Bugs item #2825243, was opened at 2009-07-22 05:01
Message generated for change (Comment added) made by matburt
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Category: Core
Group: None
Status: Open
Resolution: None
Priority: 9
Private: No
Submitted By: heangu (heangu)
Assigned to: Niels Nes (nielsnes)
Summary: Data lost when restart
Initial Comment:
I opened two sessions at the same time, use session one to insert data,
session two execute START TRANSACTION but without COMMIT. When restart, I found
the data just inserted was lost!! MY test case is as follows:
1. Start the server.
2. Open one session. mclient -lsql -dtest. (Denote it as S1)
3. Open the second session as step 2. (Denote it as S2)
4. IN S1:
CREATE TABLE t(a int);
CREATE TABLE x(a int);
INSERT INTO t VALUES(1);
INSERT INTO t SELECT * FROM t;
INSERT INTO t SELECT * FROM t;
INSERT INTO t SELECT * FROM t;
INSERT INTO t SELECT * FROM t;
INSERT INTO t SELECT * FROM t;
INSERT INTO t SELECT * FROM t;
INSERT INTO t SELECT * FROM t;
INSERT INTO t SELECT * FROM t;
INSERT INTO t SELECT * FROM t;
INSERT INTO t SELECT * FROM t;
5. IN S2:
START TRANSACTION;
6. IN S1:
INSERT INTO x VALUES(1);
INSERT INTO x VALUES(2);
7. IN S2:
COMMIT;
UPDATE t SET a = 8;
8. WAIT a few minutes.
9. KILL server and start it.
10. Open session S1. (mclient -lsql -dtest)
11. IN S1:
SELECT * FROM x;
Here is the problem. I should have got two lines (1 and 2) in STEP 11, but in
fact I only got an empty set.
Where has my data gone?
It can't be other person who deleted it. And I can have it occur many times.
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Comment By: Matthew W. Jones (matburt)
Date: 2009-07-27 10:19
Message:
"test_table" and "raw_plays" are the same in this case, I did not do a good
enough job cleaning up the names before posting here.
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Comment By: Matthew W. Jones (matburt)
Date: 2009-07-27 10:15
Message:
I am experiencing widespread data corruption when restarting the
May2009-SP1 MonetDB release also, but mine is much simpler.
On 64-bit ubuntu:
Linux dsvm01 2.6.24-23-server #1 SMP Wed Apr 1 22:14:30 UTC 2009 x86_64
GNU/Linux
With a table defined as follows:
CREATE TABLE "tablespace"."test_table" (
"col1" varchar(50),
"col2" varchar(50),
"col3" varchar(50),
"col4" varchar(50),
"col5" varchar(50),
"col6" int,
"col7" timestamp(7),
"col8" int,
"col9" int,
"col10" int
);
I imported 20998687 records into this table with all columns populated and
ran a couple of queries to check the data:
select count(*) from raw_plays ;
[ 20998687 ]
select count(*) from raw_plays where col1 = '' or col2 = '' or col3 = '' ;
[ 0 ]
select max(col7), min(col7) from test_table ;
[ 2009-07-25 14:17:15.538000, 2009-07-24 15:29:12.524000 ]
During the time I loaded the data and ran these queries I did not restart
the database, it had been up for about 3 days I then issued:
monetdb stop db
and
monetdb start db
and re-ran the queries:
select count(*) from raw_plays ;
[ 20998687 ]
select count(*) from raw_plays where col1 = '' or col2 = '' or col3 = '' ;
[ 20852061 ]
select max(col7), min(col7) from test_table ;
[ 2009-07-25 14:17:15.538000, -1-01-01 00:00:00.000000 ]
This is some serious data corruption, I've lost data in the vast majority
of these records!
I wasn't sure if this is the same issue that is seen here, if need-be I
can open a new bug report.
----------------------------------------------------------------------
Comment By: heangu (heangu)
Date: 2009-07-22 23:38
Message:
I think the bug 2819966 is possible because of this data lost. This bug is
found while trying to reproduce the bug 2819966 that I reported a few days
ago.
In this case, if I execute an update on x before restarting server, older
versions of MONET will complain ASSERT failed in void_inplace. But new
versions of MONET seems OK but data lost.
----------------------------------------------------------------------
Comment By: Fabian (mr-meltdown)
Date: 2009-07-22 05:09
Message:
I can reproduce the problem
----------------------------------------------------------------------
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