Often we find out about a problem reported by a customer after the incident has passed. This might be from a trouble ticket or even an email that we didn’t see until a period of time has passed.

How can we look back at the activity of a server in the past? This post looks how a DBA can time travel back to a situation that occurred in the past.

This is part of a series of posts on Redgate Monitor. Click to see the other posts

Time Traveling

Let’s imagine I get a ticket that said there was a problem at 2:15am from a user running a process. I didn’t get to this at 2am, but at 9:15am when I receive it, I need to look back at what was happening.

If I pick a server in Redgate Monitor, I’ll see the view below. This is of the staging02 server on monitor.red-gate.com. By default, this shows me the last hour of activity on the server.

In the upper right corner, I can see the time frame selected on the left (below) and the amount of time. I’ve selected the drop down, and there are many other choices. I also see the metric time at the top, just in case, I’ve started to mess with other values.

Note: there is a calendar control to the left that can go back to previous days if you don’t want to use the time duration drop down.

In this case, let’s jump to the last 12 hours. If I select that, you can see my display changes a bit, zoomed out to show 12 hours not 1. The four charts below haven’t changed, however.

Most of the top chart has a darker background, except for a portion at the far right, which has a white background. This white background part is the focus window, and it determines what the 4 graphs below show, as well as the query information and other data.

This is set to 1 hour, but I can expand it. If I drag the box on the left side of this further to the left, I can expand the amount of time shown. If you look below, I’ve expanded this to 7:37am as the start.

I can also slide this. I’ll slide this to the left to cover to 2:00am-3:00am part of the graph. Now I see different views below in the four graphs.

In this case, I now can focus on the 2:00am issue. I see an annotation that there was a Flyway deployment at 2:00am. You can see the annotation zoomed in with the tooltip when I hover the mouse on this icon.

I can scroll down to the query area, and I see the top queries, of which there were just a few.

The top one has a lot of duration, and if I expand it, I can see the query history. Note there was a query plan change just after 2:00, when my deployment occurred. The duration went up and then started to slightly drop. I see another plan change at 2:40am, and if I were to look back at the top, I’d see a second deployment from Flyway at that time.

I don’t quite know what changed in the deployment, but I’d start looking here to see if this affected my query.

Summary

The focus window in the overview for an instance allows you to set the time frame in which you see data related to that instance. This lets you time travel back to look at the server as it existed in the past. The amount of time you can travel back depends on your data retention settings, which we’ll examine in another tip.

Hopefully this gives you a quick tip on how you can focus your efforts to a relevant period of time when you get an issue to review.

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