Method loadNextItems

packages/db/src/query/effect.ts:901–934

* Load n more items from the source collection, starting from the cursor * position (the biggest value sent so far).

(orderByInfo: OrderByOptimizationInfo, n: number)

   * position (the biggest value sent so far).
   */
  private loadNextItems(orderByInfo: OrderByOptimizationInfo, n: number): void {
    const { alias } = orderByInfo
    const subscription = this.subscriptions[alias]
    if (!subscription) return

    const cursor = computeOrderedLoadCursor(
      orderByInfo,
      this.biggestSentValue.get(alias),
      this.lastLoadRequestKey.get(alias),
      alias,
      n,
    )
    if (!cursor) return // Duplicate request — skip

    this.lastLoadRequestKey.set(alias, cursor.loadRequestKey)

    subscription.requestLimitedSnapshot({
      orderBy: cursor.normalizedOrderBy,
      limit: n,
      minValues: cursor.minValues,
      trackLoadSubsetPromise: false,
      onLoadSubsetResult: (loadResult: Promise<void> | true) => {
        // Track in-flight load to prevent redundant concurrent requests
        if (loadResult instanceof Promise) {
          this.pendingOrderedLoadPromise = loadResult
          loadResult.finally(() => {
            if (this.pendingOrderedLoadPromise === loadResult) {
              this.pendingOrderedLoadPromise = undefined
            }
          })
        }
      },
    })
  }

  /**
   * Track the biggest value sent for a given ordered alias.