Function deepCopyQuery

packages/db/src/query/optimizer.ts:827–852

* Helper function to create a deep copy of a QueryIR object for immutability. * * This ensures that all optimizations create new objects rather than modifying * existing ones, preventing infinite recursion and shared reference issues. * * @param query - QueryIR to deep copy * @returns New Quer

(query: QueryIR)

 * @returns New QueryIR object with all nested objects copied
 */
function deepCopyQuery(query: QueryIR): QueryIR {
  return {
    // Recursively copy the FROM clause
    from: deepCopyFrom(query.from),

    // Copy all other fields, creating new arrays where necessary
    select: query.select,
    join: query.join
      ? query.join.map((joinClause) => ({
          type: joinClause.type,
          left: joinClause.left,
          right: joinClause.right,
          from: deepCopyJoinFrom(joinClause.from),
        }))
      : undefined,
    where: query.where ? [...query.where] : undefined,
    groupBy: query.groupBy ? [...query.groupBy] : undefined,
    having: query.having ? [...query.having] : undefined,
    orderBy: query.orderBy ? [...query.orderBy] : undefined,
    limit: query.limit,
    offset: query.offset,
    fnSelect: query.fnSelect,
    fnWhere: query.fnWhere ? [...query.fnWhere] : undefined,
    fnHaving: query.fnHaving ? [...query.fnHaving] : undefined,
  }
}

function deepCopyFrom(from: From): From {
  if (from.type === `collectionRef`) {