标签: django-postgresql

我的堆栈包括 django (1.4.3)、psycopg2 (0.0.3) 和 postgres (9.1)。此外，我正在使用 psycogreen.gevent.patch_psycopg，因为我正在使用 gunicorn 和 gevent 提供我的 django。

一切似乎都很愉快，但我得到了很多（约 40 个）打开的数据库连接。直到我在 django 数据库设置中将 'autocommit' 设置为 True 之前，它们都处于“事务空闲”状态。现在他们都只是“空闲”。

这是我的 pg_top 输出示例。

last pid: 22043;  load avg:  0.09,  0.05,  0.05;       up 6+21:49:58                                                    16:21:08
45 processes: 45 sleeping
CPU states:  3.0% user,  0.9% nice,  0.2% system, 96.0% idle,  0.0% iowait
Memory: 871M used, 130M free, 32M buffers, 530M cached
Swap: 10M used, 246M free, 2192K cached

  PID USERNAME PRI NICE  SIZE   RES STATE   TIME   WCPU    CPU COMMAND
10035 …

在一个应用程序中参考Django文档中的多个数据库的示例,

https://docs.djangoproject.com/en/dev/topics/db/multi-db/#an-example

"它也没有考虑事务与数据库利用策略的交互."

我如何处理上述交互.

场景是这样的:

我使用postgresql作为我的数据库.我已经设置了一个副本,并希望所有对"auth"表的读取都转到副本.根据文档,我写了一个数据库路由器.现在每当我尝试登录我的应用程序时都会抛出以下错误.

DatabaseError: cannot execute UPDATE in a read-only transaction.

当Django试图保存"last_login"时间时会发生这种情况.因为,在同一视图中,它首先从副本提取记录,然后尝试更新last_login时间.由于它发生在一个事务中,因此使用相同的数据库,即副本.

我该如何处理？

思考？

我想使用date_trunc SQL函数,但它似乎不适用于时区.

用Django测试1:

from django.db import connection
cursor = connection.cursor()
cursor.execute("""
SELECT (date_trunc('day', when_start)) AS "d", 
COUNT("stats_histo_call"."id") AS "agg"
FROM "stats_histo_call"
WHERE ("stats_histo_call"."offre_id" = 28 
AND "stats_histo_call"."when_start" BETWEEN '2014-08-04 00:00:00+02:00' and '2014-08-08 23:59:59.999999+02:00')
GROUP BY (date_trunc('day', when_start))""")

print cursor.fetchone()
print cursor.fetchone()
print cursor.fetchone()
print cursor.fetchone()
print cursor.fetchone()

postgres日志中的SQL查询:

2014-08-21 15:18:31 CEST LOG:  instruction : SELECT (date_trunc('day', when_start)) AS "d", COUNT("stats_histo_call"."id") AS "agg" FROM "stats_histo_call" WHERE ("stats_histo_call"."offre_id" = 28  AND "stats_histo_call"."when_start" BETWEEN '2014-08-04 00:00:00+02:00' and '2014-08-08 23:59:59.999999+02:00') GROUP BY (date_trunc('day', …

所以我正在尝试将SearchVectorField添加到 Django 中的模型中：

class JobPosting(models.Model):
    ...
    ...
    search_vector = SearchVectorField()

我知道它应该是nullable或具有默认值才能迁移，因此我删除了表中的所有条目以防止出现此问题。

但是，运行时出现以下错误makemigrations：

You are trying to add a non-`nullable` field 'search_vector' to jobposting without a default;
we can't do that (the database needs something to populate existing rows).
Please select a fix:
   1) Provide a one-off default now
      (will be set on all existing rows with a null value for this column)
   2) Quit, and let me add a default in models.py
Select an …

我遇到了Django应用程序的问题.对模型Scope的查询极其缓慢,经过一些调试后我仍然不知道问题所在.

当我scope = Scope.objects.get(pk='Esoterik I')在django中查询db 时需要5到10秒.该数据库的主键少于10个条目和索引.所以这太慢了.在db上执行等效查询时,SELECT * FROM scope WHERE title='Esoterik I';一切正常,只需要大约50ms.

如果我使用一组结果进行查询,scope_list = Scope.objects.filter(members=some_user)然后执行例如print(scope_list)或迭代列表的元素,则会出现同样的问题.查询本身只需要几毫秒,但元素的打印或迭代再次需要5到10秒,但该集只有两个条目.

数据库后端是Postgresql.问题在本地开发服务器和apache上发生相同.

