在sqlite3数据库中插入1000000行

Question

我想在数据库中插入10,00,000行,但插入时需要花费太长时间.

例如,现在我正在尝试使用2055行,将这些数据上传到数据库需要3分钟.这次对于2055个条目来说太多了.

以下是我将数据插入数据库的方法:

      public void insert_database(Context context,String field1,String field2,String field3,String field4,String field5,String field6 ,String field7,String field8,String field9,String field10)
{

    try
    {
        //RayAllen_Database.beginTransaction();
        RayAllen_Database.execSQL(" insert or replace into "+ TableName_csv+" values( '"+field1+"' ,'"+field2+"','"+field3+"','"+field4+"','"+field5+"','"+field6+"','"+field7+"','"+field8+"','"+field9+"','"+field10+"');");


    }
    catch(Exception e)
    {
        //Log.i("Database Exception", "Exception");
        e.printStackTrace();
    }

}

在另一个名为:解析数据的类中:这里我正在解析csv文件并在解析时:

尝试{

CSVReader reader=new CSVReader(new FileReader(filename));
String [] nextLine;

//create database
obj.create_database(context);
obj.OpenDatabase(context);
//reader.readNext();

while ((nextLine=reader.readNext())!=null)
{
          //here I am calling the insert_database function
    }
 }

它在这里逐个解析行并调用insert方法将条目插入到数据库中.

但这是太多的时间采取..我怎样才能提高这个性能？

Answer 1

快速举例说明为什么你应该做正确的事而不是"错误的".这是在ICS 4.0.4上运行测试的,它具有可怕的INSERT性能.

首先,一个简单的方法SQLiteOpenHelper是创建一个UNIQUE对列具有约束的表,以便立即引发冲突.

class SimpleHelper extends SQLiteOpenHelper {
    // InsertHelpers are a really good idea - they format a prepared statement
    // for you automatically.
    InsertHelper mInsert;
    public SimpleHelper(Context context) {
        super(context, "tanika.db", null, 1);
    }
    @Override
    public void onOpen(SQLiteDatabase db) {
        super.onOpen(db);
        mInsert = new InsertHelper(db, "target");
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE target (\n" +
                "_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,\n" +
                "val1 TEXT NOT NULL,\n" +
                "val2 TEXT NOT NULL,\n" +
                "val3 TEXT NOT NULL,\n" +
                // Let's make one unique so we can get some juicy conflicts
                "val4 TEXT NOT NULL UNIQUE\n" +
                ")");
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }
}

捆绑在任何旧的Activity我们添加以下简单的测试方法:

long test(final int n) {
    long started = System.currentTimeMillis();
    ContentValues values = new ContentValues();

    for (int i = 0; i < n; i++) {
        values.clear();
        // Every 20th insert, generate a conflict in val4
        String val4 = String.valueOf(started + i);
        if (i % 20 == 0) {
            val4 = "conflict";
        }
        values.put("val1", "Value1");
        values.put("val2", "Value2");
        values.put("val3", "Value3");
        values.put("val4", val4);
        mHelper.mInsert.replace(values);
    }
    return System.currentTimeMillis() - started;
}

如您所见,这将导致每20个INSERT左右发生冲突.调用InsertHelper#replace(..)会导致帮助程序使用INSERT OR REPLACEon冲突.

现在,让我们运行这个测试代码,包括和不包含它的事务.

class Test1 extends AsyncTask<Integer, Void, Long> {
    @Override
    protected Long doInBackground(Integer... params) {
        return test(params[0]);
    }
    @Override
    protected void onPostExecute(Long result) {
        System.out.println(getClass().getSimpleName() + " finished in " + result + "ms");
    }
}

class Test2 extends AsyncTask<Integer, Void, Long> {
    protected Long doInBackground(Integer... params) {
        SQLiteDatabase db = mHelper.getWritableDatabase();
        db.beginTransaction();
        long started = System.currentTimeMillis();
        try {
            test(params[0]);
            db.setTransactionSuccessful();
        } finally {
            db.endTransaction();
        }
        return System.currentTimeMillis() - started;
    }
    @Override
    protected void onPostExecute(Long result) {
        System.out.println(getClass().getSimpleName() + " finished in " + result + "ms");
    }
}

一切都是这样开始的:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    mHelper = new SimpleHelper(this);
    mHelper.getWritableDatabase(); // Forces the helper to initialize.
    new Test1().execute(2055);
    new Test2().execute(2055);
}

结果呢？如果没有交易,则INSERT需要41072毫秒.交易时间为940毫秒.简而言之,FFS,开始使用InsertHelpers和事务.