Utilizing Question Logs in Rockset

At Rockset, we regularly search for methods to provide our prospects higher visibility into the product. Towards this objective, we just lately determined to enhance our customer-facing question logging. Our earlier iteration of question logs was primarily based in certainly one of our shared companies referred to as apiserver. As a part of the work that apiserver would do when finishing a question execution request, it could create a log that will ultimately be ingested into the _events assortment. Nonetheless, there have been points that made us rethink this implementation of question logs:

1. No isolation: as a result of the question logs in _events relied on shared companies, heavy site visitors from one org may have an effect on question logging in different orgs.
2. Incomplete logs: due to the problems prompted through the use of shared companies, we solely logged question errors – profitable queries wouldn’t be logged. Moreover, it was not attainable for us to log knowledge about async queries.
3. No means to debug question efficiency – the question logs in _events solely contained primary details about every question. There was no manner for the person to get details about why a given question could have run slowly or exhausted compaute sources for the reason that logs contained no details about the question plan.

Improved Question Logging

The brand new question logs characteristic addresses all of those points. The mechanisms that deal with question logs are contained totally inside your Digital Occasion versus being inside certainly one of Rockset’s shared companies. This provides question logs the benefit of isolation. Moreover, each question you submit might be routinely logged when you have already created a set with a question logs supply (offered you don’t hit a fee restrict).

How Question Logs Work

Question logging begins on the finish of question execution. As a part of the steps which might be run within the last aggregator when a question has accomplished, a report containing metadata related along with your question is created. At this level, we can also have to gather info from different aggregators that had been concerned within the question. After that is finished, the report is briefly saved in an in-memory buffer. The contents of this buffer are flushed to S3 each few seconds. As soon as question logs have been dumped to S3, they are going to be ingested into any of your question log collections which have been created.

INFO vs DEBUG Logs

Once we first designed this challenge, we had all the time meant for it to work with the question profiler within the console. This might enable our prospects to debug question bottlenecks with these logs. Nonetheless, the question profiler requires fairly a bit of knowledge, which means it could be unattainable for each question log to include all the data obligatory for the profiler. To resolve this downside, we opted to create two tiers of question logs – INFO and DEBUG logs.

INFO logs are routinely created for each question issued by your org. They include some primary metadata related along with your question however can’t be used with the question profiler. When that you could be need to have the power to debug a sure question with the profiler, you’ll be able to specify a DEBUG log threshold along with your question request. If the question execution time is bigger than the required threshold, Rockset will create each an INFO and a DEBUG log. There are two methods of specifying a threshold:

1. Use the debug_log_threshold_ms question trace

   SELECT * FROM _events HINT(debug_log_threshold_ms=1000)

2. Use the debug_threshold_ms parameter in API requests. That is obtainable for each question and question lambda execution requests.

Notice that since DEBUG logs are a lot bigger than INFO logs, the speed restrict for DEBUG logs is way decrease. For that reason, it is suggested that you simply solely present a DEBUG log threshold when that this info may very well be helpful. In any other case, you run the chance of hitting the speed restrict whenever you most want a DEBUG log.

System Sources

As a part of this challenge, we determined to introduce a brand new idea referred to as system sources. These are sources which ingest knowledge originating from Rockset. Nonetheless, not like the _events assortment, collections with system sources are managed totally by your group. This lets you configure all the settings of those collections. We might be introducing extra system supply sorts as time goes on.

Getting Began with Question Logging

To be able to begin logging your queries, all you could do is create a set with a question logs supply. This may be finished via the console.

Rockset will start ingesting question logs into this assortment as you submit queries. Logs for the final 24 hours of queries can even be ingested into this assortment. Please observe that it may possibly take a couple of minutes after a question has accomplished earlier than the related log will present up in your assortment.

To be able to use the question profiler with these logs, open the Rockset Console’s question editor and situation a question that targets certainly one of your question logs collections. The question editor will detect that you’re making an attempt to question a set with a question logs supply and a column referred to as ‘Profiler’ might be added to the question outcomes desk. Any paperwork which have a populated stats subject may have a hyperlink on this column. Clicking on this hyperlink will open the question profile in a brand new tab.

Notice that customized ingest transformations or question aliases can intervene with this performance so it is suggested that you don’t rename any columns.

For an in depth dive into utilizing Rockset’s Question Profiler, please consult with the video obtainable right here.

Conclusion

Hopefully, this has given you a fast look into the performance that question logs can provide. Whether or not you could debug question efficiency or verify why beforehand accomplished queries have failed, your expertise with Rockset might be improved by making use of question logs.