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我试图在Android和iOS上为项目执行SQLite性能之间的基准测试，并且与Android相比，iOS平台上的性能似乎非常糟糕。Android和iOS上的SQLite之间的性能差异
我想实现的是测量插入SQLite数据库中的行数（5000）和平台之间比较的时间。对于Android，我得到500ms左右的结果来执行所有5000次插入，但对于iOS，同样的操作需要20秒以上。怎么会这样？
这是我的iOS代码（插入部分）片段，dataArray中的是5000个随机100字符NSString的数组：
int numEntries = 5000;
self.dataArray = [[NSMutableArray alloc] initWithCapacity:numEntries];//Array for random data to write to database
//generate random data (100 char strings)
for (int i=0; i<numEntries; i++) {
[self.dataArray addObject:[self genRandStringLength:100]];
}
// Get the documents directory
NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docsDir = [dirPaths objectAtIndex:0];
// Build the path to the database file
NSString *databasePath = [[NSString alloc] initWithString:[docsDir stringByAppendingPathComponent: @"benchmark.db"]];
NSString *resultHolder = @"";
//Try to open DB, if file not present, create it
if (sqlite3_open([databasePath UTF8String], &db) == SQLITE_OK){
sql = @"CREATE TABLE IF NOT EXISTS BENCHMARK(ID INTEGER PRIMARY KEY AUTOINCREMENT, TESTCOLUMN TEXT)";
//Create table
if (sqlite3_exec(db, [sql UTF8String], NULL, NULL, NULL) == SQLITE_OK){
NSLog(@"DB created");
}else{
NSLog(@"Failed to create DB");
}
//START: INSERT BENCHMARK
NSDate *startTime = [[NSDate alloc] init];//Get timestamp for insert-timer
//Insert values in DB, one by one
for (int i = 0; i<numEntries; i++) {
sql = [NSString stringWithFormat:@"INSERT INTO BENCHMARK (TESTCOLUMN) VALUES('%@')",[self.dataArray objectAtIndex:i]];
if (sqlite3_exec(db, [sql UTF8String], NULL, NULL, NULL) == SQLITE_OK){
//Insert successful
}
}
//Append time consumption to display string
resultHolder = [resultHolder stringByAppendingString:[NSString stringWithFormat:@"5000 insert ops took %f sec\n", [startTime timeIntervalSinceNow]]];
//END: INSERT BENCHMARK
Android的代码片段：
// SETUP
long startTime, finishTime;
// Get database object
BenchmarkOpenHelper databaseHelper = new BenchmarkOpenHelper(getApplicationContext());
SQLiteDatabase database = databaseHelper.getWritableDatabase();
// Generate array containing random data
int rows = 5000;
String[] rowData = new String[rows];
int dataLength = 100;
for (int i=0; i<rows; i++) {
rowData[i] = generateRandomString(dataLength);
}
// FIRST TEST: Insertion
startTime = System.currentTimeMillis();
for(int i=0; i<rows; i++) {
database.rawQuery("INSERT INTO BENCHMARK (TESTCOLUMN) VALUES(?)", new String[] {rowData[i]});
}
finishTime = System.currentTimeMillis();
result += "Insertion test took: " + String.valueOf(finishTime-startTime) + "ms \n";
// END FIRST TEST
我没有Android设备来测试，所以我不知道。但是，我在OS X和Linux上使用SQLite的经验是，OS X实际上承认了“刷新到磁盘”的请求，这会导致I/O阻塞，而Linux只是一种手动方式，并且不会阻塞。这可能可以解释它。 – StilesCrisis
我觉得C（iOS）的做法比Java（Android）方式快一点。 –
谢谢。我通过turing的同步获得了一些速度！ – Andain