Django officially supports the following databases:
\nThere are also a number of database backends provided by third parties.
\nDjango attempts to support as many features as possible on all database\nbackends. However, not all database backends are alike, and we’ve had to make\ndesign decisions on which features to support and which assumptions we can make\nsafely.
\nThis file describes some of the features that might be relevant to Django\nusage. It is not intended as a replacement for server-specific documentation or\nreference manuals.
\nPersistent connections avoid the overhead of reestablishing a connection to\nthe database in each HTTP request. They’re controlled by the\nCONN_MAX_AGE parameter which defines the maximum lifetime of a\nconnection. It can be set independently for each database.
The default value is 0, preserving the historical behavior of closing the\ndatabase connection at the end of each request. To enable persistent\nconnections, set CONN_MAX_AGE to a positive integer of seconds. For\nunlimited persistent connections, set it to None.
When using ASGI, persistent connections should be disabled. Instead, use your\ndatabase backend’s built-in connection pooling if available, or investigate a\nthird-party connection pooling option if required.
\nDjango opens a connection to the database when it first makes a database\nquery. It keeps this connection open and reuses it in subsequent requests.\nDjango closes the connection once it exceeds the maximum age defined by\nCONN_MAX_AGE or when it isn’t usable any longer.
In detail, Django automatically opens a connection to the database whenever it\nneeds one and doesn’t have one already — either because this is the first\nconnection, or because the previous connection was closed.
\nAt the beginning of each request, Django closes the connection if it has\nreached its maximum age. If your database terminates idle connections after\nsome time, you should set CONN_MAX_AGE to a lower value, so that\nDjango doesn’t attempt to use a connection that has been terminated by the\ndatabase server. (This problem may only affect very low traffic sites.)
At the end of each request, Django closes the connection if it has reached its\nmaximum age or if it is in an unrecoverable error state. If any database\nerrors have occurred while processing the requests, Django checks whether the\nconnection still works, and closes it if it doesn’t. Thus, database errors\naffect at most one request per each application’s worker thread; if the\nconnection becomes unusable, the next request gets a fresh connection.
\nSetting CONN_HEALTH_CHECKS to True can be used to improve the\nrobustness of connection reuse and prevent errors when a connection has been\nclosed by the database server which is now ready to accept and serve new\nconnections, e.g. after database server restart. The health check is performed\nonly once per request and only if the database is being accessed during the\nhandling of the request.
Since each thread maintains its own connection, your database must support at\nleast as many simultaneous connections as you have worker threads.
\nSometimes a database won’t be accessed by the majority of your views, for\nexample because it’s the database of an external system, or thanks to caching.\nIn such cases, you should set CONN_MAX_AGE to a low value or even\n0, because it doesn’t make sense to maintain a connection that’s unlikely\nto be reused. This will help keep the number of simultaneous connections to\nthis database small.
The development server creates a new thread for each request it handles,\nnegating the effect of persistent connections. Don’t enable them during\ndevelopment.
\nWhen Django establishes a connection to the database, it sets up appropriate\nparameters, depending on the backend being used. If you enable persistent\nconnections, this setup is no longer repeated every request. If you modify\nparameters such as the connection’s isolation level or time zone, you should\neither restore Django’s defaults at the end of each request, force an\nappropriate value at the beginning of each request, or disable persistent\nconnections.
\nIf a connection is created in a long-running process, outside of Django’s\nrequest-response cycle, the connection will remain open until explicitly\nclosed, or timeout occurs. You can use django.db.close_old_connections() to\nclose all old or unusable connections.
Django assumes that all databases use UTF-8 encoding. Using other encodings may\nresult in unexpected behavior such as „value too long” errors from your\ndatabase for data that is valid in Django. See the database specific notes\nbelow for information on how to set up your database correctly.
\nDjango supports PostgreSQL 14 and higher. psycopg 3.1.12+ or psycopg2\n2.9.9+ is required, though the latest psycopg 3.1.12+ is recommended.
\n\nSee HOST for details.
