sql

README

SQL Output Plugin

The SQL output plugin saves Telegraf metric data to an SQL database.

The plugin uses a simple, hard-coded database schema. There is a table for each metric type and the table name is the metric name. There is a column per field and a column per tag. There is an optional column for the metric timestamp.

A row is written for every input metric. This means multiple metrics are never merged into a single row, even if they have the same metric name, tags, and timestamp.

The plugin uses Golang's generic "database/sql" interface and third party drivers. See the driver-specific section below for a list of supported drivers and details. Additional drivers may be added in future Telegraf releases.

Getting started

To use the plugin, set the driver setting to the driver name appropriate for your database. Then set the data source name (DSN). The format of the DSN varies by driver but often includes a username, password, the database instance to use, and the hostname of the database server. The user account must have privileges to insert rows and create tables.

Generated SQL

The plugin generates simple ANSI/ISO SQL that is likely to work on any DBMS. It doesn't use language features that are specific to a particular DBMS. If you want to use a feature that is specific to a particular DBMS, you may be able to set it up manually outside of this plugin or through the init_sql setting.

The insert statements generated by the plugin use placeholder parameters. Most database drivers use question marks as placeholders but postgres uses indexed dollar signs. The plugin chooses which placeholder style to use depending on the driver selected.

Advanced options

When the plugin first connects it runs SQL from the init_sql setting, allowing you to perform custom initialization for the connection.

Before inserting a row, the plugin checks whether the table exists. If it doesn't exist, the plugin creates the table. The existence check and the table creation statements can be changed through template settings. The template settings allows you to have the plugin create customized tables or skip table creation entirely by setting the check template to any query that executes without error, such as "select 1".

The name of the timestamp column is "timestamp" but it can be changed with the timestamp_column setting. The timestamp column can be completely disabled by setting it to "".

By changing the table creation template, it's possible with some databases to save a row insertion timestamp. You can add an additional column with a default value to the template, like "CREATE TABLE {TABLE}(insertion_timestamp TIMESTAMP DEFAULT CURRENT_TIMESTAMP, {COLUMNS})".

The mapping of metric types to sql column types can be customized through the convert settings.

Configuration

# Save metrics to an SQL Database
[[outputs.sql]]
  ## Database driver
  ## Valid options: mssql (Microsoft SQL Server), mysql (MySQL), pgx (Postgres),
  ##  sqlite (SQLite3), snowflake (snowflake.com) clickhouse (ClickHouse)
  # driver = ""

  ## Data source name
  ## The format of the data source name is different for each database driver.
  ## See the plugin readme for details.
  # data_source_name = ""

  ## Timestamp column name
  # timestamp_column = "timestamp"

  ## Table creation template
  ## Available template variables:
  ##  {TABLE} - table name as a quoted identifier
  ##  {TABLELITERAL} - table name as a quoted string literal
  ##  {COLUMNS} - column definitions (list of quoted identifiers and types)
  # table_template = "CREATE TABLE {TABLE}({COLUMNS})"

  ## Table existence check template
  ## Available template variables:
  ##  {TABLE} - tablename as a quoted identifier
  # table_exists_template = "SELECT 1 FROM {TABLE} LIMIT 1"

  ## Initialization SQL
  # init_sql = ""

  ## Metric type to SQL type conversion
  ## The values on the left are the data types Telegraf has and the values on
  ## the right are the data types Telegraf will use when sending to a database.
  ##
  ## The database values used must be data types the destination database
  ## understands. It is up to the user to ensure that the selected data type is
  ## available in the database they are using. Refer to your database
  ## documentation for what data types are available and supported.
  #[outputs.sql.convert]
  #  integer              = "INT"
  #  real                 = "DOUBLE"
  #  text                 = "TEXT"
  #  timestamp            = "TIMESTAMP"
  #  defaultvalue         = "TEXT"
  #  unsigned             = "UNSIGNED"
  #  bool                 = "BOOL"

  ## This setting controls the behavior of the unsigned value. By default the
  ## setting will take the integer value and append the unsigned value to it. The other
  ## option is "literal", which will use the actual value the user provides to
  ## the unsigned option. This is useful for a database like ClickHouse where
  ## the unsigned value should use a value like "uint64".
  # conversion_style = "unsigned_suffix"

Driver-specific information

go-sql-driver/mysql

MySQL default quoting differs from standard ANSI/ISO SQL quoting. You must use MySQL's ANSI_QUOTES mode with this plugin. You can enable this mode by using the setting init_sql = "SET sql_mode='ANSI_QUOTES';" or through a command-line option when running MySQL. See MySQL's docs for details on ANSI_QUOTES and how to set the SQL mode.

You can use a DSN of the format "username:password@tcp(host:port)/dbname". See the driver docs for details.

jackc/pgx

You can use a DSN of the format "postgres://username:password@host:port/dbname". See the driver docs for more details.

modernc.org/sqlite

This driver is not available on all operating systems and architectures. It is only included in Linux builds on amd64, 386, arm64, arm, and Darwin on amd64. It is not available for Windows, FreeBSD, and other Linux and Darwin platforms.

The DSN is a filename or url with scheme "file:". See the driver docs for details.

clickhouse

Use this metric type to SQL type conversion:

  [outputs.sql.convert]
    integer              = "Int64"
    text                 = "String"
    timestamp            = "DateTime"
    defaultvalue         = "String"
    unsigned             = "UInt64"
    bool                 = "UInt8"

See ClickHouse data types for more info.

denisenkom/go-mssqldb

Telegraf doesn't have unit tests for go-mssqldb so it should be treated as experimental.

snowflakedb/gosnowflake

Telegraf doesn't have unit tests for gosnowflake so it should be treated as experimental.

Documentation

Index

• type ConvertStruct
• type SQL
  • func (p *SQL) Close() error
  • func (p *SQL) Connect() error
  • func (*SQL) SampleConfig() string
  • func (p *SQL) Write(metrics []telegraf.Metric) error

Types

type ConvertStruct

type ConvertStruct struct {
	Integer         string
	Real            string
	Text            string
	Timestamp       string
	Defaultvalue    string
	Unsigned        string
	Bool            string
	ConversionStyle string
}

type SQL

type SQL struct {
	Driver              string
	DataSourceName      string
	TimestampColumn     string
	TableTemplate       string
	TableExistsTemplate string
	InitSQL             string `toml:"init_sql"`
	Convert             ConvertStruct

	Log telegraf.Logger `toml:"-"`
	// contains filtered or unexported fields
}

func (*SQL) Close

func (p *SQL) Close() error

func (*SQL) Connect

func (p *SQL) Connect() error

func (*SQL) SampleConfig

func (*SQL) SampleConfig() string

func (*SQL) Write

func (p *SQL) Write(metrics []telegraf.Metric) error