I have pretty big database that I need to query to get some data and present in a ListView on Android. The db is about 5MB, it’s stored on SD card. It has 60k records in 2 tables. The problem is that querying the db to get all the records from one specific column takes ridiculously long time – like a few minutes on both emulator and my phone. I’ve tried everything – storing this data in flat files, xml – sqlite is my last hope. This is the class I’m using to open the database and query it:
public class DataHelper {
private static final int DATABASE_VERSION = 1;
private static final String TABLE_NAME = "TableName";
private Context context;
private SQLiteDatabase db;
private SQLiteStatement insertStmt;
public DataHelper(Context context) {
this.context = context;
OpenHelper openHelper = new OpenHelper(this.context);
// this.db = openHelper.getReadableDatabase();
this.db = SQLiteDatabase.openDatabase(
Environment.getExternalStorageDirectory()
+ "/myDB.db", null,
SQLiteDatabase.NO_LOCALIZED_COLLATORS);
// this.insertStmt = this.db.compileStatement(INSERT);
}
public void deleteAll() {
this.db.delete(TABLE_NAME, null, null);
}
public List<String> selectBrands() {
List<String> list = new ArrayList<String>();
Cursor cursor = this.db.query(TABLE_NAME, new String[] { "ColumnName" },
null, null, null, null, null);
}
if (cursor.moveToFirst()) {
do {
if (!(list.contains(cursor.getString(0)))) {
list.add(cursor.getString(0));
}
} while (cursor.moveToNext());
}
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
return list;
}
private static class OpenHelper extends SQLiteOpenHelper {
OpenHelper(Context context) {
super(context, null, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
onCreate(db);
}
}
and putting on the ListView part:
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
try {
ctxContext = this.getApplicationContext();
lView = (ListView) findViewById(R.id.ListView01);
lView.setTextFilterEnabled(true);
ParseSQLITETask task = new ParseSQLITETask();
task.execute(null);
} catch (Exception e) {
LogErr(e.getMessage());
}
}
private class ParseSQLITETask extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... urls) {
try {
DataHelper dHelper = new DataHelper(getApplicationContext());
list = (ArrayList<String>) dHelper.selectBrands();
} catch (Exception e) {
LogErr(e.getMessage());
}
return null;
}
@Override
protected void onProgressUpdate(Void... progress) {
}
@Override
protected void onPostExecute(Void result) {
try {
lView.setAdapter(new ArrayAdapter<String>(ctxContext,
R.layout.list_item, list));
} catch (Exception e) {
LogErr(e.getMessage());
}
}
}
You are retrieving the entire record set and converting it into an
ArrayList. Don’t do this. Pass a Cursor back and use an appropriate Adapter (such as SimpleCursorAdapter).EDIT: you may also want to consider creating an index on that column, as it may speed up your retrieval time.