diff --git a/Test/Opaleye/Test/Arbitrary.hs b/Test/Opaleye/Test/Arbitrary.hs
index d1eeb4a27..6401e9de7 100644
--- a/Test/Opaleye/Test/Arbitrary.hs
+++ b/Test/Opaleye/Test/Arbitrary.hs
@@ -471,7 +471,7 @@ genSelectArr =
 genSelectMapper :: [TQ.Gen (O.Select Fields -> O.Select Fields)]
 genSelectMapper =
     [ do
-        return (O.distinctExplicit distinctFields)
+        return (O.distinctExplicit unpackFields distinctFields)
     , do
         ArbitraryPositiveInt l <- TQ.arbitrary
         return (O.limit l)
@@ -481,9 +481,8 @@ genSelectMapper =
     , do
         o                <- TQ.arbitrary
         return (O.orderBy (arbitraryOrder o))
-
     , do
-        return (O.aggregate aggregateFields)
+        return (O.aggregateExplicit unpackFields aggregateFields)
     , do
         let q' q = P.dimap (\_ -> fst . firstBoolOrTrue (O.sqlBool True))
                            (fieldsList
diff --git a/Test/QuickCheck.hs b/Test/QuickCheck.hs
index 6ec4e4a4e..6738fd278 100644
--- a/Test/QuickCheck.hs
+++ b/Test/QuickCheck.hs
@@ -432,7 +432,7 @@ order o (ArbitrarySelect q) =
 
 distinct :: ArbitrarySelect -> Connection -> IO TQ.Property
 distinct =
-  compareDenotation' (O.distinctExplicit distinctFields) nub
+  compareDenotation' (O.distinctExplicit unpackFields distinctFields) nub
 
 -- When we generalise compareDenotation... we can just test
 --
@@ -455,7 +455,7 @@ valuesEmpty l =
 
 aggregate :: ArbitrarySelect -> Connection -> IO TQ.Property
 aggregate =
-  compareDenotationNoSort' (O.aggregate aggregateFields)
+  compareDenotationNoSort' (O.aggregateExplicit unpackFields aggregateFields)
                            aggregateDenotation
 
 
diff --git a/Test/Test.hs b/Test/Test.hs
index 77ed58b33..658457042 100644
--- a/Test/Test.hs
+++ b/Test/Test.hs
@@ -620,7 +620,7 @@ testStringArrayAggregateOrdered = it "" $ q `selectShouldReturnSorted` expected
 
 
 testStringArrayAggregateOrderedDistinct :: Test
-testStringArrayAggregateOrderedDistinct = xit "" $ q `selectShouldReturnSorted` expected
+testStringArrayAggregateOrderedDistinct = it "" $ q `selectShouldReturnSorted` expected
   where q =
           O.aggregateOrdered
             (O.asc snd)
@@ -1477,7 +1477,7 @@ testUnnest = do
 
 testSetAggregate :: Test
 testSetAggregate = do
-  xit "set aggregate (percentile_cont)" $ testH query (`shouldBe` [expectation])
+  it "set aggregate (percentile_cont)" $ testH query (`shouldBe` [expectation])
   where query :: Select (Field O.SqlFloat8)
         query = O.aggregate median (O.values as)
 
diff --git a/src/Opaleye/Aggregate.hs b/src/Opaleye/Aggregate.hs
index 6b00f9f8c..f6e936aa7 100644
--- a/src/Opaleye/Aggregate.hs
+++ b/src/Opaleye/Aggregate.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DataKinds #-}
+{-# LANGUAGE FlexibleContexts #-}
 
 -- | Perform aggregation on 'S.Select's.  To aggregate a 'S.Select' you
 -- should construct an 'Aggregator' encoding how you want the
@@ -33,11 +34,14 @@ module Opaleye.Aggregate
        , stringAgg
        -- * Counting rows
        , countRows
+       -- * Explicit
+       , aggregateExplicit
        ) where
 
-import           Control.Arrow (second)
+import           Control.Arrow (second, (<<<))
 import           Data.Profunctor     (lmap)
 import qualified Data.Profunctor as P
+import qualified Data.Profunctor.Product.Default as D
 
 import qualified Opaleye.Internal.Aggregate as A
 import           Opaleye.Internal.Aggregate (Aggregator, orderAggregate)
@@ -46,6 +50,7 @@ import qualified Opaleye.Internal.QueryArr as Q
 import qualified Opaleye.Internal.HaskellDB.PrimQuery as HPQ
 import qualified Opaleye.Internal.Operators as O
 import qualified Opaleye.Internal.PackMap as PM
+import           Opaleye.Internal.Rebind (rebindExplicit)
 import qualified Opaleye.Internal.Tag as Tag
 import qualified Opaleye.Internal.Unpackspec as U
 
