The rollback journal is used to return the database to its previous state in
the case of a partial write, not complete writes which are interrupted. As you
didn't commit the transaction, no write occurred, never mind a partial one, so
the database remained in its initial state.
Deleting a rollback journal is a bad idea. In this case it was harmless, but
normally it's an excellent way to corrupt your database.
As to where uncommitted transactions live, I am not sure. I'll let someone else
answer that.
On November 23, 2017 9:13:20 PM EST, "林自均" <johnl...@gmail.com> wrote:
>Hi folks,
>
>When I was learning about rollback journal, I did the following tests:
>
>(in shell 1)
>$ sqlite3 /tmp/db.sqlite
>SQLite version 3.21.0 2017-10-24 18:55:49
>Enter ".help" for usage hints.
>sqlite> PRAGMA journal_mode;
>delete
>sqlite> CREATE TABLE bank (name STR, money INT);
>sqlite> INSERT INTO bank VALUES ("john", 5566);
>sqlite> BEGIN;
>sqlite> UPDATE bank SET money = money + 100 WHERE name = "john";
>sqlite>
>
>(then in shell 2)
>$ kill -kill $(pidof sqlite3) # kills the sqlite3 process in shell 1
>$ rm -f /tmp/db.sqlite-journal
>$ sqlite3 /tmp/db.sqlite .dump
>PRAGMA foreign_keys=OFF;
>BEGIN TRANSACTION;
>CREATE TABLE bank (name STR, money INT);
>INSERT INTO bank VALUES('john',5566);
>COMMIT;
>
>I was expecting that deleting the rollback journal would commit the
>uncommitted transaction (i.e. increase money from 5566 to 5666).
>However,
>it didn't.
>
>I also noticed that the md5sum of db.sqlite are the same before the
>UPDATE
>query and after it, which means that the UPDATE query doesn't really
>write
>into db.sqlite. Does it only write into memory?
>
>Thanks for answering my questions.
>
>John Lin
>_______________________________________________
>sqlite-users mailing list
>sqlite-users@mailinglists.sqlite.org
>http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
_______________________________________________
sqlite-users mailing list
sqlite-users@mailinglists.sqlite.org
http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
