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Version: v2.x

Cloud & EE: 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 name 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)

Standard

This format makes a collection of key=value pairs and separates each pair by a comma , . This is the default format for Query Tags

For eg:

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

SQLCommenter

The specification for this format is defined at https://google.github.io/sqlcommenter/spec/

For eg:

SELECT name 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.

Query and Mutation

  1. Request ID (request_id)
  2. Operation Name (operation_name)
  3. (Root) field name (alias if provided) (field_name)
  4. Parameterized Query Hash (parameterized_query_hash)

Subscriptions

  1. (Root) field name (alias if provided) (field_name)
  2. Parameterized Query Hash (parameterized_query_hash)

Metadata Specification

sources:
name: # Name of the source
configuration:
query_tags: # Optional Field
disabled: # Optional Field | Type: Bool | Values: true or false
format: # Optinal Field | Values: standard or sqlcommenter
info

Note The default format for the Query Tags is Standard and it is enabled by default for all sources.

In the above metadata spec:

  1. The query_tags field is optional. If the query_tags field is not present for a source, then query tags is enabled for the source and the format used is standard.
  2. To disable query tags for any source, set the value of disabled field to true.
  3. To override the default format (Standard) for query tags, use the format field.

Example Metadata Specification

sources:
- name: test_db
configuration:
query_tags:
disabled: true

- name: hasura_db_herokou
configuration:
query_tags:
format: sqlcommenter

- name: hasura_db_2
configuration:
query_tags:
format: standard
disabled: true

Metadata API To Set Query Tags

type: 'set_query_tags'
args:
source_name: # Name of the source | Required
disabled: # Optional Field | Type: Bool | Values: true or false
format: # Optional Field | Values: standard or sqlcommenter