Questions tagged [database-concurrency]

Database concurrency is a database property that allows users to access data at the same time.

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Simultaneous inserting in MySQL(innodb)

Consider we have a table t_log in database Test. The t_log looks like the following create table `t_log`( `F_log_id` bigint(20) not null AUTO_INCREMENT, `F_trans_id` bigint(20) not null, `F_action` tinyint(3) not null, primariy…
Junjie
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Oracle Transactions and Read Consistency

Consider i am offering a lottery for all those who enroll themselves with thier friends using sql*plus before 12 o clock. There is no column to store the timestamp say just a list of names in each row. A person m1 inserted his ticket already before…
cdummy
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What is a good approach for safe concurrent updates in a relational database?

I'm writing a Java app to update a relational database (currently H2). I have a process which does the following: Query an external system for certain data items Check whether or not those items have already been imported into our system…
user3364825
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Confusion on timestamping: solution for concurrency issue

I'm currently developing a website and while working on database design, i had some concern on concurrency issue, I'm considering using timestamping to avoid this. My understanding in timestamping is that it works this way: There is a field for…
Echusen
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Understanding Transaction Isolation Levels

I am new to the topic, and I am trying to verify what I understand. so please consider the following example:- Transaction contains a select and update statements, where update statement depends on the result set returned from the select statement.…
Costa
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Lock an entire single table but still allow to access other tables in the same session on MySQL

Is it possible to lock a single table on MySQL for a session and still be able to read and write on other unlocked tables on the same session that locked that table while the table is still locked?
razenha
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Why aren't time stamped based concurrency control protocols used more extensively?

As a database theoretic concept I've been a big fan of time stamped based concurrency control protocols since I first learned about them. I've noticed they don't seem to be used much. Why is that? Or am I just wrong? Edit: I mean timestamped data…
Aaron Watters
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postgresql writable common table expression concurrency

I just learned about using writable common table expressions in postgres-9.1, specifically from this site. http://vibhorkumar.wordpress.com/2011/10/26/upsertmerge-using-writable-cte-in-postgresql-9-1/ WITH upsert as (update mytable2 m set…
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How to avoid the concurrent problem in back-end when select-then-update from MySQL

I'm using Java and MySQL. And I have a table: create table serial_number ( id int not null primary key auto_increment, -- PK sn int, -- The serial number available tinyint -- 0: unavailable; 1: available ); Here is the…
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Concept related to transaction?

I was reading about transactions in DBMS. Just get started with it. But I am super confused with one concept. Suppose initially A=100 For T1 A=100 and doing A = A-50 For T2 temp would be 10 and change A=90. So T2 would write A=90. Now when T1 is…
Hash Blog
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How is active-active database architecture different from replica set based traditional architecture?

I have read somewhere that active-active architecture facilitates concurrent write facility. Is it feasible? Basically I need to understand the core functionalities offered by this architecture which makes it a widely adopted paradigm.
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Java Object Update after Column update

I have a question about concurrency control. Here is the scenario. A java API/Thread reads an entity/row from the database. Another thread updates the same row. Now, if I want to update the object/row which I read from step 1, how can I do it?
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