Function isCollectionReference

packages/db/src/query/optimizer.ts:296–314

* Determines if a source alias refers to a collection reference (not a subquery). * This is used to identify WHERE clauses that can be pushed down to collection subscriptions. * * @param query - The query to analyze * @param sourceAlias - The source alias to check * @returns True if the alias r

(query: QueryIR, sourceAlias: string)

 * @returns True if the alias refers to a collection reference
 */
function isCollectionReference(query: QueryIR, sourceAlias: string): boolean {
  // Check the FROM clause
  for (const source of getFromSources(query.from)) {
    if (source.alias === sourceAlias) {
      return source.type === `collectionRef`
    }
  }

  // Check JOIN clauses
  if (query.join) {
    for (const joinClause of query.join) {
      if (joinClause.from.alias === sourceAlias) {
        return joinClause.from.type === `collectionRef`
      }
    }
  }

  return false
}

/**
 * Returns the set of source aliases that are on the nullable side of outer joins.