postgres_query
The `postgres_query` directive defines the SQL query to execute against a PostgreSQL database, potentially conditionally based on the specified HTTP methods.
Description
The postgres_query directive within the NGINX PostgreSQL module allows the user to specify SQL queries that will be executed in response to incoming HTTP requests. It can accept one or more methods as its parameter, specifying under which HTTP methods the queries should be applied. This flexibility enables users to tailor their database operations based on the type of request made, optimizing interactions with the PostgreSQL backend accordingly.
The query itself can include variables, enhancing its dynamism by allowing data to be derived from the request context or environment. When this directive is used multiple times within the same configuration context (such as http, server, or location), multiple queries can be defined for different scenarios, allowing for complex database manipulations dependent on the specifics of the incoming request. If a method is specified, the associated query will be executed only for that method; if no method is specified, the query is applied to all requests.
As with other NGINX directives, proper syntax and context usage are crucial to ensure the expected behavior. Queries that are incorrectly formatted or that contain unrecognized syntax may result in server errors or unintended responses leading to potential service disruptions.
Config Example
location /api/data {
postgres_pass my_upstream;
postgres_query GET SELECT * FROM users WHERE id = $arg_id;
postgres_query POST INSERT INTO users (name) VALUES ($arg_name);
}Using unsupported SQL queries can lead to server errors; ensure SQL syntax is compatible with PostgreSQL.
The order of postgres_query directives may affect which query is executed for a given request method, as NGINX processes directives sequentially.
Improper variable usage within queries might lead to unexpected results or errors.