An InfluxQL function that returns an aggregated value across a set of points


A collection of points in line protocol format, separated by newlines(0x0A). A batch of points may be submitted to the database using a single HTTP request to the write endpoint. This makes writes via the HTTP API much more performant by drastically reducting the HTTP overhead. InfluxData recommends batch size of 5,000-10,000 points, although different use cases may be better served by significantly smaller or larger batches.

continuous query(CQ)

An InfluxQL query that runs automatically and periodically within a database. Continuous queries require a function in the SELECT clause and must include a GROUP BY time() clause.


A logical container for users, retention policies, continuous queries, and time series data.


The attribute of the retention policy that determines how long InfluxDB stores data. Data older than the duration are automatically dropped from the database.


The key-value pair in InfluxDB’s data structure that records metadata and the actual data value. Fields are required in InfluxDB’s data structure and they are not indexed - queries on field values scan all points that match the specified time range and , as a result, are not performant relative to tags.

Query tip: Compare fields to tags: tags are indexed

field key

The key part of the key-value pair that makes up a field. Field keys are strings and they store metadata.

field set

The collection of field keys and field values on a point.

field value

The value part of the key-value pair that makes up a field. Field values are the actual data: they can be strings, floats, integers, or booleans. A field value is always associated with a timestamp.

Field values are not indexed - queries on field values scan all points that match the specified time range and, as a result, are not performant.


InfluxQL aggregation, selectors, and transformations.


Tokens that refer to continuous query names, database names, field keys, measurement names, retention policy names, subscription names, tag keys and user names.

line protocol

The text based format for writing points to InfluxDB.


The part of InfluxDB’s structure that describes the data stored in the associated fields. Measurements are strings.


Contains internal information about the status of the system. The metastore contains the user information, databse, retention policies, shard metadata, continuous queries, and subscriptions.


An independent influxd process


The local server’s nanosecond timestamp


The part of InfluxDB’s data structure taht consists of a single collection of fields in a series. Each point is uniquely idenfified by its series and timestamp.

You cannot store more than one point with the same timestamp in the same series. Instead, when you write a new point to the same series with the same timestamp as an existing point in that series, the field set becomes the union of the old field set and the new field set, where any ties tgo to the new field set.


An operation that retrieves data from InfluxDB.

replication factor

The attribute of the retention policy that determines how many copies of the data are stored in the cluster.

Replication factors do not seve a purpose with single node instances.

retention policy (RP)

The part of InfluxDB’s data structure that describes for how long InfluxDB keeps data(ducation), how many copies of those data are stored in the cluster(replication factor), and the time range covered by shard groups(shard group duration). RPs are unique per databse and along with the measurement and tag set define a series.

When you create a database, InfluxDB automatically creates a retention policy called autogen with an infinite duration, a replication factor set to one, and a shard group duration set to seven days.


How the data are organized in InfluxDB. The fundamentals of the InfluxDB schema are database, retention policies, series, measurements, tag keys, tag values, and field keys.


An InfluxQL function that returns a single point from the range of specified points.


The collection of data in InfluxDB’s data structure that share a measurement, tag set and retention policy.

The field set is not part of the series identification.

series cardinality

The number of unique database, measurement, and tag set combinations in an InfluxDB instance.

For example, assume that an InfluxDB instance has a single database and one measurement. The single measurement has two tag keys: email and status. If there are three different emails, and each email address is associated with two different status, then the series cardinality for the measurement is 6.

Note that, in some cases, simply performing that multiplication may overestimate series cardinality because of the presence of dependent tags.


A machine virtual or physical, that is running InfluxDB. There should only be one InfluxDB process per server.


A shard contains the actual encoded and compressed data, and is represented by a TSM file on disk. Every shard belongs to one and only one shard group. Multiple shards may exist in a single shard group. Each shard contains a specific set of series. All points falling on a given series in a given shard group will be stored in the same shard(TSM file) on disk.

shard duration

The shard duration determines hwo much time each shard group spans. The specific interval is determined by the SHARD DURATION of the retention policy.

For example, given a retention policy with SHARD DURATION set to 1w, each shard group will span a single week and contain all points with timestamps in that week.

shard group

Shard groups are logical container for shards. Shard groups are organized by time and retention policy. Every retention policy that contains data has at least one associated shard group. A given shard group contains all shards with data for the interval covered by the shard group. The interval spanned by each shard group is the shard duration.


Subscription allows Kapacitor to receive data from InfluxDB in a push model rather than the pull model based on querying data. When Kapacitor is configured to work with InfluxDB, the subscription will automatically push every write for the subscribed databse form InfluxDB to Kapacitor. Subscription can use TCP or UDP for transmitting the writes.


The key-value pair in InfluxDB’s data structure that records metadata. Tags are an optional part of InfluxDB’s data structure but they are useful for storing commonly-queried metadata; tags are indexed so queries on tags are performant

tag key

The key part of the key-value pair that makes up a tag. Tag keys are strings and they store metadata. Tag keys are indexed so queires on tag keys are performant.

tag set

The collection of tag keys and tag values on a point.

tag value

The value part of the key-value pair that makes up a tag. Tag values are strings and they store metadata. Tag values are indexed so queries on tag values are performant.


The date and time associated with a point. All time in influxDB is UTC.


An InfluxQl function that returns a value or a set of values calculated from specified points, but does not return an aggregated value across those points.

tsm (Time Structured Merge Tree)

The purpose-built data storage format for InfluxDB. TSM allows for greater compaction and higher write and read throughput than exsiting B+ or LSM tree implementations.


There are two kinds of users in InfluxDB:

  • Admin users have READ and WRITE access to all database and full across to administrative queries and user management commands.

  • Non-admin users have READ, WRITE, or ALT (both READ, WRITE) access to per database.

When authentication is enabled, InfluxDB only executes HTTP requests that are spent with a valid username and password.

values per second

The preferred measurement of the rate at which data are persisted to InfluxDB. Write speeds are generally quoted in values per second.