Django Postgres 全文 TrigramSimilarity 多个字段

Question

我正在尝试弄清楚如何将TrigramSimilarity 与unaccent 一起用于多个字段。

到目前为止我有：

def filter_by_location(self, queryset, location):
    log.info('Filtering location: "{location}"'.format(**locals()))
    queryset = queryset.filter(
        Q(accommodation__district__name__unaccent__trigram_similar=location) |
        Q(accommodation__municipality__name__unaccent__trigram_similar=location) |
        Q(accommodation__settlement__name__unaccent__trigram_similar=location)
    )

但我在documentation 中读到我可以通过similarity 订购（不确定上面的代码是否自动执行此操作），所以我尝试这样做：

    queryset = queryset.filter(
        Q(accommodation__district__name__unaccent__trigram_similar=location) |
        Q(accommodation__municipality__name__unaccent__trigram_similar=location) |
        Q(accommodation__settlement__name__unaccent__trigram_similar=location)
    ).annotate(
        similarity=TrigramSimilarity(
            'accommodation__district__name', location
        ) + TrigramSimilarity(
            'accommodation__municipality__name', location
        ) + TrigramSimilarity(
            'accommodation__settlement__name', location
        ),
    ).filter(similarity__gt=0.3).order_by('-similarity')

我很快意识到TrigramSimilarity 中的+ 没有在做OR，但我需要在所有这些不同的字段中进行全文搜索。

考虑到查询性能，我实现这一目标的正确语法是什么（使用OR 而不是AND）？

谢谢

Answer 1

我认为下面的代码可能会有所帮助，但我还没有运行它：

queryset = queryset.annotate(
    similarity = Greatest(
        TrigramSimilarity('accommodation__district__name', location),
        TrigramSimilarity('accommodation__municipality__name', location),
        TrigramSimilarity('accommodation__settlement__name', location))
).filter(
    Q(accommodation__district__name__unaccent__trigram_similar=location) |
    Q(accommodation__municipality__name__unaccent__trigram_similar=location) |
    Q(accommodation__settlement__name__unaccent__trigram_similar=location),
  similarity__gt=0.3).order_by('-similarity')

Greatest 可以像下面这样导入：

from django.db.models.functions import Greatest