feat: insert-multi! :batch option

Adds support for using a `:batch` option to make `insert-multi!` use
`execute-batch!` instead of `execute!`.

src/next/jdbc/sql.clj

@@ -21,7 +21,7 @@
 
   In addition, `find-by-keys` supports `:order-by` to add an `ORDER BY`
   clause to the generated SQL."
-  (:require [next.jdbc :refer [execute! execute-one!]]
+  (:require [next.jdbc :refer [execute! execute-one! execute-batch!]]
             [next.jdbc.sql.builder
              :refer [for-delete for-insert for-insert-multi
                      for-query for-update]]))
@@ -53,8 +53,12 @@
   Also supports a sequence of hash maps with keys corresponding to column
   names.
 
-  Note: this expands to a single SQL statement with placeholders for every
+  If called with `:batch` true will call `execute-batch!` - see its documentation
-  value being inserted -- for large sets of rows, this may exceed the limits
+  for situations in which the generated keys may or may not be returned as well as
+  additional options that can be passed.
+
+  Note: without `:batch` this expands to a single SQL statement with placeholders for
+  every value being inserted -- for large sets of rows, this may exceed the limits
   on SQL string size and/or number of parameters for your JDBC driver or your
   database!"
   {:arglists '([connectable table hash-maps]
@@ -72,10 +76,15 @@
        (insert-multi! connectable table cols (map ->row hash-maps-or-cols) opts-or-rows))))
   ([connectable table cols rows opts]
    (if (seq rows)
-     (let [opts (merge (:options connectable) opts)]
+     (let [opts   (merge (:options connectable) opts)
+           batch? (:batch opts)]
+       (if batch?
+         (let [[sql & param-groups] (for-insert-multi table cols rows opts)]
+              (execute-batch! connectable sql param-groups
+                     (merge {:return-keys true :return-generated-keys true} opts)))
          (execute! connectable
                    (for-insert-multi table cols rows opts)
-                 (merge {:return-keys true} opts)))
+                   (merge {:return-keys true} opts))))
      [])))
 
 (defn query

src/next/jdbc/sql/builder.clj

@@ -137,6 +137,10 @@
 
   Applies any `:table-fn` / `:column-fn` supplied in the options.
 
+  If `:batch` is set to `true` in `opts` the INSERT statement will be prepared
+  using a single set of placeholders and remaining parameters in the vector will
+  be grouped at the row level.
+
   If `:suffix` is provided in `opts`, that string is appended to the
   `INSERT ...` statement."
   [table cols rows opts]
@@ -147,15 +151,16 @@
   (assert (seq rows) "rows may not be empty")
   (let [table-fn  (:table-fn opts identity)
         column-fn (:column-fn opts identity)
+        batch?    (:batch opts)
         params    (str/join ", " (map (comp column-fn name) cols))
         places    (as-? (first rows) opts)]
     (into [(str "INSERT INTO " (table-fn (safe-name table))
                 " (" params ")"
                 " VALUES "
-                (str/join ", " (repeat (count rows) (str "(" places ")")))
+                (str/join ", " (repeat (if batch? 1 (count rows)) (str "(" places ")")))
                 (when-let [suffix (:suffix opts)]
                   (str " " suffix)))]
-          cat
+          (if batch? identity cat)
           rows)))
 
 (defn for-order-col

test/next/jdbc/sql/builder_test.clj

@@ -146,11 +146,19 @@
                                {:id 9 :status 42 :opt nil}
                                {:table-fn sql-server :column-fn mysql})
            ["INSERT INTO [user] (`id`, `status`, `opt`) VALUES (?, ?, ?)" 9 42 nil])))
-  (testing "multi-row insert"
+  (testing "multi-row insert (normal mode)"
     (is (= (builder/for-insert-multi :user
                                      [:id :status]
                                      [[42 "hello"]
                                       [35 "world"]
                                       [64 "dollars"]]
                                      {:table-fn sql-server :column-fn mysql})
-           ["INSERT INTO [user] (`id`, `status`) VALUES (?, ?), (?, ?), (?, ?)" 42 "hello" 35 "world" 64 "dollars"]))))
+           ["INSERT INTO [user] (`id`, `status`) VALUES (?, ?), (?, ?), (?, ?)" 42 "hello" 35 "world" 64 "dollars"])))
+  (testing "multi-row insert (batch mode)"
+    (is (= (builder/for-insert-multi :user
+                                     [:id :status]
+                                     [[42 "hello"]
+                                      [35 "world"]
+                                      [64 "dollars"]]
+                                     {:table-fn sql-server :column-fn mysql :batch true})
+           ["INSERT INTO [user] (`id`, `status`) VALUES (?, ?)" [42 "hello"] [35 "world"] [64 "dollars"]]))))