sql_select

Runs an SQL select query against a database and returns the result as an array of objects, one for each row returned, containing a key for each column queried and its value.

Introduced in version 3.59.0.

Common
Advanced

# Common config fields, showing default values
label: ""
sql_select:
  driver: "" # No default (required)
  dsn: clickhouse://username:password@host1:9000,host2:9000/database?dial_timeout=200ms&max_execution_time=60 # No default (required)
  table: foo # No default (required)
  columns: [] # No default (required)
  where: meow = ? and woof = ? # No default (optional)
  args_mapping: root = [ this.cat.meow, this.doc.woofs[0] ] # No default (optional)

# Advanced config fields, showing default values
label: ""
sql_select:
  driver: "" # No default (required)
  dsn: clickhouse://username:password@host1:9000,host2:9000/database?dial_timeout=200ms&max_execution_time=60 # No default (required)
  table: foo # No default (required)
  columns: [] # No default (required)
  where: meow = ? and woof = ? # No default (optional)
  args_mapping: root = [ this.cat.meow, this.doc.woofs[0] ] # No default (optional)
  prefix: "" # No default (optional)
  suffix: "" # No default (optional)
  init_files: [] # No default (optional)
  init_statement: | # No default (optional)
    CREATE TABLE IF NOT EXISTS some_table (
      foo varchar(50) not null,
      bar integer,
      baz varchar(50),
      primary key (foo)
    ) WITHOUT ROWID;
  conn_max_idle_time: "" # No default (optional)
  conn_max_life_time: "" # No default (optional)
  conn_max_idle: 2
  conn_max_open: 0 # No default (optional)

If the query fails to execute then the message will remain unchanged and the error can be caught using error handling methods.

Examples

Table Query (PostgreSQL)

Here we query a database for columns of footable that share a user_id with the message user.id. A branch processor is used in order to insert the resulting array into the original message at the path foo_rows:

pipeline:
  processors:
    - branch:
        processors:
          - sql_select:
              driver: postgres
              dsn: postgres://foouser:foopass@localhost:5432/testdb?sslmode=disable
              table: footable
              columns: [ '*' ]
              where: user_id = ?
              args_mapping: '[ this.user.id ]'
        result_map: 'root.foo_rows = this'

Fields

`driver`

A database driver to use.

Type: string

Options: mysql , postgres , clickhouse , mssql , sqlite , oracle , snowflake , trino , gocosmos .

`dsn`

A Data Source Name to identify the target database.

Drivers

:driver-support: mysql=certified, postgres=certified, clickhouse=community, mssql=community, sqlite=certified, oracle=certified, snowflake=community, trino=community, gocosmos=community

The following is a list of supported drivers, their placeholder style, and their respective DSN formats:

|=== | Driver | Data Source Name Format

| clickhouse | [clickhouse://[username[:password\](https://github.com/ClickHouse/clickhouse-go#dsn)@\][netloc\][:port\]/dbname[?param1=value1&...&paramN=valueN\]^]

| mysql | [username[:password]@][protocol[(address)]]/dbname[?param1=value1&...&paramN=valueN]

| postgres | postgres://[user[:password]@][netloc][:port][/dbname][?param1=value1&...]

| mssql | sqlserver://[user[:password]@][netloc][:port][?database=dbname&param1=value1&...]

| sqlite | file:/path/to/filename.db[?param&=value1&...]

| oracle | oracle://[username[:password]@][netloc][:port]/service_name?server=server2&server=server3

| snowflake | username[:password]@account_identifier/dbname/schemaname[?param1=value&...&paramN=valueN]

| trino | [http[s\](https://github.com/trinodb/trino-go-client#dsn-data-source-name)://user[:pass\]@host[:port\][?parameters\]^]

| gocosmos | [AccountEndpoint=<cosmosdb-endpoint>;AccountKey=<cosmosdb-account-key>[;TimeoutMs=<timeout-in-ms>\](https://pkg.go.dev/github.com/microsoft/gocosmos#readme-example-usage)[;Version=<cosmosdb-api-version>\][;DefaultDb/Db=<db-name>\][;AutoId=<true/false>\][;InsecureSkipVerify=<true/false>\]^] |===

Please note that the postgres driver enforces SSL by default, you can override this with the parameter sslmode=disable if required.

