Now it is possible to get away without using DBMS_LOCK. Snapper used to require access to DBMS_LOCK, so it could sleep for X seconds between the “before” and “after” performance data snapshots.
Update: If you want to see what Snapper is capable of (it’s about the old version 3), check this document about using Snapper for Oracle performance measurement. This is why I have kept the old snapper v3 (which is more stable and pretty efficient) in the standard (old) snapper address.
Snapper 4 is still beta! Some queries (like the qc=) one may take a while to run, running dynamic queries with subqueries against GV$ views efficiently is tricky business. I will write about the other major features in separate blog entries, but if you want to learn about it now, then grab a beer (or coffe) and watch the latest show (it’s a bit over 2 hours :-)) If you use for example, then Snapper would only look for QC in the instance #2 and any slaves that are also in instance #2 (but with inter-instance parallelism you may have slaves in other instances too). Snapper still supports the qc= syntax too, to list all sessions started by a PX query coordinator session: ash 5 1 that the qc= syntax is a bit broken/inconsistent right now – what the means right now is that Snapper looks up the SID 1234 from every instance and lists slave sessions from all instances.
You can pass multiple inst_id,SID tuples to the snapper though: ash 5 1 (2,1234),(4,5678),(3,999) Note that the brackets are important, as otherwise snapper thinks that you want to measure SID 2 and SID 1234 in the local instance. … it will still query only local instance’s sessions.īut if you want to measure all tanel’s sessions in let’s say instance #2 only, you can just add to the session filter condition: ash 5 1 if you want all instances then use ash 5 1 you want to measure a single session with sid 1234 in instance #2, you can do it in two ways: ash 5 1 use the inst_id,sid tuple syntax: ash 5 1 (2,1234) I have kept the syntax backwards-compatible, so when you run Snapper like this … ash 5 1 user=tanel I will keep adding new averages over the coming weeks. average bytes sent/received per roundtrip etc). Useful averages in the right side of the output (e.g.No need to use DBMS_LOCK to sleep for a certain number of seconds between snapshots Manually taken “before” and “after” snapshot support.RAC support (query remote instance’s sessions performance data via GV$).I have not updated the snapper documentation yet, but here are the main improvements: I have also uploaded the launch party hacking session video to : I have fixed most of the bugs that showed up during the Snapper launch party session and uploaded the new version (v4.02) of Snapper here:
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