MongoDB的性能调优工具 -- Dex

jieforest

Step 3: Recommend an index (if necessary)
Once evaluation is complete, Dex considers an ideal index to have Coverage ‘full’ and Ideal Order true. If these conditions are not met, and the query itself contains no UNSUPPORTED terms, Dex recommends an ideal index (with an index order of 1 for all fields).

Note: Dex does not really need to look at existing indexes in order suggest the ideal index for a given query. But Dex does examine existing indexes as a courtesy to users who already have them in place — both to provide analysis of partial indexes (in verbose mode), and to avoid suggesting indexes that already exist.

jieforest

Future Directions

(1) Line Parsers: Better coverage of log lines, with a goal of complete coverage of all indexable queries

(2) Analyze the system.profile collection with -p option

(3) Constrain analysis by a time range with -t option

(4) Add Dex’s own “SLOW_MS” to narrow results if desired

(5) Support geospatial queries

(6) Improved recommendation caching, storing queries by mask and summing:
(6.1) Number of like queries
(6.2) Time consumed
(6.3) Min/max time range
(6.4) Min/max nscanned/nreturned

(7) Improved recommendations:
(7.1) Combine like recommendations (or generate recommendations from multiple like queries)
(7.2) Measure cardinality (yay aggregation framework) in the collection to inform recommended index key order.

jieforest

Conclusion

We’re really excited about Dex at MongoLab and look forward to the many improvements that are possible in the MongoDB automation space. I’m presenting Dex at the June MongoDB San Francisco User’s Group today, June 19, 2012. If you can make it on such short notice, check out the details here. We will follow up with a link to presentation slides a short time later.

Finally, for those interested in the indexing knowledge we’ve accumulated as Dex was built, check out my Cardinal $ins blog here.

As always, good luck out there!

jieforest

昨日计算机出问题了，今天把文章补发完整。