[sqlite] backup memory database not working
Thank you Clemens, this way all is fine! Am 11.03.2016 um 16:27 schrieb Clemens Ladisch: > asdf asdf wrote: >> My intention: >> - loading a file db into a memory db. > This is not done with ATTACH, but by making a backup of the > file DB with the memory DB as destination. > > > Regards, > Clemens > ___ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] backup memory database not working
I am not sure if i understand you correctly. My intention: - loading a file db into a memory db. - work with memory db during runtime. so it could be changed - save mem db back to file db. Is this possible ? Thank you Am 11.03.2016 um 16:19 schrieb Clemens Ladisch: > asdf asdf wrote: >> - create a memory db >> - attach a file db >> - backup memory db >> this fails. > An attached database stays separate, i.e., its data is not merged into > the backup. > > To backup the file DB, give its name (and not "main") to > sqlite3_backup_init(). > > > Regards, > Clemens > ___ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] backup memory database not working
Hello,
meanwhile i could reproduce my situation more precisely.
Short:
- create a memory db
- attach a file db
- backup memory db
this fails.
Please watch my compile ready example (VS 2013) attached.
Thank you for help
Am 10.03.2016 um 21:56 schrieb R Smith:
>
>
> On 2016/03/10 10:41 PM, asdf asdf wrote:
>> Hello,
>> what do you mean, please ? What code is not shown:my own code (and what
>> could be the cause then) using the example or what i posted in
>> stackoverflow.
>>
>> I would be happy to solve it. Any information appreciated-
>
> He means that there is something else that is wrong in your code that
> you've used to test this Backup feature. We cannot see your full code,
> so we do not know what is wrong with it, but we know something is
> wrong because the backup from memory works when we do it, and works
> when done like the example. You can easily use the command line
> SQLite3.exe tool to test it.
>
> So, if it works correctly for us, meaning it is not an SQLite bug, but
> there might be something in your code that is missing or weird and we
> would like to help you find it, however, only if you show us the exact
> code you've used to test with. Also the DB schema - some SQL perhaps
> to populate the in-memory database. Perhaps something about the schema
> is strange and causes the problem, then it might even be a bug - but
> we can't know that until we have exactly what you have.
>
> Thanks,
> Ryan
>
> ___
> sqlite-users mailing list
> sqlite-users at mailinglists.sqlite.org
> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
-- next part --
#include "stdafx.h"
#include "sqlite3.h"
#include
#include
#include
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, );
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);
if(xProgress != nullptr)
{
xProgress(
sqlite3_backup_remaining(pBackup),
sqlite3_backup_pagecount(pBackup)
);
}
if( rc==SQLITE_OK || rc==SQLITE_BUSY || rc==SQLITE_LOCKED ){
sqlite3_sleep(5);
}
} 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;
}
booldo_select(sqlite3*db, const std::string& sql, const std::string&
comment = "")
{
if (db == nullptr)
std::cout << "\ndo_select: no database";;
sqlite3_stmt* stmt = nullptr;
std::cout << "\ndo_select("<<comment<<") <"<<sql<<">";
int res = sqlite3_prepare_v2(db, sql.c_str(), -1, , 0);
if (res == SQLITE_OK)
{
/// cycle result rows
do{
res = sqlite3_step(stmt);
int row = 0;
int cols = sqlite3_column_count(stmt);
switch (res)
{
case SQLITE_DONE:
break;
case SQLITE_ROW:
{
/// cycle result columns
for (int col = 0; col < cols; col++)
{
std::string sres = (const char*)sqlite3_column_text(stmt,
0);
std::cout << "\n\t" <<"(" << row << "," << col << ") : " <<
sres.c_str();
}
}
break;
default:
{
sqlite3_finalize(stmt);
std::cout << "\n\t"<< "sql error: " << sql.c_str();
return false;
}
break;
[sqlite] backup memory database not working
Thank you Ryan,
i wrote a small test routine using the same backup routine i use in my code
and in fact, here it works. Attached.
Need to investigate for differences.
Thanks to community for support
Am 10.03.2016 um 21:56 schrieb R Smith:
>
>
> On 2016/03/10 10:41 PM, asdf asdf wrote:
>> Hello,
>> what do you mean, please ? What code is not shown:my own code (and what
>> could be the cause then) using the example or what i posted in
>> stackoverflow.
>>
>> I would be happy to solve it. Any information appreciated-
>
> He means that there is something else that is wrong in your code that
> you've used to test this Backup feature. We cannot see your full code,
> so we do not know what is wrong with it, but we know something is
> wrong because the backup from memory works when we do it, and works
> when done like the example. You can easily use the command line
> SQLite3.exe tool to test it.
>
> So, if it works correctly for us, meaning it is not an SQLite bug, but
> there might be something in your code that is missing or weird and we
> would like to help you find it, however, only if you show us the exact
> code you've used to test with. Also the DB schema - some SQL perhaps
> to populate the in-memory database. Perhaps something about the schema
> is strange and causes the problem, then it might even be a bug - but
> we can't know that until we have exactly what you have.
>
> Thanks,
> Ryan
>
> ___
> sqlite-users mailing list
> sqlite-users at mailinglists.sqlite.org
> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
-- next part --
#include "stdafx.h"
#include "sqlite3.h"
#include
#include
#include
//#include "sqlite3ext.h"
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, );
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);
if(xProgress != nullptr)
{
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;
}
boolbackup_test_sqlite_mem(void)
{
sqlite3*db=nullptr;
/// create memory db
if(sqlite3_open(":memory:", ) == SQLITE_OK)
{
/// create table
std::string sql = "CREATE TABLE IF NOT EXISTS [stock] ("
"[sid] VARCHAR(40) UNIQUE NOT NULL PRIMARY KEY,"
"[price] FLOAT "
" ) ";
char* db_err = nullptr;
if(sqlite3_exec(db, sql.c_str(), nullptr, nullptr, _err) ==
SQLITE_OK)
{
/// fill table with 1 records
for(int i=0;i < 1;i++)
{
std::ostringstream sstr;
sstr<<"INSERT INTO stock (sid,price) VALUES(";
sstr<<"'"<<i<<"',";
sstr<<(double) i / 7;
sstr<<")";
sql=sstr.str();
if(sqlite3_exec(db, sql.c_str(), nullptr, nullptr, _err) !=
SQLITE_OK)
{
std::cout<<"\nsql error: "<<sql.c_str();
return false;
}
}
/// check we have content
sqlite3_stmt* stmt=nullptr;
sql="SELECT count(*) FROM stock";
int r
[sqlite] backup memory database not working
Hello, what do you mean, please ? What code is not shown:my own code (and what could be the cause then) using the example or what i posted in stackoverflow. I would be happy to solve it. Any information appreciated- Am 10.03.2016 um 20:39 schrieb Clemens Ladisch: > asdf asdf wrote: >> Backing up a file database works well;not so memory. >> >> I described the issue here: >> http://stackoverflow.com/questions/35834529/sqlite-backup-memory-database-c > There is an error in your code. Which you have not shown. > > > Regards, > Clemens > ___ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] backup memory database not working
Hello, the examples for the back API as exposed here: https://www.sqlite.org/backup.html work not for memory database. Tested with latest amalgamation VC++ VS 2013. Backing up a file database works well;not so memory. I described the issue here: http://stackoverflow.com/questions/35834529/sqlite-backup-memory-database-c Thank you for help
