Unlogged vs. In-Memory

Josh Berkus <josh@agliodbs.com>

From: Joshua Berkus <josh@agliodbs.com>
To: PostgreSQL Advocacy <pgsql-advocacy@postgresql.org>
Date: 2011-05-03T17:46:51Z
Lists: pgsql-hackers
All,

This has come up a couple times off-list, so I thought we should hammer it out here regarding messaging for 9.1.

I was discussing the Unlogged Tables feature with an industry analyst.  He advised me fairly strongly that we should call it, or at least describe it, as "in-memory tables".  While I'm not that sanguine about renaming the feature, I'm happy to use marketing terms in descriptive text in a press release if it gets people interested.

Our basic issue with the cool features in 9.1 is the elevator pitch problem.  Try to describe SSI to a reporter in 20 seconds or less.  Unlogged tables suffers from this.  "What's an unlogged table? Why is *not* having something a feature?"  "long description here ..." "nevermind, I have enough."  

Saying "It's like a in-memory table" is a lot more successful.  And it's using the term "in-memory" the same way a lot of other DBMSes market it, i.e. in-memory == non-durable & no disk writes.  The important thing from my perspective is that unlogged tables give us the capabilities of a lot of the "in-memory" databases ... with unlogged tables and fsync off, for example, PostgreSQL becomes a viable caching database.

When doing PR, it's more important to use terms people recognize than to use terms which are perfectly accurate.  Nobody expects a news article to be perfectly accurate anyway.

However, I posted this because I think that several folks in the community feel that this is going too far into the land of marketese, and I want to hash it out and get consensus before we start pitching 9.1 final.

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
San Francisco