That is because "host" is a tag <https://docs.influxdata.com/influxdb/v1.0/concepts/glossary/#tag>, not a field <https://docs.influxdata.com/influxdb/v1.0/concepts/glossary/#field>. SELECT statements must include at least one field.
If you want only the values of "host", that's a SHOW <https://docs.influxdata.com/influxdb/v1.0/query_language/schema_exploration/#explore-tag-values-with-show-tag-values> query, not a SELECT <https://docs.influxdata.com/influxdb/v1.0/query_language/data_exploration/#the-select-statement-and-the-where-clause> query: SHOW TAG VALUES FROM mem_usage_percent WITH KEY = "host" Note that the SHOW query does not accept a "WHERE time" clause. To get hosts during a particular time, use a SELECT query with a field as well: SELECT "host", "value" FROM mem_usage_percent WHERE time > ... On Tue, Sep 27, 2016 at 12:04 AM, Paul Letskii <[email protected]> wrote: > Ok. But how have I change this query: "SELECT "host" FROM > "mem_usage_percent"" to get just hosts field? > According to documentation it is correct query ( > https://docs.influxdata.com/influxdb/v1.0/query_language/ > data_exploration/#the-select-statement-and-the-where-clause) > > > On Monday, September 26, 2016 at 6:00:06 PM UTC+3, Sean Beckett wrote: >> >> Every SELECT statement must have at least one field. You selecting only a >> tag. Use either "SHOW TAG VALUES" or include a field in the query. >> >> On Mon, Sep 26, 2016 at 6:55 AM, Paul Letskii <[email protected]> wrote: >> >>> Hi all! >>> >>> InfluxDB version 1.0\ >>> >>> I'm trying to get list of hosts from measurement "mem_usage_percent". >>> >>> This query works: >>> SELECT * FROM "mem_usage_percent" >>> >>> This one doesn't: >>> SELECT "host" FROM "mem_usage_percent" >>> Accordingly to documentation it has to. >>> >>> My final goal is to count number of unique hosts. Like: SELECT >>> count("host") FROM "mem_usage_percent" >>> >>> What is correct syntax to get information from certain field? >>> >>> Thank you in advance! >>> >>> Best regards, >>> Paul Letskii >>> >>> -- >>> Remember to include the InfluxDB version number with all issue reports >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "InfluxDB" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at https://groups.google.com/group/influxdb. >>> To view this discussion on the web visit https://groups.google.com/d/ms >>> gid/influxdb/f3c71013-7e8c-4fdb-9808-0b1fb35e9052%40googlegroups.com >>> <https://groups.google.com/d/msgid/influxdb/f3c71013-7e8c-4fdb-9808-0b1fb35e9052%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> >> >> -- >> Sean Beckett >> Director of Support and Professional Services >> InfluxDB >> > -- > Remember to include the InfluxDB version number with all issue reports > --- > You received this message because you are subscribed to the Google Groups > "InfluxDB" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/influxdb. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/influxdb/215c75a2-3837-4c60-b5bd-14bb26f74fbe%40googlegroups.com > <https://groups.google.com/d/msgid/influxdb/215c75a2-3837-4c60-b5bd-14bb26f74fbe%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- Sean Beckett Director of Support and Professional Services InfluxDB -- Remember to include the InfluxDB version number with all issue reports --- You received this message because you are subscribed to the Google Groups "InfluxDB" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/influxdb. To view this discussion on the web visit https://groups.google.com/d/msgid/influxdb/CALGqCvPgsc3x2wVsqq%3DNNx0a77fdzc86rWyzrXech3XhKdKXqA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
