I never use the freeze and unfreeze commands but your understanding of
them sounds correct and is consistent with the following ij experiment:
ij version 10.17
ij> CONNECT 'jdbc:derby:zdb;create=true';
ij> CREATE TABLE t(a INT);
0 rows inserted/updated/deleted
ij> INSERT INTO t VALUES (1);
1 row inserted/updated/deleted
ij> CALL SYSCS_UTIL.SYSCS_FREEZE_DATABASE();
0 rows inserted/updated/deleted
ij> SELECT * FROM t;
A
---
1
1 row selected
ij> DISCONNECT;
ij> CONNECT 'jdbc:derby:zdb';
ij> SELECT * FROM t;
A
---
1
1 row selected
ij> CALL SYSCS_UTIL.SYSCS_UNFREEZE_DATABASE();
0 rows inserted/updated/deleted
ij> INSERT INTO t VALUES (2);
1 row inserted/updated/deleted
ij> SELECT * FROM t;
A
---
1
2
2 rows selected
Hope this helps,
-Rick
On 8/7/23 2:55 PM, fed wrote:
Hi,
I have a derby network server running with some databases connected and I
want to backup the databases directory with my backup utility.
My idea is to connect to every database in the network server and call the
freeze procedure, execute the backup of the databases directories and then
call the unfreeze procedure on every db, but I have some doubts.
Q1:
I am going for every database to get a connection, execute
CALL SYSCS_UTIL.SYSCS_FREEZE_DATABASE()
and then close the connection. After this I execute the backup with my
backup utility and then later after the backup is finished for every
database get a new connection and execute:
CALL SYSCS_UTIL.SYSCS_UNFREEZE_DATABASE() , is this correct?
>From the example in the documentation it seems that I have to use the same
connection to call the two stored procedures, but this is not required,
right?
public static void backUpDatabaseWithFreeze(Connection conn)
throws SQLException {
Statement s = conn.createStatement();
s.executeUpdate(
"CALL SYSCS_UTIL.SYSCS_FREEZE_DATABASE()");
*//copy the database directory during this interval*
s.executeUpdate(
"CALL SYSCS_UTIL.SYSCS_UNFREEZE_DATABASE()");
s.close();
}
Q2:
If I stop the network server while the database is in "freeze" state when I
restart it, it is still in "freeze" state and I have to call unfreeze on it?
My concern is that It is not possible that I get stuck in the "freeze"
state of the database, I can always "unfreeze" it, right?
Q3:
Last question, sorry for lots of questions: just to confirm even if in a
freeze state I can acquire a connection and execute a read operation
(select) on the database even in a transaction, right?
Thanks for the help
- fed
