Sfaturi Oracle / Tips and tricks OracleDBA

2020-02-20

black box thinking

https://archive.org/stream/BlackBoxThinkingByMatthewSyed/Black%20Box%20Thinking%20by%20Matthew%20Syed_djvu.txt

"a failure to learn from mistakes

has been one of the single greatest obstacles to human progress"

2020-01-30

clickhouse replication

https://www.slideshare.net/Altinity/introduction-to-the-mysteries-of-clickhouse-replication-by-robert-hodges-and-altinity-engineering-team

2020-01-28

decode tetra

https://www.rtl-sdr.com/rtl-sdr-tutorial-listening-tetra-radio-channels/

https://www.altinity.com/blog/2019/11/27/amplifying-clickhouse-capacity-with-multi-volume-storage-part-1

multi-volume storage is a feature of ClickHouse starting in version 19.15
The idea is that you store new data on fast storage, like NVMe SSD, and move it later to slower storage, such as high-density disk. Not only does this save on storage, but you can often reduce the overall number of servers without giving up performance. It’s a double win for efficiency that can reduce hardware costs up to 80% as this example spreadsheet shows. Not surprisingly tiered storage has been a top feature request for years.

uv-82

https://www.airsoft-cluj.ro/pub/media/UV-82-Manual-Utilizare.pdf

2020-01-07

hadoop is not dead

https://tech.marksblogg.com/is-hadoop-dead.html

When you hear "No one needs big data", look over the CV of the speaker. An African telecoms carrier going through amazing levels of growth is not going to reach out to a greenfield JavaScript Web Developer and ask them if they could help architect their data platform and optimise their billing calculations. You might find a lot of internally-hosted web applications in an Airline's headquarters but when it comes to analysing PBs of aircraft telemetry for predictive maintenance there might not be any PHP developers on that project.

Companies producing PBs of data often have a queue of experienced consultants and solutions providers at their door. I've rarely seen anyone plucked out of web development by their employer and brought into the data platform engineering space; it's almost always a lengthy, self-retraining exercise.

Disks are catching up in speeds as well. There was a 4 x 2 TB PCIe 4.0 NVMe SSD card announced recently that could read and write at 15 GB/s. The price point of the PCIe 4.0 NVMe drives will be very competitive with RAM and provide non-volatile storage. I can't wait to see an HDFS cluster with some good networking using those drives as it'll demonstrate what an in-memory data store with non-volatile storage with the rich, existing tooling of the Hadoop ecosystem looks like.

The migration to a columnar storage solution for this client brought down those infrastructure costs by two orders-of-magnitude and sped up querying times by two orders-of-magnitude.