Hi there,
i am new to android programming, however i am quite used working with
sqlite databases.
- my application opens a sqlite3 database on the sd card and runs a
kinda complex query (5 joins, 1 subquery, 2 where clauses) using
SQLiteDatabase.rawQuery
public Cursor queryDataBase(String sql, String[] selectionArgs){
Cursor c = myDB.rawQuery(sql, selectionArgs);
return c;
}
- the sql statement is given by a hardcoded String
- the query returns 585 rows with 24 columns
- i had to do a trade-off between storage space and indexing, but on
all bigger tables (about ~ 40 000 entries, for now) indexes are used,
SQLite shows for the query: Steps: 155 , Sorts: 0, AutoIdx: 1077
- i am not using primary keys, thus i also didn't rename anything to
"_id"
- the execution of rawQuery is kinda fast, execution time is about 2
ms
- however accessing this data takes way too much time, e.g. by
c.moveToFirst(), execution time about 1700 ms ! (same for
Cursor.getRowCount(), or apparently all first time access to the
actual result set)
- doing the same on a PC ( 2 Ghz, 1 GB RAM) with e.g. SQLiteSpy it
takes 15 ms to display the result set
- doing it on the PC with a C++ Implementation it's also 15 ms up to
30 ms
So what am i missing here? Is it actually possible that my Handset
with 800 MHz and 2 GB RAM is about 120 times slower??
( of course i am also aware of the speed difference between a microSD
card and a sata2 hdd, but that shouldn't explain this huge difference,
right? )
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