|8|] { matchHeaders = [matchContentTypeJson] }
 
     it "can map a RAISE error code and message to a http status" $
       get "/rpc/raise_pt402"
@@ -291,7 +297,7 @@ spec =
     context "expects a single json object" $ do
       it "does not expand posted json into parameters" $
         request methodPost "/rpc/singlejsonparam"
-          [("Prefer","params=single-object")] [json| { "p1": 1, "p2": "text", "p3" : {"obj":"text"} } |] `shouldRespondWith`
+          [("prefer","params=single-object")] [json| { "p1": 1, "p2": "text", "p3" : {"obj":"text"} } |] `shouldRespondWith`
           [json| { "p1": 1, "p2": "text", "p3" : {"obj":"text"} } |]
           { matchHeaders = [matchContentTypeJson] }
 
@@ -304,6 +310,25 @@ spec =
                  , "boolean":"false", "date":"1900-01-01", "money":"$3.99", "enum":"foo" } |]
                  { matchHeaders = [matchContentTypeJson] }
 
+      it "works with GET" $
+        request methodGet "/rpc/singlejsonparam?p1=1&p2=text" [("Prefer","params=single-object")] ""
+          `shouldRespondWith` [json|{ "p1": "1", "p2": "text"}|]
+          { matchHeaders = [matchContentTypeJson] }
+
+    it "should work with an overloaded function" $ do
+      get "/rpc/overloaded" `shouldRespondWith`
+        [json|[{ "overloaded": 1 },
+               { "overloaded": 2 },
+               { "overloaded": 3 }]|]
+        { matchHeaders = [matchContentTypeJson] }
+      request methodPost "/rpc/overloaded" [("Prefer","params=single-object")]
+        [json|[{"x": 1, "y": "first"}, {"x": 2, "y": "second"}]|]
+       `shouldRespondWith`
+        [json|[{"x": 1, "y": "first"}, {"x": 2, "y": "second"}]|]
+        { matchHeaders = [matchContentTypeJson] }
+      get "/rpc/overloaded?a=1&b=2" `shouldRespondWith` [str|3|]
+      get "/rpc/overloaded?a=1&b=2&c=3" `shouldRespondWith` [str|"123"|]
+
     context "only for POST rpc" $
       it "gives a parse filter error if GET style proc args are specified" $
         post "/rpc/sayhello?name=John" [json|{}|] `shouldRespondWith` 400
diff --git a/test/fixtures/schema.sql b/test/fixtures/schema.sql
index a8206d027..df2b821c7 100755
--- a/test/fixtures/schema.sql
+++ b/test/fixtures/schema.sql
@@ -1325,6 +1325,23 @@ $$ language sql;
 create or replace function test.set_cookie_twice() returns void as $$
   set local "response.headers" = '[{"Set-Cookie": "sessionid=38afes7a8; HttpOnly; Path=/"}, {"Set-Cookie": "id=a3fWa; Expires=Wed, 21 Oct 2015 07:28:00 GMT; Secure; HttpOnly"}]';
 $$ language sql;
---
--- PostgreSQL database dump complete
---
+
+create or replace function test.three_defaults(a int default 1, b int default 2, c int default 3) returns int as $$
+select a + b + c
+$$ language sql;
+
+create or replace function test.overloaded() returns setof int as $$
+  values (1), (2), (3);
+$$ language sql;
+
+create or replace function test.overloaded(pg_catalog.json) returns table(x int, y text) as $$
+  select * from json_to_recordset($1) as r(x int, y text);
+$$ language sql;
+
+create or replace function test.overloaded(a int, b int) returns int as $$
+  select a + b
+$$ language sql;
+
+create or replace function test.overloaded(a text, b text, c text) returns text as $$
+  select a || b || c
+$$ language sql;