To connect using a service name from the connection service file and a\npassword from the password file, you must specify them in the\nOPTIONS part of your database configuration in DATABASES:
settings.pyDATABASES = {\n "default": {\n "ENGINE": "django.db.backends.postgresql",\n "OPTIONS": {\n "service": "my_service",\n "passfile": ".my_pgpass",\n },\n }\n}\n.pg_service.conf[my_service]\nhost=localhost\nuser=USER\ndbname=NAME\nport=5432\n.my_pgpasslocalhost:5432:NAME:USER:PASSWORD\nThe PostgreSQL backend passes the content of OPTIONS as keyword\narguments to the connection constructor, allowing for more advanced control\nof driver behavior. All available parameters are described in detail in the\nPostgreSQL documentation.
Django needs the following parameters for its database connections:
\nclient_encoding: 'UTF8',
default_transaction_isolation: 'read committed' by default,\nor the value set in the connection options (see below),
If these parameters already have the correct values, Django won’t set them for\nevery new connection, which improves performance slightly. You can configure\nthem directly in postgresql.conf or more conveniently per database\nuser with ALTER ROLE.
Django will work just fine without this optimization, but each new connection\nwill do some additional queries to set these parameters.
\nLike PostgreSQL itself, Django defaults to the READ COMMITTED isolation\nlevel. If you need a higher isolation level such as REPEATABLE READ or\nSERIALIZABLE, set it in the OPTIONS part of your database\nconfiguration in DATABASES:
from django.db.backends.postgresql.psycopg_any import IsolationLevel\n\nDATABASES = {\n # ...\n "OPTIONS": {\n "isolation_level": IsolationLevel.SERIALIZABLE,\n },\n}\nIf you need to use a different role for database connections than the role used\nto establish the connection, set it in the OPTIONS part of your\ndatabase configuration in DATABASES:
DATABASES = {\n "default": {\n "ENGINE": "django.db.backends.postgresql",\n # ...\n "OPTIONS": {\n "assume_role": "my_application_role",\n },\n },\n}\nTo use a connection pool with psycopg, you can either set "pool" in the\nOPTIONS part of your database configuration in DATABASES\nto be a dict to be passed to ConnectionPool, or\nto True to use the ConnectionPool defaults:
DATABASES = {\n "default": {\n "ENGINE": "django.db.backends.postgresql",\n # ...\n "OPTIONS": {\n "pool": True,\n },\n },\n}\nThis option requires psycopg[pool] or psycopg-pool to be installed\nand is ignored with psycopg2.
With psycopg 3.1.8+, Django defaults to the client-side binding\ncursors. If you want to use the\nserver-side binding set it in the\nOPTIONS part of your database configuration in\nDATABASES:
DATABASES = {\n "default": {\n "ENGINE": "django.db.backends.postgresql",\n # ...\n "OPTIONS": {\n "server_side_binding": True,\n },\n },\n}\nThis option is ignored with psycopg2.
varchar and text columnsLink to this heading#When specifying db_index=True on your model fields, Django typically\noutputs a single CREATE INDEX statement. However, if the database type\nfor the field is either varchar or text (e.g., used by CharField,\nFileField, and TextField), then Django will create\nan additional index that uses an appropriate PostgreSQL operator class\nfor the column. The extra index is necessary to correctly perform\nlookups that use the LIKE operator in their SQL, as is done with the\ncontains and startswith lookup types.
If you need to add a PostgreSQL extension (like hstore, postgis, etc.)\nusing a migration, use the\nCreateExtension operation.
When using QuerySet.iterator(), Django opens a server-side\ncursor. By default, PostgreSQL assumes that\nonly the first 10% of the results of cursor queries will be fetched. The query\nplanner spends less time planning the query and starts returning results\nfaster, but this could diminish performance if more than 10% of the results are\nretrieved. PostgreSQL’s assumptions on the number of rows retrieved for a\ncursor query is controlled with the cursor_tuple_fraction option.
Using a connection pooler in transaction pooling mode (e.g. PgBouncer)\nrequires disabling server-side cursors for that connection.
\nServer-side cursors are local to a connection and remain open at the end of a\ntransaction when AUTOCOMMIT is True. A\nsubsequent transaction may attempt to fetch more results from a server-side\ncursor. In transaction pooling mode, there’s no guarantee that subsequent\ntransactions will use the same connection. If a different connection is used,\nan error is raised when the transaction references the server-side cursor,\nbecause server-side cursors are only accessible in the connection in which they\nwere created.
