diff --git a/esqueleto.cabal b/esqueleto.cabal
--- a/esqueleto.cabal
+++ b/esqueleto.cabal
@@ -1,5 +1,5 @@
 name:                esqueleto
-version:             2.2.7
+version:             2.2.8
 synopsis:            Type-safe EDSL for SQL queries on persistent backends.
 homepage:            https://github.com/prowdsponsor/esqueleto
 license:             BSD3
@@ -57,6 +57,7 @@
 library
   exposed-modules:
     Database.Esqueleto
+    Database.Esqueleto.PostgreSQL
     Database.Esqueleto.Internal.Language
     Database.Esqueleto.Internal.Sql
   other-modules:
diff --git a/src/Database/Esqueleto.hs b/src/Database/Esqueleto.hs
--- a/src/Database/Esqueleto.hs
+++ b/src/Database/Esqueleto.hs
@@ -87,6 +87,9 @@
   , (<#)
   , (<&>)
 
+    -- * RDBMS-specific modules
+    -- $rdbmsSpecificModules
+
     -- * Helpers
   , valkey
   , valJ
@@ -375,6 +378,22 @@
 --
 --  * Everything from "Database.Persist.Sql" except for
 --    @deleteWhereCount@ and @updateWhereCount@.
+
+
+----------------------------------------------------------------------
+
+
+-- $rdbmsSpecificModules
+--
+-- There are many differences between SQL syntax and functions
+-- supported by different RDBMSs.  Since version 2.2.8,
+-- @esqueleto@ includes modules containing functions that are
+-- specific to a given RDBMS.
+--
+--  * PostgreSQL: "Database.Esqueleto.PostgreSQL".
+--
+-- In order to use these functions, you need to explicitly import
+-- their corresponding modules, they're not re-exported here.
 
 
 ----------------------------------------------------------------------
diff --git a/src/Database/Esqueleto/PostgreSQL.hs b/src/Database/Esqueleto/PostgreSQL.hs
new file mode 100644
--- /dev/null
+++ b/src/Database/Esqueleto/PostgreSQL.hs
@@ -0,0 +1,34 @@
+{-# LANGUAGE OverloadedStrings
+ #-}
+-- | This module contain PostgreSQL-specific functions.
+--
+-- /Since: 2.2.8/
+module Database.Esqueleto.PostgreSQL
+  ( arrayAgg
+  , stringAgg
+  ) where
+
+import Data.String (IsString)
+
+import Database.Esqueleto.Internal.Language
+import Database.Esqueleto.Internal.Sql
+
+
+-- | (@array_agg@) Concatenate input values, including @NULL@s,
+-- into an array.
+--
+-- /Since: 2.2.8/
+arrayAgg :: SqlExpr (Value a) -> SqlExpr (Value [a])
+arrayAgg = unsafeSqlFunction "array_agg"
+
+
+-- | (@string_agg@) Concatenate input values separated by a
+-- delimiter.
+--
+-- /Since: 2.2.8/
+stringAgg
+  :: IsString s
+  => SqlExpr (Value s) -- ^ Input values.
+  -> SqlExpr (Value s) -- ^ Delimiter.
+  -> SqlExpr (Value s) -- ^ Concatenation.
+stringAgg expr delim = unsafeSqlFunction "string_agg" (expr, delim)
diff --git a/test/Test.hs b/test/Test.hs
--- a/test/Test.hs
+++ b/test/Test.hs
@@ -53,6 +53,7 @@
 import qualified Data.List as L
 import qualified Data.Set as S
 import qualified Data.Text.Lazy.Builder as TLB
+import qualified Database.Esqueleto.PostgreSQL as EP
 import qualified Database.Esqueleto.Internal.Sql as EI
 
 
@@ -1312,6 +1313,34 @@
       it "looks sane for ForUpdate"       $ sanityCheck ForUpdate       "FOR UPDATE"
       it "looks sane for ForShare"        $ sanityCheck ForShare        "FOR SHARE"
       it "looks sane for LockInShareMode" $ sanityCheck LockInShareMode "LOCK IN SHARE MODE"
+
+    describe "PostgreSQL module" $ do
+      it "should be tested on the PostgreSQL database" $
+#if !defined(WITH_POSTGRESQL)
+        pendingWith "test suite not running under PostgreSQL, skipping"
+#else
+        (return () :: IO ())
+
+      it "arrayAgg looks sane" $
+        run $ do
+          let people = [p1, p2, p3, p4, p5]
+          mapM_ insert people
+          [Value ret] <-
+            select $
+            from $ \p -> do
+            return (EP.arrayAgg (p ^. PersonName))
+          liftIO $ L.sort ret `shouldBe` L.sort (map personName people)
+
+      it "stringAgg looks sane" $
+        run $ do
+          let people = [p1, p2, p3, p4, p5]
+          mapM_ insert people
+          [Value ret] <-
+            select $
+            from $ \p -> do
+            return (EP.stringAgg (p ^. PersonName) (val " "))
+          liftIO $ L.sort (words ret) `shouldBe` L.sort (map personName people)
+#endif
 
 
 ----------------------------------------------------------------------