added sqlite wal mode enable logic

src/driver/sqlite/SqliteConnectionOptions.ts

@@ -26,9 +26,18 @@ export interface SqliteConnectionOptions extends BaseConnectionOptions {
      * Since SQLite cannot handle parallel saves this error cannot be avoided.
      *
      * To simplify life's of those who have this error this particular option sets a timeout within which ORM will try
-     * to perform requested write operation again and again until it recieves SQLITE_BUSY error.
+     * to perform requested write operation again and again until it receives SQLITE_BUSY error.
      *
+     * Enabling WAL can improve your app performance and face less SQLITE_BUSY issues.
      * Time in milliseconds.
      */
     readonly busyErrorRetry?: number;
+
+    /**
+     * Enables WAL mode. By default its disabled.
+     *
+     * @see https://www.sqlite.org/wal.html
+     */
+    readonly enableWAL?: boolean;
+
 }

src/driver/sqlite/SqliteQueryRunner.ts

@@ -4,6 +4,7 @@ import {AbstractSqliteQueryRunner} from "../sqlite-abstract/AbstractSqliteQueryR
 import {SqliteConnectionOptions} from "./SqliteConnectionOptions";
 import {SqliteDriver} from "./SqliteDriver";
 import {Broadcaster} from "../../subscriber/Broadcaster";
+import {IsolationLevel} from "../types/IsolationLevel";
 
 /**
  * Runs queries on a single sqlite database connection.
@@ -83,4 +84,12 @@ export class SqliteQueryRunner extends AbstractSqliteQueryRunner {
             await execute();
         });
     }
-}
+
+    async startTransaction(isolationLevel?: IsolationLevel): Promise<void> {
+        if ((this.connection.options as SqliteConnectionOptions).enableWAL === true) {
+            await this.query("PRAGMA journal_mode = WAL");
+        }
+
+        return super.startTransaction(isolationLevel);
+    }
+}