xml - 延迟解析巨大 XML 中的元素

Question

我们正在处理OTDS文件。简而言之，它们是包含大量数据并且可能超过 15GB 的 XML。

我们选择scalesXml库是为了有效地处理这些文件。

让我给你看一个例子：

<?xml version="1.0" encoding="UTF-8"?>
<Otds UpdateMode="Merge"
xmlns="http://otds-group.org/otds"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
Version="1.9.1" xsi:schemaLocation="http://otds-group.org/otds ../xsd/otds.xsd">
 <Brands>
     ...
 </Brands>
 <Accommodations>
  <Accommodation Key="A">
   ...
   <SellingAccom>
    ...
    <PriceItems Key="1">...</PriceItems>
    ...
   </SellingAccom>
   ...
  </Accommodation>

...  <!-- A lot of <Accomodation> tags -->

  <Accommodation Key="Z">
  ...
  </Accommodation>
  <PriceItems Key="Global1"></PriceItems>   <!-- Collect all of these     -->
  <PriceItems Key="Global2"></PriceItems>
 </Accommodations>
</Otds>

我们遇到了这个问题。XML 包含大量繁重的<Accomodation>标签。我们将提取所有标签<PriceItems>的直接子代。<Accommodations>

我创建了真正的简化文件：

<?xml version="1.0" encoding="UTF-8"?>
<Otds UpdateMode="Merge"
xmlns="http://otds-group.org/otds"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
Version="1.9.1" xsi:schemaLocation="http://otds-group.org/otds ../xsd/otds.xsd">
 <Brands>
  <Brand>EBIWA</Brand>
 </Brands>
 <Accommodations>
  <Accommodation Key="ATH432">
   <SellingAccom>
    <PriceItems Key="1"></PriceItems>
   </SellingAccom>
  </Accommodation>
  <Accommodation Key="ATH433">
   <SellingAccom>
    <PriceItems Key="2"></PriceItems>
   </SellingAccom>
  </Accommodation>
  <PriceItems Key="Global"></PriceItems>
 </Accommodations>
</Otds>

我目前的做法：

1. 它返回所有 PriceItems 的 Iterator[PriceItems]，而不仅仅是预期的最后一个

   val ns = Namespace("http://otds-group.org/otds")
   val Otds = ns("Otds")
   val Accommodations = ns("Accommodations")
   val PriceItems = ns("PriceItems")
   val Accommodation = ns("Accommodation")
   
   val priceItemsPath = List(Otds, Accommodations, PriceItems)
   
   val xml = pullXml(inputstream, optimisationStrategy = QNameElemTreeOptimisation)
   
   val itr = iterate(priceItemsPath, xml)
   
   for {
     priceItems <- itr
   } yield {
     val parsedJson = parseXml(priceItems)
     val result = parsedJson.children.head.extract[PriceItems]
     result
   }
   

如何在不解析整个内容的情况下快速提取这个巨大文件末尾的元素？