这里是模型的代码:

class Scope(models.Model):
    title = models.CharField(primary_key=True, max_length=30)

    ## the semester the scope is linked with
    assoc_semester  =   models.ForeignKey(Semester, null=True) 

    ## the grade of the scope. can be Null if the scope is not a class
    assoc_grade     =   models.ForeignKey(Grade, null=True)

    ## the timetable of the scope. can be null if the scope is not direct associated with …

安装django_postgrespool并相应地配置我的项目后,我收到以下错误:

Traceback (most recent call last):
  File "C:\Users\Administrator\Documents\my_proj\my_module.py", line 14, in <module>
    from cortex.my_app.models import MyModel
  File "C:\Users\Administrator\Documents\my_proj\my_app\models.py", line 3, in <module>
    from django.db import models
  File "C:\Users\Administrator\virtual_environments\spyker\lib\site-packages\django\db\__init__.py", line 40, in <module>
    backend = load_backend(connection.settings_dict['ENGINE'])
  File "C:\Users\Administrator\virtual_environments\spyker\lib\site-packages\django\db\__init__.py", line 34, in __getattr__
    return getattr(connections[DEFAULT_DB_ALIAS], item)
  File "C:\Users\Administrator\virtual_environments\spyker\lib\site-packages\django\db\utils.py", line 92, in __getitem__
    backend = load_backend(db['ENGINE'])
  File "C:\Users\Administrator\virtual_environments\spyker\lib\site-packages\django\db\utils.py", line 44, in load_backend
    raise ImproperlyConfigured(error_msg)
django.core.exceptions.ImproperlyConfigured: 'django_postgrespool' isn't an available database backend.
Try using django.db.backends.XXX, where XXX is one of:
    'dummy', 'mysql', …

我正在heroku上设置我的django项目.我一直在关注文档,但是当foreman start我收到一个我无法弄清楚的错误时.我已经设置了我的引擎文件,但它似乎不想工作.

完全追溯:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/nir/nirla/venv/lib/python2.7/site-packages/django/core/management/__init__.py", line 399, in execute_from_command_line
    utility.execute()
  File "/Users/nir/nirla/venv/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/nir/nirla/venv/lib/python2.7/site-packages/django/core/management/base.py", line 242, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/nir/nirla/venv/lib/python2.7/site-packages/django/core/management/base.py", line 285, in execute
    output = self.handle(*args, **options)
  File "/Users/nir/nirla/venv/lib/python2.7/site-packages/django/core/management/base.py", line 415, in handle
    return self.handle_noargs(**options)
  File "/Users/nir/nirla/venv/lib/python2.7/site-packages/django/core/management/commands/syncdb.py", line 57, in handle_noargs
    cursor = connection.cursor()
  File "/Users/nir/nirla/venv/lib/python2.7/site-packages/django/db/backends/__init__.py", line 160, in cursor
    cursor = self.make_debug_cursor(self._cursor())
  File "/Users/nir/nirla/venv/lib/python2.7/site-packages/django/db/backends/dummy/base.py", line 15, in …

我在我的django应用程序中使用postgres,我在数据库中手动创建了hstore扩展.但是,当我运行测试时,它会尝试创建一个新数据库,并在找不到hstore扩展时失败.

我收到以下错误:

django.db.utils.ProgrammingError: hstore type not found in the database. please install it from your 'contrib/hstore.sql' file

我按照这篇文章更新了我的迁移,结果如下:

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import models, migrations
from django.conf import settings
from django.contrib.postgres.operations import HStoreExtension
import django.contrib.postgres.fields
import django.contrib.postgres.fields.hstore


class Migration(migrations.Migration):

    dependencies = [
        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
    ]

    operations = [
        HStoreExtension(),
        migrations.CreateModel(
        name='AppUser',
        fields=[
            ('id', models.AutoField(serialize=False, verbose_name='ID', primary_key=True, auto_created=True)),
            ('created_date', models.DateTimeField(auto_now_add=True)),
            ('modified_date', models.DateTimeField(auto_now=True)),
            ('lock', models.BooleanField(default=False)),
            ('username', models.CharField(max_length=100)),
            ('email', models.EmailField(max_length=150)),
            ('social_data', django.contrib.postgres.fields.hstore.HStoreField(blank=True, default='')), …

我有一个像下面这样的元组列表 -

[(float.inf, 1.0), (270, 0.9002), (0, 0.0)]

我正在寻找一个简单的序列化器/反序列化器，它可以帮助我将此元组存储在 PostgreSQL 的 jsonb 字段中。

我尝试使用JSONEncoder().encode(a_math_function)但没有帮助。

我在尝试将上述列表存储在 jsonb 字段中时遇到以下错误 -

django.db.utils.DataError: invalid input syntax for type json
LINE 1: ...", "a_math_function", "last_updated") VALUES (1, '[[Infinit...
DETAIL:  Token "Infinity" is invalid.

注意：字段 a_math_function 是 JSONField() 类型

我试图运行python3 manage.py migrate，但出现此错误：

  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/django /db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: cannot cast type integer to uuid
LINE 1: ...BLE "core_post" ALTER COLUMN "id" TYPE uuid USING "id"::uuid

我正在使用PostgreSQL

我的models.py： 链接到pastebin

我希望你能帮助我）

谢谢！