Django ORM get_or_create

用 get_or_create 多线程创建数据时会产生重复数据；

方法的源码如下：

    def get_or_create(self, defaults=None, **kwargs):
        """
        Looks up an object with the given kwargs, creating one if necessary.
        Returns a tuple of (object, created), where created is a boolean
        specifying whether an object was created.
        """
        lookup, params = self._extract_model_params(defaults, **kwargs)
        # The get() needs to be targeted at the write database in order
        # to avoid potential transaction consistency problems.
        self._for_write = True
        try:
            return self.get(**lookup), False
        except self.model.DoesNotExist:
            return self._create_object_from_params(lookup, params)

问题解决：

在创建表的时候指定联合索引；

配合事务一起使用；

在model层加限制unique或 unique_together

　　例子如下：

class PangleData(models.Model):
    time_zone = models.CharField(max_length=3, verbose_name='Timezone')
    currency = models.CharField(max_length=32, verbose_name='Currency')
    region = models.CharField(max_length=6, verbose_name='Region')
    app_id = models.IntegerField(verbose_name='App id on Pangle platform')
    app_name = models.CharField(max_length=32, verbose_name='App Name on Pangle platform')
    ad_slot_id = models.BigIntegerField(verbose_name='Placement id on Pangle platform')
    ad_slot_type = models.IntegerField(verbose_name='Also known as Ad type')
    package_name = models.CharField(max_length=32, verbose_name='Package name')
    request = models.IntegerField(verbose_name='request')
    P_return = models.IntegerField(verbose_name='return')
    fill_rate = models.FloatField(null=True, verbose_name='fill_rate')
    show = models.IntegerField(verbose_name='Impressions')
    click = models.IntegerField(verbose_name='click')
    click_rate = models.FloatField(verbose_name='Click Through Rate')
    revenue = models.FloatField(verbose_name='Estimated Revenue')
    ecpm = models.FloatField(verbose_name='Estimated Ecpm')
    media_name = models.CharField(max_length=12, verbose_name='Account name')
    code_name = models.CharField(max_length=64, verbose_name='Slot name on Pangle platform')
    os = models.CharField(max_length=12, verbose_name='Operating system')
    use_mediation = models.IntegerField(verbose_name='Is use pangle mediation. 0 (Not) 、1 (Yes)')
    bidding_type = models.IntegerField(verbose_name='RIT bidding type. 0 (standard) 、1 (in-app bidding) 、'
                                                    '2 (client bidding)')
    date = models.DateField(null=True, verbose_name='Date')
    media_m_ssr = models.IntegerField(verbose_name='media_m_ssr')

    class Meta:
        unique_together = ['region', 'app_id', 'ad_slot_id']