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Thoughts on Time-series Databases

jmoiron.net

101–110 of 132 posts

Re: Thoughts on Time-series Databases

#101
post #70

Earlier quoted context omitted.

It'd be great to see a more detailed guide to using and tuning PGSQL for use as a TS DB.

As an addendum, I'd like to be able to do time-based append-only operations in Postgres, a la Datomic. It pains me to UPDATE and DELETE, thereby destroying useful data.

Would Timetravel module work for your use-case: http://www.postgresql.org/docs/9.1/static/contrib-spi.html#A...

Re: Thoughts on Time-series Databases

#102
post #36
post #12

I actually just migrated 20 million rows of Magic: the Gathering price data from influxDB to postgres this week. For a few days of effort, I decreased my query latency by an order of a magnitude; a full set query, roughly 270 cards, went from 30 to 3 seconds with a cold cache. The migration was prompted by influxDB 0.8 eating 50% of the VPS' cpu and 77% of the ram while idling. It had no capability to index along any…

Just for the record, InfluxDB 0.9 seems to actually be production ready now. Though it doesn't look there's an easy way to migrate to it yet from 0.8.

"Seems to be", sure. Sinks like a tanker when you try to actually use it, though. None of the software libraries have been updated for 0.9 yet.

Re: Thoughts on Time-series Databases

#103
post #12

I actually just migrated 20 million rows of Magic: the Gathering price data from influxDB to postgres this week. For a few days of effort, I decreased my query latency by an order of a magnitude; a full set query, roughly 270 cards, went from 30 to 3 seconds with a cold cache. The migration was prompted by influxDB 0.8 eating 50% of the VPS' cpu and 77% of the ram while idling. It had no capability to index along any…

For those of you reading this that are interested in getting on InfluxDB 0.9. If you intend to use authentication and have a somewhat high request rate, I advise you to wait until the fixes related to #3102 (https://github.com/influxdb/influxdb/issues/3102) are included. Without that fix your CPU is killed because InfluxDB is bcrypting on every request.

Re: Thoughts on Time-series Databases

#104
post #36
post #12

I actually just migrated 20 million rows of Magic: the Gathering price data from influxDB to postgres this week. For a few days of effort, I decreased my query latency by an order of a magnitude; a full set query, roughly 270 cards, went from 30 to 3 seconds with a cold cache. The migration was prompted by influxDB 0.8 eating 50% of the VPS' cpu and 77% of the ram while idling. It had no capability to index along any…

Just for the record, InfluxDB 0.9 seems to actually be production ready now. Though it doesn't look there's an easy way to migrate to it yet from 0.8.

Authentication in 0.9 has a high CPU penalty right now: https://news.ycombinator.com/item?id=9810538.

Re: Thoughts on Time-series Databases

#105
post #59
post #12

I actually just migrated 20 million rows of Magic: the Gathering price data from influxDB to postgres this week. For a few days of effort, I decreased my query latency by an order of a magnitude; a full set query, roughly 270 cards, went from 30 to 3 seconds with a cold cache. The migration was prompted by influxDB 0.8 eating 50% of the VPS' cpu and 77% of the ram while idling. It had no capability to index along any…

Curious if anyone has experienced problems like this in InfluxDB 0.9 ?? My 0.9 implementation is performing well, but has only small amounts of metrics for testing - not yet rolled out to production.

Authentication in 0.9 has a high CPU penalty right now: https://news.ycombinator.com/item?id=9810538.

Re: Thoughts on Time-series Databases

#106
post #48

Earlier quoted context omitted.

Possibly he might measure some other thing, but still after your question I started to wonder how much a passenger plane moves per thousandth of a second. So: some quick googling suggests that "economical cruising speed" of an Airbus A320 is 840km/h [1]. After quick back-of-envelope calculations, this gives ~230m/s, so 0.2m per 0.001s. Given some possible uncertainty of a single measurement, I'd imagine that's not un…

I guess I should mention that GPS position is a perfectly normal thing to include in a telemetry stream.

+ ins position of course; gps position is not reliable enough (less gbas) to land a big plane with.

Re: Thoughts on Time-series Databases

#109

Earlier quoted context omitted.

I've got a system here capable of collecting data close to a hundred thousand times per second from tens of sources, with perceptual real time ( It's called multitrack audio recording, and commonly runs on your run of the mill laptop. HD video would probably be a few orders of magnitude more data than that, with even more processing. Computers are really, really good at these kinds of things if only the software is e…

Your last sentence is well taken, but the rest leaves me a bit puzzled about what you meant. Your run of the mill laptop is a wonderful machine capable of amazing things. But that laptop is not rated to withstand extreme vibration and shock and huge temperature ranges. Nor does it have the external interfaces to deal with large numbers of custom, high speed digital data buses, nor does it contain the signal condition…

I apologize if it came across as a snarky comment or one-upmanship, I merely intended to support your original comment.

Re: Thoughts on Time-series Databases

#110
post #12

I actually just migrated 20 million rows of Magic: the Gathering price data from influxDB to postgres this week. For a few days of effort, I decreased my query latency by an order of a magnitude; a full set query, roughly 270 cards, went from 30 to 3 seconds with a cold cache. The migration was prompted by influxDB 0.8 eating 50% of the VPS' cpu and 77% of the ram while idling. It had no capability to index along any…

I've found PostgreSQL to be extremely fast if you store time series in arrays ( http://www.postgresql.org/docs/9.4/static/arrays.html ) in a round-robin fashion. You can also limit the array size, so that you have a fixed number of points per table row (thereby splitting your series across multiple rows), and if you adjust it such that it fits on one PG page it is quite performant.

I don't think you can limit them: However, the current implementation ignores any supplied array size limits, i.e., the behavior is the same as for arrays of unspecified length.
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