헌데, 가끔 머드상에서 웹서버 데이터베이스에 저장해놓은 데이터들을 가져와야할 경우가 간혹 생긴다. (단순 Select)
데이터가 정확히 일치해야할 필요성은 없지만, 그래도 대략적으로 정보가 필요한지라... 이걸 매번 웹서버내의 데이터베이스에서 가져오려니 속도감이 좀 느껴지는지라, 크론탭에 등록하여 Mysql 데이터를 Sqlite3로 변환시켜 로컬에 저장해두도록 하였다.
헌데 Mysql에서 Select한 데이터를 한컬럼씩 가져올때마다 Sqlite3에 인서트 하려니 속도가 많이 느려서 우선은 Sqlite3 메모리 디비에 내용을 저장한다음 이 메모리 디비를 로컬(머드 구동서버)에 저장하는 형태로 작업을 진행하였다.
현재로서는 결과에 만족...... 작업하면서 참고한 자료는 아래와 같음
출처 : http://www.sqlite.org/backup.html
◆ 메모리 디비를 파일 디비로 저장하는 방법
/*
** This function is used to load the contents of a database file on disk
** into the "main" database of open database connection pInMemory, or
** to save the current contents of the database opened by pInMemory into
** a database file on disk. pInMemory is probably an in-memory database,
** but this function will also work fine if it is not.
**
** Parameter zFilename points to a nul-terminated string containing the
** name of the database file on disk to load from or save to. If parameter
** isSave is non-zero, then the contents of the file zFilename are
** overwritten with the contents of the database opened by pInMemory. If
** parameter isSave is zero, then the contents of the database opened by
** pInMemory are replaced by data loaded from the file zFilename.
**
** If the operation is successful, SQLITE_OK is returned. Otherwise, if
** an error occurs, an SQLite error code is returned.
*/
int loadOrSaveDb(sqlite3 *pInMemory, const char *zFilename, int isSave){
int rc; /* Function return code */
sqlite3 *pFile; /* Database connection opened on zFilename */
sqlite3_backup *pBackup; /* Backup object used to copy data */
sqlite3 *pTo; /* Database to copy to (pFile or pInMemory) */
sqlite3 *pFrom; /* Database to copy from (pFile or pInMemory) */
/* Open the database file identified by zFilename. Exit early if this fails
** for any reason. */
rc = sqlite3_open(zFilename, &pFile);
if( rc==SQLITE_OK ){
/* If this is a 'load' operation (isSave==0), then data is copied
** from the database file just opened to database pInMemory.
** Otherwise, if this is a 'save' operation (isSave==1), then data
** is copied from pInMemory to pFile. Set the variables pFrom and
** pTo accordingly. */
pFrom = (isSave ? pInMemory : pFile);
pTo = (isSave ? pFile : pInMemory);
/* Set up the backup procedure to copy from the "main" database of
** connection pFile to the main database of connection pInMemory.
** If something goes wrong, pBackup will be set to NULL and an error
** code and message left in connection pTo.
**
** If the backup object is successfully created, call backup_step()
** to copy data from pFile to pInMemory. Then call backup_finish()
** to release resources associated with the pBackup object. If an
** error occurred, then an error code and message will be left in
** connection pTo. If no error occurred, then the error code belonging
** to pTo is set to SQLITE_OK.
*/
pBackup = sqlite3_backup_init(pTo, "main", pFrom, "main");
if( pBackup ){
(void)sqlite3_backup_step(pBackup, -1);
(void)sqlite3_backup_finish(pBackup);
}
rc = sqlite3_errcode(pTo);
}
/* Close the database connection opened on database file zFilename
** and return the result of this function. */
(void)sqlite3_close(pFile);
return rc;
}위나 아래나 뭐 별반 다를바 없는거라 생각한다.... Source Database를 어떤걸 지정해주느냐의 차이일테니
반대로 적용하면 로컬데이터베이스를 메모리 디비로 읽어들이는 것도 쉽게 될듯.
◆ 지정 디비와 동일한 디비를 생성(백업)하는 방법
/*
** Perform an online backup of database pDb to the database file named
** by zFilename. This function copies 5 database pages from pDb to
** zFilename, then unlocks pDb and sleeps for 250 ms, then repeats the
** process until the entire database is backed up.
**
** The third argument passed to this function must be a pointer to a progress
** function. After each set of 5 pages is backed up, the progress function
** is invoked with two integer parameters: the number of pages left to
** copy, and the total number of pages in the source file. This information
** may be used, for example, to update a GUI progress bar.
**
** While this function is running, another thread may use the database pDb, or
** another process may access the underlying database file via a separate
** connection.
**
** If the backup process is successfully completed, SQLITE_OK is returned.
** Otherwise, if an error occurs, an SQLite error code is returned.
*/
int backupDb(
sqlite3 *pDb, /* Database to back up */
const char *zFilename, /* Name of file to back up to */
void(*xProgress)(int, int) /* Progress function to invoke */
){
int rc; /* Function return code */
sqlite3 *pFile; /* Database connection opened on zFilename */
sqlite3_backup *pBackup; /* Backup handle used to copy data */
/* Open the database file identified by zFilename. */
rc = sqlite3_open(zFilename, &pFile);
if( rc==SQLITE_OK ){
/* Open the sqlite3_backup object used to accomplish the transfer */
pBackup = sqlite3_backup_init(pFile, "main", pDb, "main");
if( pBackup ){
/* Each iteration of this loop copies 5 database pages from database
** pDb to the backup database. If the return value of backup_step()
** indicates that there are still further pages to copy, sleep for
** 250 ms before repeating. */
do {
rc = sqlite3_backup_step(pBackup, 5);
xProgress(
sqlite3_backup_remaining(pBackup),
sqlite3_backup_pagecount(pBackup)
);
if( rc==SQLITE_OK || rc==SQLITE_BUSY || rc==SQLITE_LOCKED ){
sqlite3_sleep(250);
}
} while( rc==SQLITE_OK || rc==SQLITE_BUSY || rc==SQLITE_LOCKED );
/* Release resources allocated by backup_init(). */
(void)sqlite3_backup_finish(pBackup);
}
rc = sqlite3_errcode(pFile);
}
/* Close the database connection opened on database file zFilename
** and return the result of this function. */
(void)sqlite3_close(pFile);
return rc;
}※ sqlite3_backup 을 사용하기 위해서는 Sqlite3 버전이 3.6.14.1 이상이어야 한다.
