TL;DR InfluxDB Tech Tips - Naming Guidelines in InfluxDB, Selecting Tags with No Value & Writing Data to InfluxDB

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In this weekly post we recap the most interesting InfluxDB time and TICK-stack related issues, workarounds, how-tos and Q&A from GitHub, IRC and the InfluxDB Google Group that you might have missed in the last week or so.

Naming guidelines in InfluxDB

Q:  I’m trying to write some data to InfluxDB. My writes seem to succeed but I can’t query the data; any idea what’s going on here?

> INSERT energy,time=morning index=2.3    <--- No error

> SELECT * FROM "energy"
name: energy
time                            index      <--- The time tag doesn't appear in the results
----                            -----
2017-02-08T22:16:39.290463266Z  2.3

A: time is a special keyword in InfluxDB. time can be a continuous query name, database name, measurement name, retention policy name, subscription name, and user name. In those cases, time does not require double quotes in queries. time cannot be a field key or tag key. If Line Protocol includes time as a field key or tag key, InfluxDB accepts the write and returns a 204, but InfluxDB silently drops that field key or tag key and its associated value.

Check out the Frequently Asked Questions page for more information.

Selecting tags with no tag value

Q: How do I SELECT data with a tag that has no value?

A: Specify an empty tag value with ''. For example:

> SELECT * FROM "vases" WHERE priceless=''
name: vases
time                   origin   priceless
2016-07-20T18:42:00Z   8

Writing data to InfluxDB

Q: I’ve recently started working with InfluxDB. When I write data to the database, does the precision of the timestamp matter?

A:  Yes. To maximize performance we recommend using the coarsest possible timestamp precision when writing data to InfluxDB.

For example, we recommend using the second of the following two requests:

curl -i -XPOST "http://localhost:8086/write?db=weather" --data-binary 'temperature,location=1 value=90 1472666050000000000'

curl -i -XPOST "http://localhost:8086/write?db=weather&precision=s" --data-binary 'temperature,location=1 value=90 1472666050'

What's next:

  • Downloads for the TICK-stack are live on our "downloads" page.
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