Fast – When developers ask how quickly a piece of code needs to run, don’t say fast. Give them a finish line so that they can know when it’s time to move on. “This query currently does over 15mm logical reads. We don’t allow production OLTP queries that do over 100k logical reads – anything higher than that needs to hit the reporting server instead.” Developers don’t want to write slow queries, but if you don’t show them how to measure their queries, they don’t know what’s slow versus fast. Show them how to measure what makes a query successful, and they’ll start measuring it long before they bring it to you.
Sometimes - When code works unpredictably, don’t say it sometimes works. Look for things it has in common when it fails. Does it bomb every Sunday, or when it handles over ten customers, or when it’s only being called once at a time? Keep digging for environmental coincidences until we can give the developers or QA staff a lead. Sometimes (see what I did there?) I find that developers want access to the production server just because they can’t get enough specific troubleshooting help from the DBAs. “Your code fails sometimes” isn’t going to cut it.
Never - When the developer tries to deploy a trigger in production, don’t say, “We never allow that.” The business, not our emotional desire, dictates the technical solutions we use. We’re here to advise the business, and sometimes the business won’t go along with our advice. Our job is to lay out our concerns clearly and concisely, preferably with risk assessments and real-life stories, and then listen. I’d love to build every box and application perfectly, but we gotta ship if we’re going to keep paying salaries.
Fine - When you’re asked how the server is performing, don’t say it’s fine. Quantify it in terms of batch requests per second, average duration for a stored procedure, or some other metric that you can measure precisely. Bonus points if we correlate this number over time, like if we can say, “We normally average 1,400 to 1,500 batch requests per second during peak weekday hours, and we’re doing 1,475 right now.”
Large – When developers asks how big a table or database or index is, don’t say large. What’s large to you is small to someone else, and vice versa. Give exact numbers: number of terabytes in the largest database, number of databases, number of rows in the largest table, or the number of times you’ve updated your resume in terror because the backup failed.
It Depends – DBAs love giving this answer as a cop-out for tough questions, and if you’re not careful, it comes off as a condescending know-it-all. For best results, immediately follow this phrase with the word “on”, as in, “It depends on the table’s access pattern – in read-focused systems like our data warehouse, we can have up to 10-15 indexes on our dimension tables, but in OLTP databases like our web site, we need to aim for 5 indexes or less per table.” The faster you can help someone to the answer they’re looking for, the more they’ll respect you as a partner, not an enemy combatant.