Executing ECSQL with the iTwin.js Frontend

ECSQL by itself is described in detail here: ECSQL

A frontend ECSQL query is executed by calling IModelConnection.createQueryReader.

On the frontend, only ECSQL SELECT statements can be executed. Data modification must be done through the API.

Avoid Chatty Patterns

An ECSQL query initiated from the frontend necessarily requires a round trip with the backend server. In Web Apps, round trips mean exposure to network latency, so a chunky request pattern will perform better than a chatty request pattern. If multiple queries are required to build up the desired result, consider moving the operation to the backend.

See Code Examples for examples of how the API is used.