Weird Database Time

[former_SQLA_member1694898]

We have a version 12 database that is exhibiting some very weird behavior. If I run the sa_conn_info procedure, it shows all the connections with a LastRequestTime of September 1st 2012. The times are changing on the last request but even the times are way off. what would cause the internal date to be off by so much? We have a nearly identical setup and it reads correctly? Do you think a DB shutdown and refire is in order? It is has been running for about 2 years without a restart and we are noticing some slow times to do basic queries.

Any help is appreciated.

[MarkCulp]

First, congratulations for keeping your server running for two years. (Let me guess that this is not running on Windows 🙂

The time used within the SQL Anywhere server to generate the last request time is not directly obtained from the system time - calls to the system to get the time of day are expensive - so a the server uses CPU tics to keep track of the time. Doing the time calculation this way can cause the reported times to drift from the "real" time (even the system clock drifts over time). The server tries to make adjustments to accommodate the time drift but its not perfect.

An issue related to time drift was recently fixed in SA 12 build 3829

Summary: The LastReqTime connection property could have the incorrect time stamp compared to current time

The LastReqTime connection property could have the incorrect time stamp compared to current time. This would have only happened if the server has been running for more than 24 hours.

Since you are using a two year old server I am pretty sure you don't have this fix. 🙂

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Regarding your slow queries: You have not given us sufficient information to determine what would be causing the slow down - it could be any number of issues including memory fragmentation, disk fragmentation, file fragmentation, etc. A restart may resolve the issues or it may not?

[VolkerBarth]

So it's patch day year this year?

[MCMartin]

Mark, we have a lot of customers running your database under Windows for years without a reboot. Trust a little bit more in your product 😉

[MarkCulp]

It is not our product that I was commenting on... it was the OS! I've had SA running on Linux for over 3+ years without a reboot (a local power failure that lasted several hours finally caused a reboot when the UPS battery ran out) ... so I know SA is solid.

[former_SQLA_member1694872]

To All,

What is the advantage of letting a database running for two years without shutting down?

And also ask what is the disadvantage of starting the database every day before he start work?

[MarkCulp]

I think the main issue to consider is if your server is running in a 24x7 environment where your services need to be available non-stop every day. In these cases if your database server (and database) has been running for 2+ years then you have achieved your five-9s availability goal.

[former_SQLA_member1694872]

Nice, @MarkCulp

Availability    Associated Downtime per Year
99%             87 hours and 36 minutes
99.5%           43 hours and 48 minutes
99.95%           4 hours and 23 minutes
99.99%          53 minutes
99.999%          5 minutes