@@ -85,11 +90,8 @@ result of an aggregation.
 -}
 -- See 'Opaleye.Internal.Sql.aggregate' for details of how aggregating
 -- by an empty query with no group by is handled.
-aggregate :: Aggregator a b -> S.Select a -> S.Select b
-aggregate agg q = Q.productQueryArr $ do
-  (a, pq) <- Q.runSimpleSelect q
-  t <- Tag.fresh
-  pure (second ($ pq) (A.aggregateU agg (a, t)))
+aggregate :: D.Default U.Unpackspec a a => Aggregator a b -> S.Select a -> S.Select b
+aggregate = aggregateExplicit D.def
 
 -- | Order the values within each aggregation in `Aggregator` using
 -- the given ordering. This is only relevant for aggregations that
@@ -100,7 +102,13 @@ aggregate agg q = Q.productQueryArr $ do
 -- you need different orderings for different aggregations, use
 -- 'Opaleye.Internal.Aggregate.orderAggregate'.
 
-aggregateOrdered  :: Ord.Order a -> Aggregator a b -> S.Select a -> S.Select b
+aggregateExplicit :: U.Unpackspec a a' -> Aggregator a' b -> S.Select a -> S.Select b
+aggregateExplicit u agg q = Q.productQueryArr $ do
+  (a, pq) <- Q.runSimpleSelect (rebindExplicit u <<< q)
+  t <- Tag.fresh
+  pure (second ($ pq) (A.aggregateU agg (a, t)))
+
+aggregateOrdered  :: D.Default U.Unpackspec a a => Ord.Order a -> Aggregator a b -> S.Select a -> S.Select b
 aggregateOrdered o agg = aggregate (orderAggregate o agg)
 
 -- | Aggregate only distinct values
diff --git a/src/Opaleye/Distinct.hs b/src/Opaleye/Distinct.hs
index adfecd7fb..299e6c3b4 100644
--- a/src/Opaleye/Distinct.hs
+++ b/src/Opaleye/Distinct.hs
@@ -18,6 +18,7 @@ import           Opaleye.Internal.Distinct
 import           Opaleye.Order
 
 import qualified Data.Profunctor.Product.Default as D
+import Opaleye.Internal.Unpackspec (Unpackspec)
 
 -- | Remove duplicate rows from the 'Select'.
 --
@@ -40,5 +41,6 @@ import qualified Data.Profunctor.Product.Default as D
 -- 'Opaleye.Lateral.laterally' 'distinct' :: 'Data.Profunctor.Product.Default' 'Distinctspec' fields fields => 'Opaleye.Select.SelectArr' i fields -> 'Opaleye.Select.SelectArr' i fields
 -- @
 distinct :: D.Default Distinctspec fields fields =>
+            D.Default Unpackspec fields fields =>
             Select fields -> Select fields
-distinct = distinctExplicit D.def
+distinct = distinctExplicit D.def D.def
diff --git a/src/Opaleye/Internal/Aggregate.hs b/src/Opaleye/Internal/Aggregate.hs
index 2f31aed02..eb69f7b75 100644
--- a/src/Opaleye/Internal/Aggregate.hs
+++ b/src/Opaleye/Internal/Aggregate.hs
@@ -135,37 +135,25 @@ aggregatorApply = Aggregator $ PM.PackMap $ \f (agg, a) ->
 aggregateU :: Aggregator a b
            -> (a, T.Tag) -> (b, PQ.PrimQuery -> PQ.PrimQuery)
 aggregateU agg (c0, t0) = (c1, primQ')
-  where (c1, projPEs_inners) =
+  where projPEs_inners :: PQ.Bindings HPQ.Aggregate
+        (c1, projPEs_inners) =
           PM.run (runAggregator agg (extractAggregateFields t0) c0)
 
-        projPEs = map fst projPEs_inners
-        inners  = concatMap snd projPEs_inners
+        projPEs = projPEs_inners
 
-        primQ' = PQ.Aggregate projPEs . PQ.Rebind True inners
+        primQ' = PQ.Aggregate projPEs
 
 extractAggregateFields
-  :: Traversable t
-  => T.Tag
-  -> t HPQ.PrimExpr
-  -> PM.PM [((HPQ.Symbol,
-              t HPQ.Symbol),
-              PQ.Bindings HPQ.PrimExpr)]
-           HPQ.PrimExpr
+  :: T.Tag
+  -> HPQ.Aggregate
+  -> PM.PM (PQ.Bindings HPQ.Aggregate) HPQ.PrimExpr
 extractAggregateFields tag agg = do
   i <- PM.new
+  let sinner = HPQ.Symbol ("result" ++ i) tag
 
-  let souter = HPQ.Symbol ("result" ++ i) tag
+  PM.write (sinner, agg)
 