One solution is to disable server-side cursors for a connection in\nDATABASES by setting DISABLE_SERVER_SIDE_CURSORS to True.
To benefit from server-side cursors in transaction pooling mode, you could set\nup another connection to the database in order to\nperform queries that use server-side cursors. This connection needs to either\nbe directly to the database or to a connection pooler in session pooling mode.
\nAnother option is to wrap each QuerySet using server-side cursors in an\natomic() block, because it disables autocommit\nfor the duration of the transaction. This way, the server-side cursor will only\nlive for the duration of the transaction.
Django uses PostgreSQL’s identity columns to store auto-incrementing primary\nkeys. An identity column is populated with values from a sequence that keeps\ntrack of the next available value. Manually assigning a value to an\nauto-incrementing field doesn’t update the field’s sequence, which might later\ncause a conflict. For example:
\n>>> from django.contrib.auth.models import User\n>>> User.objects.create(username="alice", pk=1)\n<User: alice>\n>>> # The sequence hasn't been updated; its next value is 1.\n>>> User.objects.create(username="bob")\nIntegrityError: duplicate key value violates unique constraint\n"auth_user_pkey" DETAIL: Key (id)=(1) already exists.\nIf you need to specify such values, reset the sequence afterward to avoid\nreusing a value that’s already in the table. The sqlsequencereset\nmanagement command generates the SQL statements to do that.
You can use the TEST['TEMPLATE'] setting to specify\na template (e.g. 'template0') from which to create a test database.
You can speed up test execution times by configuring PostgreSQL to be\nnon-durable.
\n\nDjango supports MariaDB 10.6 and higher.
\nTo use MariaDB, use the MySQL backend, which is shared between the two. See the\nMySQL notes for more details.
\nDjango supports MySQL 8.0.11 and higher.
\nDjango’s inspectdb feature uses the information_schema database, which\ncontains detailed data on all database schemas.
Django expects the database to support Unicode (UTF-8 encoding) and delegates\nto it the task of enforcing transactions and referential integrity. It is\nimportant to be aware of the fact that the two latter ones aren’t actually\nenforced by MySQL when using the MyISAM storage engine, see the next section.
\nMySQL has several storage engines. You can change the default storage engine\nin the server configuration.
\nMySQL’s default storage engine is InnoDB. This engine is fully transactional\nand supports foreign key references. It’s the recommended choice. However, the\nInnoDB autoincrement counter is lost on a MySQL restart because it does not\nremember the AUTO_INCREMENT value, instead recreating it as „max(id)+1”.\nThis may result in an inadvertent reuse of AutoField\nvalues.
The main drawbacks of MyISAM are that it doesn’t support transactions or\nenforce foreign-key constraints.
\nMySQL has a couple drivers that implement the Python Database API described in\nPEP 249:
\nmysqlclient is a native driver. It’s the recommended choice.
MySQL Connector/Python is a pure Python driver from Oracle that does not\nrequire the MySQL client library or any Python modules outside the standard\nlibrary.
In addition to a DB API driver, Django needs an adapter to access the database\ndrivers from its ORM. Django provides an adapter for mysqlclient while MySQL\nConnector/Python includes its own.
\nDjango requires mysqlclient 2.2.1 or later.
\nMySQL Connector/Python is available from the download page.\nThe Django adapter is available in versions 1.1.X and later. It may not\nsupport the most recent releases of Django.
\nIf you plan on using Django’s timezone support,\nuse mysql_tzinfo_to_sql to load time zone tables into the MySQL database.\nThis needs to be done just once for your MySQL server, not per database.
\nYou can create your database using the command-line tools and this SQL:
\nCREATE DATABASE <dbname> CHARACTER SET utf8mb4;\nThis ensures all tables and columns will use UTF-8 by default.
\nThe collation setting for a column controls the order in which data is sorted\nas well as what strings compare as equal. You can specify the db_collation\nparameter to set the collation name of the column for\nCharField and\nTextField.
