我的页面加载速度太慢。我需要以某种方式改进查询数据的方式(缓存?部分加载/页面?等)
请注意,我是一个 django 菜鸟,还没有完全了解 model.Manager
和 models.query.QuerySet
所以如果这个设置看起来很尴尬...... ..
目前,页面加载查询集大约需要 18 秒,目前只有大约 500 条记录。平均每天大约有 100 条新记录。
数据库是Postgresql
缓慢的 View :
def approvals(request):
...
approved_submissions = QuestSubmission.objects.all_approved()
...
缓慢的查询集:
class QuestSubmissionQuerySet(models.query.QuerySet):
...
def approved(self):
return self.filter(is_approved=True)
def completed(self):
return self.filter(is_completed=True).order_by('-time_completed')
...
class QuestSubmissionManager(models.Manager):
def get_queryset(self):
return QuestSubmissionQuerySet(self.model, using=self._db)
def all_approved(self, user=None):
return self.get_queryset().approved().completed()
...
QuestSubmission.objects.all_approved()
生成的 SQL:
'SELECT "quest_manager_questsubmission"."id", "quest_manager_questsubmission"."quest_id", "quest_manager_questsubmission"."user_id", "quest_manager_questsubmission"."ordinal", "quest_manager_questsubmission"."is_completed", "quest_manager_questsubmission"."time_completed", "quest_manager_questsubmission"."is_approved", "quest_manager_questsubmission"."time_approved", "quest_manager_questsubmission"."timestamp", "quest_manager_questsubmission"."updated", "quest_manager_questsubmission"."game_lab_transfer" FROM "quest_manager_questsubmission" WHERE ("quest_manager_questsubmission"."is_approved" = True AND "quest_manager_questsubmission"."is_completed" = True) ORDER BY "quest_manager_questsubmission"."time_completed" DESC'
慢速模型:
class QuestSubmission(models.Model):
quest = models.ForeignKey(Quest)
user = models.ForeignKey(settings.AUTH_USER_MODEL, related_name="quest_submission_user")
ordinal = models.PositiveIntegerField(default = 1, help_text = 'indicating submissions beyond the first for repeatable quests')
is_completed = models.BooleanField(default=False)
time_completed = models.DateTimeField(null=True, blank=True)
is_approved = models.BooleanField(default=False)
time_approved = models.DateTimeField(null=True, blank=True)
timestamp = models.DateTimeField(auto_now=True, auto_now_add=False)
updated = models.DateTimeField(auto_now=False, auto_now_add=True)
game_lab_transfer = models.BooleanField(default = False, help_text = 'XP not counted')
class Meta:
ordering = ["time_approved", "time_completed"]
objects = QuestSubmissionManager()
#other methods
....
有什么策略可以解决这个问题?我尝试使用 django 的分页器,但它似乎只显示在页面中,但它仍然加载整个查询集。
最佳答案
首先要看:
- 这个查询很慢是因为它返回了一个非常大的结果集吗?
或
- 这个查询很慢是因为它需要一段时间来过滤表格吗?
假设是前者,除了“返回更少的数据”之外,您没有太多好的选择。
如果是后者,您可能应该在数据库上运行 EXPLAIN
,但马上我会说您可能需要一个索引,可能在 (is_approved, is_completed) 上
。这可以通过以下方式完成:
class Meta:
index_together = [
["is_completed", "is_approved"],
]
关于python - 从庞大且不断增长的数据集中优化慢速 Django 查询集,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/32670603/