Fix test bank with accounts in separate tables

Test "bank-multitable-lua" fetched balances from different tables in separate
requests and so in different transactions. When we run it on synchronous
cluster it led to incorrect sum on all bank accounts. Now test fetches all
balances in an SQL transaction.

Closes tarantool/tarantool#5848
Closes tarantool/tarantool#5513

Test passed on cluster with three nodes with and wo MVCC:
lein run test --workload bank-multitable-lua --nodes-file nodes
    --username ubuntu --version 2.8 --leave-db-running --mvcc
lein run test --workload bank-multitable-lua --nodes-file nodes
    --username ubuntu --version 2.8 --leave-db-running

Test passed on a single instance with and wo MVCC:
lein run test --workload bank-multitable-lua --nodes-file node
    --username ubuntu --version 2.8 --mvcc --leave-db-running
lein run test --workload bank-multitable-lua --nodes-file node
    --username ubuntu --version 2.8 --mvcc --leave-db-running --mvcc

Author: ligurio

resources/tarantool/jepsen.lua

@@ -137,13 +137,13 @@ box.schema.func.create('_WITHDRAW_MULTITABLE',
              local space_from = box.space[table_from]
              local space_to = box.space[table_to]
              box.begin()
-               local bal_from = space_from:get(0)[2] - amount
-               local bal_to = space_to:get(0)[2] + amount
+               local bal_from = space_from:get(0).BALANCE - amount
+               local bal_to = space_to:get(0).BALANCE + amount
                if bal_from < 0 or bal_to < 0 then
                  return false
                end
-               space_from:update(0, {{'-', 2, amount}})
-               space_to:update(0, {{'+', 2, amount}})
+               space_from:update(0, {{'-', 'BALANCE', amount}})
+               space_to:update(0, {{'+', 'BALANCE', amount}})
              box.commit()
 
              return true

src/tarantool/bank.clj

@@ -87,29 +87,33 @@
               (doseq [a (:accounts test)]
                 (info "Creating table" table-name a)
                 (j/execute! conn [(str "CREATE TABLE IF NOT EXISTS " table-name a
-                                       "(id     INT NOT NULL PRIMARY KEY,"
+                                       "(id             INT NOT NULL PRIMARY KEY,"
+                                       "account_id      INT NOT NULL,"
                                        "balance INT NOT NULL)")])
                   (info "Populating account" a)
                   (sql/insert! conn (str table-name a)
                              {:id 0
-                              :balance (if (= a (first (:accounts test)))
-                                         (:total-amount test)
-                                         0)})))))
+                              :account_id a
+                              :balance 10})))))
         (assoc this :conn conn :node node))))
 
   (invoke! [this test op]
     (try
+      ; op struct example: {:type :invoke, :f :read, :process 0, :time 65183208864}
       (case (:f op)
         :read
-        (->> (:accounts test)
-             (map (fn [x]
-                    [x (->> (sql/query conn [(str "SELECT balance FROM " table-name
-                                             x)]
-                                     {:row-fn :BALANCE})
-                            first)]))
+        (->> (sql/query conn ["SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS0 UNION
+                               SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS1 UNION
+                               SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS2 UNION
+                               SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS3 UNION
+                               SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS4 UNION
+                               SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS5 UNION
+                               SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS6 UNION
+                               SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS7 UNION
+                               SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS8 UNION
+                               SELECT ACCOUNT_ID, BALANCE FROM ACCOUNTS9"])
+             (map (juxt :ACCOUNT_ID :BALANCE))
              (into (sorted-map))
-             (map (fn [[k {b :BALANCE}]] [k b]))
-             (into {})
              (assoc op :type :ok, :value))
 
         :transfer