- Don’t
SELECT *
, Specify explicit column names (columnar store) - Avoid large JOINs (filter each table first)
- In PRESTO tables are joined in the order they are listed!!
- Join small tables earlier in the plan and leave larger fact tables to the end
- Avoid cross joins or 1 to many joins as these can degrade performance
- Order by and group by take time
- only use order by in subqueries if it is really necessary
- When using GROUP BY, order the columns by the highest cardinality (that is, most number of unique values) to the lowest.
- https://cloud.google.com/anthos/gke/docs/on-prem/reference/cheatsheet
- https://medium.com/flant-com/kubectl-commands-and-tips-7b33de0c5476
- https://prefetch.net/blog/2019/10/16/the-beginners-guide-to-creating-kubernetes-manifests/
- https://kubernetes.io/docs/user-guide/kubectl-cheatsheet/
- https://learnk8s.io/blog/kubectl-productivity/
- https://medium.com/faun/kubectl-commands-cheatsheet-43ce8f13adfb
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Latency Comparison Numbers (~2012) | |
---------------------------------- | |
L1 cache reference 0.5 ns | |
Branch mispredict 5 ns | |
L2 cache reference 7 ns 14x L1 cache | |
Mutex lock/unlock 25 ns | |
Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
Compress 1K bytes with Zippy 3,000 ns 3 us | |
Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |
SQL to MongoDB Mapping Chart¶
In addition to the charts that follow, you might want to consider the Frequently Asked Questions section for a selection of common questions about MongoDB.
Executables¶
The following table presents the MySQL/Oracle executables and the corresponding MongoDB executables.