The collation can also be set on a database-wide level and per-table. This is\ndocumented thoroughly in the MySQL documentation. In such cases, you must\nset the collation by directly manipulating the database settings or tables.\nDjango doesn’t provide an API to change them.
\nBy default, with a UTF-8 database, MySQL will use the\nutf8mb4_0900_ai_ci collation. This results in all string equality\ncomparisons being done in a case-insensitive manner. That is, "Fred" and\n"freD" are considered equal at the database level. If you have a unique\nconstraint on a field, it would be illegal to try to insert both "aa" and\n"AA" into the same column, since they compare as equal (and, hence,\nnon-unique) with the default collation. If you want case-sensitive comparisons\non a particular column or table, change the column or table to use the\nutf8mb4_0900_as_cs collation.
Please note that according to MySQL Unicode Character Sets, comparisons for\nthe utf8mb4_general_ci collation are faster, but slightly less correct,\nthan comparisons for utf8mb4_unicode_ci. If this is acceptable for your\napplication, you should use utf8mb4_general_ci because it is faster. If\nthis is not acceptable (for example, if you require German dictionary order),\nuse utf8mb4_unicode_ci because it is more accurate.
Refer to the settings documentation.
\nConnection settings are used in this order:
\n\nIn other words, if you set the name of the database in OPTIONS,\nthis will take precedence over NAME, which would override\nanything in a MySQL option file.
Here’s a sample configuration which uses a MySQL option file:
\n# settings.py\nDATABASES = {\n "default": {\n "ENGINE": "django.db.backends.mysql",\n "OPTIONS": {\n "read_default_file": "/path/to/my.cnf",\n },\n }\n}\n# my.cnf\n[client]\ndatabase = NAME\nuser = USER\npassword = PASSWORD\ndefault-character-set = utf8mb4\nSeveral other MySQLdb connection options may be useful, such as ssl,\ninit_command, and sql_mode.
sql_modeLink to this heading#The default value of the sql_mode option contains STRICT_TRANS_TABLES.\nThat option escalates warnings into errors when data are truncated upon\ninsertion, so Django highly recommends activating a strict mode for MySQL to\nprevent data loss (either STRICT_TRANS_TABLES or STRICT_ALL_TABLES).
If you need to customize the SQL mode, you can set the sql_mode variable\nlike other MySQL options: either in a config file or with the entry\n'init_command': "SET sql_mode='STRICT_TRANS_TABLES'" in the\nOPTIONS part of your database configuration in DATABASES.
When running concurrent loads, database transactions from different sessions\n(say, separate threads handling different requests) may interact with each\nother. These interactions are affected by each session’s transaction isolation\nlevel. You can set a connection’s isolation level with an\n'isolation_level' entry in the OPTIONS part of your database\nconfiguration in DATABASES. Valid values for\nthis entry are the four standard isolation levels:
'read uncommitted'
'read committed'
'repeatable read'
'serializable'
or None to use the server’s configured isolation level. However, Django\nworks best with and defaults to read committed rather than MySQL’s default,\nrepeatable read. Data loss is possible with repeatable read. In particular,\nyou may see cases where get_or_create()\nwill raise an IntegrityError but the object won’t appear in\na subsequent get() call.
When Django generates the schema, it doesn’t specify a storage engine, so\ntables will be created with whatever default storage engine your database\nserver is configured for. The easiest solution is to set your database server’s\ndefault storage engine to the desired engine.
\nIf you’re using a hosting service and can’t change your server’s default\nstorage engine, you have a couple of options.
\nAfter the tables are created, execute an ALTER TABLE statement to\nconvert a table to a new storage engine (such as InnoDB):
ALTER TABLE <tablename> ENGINE=INNODB;\nThis can be tedious if you have a lot of tables.
\nAnother option is to use the init_command option for MySQLdb prior to\ncreating your tables:
"OPTIONS": {\n "init_command": "SET default_storage_engine=INNODB",\n}\nThis sets the default storage engine upon connecting to the database.\nAfter your tables have been created, you should remove this option as it\nadds a query that is only needed during table creation to each database\nconnection.
