Function optimizeOrExpression

packages/db/src/utils/index-optimization.ts:685–715

* Optimizes OR expressions

(
  expression: BasicExpression,
  collection: CollectionLike<T, TKey>,
)

 * Optimizes OR expressions
 */
function optimizeOrExpression<T extends object, TKey extends string | number>(
  expression: BasicExpression,
  collection: CollectionLike<T, TKey>,
): OptimizationResult<TKey> {
  if (expression.type !== `func` || expression.args.length < 2) {
    return { canOptimize: false, matchingKeys: new Set(), isExact: false }
  }

  const results: Array<OptimizationResult<TKey>> = []

  // Every disjunct must be optimizable: rows matched only by a disjunct
  // that cannot use an index would be missing from the union, and no
  // post-filtering can recover them. In that case fall back to a full scan.
  for (const arg of expression.args) {
    const result = optimizeQueryRecursive(arg, collection)
    if (!result.canOptimize) {
      return { canOptimize: false, matchingKeys: new Set(), isExact: false }
    }
    results.push(result)
  }

  // Use unionSets utility for OR logic
  const allMatchingSets = results.map((r) => r.matchingKeys)
  const unionedKeys = unionSets(allMatchingSets)
  return {
    canOptimize: true,
    matchingKeys: unionedKeys,
    // An inexact (superset) disjunct makes the union a superset as well
    isExact: results.every((r) => r.isExact),
  }
}

/**
 * Checks if an OR expression can be optimized