On Thursday, 15 June, 2017 09:40, David Raymond <[email protected]>
wrote:
> In the same train of thought: What's the difference between .backup and
> .clone in the CLI, and would either of those do the equivalent?
> .backup ?DB? FILE Backup DB (default "main") to FILE
> .clone NEWDB Clone data into NEWDB from the existing database
.backup makes a backup of the database file using the backup API call,
effectively copying all the pages (without looking at them to much) from main
to the new file.
.clone "copies" the data to a new database file by effectively doing the
following:
open the newfile
begin exclusive on newfile
for each sqlstatement in main.sqlite_master
if type=='table'
execute retrieved sql in newfile
prepare select * from main.table
prepare insert or replace into newfile.table
step select from main.table
while (SQLITE_ROW)
bind values from selected row to prepared insert
step insert statement
step select statement
for each sqlstatement in main.sqlite_master
if type != 'table'
execute retrieved sql in newfile
commit newfile
close newfile
So, backup will be faster. clone may permit data to be recovered from
corrupted databases. Sort of like how dump/load works, only without the
overhead of writing a dump file and reloading it, or generating SQL statements.
In most cases similar to:
sqlite3 main.db .dump | sqlite3 newfile.db
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