Method createFromScratch

fdbserver/KeyValueStoreSQLite.actor.cpp:1542–1577

}

void SQLiteDB::createFromScratch() {
	int sqliteFlags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE;
	checkError("open", sqlite3_open_v2(filename.c_str(), &db, sqliteFlags, nullptr));

	Statement(*this, "PRAGMA page_size = 4096").nextRow(); // fast
	btree = db->aDb[0].pBt;
	initPagerCodec();

	Statement(*this, "PRAGMA auto_vacuum = 2").nextRow(); // slow all the time
	Statement(*this, "PRAGMA journal_mode = WAL").nextRow(); // sometimes slow
	sqlite3_extended_result_codes(db, 1);

	sqlite3_mutex_enter(db->mutex);
	haveMutex = true;

	beginTransaction(true);
	u32 pgnoRoot = -1;
	sqlite3BtreeGetMeta(btree, BTREE_LARGEST_ROOT_PAGE, &pgnoRoot);

	// We expect our tables are #3, #4 (since autovacuum is enabled, there is a pointer map page at #2)
	if (pgnoRoot == 4) {
		table = pgnoRoot - 1;
		freetable = pgnoRoot;
		rollback();
	} else if (pgnoRoot == 1) {
		// The database is empty; create tables
		checkError("BtreeCreateTable", sqlite3BtreeCreateTable(btree, &table, BTREE_BLOBKEY));
		ASSERT(table == 3);
		checkError("BtreeCreateTable2", sqlite3BtreeCreateTable(btree, &freetable, BTREE_INTKEY));
		ASSERT(freetable == table + 1);
		endTransaction();
	} else {
		TraceEvent("PgnoRoot").detail("Value", pgnoRoot);
		checkError("CheckTables", SQLITE_CORRUPT);
	}
}

struct ThreadSafeCounter {
	volatile int64_t counter;