sql_select

Type:

Available in: Cloud, Self-Managed

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.

  • Common

  • Advanced

# Common configuration 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)
# All configuration 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

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") ]

columns[]

A list of columns to query.

Type: array

# Examples:
columns:
  - "*"

  - foo
  - bar
  - baz

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_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_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

driver

A database driver to use.

Type: string

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

dsn

A Data Source Name to identify the target database.

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

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

# Examples:
init_files:
  - ./init/*.sql

  - ./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

# Examples:
init_statement: |-

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

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

table

The table to query.

Type: string

# Examples:
table: foo

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 = ?