Questions tagged [read-committed]
29 questions
0
votes
2 answers
How Read Committed Isolation Level prevents dirty reads
i start with a simple question:
according to Dirty Read definition in
Wikipedia
and Msdn :
we have 2 concurrent transactions, T1 and T2
Dirty Reads Occur in ,when T1 is Updating a row and T2 is reading row that "is not Committed yet" by T1
but at…
raoof hojat
- 355
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- 12
0
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1 answer
JPA with Isolation.READ_COMMITTED acts as REPEATABLE_READ
I'm seeing a behaviours that is a little strange in my test JPA app.
Simple table;
id
count
@Transactional(isolation = Isolation.READ_COMMITTED)
public void testCount() {
// I randomly fetch a row which has a count > 4
Counts counts =…
Alexis
- 1,825
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0
votes
1 answer
kafka stream with exactly_once enabled generate several duplicated messages
Kafka stream with exactly_once enabled generate several duplicated messages with (not committed transaction status)
I did a tests in my pc :
without "exactly_once"
for 100_000 messages, I got 100_000 on topic target.
with…
elhadi
- 1
0
votes
0 answers
mysql select for update read committed deadlock
mysql version:5.7.23-log
isolation level:read committed
mysql data
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for app_record_lock_test
-- ----------------------------
DROP TABLE IF EXISTS…
jiankunking
- 11
- 4
0
votes
1 answer
PostgreSQL read commit on different transactions
I was running some tests to better understanding read commits for postgresql.
I have two transactions running in parallel:
-- transaction 1
begin;
select id from item order by id asc FETCH FIRST 500 ROWS ONLY;
select…
Toothless
- 3
- 1
0
votes
2 answers
How is atomic rule ensured when using default (read commited) isolation mode?
An important property of transaction is atomicity.
The default mode is read commited. This prevents dirty reads. But we have problem of repeatable reads and phantom rows.
How is atomic rule ensured when using default (read commited) isolation…
variable
- 8,262
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0
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1 answer
Prevent deadlock in read-committed SELECT
I am extracting data from a business system supplied by a third party to use in reporting. I am using a single SELECT statement issued from an SSIS data flow task source component that joins across multiple tables in the source system to create the…
GreatApe
- 23
- 7
0
votes
0 answers
Read committed isolation level blocking
I'm trying to understand and use spring transactional isolation level. I need to maximize concurrency of my application and I just need to be careful about dirty reads. Phantom read and other scenarios are really not required to be taken care. So…
Harry
- 75
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0
votes
1 answer
How to read -when requested- JPA committed only (avoid flushed entities)
As far as I've experienced JPA/hibernate will return entities that either exists at the database or have been persisted during the transaction and then flushed to the database.
I'd like to be able for certain queries to ask Hibernate for the…
lobor7
- 9
- 2
0
votes
1 answer
should we use read-committed isolation level?
I have a mysql innodb table named "radacct". This table contains the users internet usage records like upload,download,account id etc(table schema below). The radacct table gets updated at random intervals with data sent by routers. We also use this…
sherpaurgen
- 3,028
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0
votes
1 answer
MySQL performing a "No impact" temporary INSERT with replication avoiding Locks
SO, we are trying to run a Report going to screen, which will not change any stored data.
However, it is complex, so needs to go through a couple of (TEMPORARY*) tables.
It pulls data from live tables, which are replicated.
The nasty bit when it…
Meh-Lindi
- 29
- 6
0
votes
1 answer
Does MySQL InnoDB locks multiple rows with READ_COMMITTED isolation level?
I am in trouble while resolving LOCK WAIT TIMEOUT EXCEED error with MySQL InnoDB.
I have gone through this article and it says if we use isolation level READ_COMMITTED then my update query should lock only those rows which match the WHERE condition,…
Vishal Zanzrukia
- 4,902
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0
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0 answers
Lock on two tables without dependences between them
I have a strange situation. I'm working on a SQL Server 2005 database, I've searched locks on DB using this.
After capture all day, stop the trace and see the results, I found a blocking query that blocks a insertion, BUT, the query is in read…
Mariano G
- 255
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-1
votes
1 answer
What is and how to produce "read-only transaction anomaly" in READ COMMITTED? (PostgreSQL)
I read Analyzing a read-only transaction anomaly under snapshot isolation. Then, It says read-only transaction anomaly happens in READ COMMITTED and SERIALIZABLE in PostgreSQL as shown below:
Actually, I don't understand read-only transaction…
Super Kai - Kazuya Ito
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