The snowflake driver supports multiple DSN formats. Please consult the docs for more details. For key pair authentication, the DSN has the following format: <snowflake_user>@<snowflake_account>/<db_name>/<schema_name>?warehouse=<warehouse>&role=<role>&authenticator=snowflake_jwt&privateKey=<base64_url_encoded_private_key>, where the value for the privateKey parameter can be constructed from an unencrypted RSA private key file rsa_key.p8 using openssl enc -d -base64 -in rsa_key.p8 | basenc --base64url -w0 (you can use gbasenc insted of basenc on OSX if you install coreutils via Homebrew). If you have a password-encrypted private key, you can decrypt it using openssl pkcs8 -in rsa_key_encrypted.p8 -out rsa_key.p8. Also, make sure fields such as the username are URL-encoded.

The gocosmos driver is still experimental, but it has support for hierarchical partition keys as well as cross-partition queries. Please refer to the SQL notes for details.

Type: string

# Examples

dsn: clickhouse://username:password@host1:9000,host2:9000/database?dial_timeout=200ms&max_execution_time=60

dsn: foouser:foopassword@tcp(localhost:3306)/foodb

dsn: postgres://foouser:foopass@localhost:5432/foodb?sslmode=disable

dsn: oracle://foouser:foopass@localhost:1521/service_name

`table`

The table to query.

Type: string

# Examples

table: foo

`columns`

A list of columns to query.

Type: array

# Examples

columns:
  - '*'

columns:
  - foo
  - bar
  - baz

`where`

An optional where clause to add. Placeholder arguments are populated with the args_mapping field. Placeholders should always be question marks, and will automatically be converted to dollar syntax when the postgres or clickhouse drivers are used.

Type: string

# Examples

where: meow = ? and woof = ?

where: user_id = ?

`args_mapping`

An optional Bloblang mapping which should evaluate to an array of values matching in size to the number of placeholder arguments in the field where.

Type: string

# Examples

args_mapping: root = [ this.cat.meow, this.doc.woofs[0] ]

args_mapping: root = [ meta("user.id") ]

`prefix`

An optional prefix to prepend to the query (before SELECT).

Type: string

`suffix`

An optional suffix to append to the select query.

Type: string

`init_files`

An optional list of file paths containing SQL statements to execute immediately upon the first connection to the target database. This is a useful way to initialise tables before processing data. Glob patterns are supported, including super globs (double star).

Care should be taken to ensure that the statements are idempotent, and therefore would not cause issues when run multiple times after service restarts. If both init_statement and init_files are specified the init_statement is executed after the init_files.

If a statement fails for any reason a warning log will be emitted but the operation of this component will not be stopped.

Type: array

Requires version 4.10.0 or newer

# Examples

init_files:
  - ./init/*.sql

init_files:
  - ./foo.sql
  - ./bar.sql

`init_statement`

An optional SQL statement to execute immediately upon the first connection to the target database. This is a useful way to initialise tables before processing data. Care should be taken to ensure that the statement is idempotent, and therefore would not cause issues when run multiple times after service restarts.

If both init_statement and init_files are specified the init_statement is executed after the init_files.

If the statement fails for any reason a warning log will be emitted but the operation of this component will not be stopped.

Type: string

Requires version 4.10.0 or newer

# Examples

init_statement: |2
  CREATE TABLE IF NOT EXISTS some_table (
    foo varchar(50) not null,
    bar integer,
    baz varchar(50),
    primary key (foo)
  ) WITHOUT ROWID;

`conn_max_idle_time`

An optional maximum amount of time a connection may be idle. Expired connections may be closed lazily before reuse. If value <= 0, connections are not closed due to a connections idle time.

Type: string

`conn_max_life_time`

An optional maximum amount of time a connection may be reused. Expired connections may be closed lazily before reuse. If value <= 0, connections are not closed due to a connections age.

Type: string

`conn_max_idle`

An optional maximum number of connections in the idle connection pool. If conn_max_open is greater than 0 but less than the new conn_max_idle, then the new conn_max_idle will be reduced to match the conn_max_open limit. If value <= 0, no idle connections are retained. The default max idle connections is currently 2. This may change in a future release.

Type: int

Default: 2

`conn_max_open`

An optional maximum number of open connections to the database. If conn_max_idle is greater than 0 and the new conn_max_open is less than conn_max_idle, then conn_max_idle will be reduced to match the new conn_max_open limit. If value <= 0, then there is no limit on the number of open connections. The default is 0 (unlimited).

Type: int