-  bindings <- for agg $ \pe -> do
-    j <- PM.new
-    let sinner = HPQ.Symbol ("inner" ++ j) tag
-    pure (sinner, pe)
-
-  let agg' = fmap fst bindings
-
-  PM.write ((souter, agg'), toList bindings)
-
-  pure (HPQ.AttrExpr souter)
+  pure (HPQ.AttrExpr sinner)
 
 unsafeMax :: Aggregator (C.Field a) (C.Field a)
 unsafeMax = makeAggr HPQ.AggrMax
diff --git a/src/Opaleye/Internal/Distinct.hs b/src/Opaleye/Internal/Distinct.hs
index 888b67859..9eb6346c7 100644
--- a/src/Opaleye/Internal/Distinct.hs
+++ b/src/Opaleye/Internal/Distinct.hs
@@ -5,19 +5,21 @@ module Opaleye.Internal.Distinct where
 import qualified Opaleye.Internal.MaybeFields as M
 import           Opaleye.Select (Select)
 import           Opaleye.Field (Field_)
-import           Opaleye.Aggregate (Aggregator, groupBy, aggregate)
+import           Opaleye.Aggregate (Aggregator, groupBy, aggregateExplicit)
 
 import qualified Data.Profunctor as P
 import qualified Data.Profunctor.Product as PP
 import           Data.Profunctor.Product.Default (Default, def)
+import           Opaleye.Internal.Unpackspec (Unpackspec)
 
 -- We implement distinct simply by grouping by all columns.  We could
 -- instead implement it as SQL's DISTINCT but implementing it in terms
 -- of something else that we already have is easier at this point.
 
-distinctExplicit :: Distinctspec fields fields'
+distinctExplicit :: Unpackspec fields fields
+                 -> Distinctspec fields fields'
                  -> Select fields -> Select fields'
-distinctExplicit (Distinctspec agg) = aggregate agg
+distinctExplicit u (Distinctspec agg) = aggregateExplicit u agg
 
 newtype Distinctspec a b = Distinctspec (Aggregator a b)
 
diff --git a/src/Opaleye/Internal/PrimQuery.hs b/src/Opaleye/Internal/PrimQuery.hs
index 88a557a2b..d19cdabd9 100644
--- a/src/Opaleye/Internal/PrimQuery.hs
+++ b/src/Opaleye/Internal/PrimQuery.hs
@@ -133,7 +133,7 @@ data PrimQuery' a = Unit
                   | Product   (NEL.NonEmpty (Lateral, PrimQuery' a)) [HPQ.PrimExpr]
                   -- | The subqueries to take the product of and the
                   --   restrictions to apply
-                  | Aggregate (Bindings (HPQ.Aggregate' HPQ.Symbol))
+                  | Aggregate (Bindings HPQ.Aggregate)
                               (PrimQuery' a)
                   | Window (Bindings (HPQ.WndwOp, HPQ.Partition)) (PrimQuery' a)
                   -- | Represents both @DISTINCT ON@ and @ORDER BY@
@@ -178,7 +178,7 @@ data PrimQueryFoldP a p p' = PrimQueryFold
   , empty             :: a -> p'
   , baseTable         :: TableIdentifier -> Bindings HPQ.PrimExpr -> p'
   , product           :: NEL.NonEmpty (Lateral, p) -> [HPQ.PrimExpr] -> p'
-  , aggregate         :: Bindings (HPQ.Aggregate' HPQ.Symbol)
+  , aggregate         :: Bindings HPQ.Aggregate
                       -> p
                       -> p'
   , window            :: Bindings (HPQ.WndwOp, HPQ.Partition) -> p -> p'
diff --git a/src/Opaleye/Internal/Sql.hs b/src/Opaleye/Internal/Sql.hs
index db25d84ff..e00a4ab34 100644
--- a/src/Opaleye/Internal/Sql.hs
+++ b/src/Opaleye/Internal/Sql.hs
@@ -160,7 +160,7 @@ product ss pes = SelectFrom $
           PQ.Lateral    -> Lateral
           PQ.NonLateral -> NonLateral
 
-aggregate :: PQ.Bindings (HPQ.Aggregate' HPQ.Symbol)
+aggregate :: PQ.Bindings HPQ.Aggregate
           -> Select
           -> Select
 aggregate aggrs' s =
@@ -191,7 +191,7 @@ aggregate aggrs' s =
         handleEmpty = ensureColumnsGen SP.deliteral
 
         aggrs :: [(Symbol, HPQ.Aggregate)]
-        aggrs = (map . Arr.second . fmap) HPQ.AttrExpr aggrs'
+        aggrs = aggrs'
 
         groupBy' :: [(symbol, HPQ.Aggregate)]
                  -> NEL.NonEmpty HSql.SqlExpr