Question : We have a table with 200k rows where we change some flags multiple times per day. If i […]
Tag: mvcc
Are snapshots generated for each sub query inside a Postgres READ_COMMITTED transaction?
Question : From what I understand – in a READ_COMMITTED Postgres transaction “the transaction obtains a snapshot whenever an SQL […]
How exactly the row visibility is determined?
Question : In the simplest case, when we insert a new row into a table (and the transaction commits), it […]
What is “special” about PostgreSQL update vs delete+insert
Question : My understanding is that an update locks a tuple, marks it as deleted, and then adds a new […]
InnoDB undo logs vs history list
Question : I was reading about InnoDB undo logs, and in the process, the articles i was reading ended up […]
InnoDB MVCC vs Locking
Question : From what I understand you InnoDB supports Row Level Locking MVCC (Multiversion Concurrency Control) Row Level Locking Locking […]
Why is ACCESS EXCLUSIVE LOCK necessary in PostgreSQL?
Question : I know PostgreSQL provides multiple lock modes for concurrency control. When I read through their documents, I cannot […]
What is the impact of DROP SCHEMA on concurrent read only workloads in PostgreSQL?
Question : I have an ELT process that deals with a pretty small amount of data. I would like to […]
Does SQL Server use multiversion concurrency control (MVCC)?
Question : Reading an older overview of CouchDB published on the IBM site HERE, I was surprised to find the […]