django：'python manage.py migrate' 花费数小时（以及其他奇怪的行为）

Question

我对 models.py 中的一个 table 进行了一些更改，并尝试使用 'python manage.py migrate,' 迁移它，这需要几个小时。我只改了三个字段（列）的名字，到现在已经运行宁了2个多小时了。当我今天早上创建 table 时，它运行在几分钟内顺利（我认为）。赛季开始是做出改变的模型。

这是 models.py 现在的样子：

from django.db import models
from django.contrib.gis.db import models as gismodels
# from django.contrib.gis import admin

# Create your models here.

class Location(models.Model): # table name automatically chirps_location
    locationID = models.IntegerField(default=0, primary_key=True)
    lat = models.FloatField(default=0.0)
    lon = models.FloatField(default=0.0)
    geom = gismodels.PointField(null=True)
    objects = gismodels.GeoManager()
    def __unicode__(self):
        return u"LocationID: " + unicode(self.locationID)

# admin.site.unregister(Location)
# admin.site.register(Location, admin.OSMGeoAdmin)


class Rainfall(models.Model):
    location = models.ForeignKey(Location)
    year = models.IntegerField(default=0)
    pentad_num = models.IntegerField(default=0)        
    pentad_val = models.FloatField(default=0.0)

    class Meta:
        ordering = ['location', 'year', 'pentad_num']

    def __unicode__(self):
        return u"LocationID: " + unicode(self.location.locationID) + u" Year: " + unicode(self.year) + u" Pentad: " + unicode(self.pentad_num)


class Start_of_Season(models.Model):
    location = models.ForeignKey(Location)
    crop = models.CharField(default='', max_length=40)
    year = models.IntegerField(default=0)
    first_rain = models.IntegerField(default=0)
    onset_rain = models.IntegerField(default=0)
    start_season = models.IntegerField(default=0)

    class Meta:
        ordering = ['location', 'crop', 'year']    

    def __unicode__(self):
        return u"LocationID: " + unicode(self.location.locationID) + u" Year: " + unicode(self.year) + u" Start of Season pentad: " + unicode(self.start_season)

在此之前还有一些我无法解释的奇怪行为，所以我也会简要地运行简要说明所有这些行为，以防它们都相关。

起初，我的 Start_of_Season class 看起来像这样（注意唯一的区别是最后 3 个字段的名称）：

class Start_of_Season(models.Model):
    location = models.ForeignKey(Location)
    crop = models.CharField(default='', max_length=40)
    year = models.IntegerField(default=0)
    first_rain_pentad = models.IntegerField(default=0)
    onset_rain_pentad = models.IntegerField(default=0)
    start_season_pentad = models.IntegerField(default=0)

    class Meta:
        ordering = ['location', 'crop', 'year']    

    def __unicode__(self):
        return u"LocationID: " + unicode(self.location.locationID) + u" Year: " + unicode(self.year) + u" Start of Season pentad: " + unicode(self.start_season)

迁移它：

python manage.py makemigrations
python manage.py migrate

似乎运行顺利。

但是当我运行一个 python 脚本（摘录）将行添加到这个新创建的 Start_of_Season table:

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "access.settings")
from chirps.models import Location, Rainfall, Start_of_Season
django.setup()

try:
    with transaction.atomic():
        for loc in Location.objects.all():
            locID = loc.locationID
            for yr in range(1981, 2014):
                # some computations to find: c1, c2, c3
                start_of_season = Start_of_Season()
                start_of_season.location = Location.objects.get(locationID = locID)
                start_of_season.crop = 'millet'
                start_of_season.year = yr
                start_of_season.first_rain_pentad = c1
                start_of_season.onset_rain_pentad = c2
                start_of_season.start_season_pentad = c3
                start_of_season.save()

起初，这些行从未添加到数据库中（至少根据 psql）。然后我得到了错误 "start_of_season has no attribute start_season" 这很奇怪，因为我从未尝试在我的脚本中访问该属性，只有 "start_of_season.start_season_pentad"

然后我想，好吧，我将更改字段的名称，以便 start_of_season 具有该属性。那时我将 models.py 编辑为看起来像 post 顶部的摘录。

更新更新后 models.py,

python manage.py makemigrations

运行没有错误：

(access_mw)mwooten@ip-10-159-67-226:~/dev/access$ python manage.py makemigrations
Did you rename start_of_season.first_rain_pentad to start_of_season.first_rain (a IntegerField)? [y/N] y
Did you rename start_of_season.onset_rain_pentad to start_of_season.onset_rain (a IntegerField)? [y/N] y
Did you rename start_of_season.start_season_pentad to start_of_season.start_season (a IntegerField)? [y/N] y
Migrations for 'chirps':
  0010_auto_20150901_1454.py:
    - Rename field first_rain_pentad on start_of_season to first_rain
    - Rename field onset_rain_pentad on start_of_season to onset_rain
    - Rename field start_season_pentad on start_of_season to start_season

，但是：

python manage.py migrate

在这里卡了几个小时：

(access_mw)mwooten@ip-10-159-67-226:~/dev/access$ python manage.py migrate
Operations to perform:
  Synchronize unmigrated apps: staticfiles, gis, djgeojson, messages, leaflet
  Apply all migrations: admin, chirps, contenttypes, auth, sessions
Synchronizing apps without migrations:
  Creating tables...
    Running deferred SQL...
  Installing custom SQL...
Running migrations:
  Rendering model states... DONE
  Applying chirps.0010_auto_20150901_1454...

我不明白为什么这会花这么长时间，因为创建实际的 table 却没有。我也不确定为什么会出现其他错误。关于发生的事情有什么想法吗？

谢谢

Answer 1

这通常是因为有另一个 SQL 客户端或 django 服务器或 shell reading/writing 到 table 您正试图修改。

在访问 table 时无法成功执行更改架构的 SQL 命令。理想情况下应该弹出一条错误消息，但通常发生的是该命令只是等待其他命令完成。

一旦您关闭所有打开的 shell 和 sql 客户端，就会发生模式更改。在最坏的情况下，您可能还需要暂时将网站下线。

django：'python manage.py migrate' 花费数小时（以及其他奇怪的行为）

django: 'python manage.py migrate' taking hours (and other weird behavior)

python

django

django-models

django-migrations