\nThere are known issues in even the latest versions of MySQL that can cause\nthe case of a table name to be altered when certain SQL statements are executed\nunder certain conditions. It is recommended that you use lowercase table\nnames, if possible, to avoid any problems that might arise from this behavior.\nDjango uses lowercase table names when it auto-generates table names from\nmodels, so this is mainly a consideration if you are overriding the table name\nvia the db_table parameter.
Both the Django ORM and MySQL (when using the InnoDB storage engine) support database savepoints.
\nIf you use the MyISAM storage engine please be aware of the fact that you will\nreceive database-generated errors if you try to use the savepoint-related\nmethods of the transactions API. The\nreason for this is that detecting the storage engine of a MySQL database/table\nis an expensive operation so it was decided it isn’t worth to dynamically\nconvert these methods in no-op’s based in the results of such detection.
\nAny fields that are stored with VARCHAR column types may have their\nmax_length restricted to 255 characters if you are using unique=True\nfor the field. This affects CharField,\nSlugField. See the MySQL documentation for more\ndetails.
TextField limitationsLink to this heading#MySQL can index only the first N chars of a BLOB or TEXT column. Since\nTextField doesn’t have a defined length, you can’t mark it as\nunique=True. MySQL will report: „BLOB/TEXT column «<db_column>» used in key\nspecification without a key length”.
MySQL can store fractional seconds, provided that the column definition\nincludes a fractional indication (e.g. DATETIME(6)).
Django will not upgrade existing columns to include fractional seconds if the\ndatabase server supports it. If you want to enable them on an existing\ndatabase, it’s up to you to either manually update the column on the target\ndatabase, by executing a command like:
\nALTER TABLE `your_table` MODIFY `your_datetime_column` DATETIME(6)\nor using a RunSQL operation in a\ndata migration.
TIMESTAMP columnsLink to this heading#If you are using a legacy database that contains TIMESTAMP columns, you\nmust set USE_TZ = False to avoid data corruption.\ninspectdb maps these columns to\nDateTimeField and if you enable timezone support,\nboth MySQL and Django will attempt to convert the values from UTC to local\ntime.
QuerySet.select_for_update()Link to this heading#MySQL and MariaDB do not support some options to the SELECT ... FOR UPDATE\nstatement. If select_for_update() is used with an unsupported option, then\na NotSupportedError is raised.
Option | \nMariaDB | \nMySQL | \n
|---|---|---|
| \nX | \nX | \n
| \nX | \nX | \n
| \n\n | X | \n
| \n\n | \n |
When using select_for_update() on MySQL, make sure you filter a queryset\nagainst at least a set of fields contained in unique constraints or only\nagainst fields covered by indexes. Otherwise, an exclusive write lock will be\nacquired over the full table for the duration of the transaction.
When performing a query on a string type, but with an integer value, MySQL will\ncoerce the types of all values in the table to an integer before performing the\ncomparison. If your table contains the values 'abc', 'def' and you\nquery for WHERE mycolumn=0, both rows will match. Similarly, WHERE\nmycolumn=1 will match the value 'abc1'. Therefore, string type fields\nincluded in Django will always cast the value to a string before using it in a\nquery.
If you implement custom model fields that inherit from\nField directly, are overriding\nget_prep_value(), or use\nRawSQL,\nextra(), or\nraw(), you should ensure that you perform\nappropriate typecasting.
Django supports SQLite 3.31.0 and later.
\nSQLite provides an excellent development alternative for applications that\nare predominantly read-only or require a smaller installation footprint. As\nwith all database servers, though, there are some differences that are\nspecific to SQLite that you should be aware of.
\nFor all SQLite versions, there is some slightly counterintuitive behavior when\nattempting to match some types of strings. These are triggered when using the\niexact or contains filters in querysets. The behavior\nsplits into two cases:
1. For substring matching, all matches are done case-insensitively. That is a\nfilter such as filter(name__contains="aa") will match a name of "Aabb".
2. For strings containing characters outside the ASCII range, all exact string\nmatches are performed case-sensitively, even when the case-insensitive options\nare passed into the query. So the iexact filter will behave exactly\nthe same as the exact filter in these cases.
