In this weekly post we recap the most interesting InfluxDB 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.
CQs and weeks
Q: I’m using a continuous query (CQ) to downsample data on a weekly basis. I’m having trouble understanding the time ranges that the queries are generating. When the query runs today (January 10, 2017) it covers the time range between January 09, 2017 up to January 16, 2017. I’d expect it to cover the time range between January 03, 2017 up to January 10, 2017. Is what I’m experiencing the expected behavior?
CREATE CONTINUOUS QUERY "whats_a_week" ON "telegraf" RESAMPLE EVERY 5m BEGIN SELECT MEAN("usage_idle") INTO "weekly_dataz" FROM "cpu" GROUP BY time(1w) END
A: The behavior you’re seeing is the result of InfluxDB’s preset epoch time boundaries. By default, InfluxDB uses those preset time boundaries, not the time at which you created the CQ, to define when a week begins and when a week ends. The current epoch week starts on January 09, 2017 and ends just before January 16, 2017.
If you want to personalize the CQ time boundaries you can use an
offset_interval of one day in the
GROUP BY time() clause:
CREATE CONTINUOUS QUERY "whats_a_week" ON "telegraf" RESAMPLE EVERY 5m BEGIN SELECT MEAN("usage_idle") INTO "weekly_dataz" FROM "cpu" GROUP BY time(1w,1d) END
SHOW FIELD KEYS and field type discrepancies
> SELECT value::integer,value::float,value::boolean,value::string FROM mixed_feelings name: mixed_feelings time value value_1 value_2 value_3 ---- ----- ------- ------- ------- 2017-01-06T17:00:00Z 4 4.5 2017-01-07T17:00:00Z 2 2 2017-01-08T17:00:00Z true 2017-01-09T17:00:00Z string cheese
SHOW FIELD KEYS query automatically returns every data type in a field:
> SHOW FIELD KEYS name: mixed_feelings fieldKey fieldType -------- --------- value float value string value boolean value integer
Note that data types can only differ across shards, not within a shard. In the same shard, InfluxDB will return an error if you attempt to write a data type to a field that previously accepted a different data type.
Local configuration settings and v1.1
My configuration file:
# [admin] # Determines whether the admin service is enabled. enabled = true
A: In InfluxDB v1.1, the section headers in the local configuration file are commented out by default. You’ll need to uncomment the
[admin] header and restart InfluxDB one more time to enable the web admin interface. We’ve changed this in version 1.2 – the section headers in the configuration file will be uncommented by default.
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