How to backup a sqlite3 database
lazarus / 16-Databases

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pedro756901 · 2015-12-08 02:27

Hi All

I am trying to backup a sqlite3 db, below is code snippet but it can't
work. The problem is that the output backup file size is zero.

Attached is a mini-project

Thank you for your help.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.Button3Click(Sender: TObject);var  backup:TSQLite3Backup;begin 
if (Edit1.Text<>'') and (Edit2.Text<>'') then  begin   
backup:=TSQLite3Backup.Create ;   
backup.OnBackupProgress:=@OnBackupProgress ;   
backup.Backup(SQLite3ConnSource,Edit2.Text,false,Edit1.Text);  //
 backup.Free ;  end;end; procedure TForm1.OnBackupProgress(Sender:
TObject; Remaining, PageCount: integer  );begin 
Label3.Caption:=IntToStr(Remaining); 
Label4.Caption:=IntToStr(PageCount);end;

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LacaK · 2015-12-08 06:13

What do you write in Edit1.Text and Edit2.Text ?
Edit1.Text should be name of dababase to backup i.e. 'main'
Edit2.Text should be name of file to which backup

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pedro756901 · 2015-12-08 07:46

I have selected "ImageTest.db3" in Edit1.Text and inputed "backup.db"
in Edit2.Text

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mirce.vladimirov · 2015-12-08 11:48

What exectly does this TSQLite3Backup do ?
SQLite databases are stored in one physical file, my backup of SQLite
db's is simple, i just copy the file. Or even send it via emails
attachment or via FTP or SSH's scp...

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rvk · 2015-12-08 12:39

Quote from: mirce.vladimirov on December 08, 2015, 12:48:34 pmWhat
exectly does this TSQLite3Backup do ?
It can copy/replicate a sqlite3 database while it is in use.
It will create a current snapshot. (it uses the sqlite3_backup api)
You can't do that with a physical copy.

Although note the warning:
Quote    //The backup process will restart when another process writes
to the database.
    //Pro: the backup is a correct snapshot
    //Contra: the backup can take a very long time when a lot of
writes to the database are made during backup
More info: https://www.sqlite.org/backup.html

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LacaK · 2015-12-08 17:48

Quote from: pedro756901 on December 08, 2015, 08:46:52 amI have
selected "ImageTest.db3" in Edit1.Text and inputed "backup.db" in
Edit2.Text
IMO it is not good.
Try write in 1st edit: main
2nd edit: backup.db

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rvk · 2015-12-09 08:43

Quote from: LacaK on December 08, 2015, 06:48:39 pmQuote from:
pedro756901 on December 08, 2015, 08:46:52 amI have selected
"ImageTest.db3" in Edit1.Text and inputed "backup.db" in Edit2.Text
IMO it is not good.
Try write in 1st edit: main
2nd edit: backup.db
Confirmed.
The SourceDB-name should be "main". You've already connected the
SQLite3ConnSource to ImageTest.db3 so you don't need to provide that
name again. In fact... The SourceDBName parameter in the Backup-call
has a default "main" so all you need is this:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.Button3Click(Sender: TObject);var  backup:
TSQLite3Backup;begin  SQLite3ConnSource.DatabaseName :=
'ImageTest.db3'; // connect to source-db  SQLite3ConnSource.Open; 
backup := TSQLite3Backup.Create;  try    backup.OnBackupProgress :=
@OnBackupProgress;    backup.Backup(SQLite3ConnSource, 'backup.db',
False);  finally    backup.Free;  end;end;

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pedro756901 · 2015-12-10 02:10

It works successfully, thank you all for the help, specially, thanks
to rvk for the code snippet.

Quote from: rvk on December 09, 2015, 09:43:55 amQuote from: LacaK on
December 08, 2015, 06:48:39 pmQuote from: pedro756901 on December 08,
2015, 08:46:52 amI have selected "ImageTest.db3" in Edit1.Text and
inputed "backup.db" in Edit2.Text
IMO it is not good.
Try write in 1st edit: main
2nd edit: backup.db
Confirmed.
The SourceDB-name should be "main". You've already connected the
SQLite3ConnSource to ImageTest.db3 so you don't need to provide that
name again. In fact... The SourceDBName parameter in the Backup-call
has a default "main" so all you need is this:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.Button3Click(Sender: TObject);var  backup:
TSQLite3Backup;begin  SQLite3ConnSource.DatabaseName :=
'ImageTest.db3'; // connect to source-db  SQLite3ConnSource.Open; 
backup := TSQLite3Backup.Create;  try    backup.OnBackupProgress :=
@OnBackupProgress;    backup.Backup(SQLite3ConnSource, 'backup.db',
False);  finally    backup.Free;  end;end;