Query Tags¶

Introduction¶

Query Tags are SQL comments which are made up of (key=value) pairs that are appended to the SQL statements generated by Hasura for GraphQL operations. This enables the ability to get some application context in the database logs and also use native database monitoring tools (e.g. pganalyze) for better performance analysis.

Example:

When the following query is sent to Hasura

query GetChild {
  child {
    name
  }
}

Hasura attaches query tags (unless disabled) to the generated SQL statement it sends to the database.

SELECT * FROM child /* request_id=487c2ed5-08a4-429a-b0e0-4666a82e3cc6, field_name=child, operation_name=GetChild */

Formats of Query Tags¶

The format of the Query Tags describes how the (Key,Value) pairs are constructed. Currently we support two formats of Query Tags:

1. Standard (standard)
2. SQLCommenter (sqlcommenter)

SELECT * FROM child /* request_id=487c2ed5-08a4-429a-b0e0-4666a82e3cc6, field_name=child, parameterized_query_hash=b2a71ce23928ca7f0021f9060e5d590e9f9bb00f, operation_name=GetChild */

SELECT * FROM child /* field_name='child', operation_name='GetChild', parameterized_query_hash='b2a71ce23928ca7f0021f9060e5d590e9f9bb00f' ,  request_id='487c2ed5-08a4-429a-b0e0-4666a82e3cc6' */

Information in Query Tags¶

The following information is present in query tags for the GraphQL operations.

Metadata Specification¶

query_tags:
  default_format: # Optional Field (Values can be sqlcommenter or standard)
  per_source_configuration: # Optional Field
    source_name: # Name of the database
      format: # Optional Field (Values can be sqlcommenter or standard)
      disabled: # Optional Field (Values can be true or false)

In the above metadata spec:

1. If default_format is not specified, Standard is used as the default format
2. The format in the source_name could be used to override the default_format
3. If the default_format and the format for a source is not mentioned then Standard is used as format.
4. If disabled is not set for any source, False is used i.e Query Tags are always enabled by default

Example Metadata Specification¶

query_tags:
  default_format: sqlcommenter
  per_source_configuration:
    avengers_database:
      format: standard
    marvel_database:
      disabled: true
    dc_database:
      format: sqlcommenter
      disable: true