diff --git a/src/PostgREST/DbStructure.hs b/src/PostgREST/DbStructure.hs
index 84843c520..162d245a9 100644
--- a/src/PostgREST/DbStructure.hs
+++ b/src/PostgREST/DbStructure.hs
@@ -15,9 +15,8 @@ import qualified Hasql.Encoders          as HE
 import qualified Hasql.Decoders          as HD
 
 import           Control.Applicative
-import           Control.Monad          (join)
+import           Control.Monad          (join, replicateM)
 import           Data.Functor.Contravariant (contramap)
-import           Data.Functor.Identity
 import           Text.InterpolatedString.Perl6 (q)
 import           Data.List              (elemIndex, find, subsequences, sort, transpose)
 import           Data.Maybe             (fromMaybe, fromJust, isJust, mapMaybe, listToMaybe)
@@ -30,13 +29,13 @@ import           GHC.Exts               (groupWith)
 import           GHC.Int                (Int32)
 import           Prelude
 
-getDbStructure :: Schema -> H.Query () DbStructure
+getDbStructure :: Schema -> H.Session DbStructure
 getDbStructure schema = do
-  tabs <- allTables
-  cols <- allColumns tabs
-  syns <- allSynonyms cols
-  rels <- allRelations tabs cols
-  keys <- allPrimaryKeys tabs
+  tabs <- H.query () $ allTables
+  cols <- H.query () $ allColumns tabs
+  syns <- H.query () $ allSynonyms cols
+  rels <- H.query () $ allRelations tabs cols
+  keys <- H.query () $ allPrimaryKeys tabs
 
   let rels' = (addManyToManyRelations . raiseRelations schema syns . addParentRelations . addSynonymousRelations syns) rels
       cols' = addForeignKeys rels' cols
@@ -83,10 +82,10 @@ decodeRelations tables cols =
   relRow = (,,,,,)
     <$> HD.value HD.text
     <*> HD.value HD.text
-    <*> HD.value (HD.array $ HD.arrayValue HD.text)
+    <*> HD.value (HD.array (HD.arrayDimension replicateM (HD.arrayValue HD.text)))
     <*> HD.value HD.text
     <*> HD.value HD.text
-    <*> HD.value (HD.array $ HD.arrayValue HD.text)
+    <*> HD.value (HD.array (HD.arrayDimension replicateM (HD.arrayValue HD.text)))
 
 decodePks :: [Table] -> HD.Result [PrimaryKey]
 decodePks tables =
@@ -132,7 +131,7 @@ doesProcReturnJWT =
 
 accessibleTables :: H.Query Schema [Table]
 accessibleTables =
-  H.statement sql (HE.value HE.text) (HD.rowsList (HD.value HD.text)) True
+  H.statement sql (HE.value HE.text) decodeTables True
  where
   sql = [q|
     select
@@ -155,8 +154,7 @@ accessibleTables =
         or has_table_privilege(c.oid, 'SELECT, INSERT, UPDATE, DELETE, TRUNCATE, REFERENCES, TRIGGER'::text)
         or has_any_column_privilege(c.oid, 'SELECT, INSERT, UPDATE, REFERENCES'::text)
       )
-    order by relname
-  |]
+    order by relname |]
 
 synonymousColumns :: [(Column,Column)] -> [Column] -> [[Column]]
 synonymousColumns allSyns cols = synCols'
diff --git a/src/PostgREST/Types.hs b/src/PostgREST/Types.hs
index 5ee53d7cb..4eb8c3487 100644
--- a/src/PostgREST/Types.hs
+++ b/src/PostgREST/Types.hs
@@ -5,6 +5,7 @@ import qualified Data.ByteString.Lazy as BL
 import qualified Data.ByteString      as BS
 import qualified Data.Vector          as V
 import Data.Aeson
+import GHC.Int (Int32)
 
 data DbStructure = DbStructure {
   dbTables :: [Table]
@@ -31,12 +32,12 @@ data Column =
     Column {
       colTable     :: Table
     , colName      :: Text
-    , colPosition  :: Int
+    , colPosition  :: Int32
     , colNullable  :: Bool
     , colType      :: Text
     , colUpdatable :: Bool
-    , colMaxLen    :: Maybe Int
-    , colPrecision :: Maybe Int
+    , colMaxLen    :: Maybe Int32
+    , colPrecision :: Maybe Int32
     , colDefault   :: Maybe Text
     , colEnum      :: [Text]
     , colFK        :: Maybe ForeignKey