我正在研究一个依赖SQLite3数据库作为数据存储库的C ++ Android NDK项目。该数据库有三个表。列数是6、8和6;行数分别为240,〜1,250万和〜400万。
SQLite驱动程序已从SQLite3合并源代码3.19.3版直接编译,未经修改直接编译到我的本机库中。
我的问题是,在运行本机库时,数据库查询导致“ SQL逻辑错误或数据库丢失”。我知道数据库在我期望的位置,并且可以访问。如果我在桌面环境(而不是在移动设备)上针对相同的数据库执行相同的查询,则会看到预期的结果。此外,如果我使用存储库中数据子集的数据库(约300条记录)在移动设备上执行相同的查询,则会看到预期的结果。
有任何想法吗?
供参考,这是我正在使用的查询:
WITH
weather_distance AS
(SELECT latitude, longitude, temperature, humidity, time, (ABS((latitude - $lat)) + ABS((longitude - $lon))) AS distance FROM Weather WHERE time BETWEEN $start AND $end),
min_weather_distance AS
(SELECT latitude, longitude, temperature, humidity, time FROM weather_distance WHERE distance = (SELECT MIN(distance) FROM weather_distance)),
solar_distance AS
(SELECT latitude, longitude, ghi, (time - 1800) AS time, (ABS((latitude - $lat)) + ABS((longitude - $lon))) AS distance FROM SolarData WHERE time BETWEEN $start AND $end),
min_solar_distance AS
(SELECT latitude, longitude, ghi, time FROM solar_distance WHERE distance = (SELECT MIN(distance) FROM solar_distance))
SELECT s.time, s.ghi, w.temperature, w.humidity FROM min_weather_distance w INNER JOIN min_solar_distance s ON w.time = s.time ORDER BY s.time ASC
和我用来进行查询的代码(C ++):
const char* getEnvQuery =
"WITH "
"weather_distance AS "
"(SELECT latitude, longitude, temperature, humidity, time, (ABS((latitude - $lat)) + ABS((longitude - $lon))) AS distance FROM Weather WHERE time BETWEEN $start AND $end), "
"min_weather_distance AS "
"(SELECT latitude, longitude, temperature, humidity, time FROM weather_distance WHERE distance = (SELECT MIN(distance) FROM weather_distance)), "
"solar_distance AS "
"(SELECT latitude, longitude, ghi, (time - 1800) AS time, (ABS((latitude - $lat)) + ABS((longitude - $lon))) AS distance FROM SolarData WHERE time BETWEEN $start AND $end), "
"min_solar_distance AS (SELECT latitude, longitude, ghi, time FROM solar_distance WHERE distance = (SELECT MIN(distance) FROM solar_distance)) "
"SELECT s.time, s.ghi, w.temperature, w.humidity FROM min_weather_distance w INNER JOIN min_solar_distance s ON w.time = s.time ORDER BY s.time ASC;\0";
sqlite3_stmt* getEnvStmt;
prepareSqlStatement(getEnvQuery, &getEnvStmt, envdbhandle, "Error preparing SQL statement to retrieve environmental data. SQLite return code: ");
sqlite3_bind_double(getEnvStmt, 1, iter->latitude); //iter is defined above quoted code
sqlite3_bind_double(getEnvStmt, 2, iter->longitude);
sqlite3_bind_double(getEnvStmt, 3, iter->startTime);
sqlite3_bind_double(getEnvStmt, 4, iter->endTime);
__android_log_print(ANDROID_LOG_DEBUG, "SPP/getEnvironment", "Bound parameters: lat=%f, lon=%f, start=%ld, end=%ld", iter->latitude, iter->longitude, iter->startTime, iter->endTime);
int rc = sqlite3_step(getEnvStmt);
__android_log_print(ANDROID_LOG_DEBUG, "SPP/getEnvironment", "step(getEnvStmt) = %d", rc);
int errCode = sqlite3_extended_errcode(envdbhandle);
__android_log_print(ANDROID_LOG_DEBUG, "SPP/getEnvironment", "Most recent SQLITE error code: %s. Message: %s", sqlite3_errstr(errCode), sqlite3_errmsg(envdbhandle));
while(rc == SQLITE_ROW)
{
EnvironmentDatum envData;
int dbTime = sqlite3_column_int(getEnvStmt, 0);
envData.UnixTime = timeconvert::secondsOfYearToUNIXTime(dbTime, year);
__android_log_print(ANDROID_LOG_DEBUG, "SPP/getEnvironment", "EnvironmentDatum dbTime=%d, UnixTime=%f", dbTime, envData.UnixTime);
envData.GHI = sqlite3_column_double(getEnvStmt, 1);
envData.Temperature = sqlite3_column_double(getEnvStmt, 2);
envData.Humidity = sqlite3_column_double(getEnvStmt, 3);
envCollection.push_back(envData);
rc = sqlite3_step(getEnvStmt);
}
sqlite3_finalize(getEnvStmt);
重要的调试信息:
sqlite3_stmt* verQueryStmt;
prepareSqlStatement("select sqlite_version();\0", &verQueryStmt, envdbhandle, "Error getting driver version. Error code:");
sqlite3_step(verQueryStmt);
std::string sqliteVersion = parseSqliteStringColumn(verQueryStmt, 0);
sqlite3_finalize(verQueryStmt);
__android_log_print(ANDROID_LOG_DEBUG, "SPP/buildScenario", "sqlite version=%s", sqliteVersion.c_str()); // outputs "sqlite version=3.19.3"
__android_log_print(ANDROID_LOG_DEBUG, "SPP/buildScenario", "env db readability=%s", (sqlite3_db_readonly(envdbhandle, "main") == 1 ? "READONLY" : (sqlite3_db_readonly(envdbhandle, "main") == 0 ? "READ/WRITE" : "NOT CONNECTED"))); // outputs "READ/WRITE"
根据请求,这是prepareStatement:
static int prepareSqlStatement(const char* query, sqlite3_stmt** statement, sqlite3* db, const char* failMsg)
{
int returnCode = sqlite3_prepare(db, query, -1, statement, NULL);
if(returnCode != SQLITE_OK || statement == NULL)
{
int errCode = sqlite3_extended_errcode(dbhandle);
std::cout << "Most recent SQLITE error code: " << sqlite3_errstr(errCode) << ". Message: " << sqlite3_errmsg(dbhandle) << std::endl;
reportError(failMsg, -1 * returnCode);
}
return returnCode;
}
并在预期中,这是reportError:
static void reportError(const char* message, int errorCode)
{
std::stringstream ss;
ss << message << errorCode;
throw std::runtime_error(ss.str());
}
当查询的中间结果太大时,数据库必须将一些数据交换到一个临时文件中。
6410是SQLITE_IOERR_GETTEMPPATH
,这意味着无法访问任何临时文件存储位置。
Android没有任何默认的Unix路径。内置数据库框架使用SQLITE_TEMP_STORE = 3编译其SQLite库的副本。如果要获取实际的临时文件,则应将它们放在Context.getCacheDir()
;返回的目录中。这将需要设置SQLITE_TMPDIR环境变量。
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