Some possible workarounds for this are documented at sqlite.org, but they\naren’t utilized by the default SQLite backend in Django, as incorporating them\nwould be fairly difficult to do robustly. Thus, Django exposes the default\nSQLite behavior and you should be aware of this when doing case-insensitive or\nsubstring filtering.
\nSQLite has no real decimal internal type. Decimal values are internally\nconverted to the REAL data type (8-byte IEEE floating point number), as\nexplained in the SQLite datatypes documentation, so they don’t support\ncorrectly-rounded decimal floating point arithmetic.
SQLite is meant to be a lightweight database, and thus can’t support a high\nlevel of concurrency. OperationalError: database is locked errors indicate\nthat your application is experiencing more concurrency than sqlite can\nhandle in default configuration. This error means that one thread or process\nhas an exclusive lock on the database connection and another thread timed out\nwaiting for the lock the be released.
Python’s SQLite wrapper has a default timeout value that determines how long\nthe second thread is allowed to wait on the lock before it times out and raises\nthe OperationalError: database is locked error.
If you’re getting this error, you can solve it by:
\nSwitching to another database backend. At a certain point SQLite becomes\ntoo „lite” for real-world applications, and these sorts of concurrency\nerrors indicate you’ve reached that point.
Rewriting your code to reduce concurrency and ensure that database\ntransactions are short-lived.
Increase the default timeout value by setting the timeout database\noption:
"OPTIONS": {\n # ...\n "timeout": 20,\n # ...\n}\nThis will make SQLite wait a bit longer before throwing „database is locked”\nerrors; it won’t really do anything to solve them.
\nSQLite supports three transaction modes: DEFERRED, IMMEDIATE, and\nEXCLUSIVE.
The default is DEFERRED. If you need to use a different mode, set it in the\nOPTIONS part of your database configuration in\nDATABASES, for example:
"OPTIONS": {\n # ...\n "transaction_mode": "IMMEDIATE",\n # ...\n}\nTo make sure your transactions wait until timeout before raising „Database\nis Locked”, change the transaction mode to IMMEDIATE.
For the best performance with IMMEDIATE and EXCLUSIVE, transactions\nshould be as short as possible. This might be hard to guarantee for all of your\nviews so the usage of ATOMIC_REQUESTS is\ndiscouraged in this case.
For more information see Transactions in SQLite.
\nQuerySet.select_for_update() not supportedLink to this heading#SQLite does not support the SELECT ... FOR UPDATE syntax. Calling it will\nhave no effect.
QuerySet.iterator()Link to this heading#There are special considerations described in Isolation In SQLite when\nmodifying a table while iterating over it using QuerySet.iterator(). If\na row is added, changed, or deleted within the loop, then that row may or may\nnot appear, or may appear twice, in subsequent results fetched from the\niterator. Your code must handle this.
To use JSONField on SQLite, you need to enable the\nJSON1 extension on Python’s sqlite3 library. If the extension is\nnot enabled on your installation, a system error (fields.E180) will be\nraised.
To enable the JSON1 extension you can follow the instruction on\nthe wiki page.
\n\nPragma options can be set upon connection by using the init_command in\nthe OPTIONS part of your database configuration in\nDATABASES. The example below shows how to enable extra durability of\nsynchronous writes and change the cache_size:
DATABASES = {\n "default": {\n "ENGINE": "django.db.backends.sqlite3",\n # ...\n "OPTIONS": {\n "init_command": "PRAGMA synchronous=3; PRAGMA cache_size=2000;",\n },\n }\n}\nDjango supports Oracle Database Server versions 19c and higher. Version\n2.3.0 or higher of the oracledb Python driver is required.
\nIn order for the python manage.py migrate command to work, your Oracle\ndatabase user must have privileges to run the following commands:
CREATE TABLE
CREATE SEQUENCE
CREATE PROCEDURE
CREATE TRIGGER
To run a project’s test suite, the user usually needs these additional\nprivileges:
\nCREATE USER
ALTER USER
DROP USER
CREATE TABLESPACE
DROP TABLESPACE
CREATE SESSION WITH ADMIN OPTION
CREATE TABLE WITH ADMIN OPTION
CREATE SEQUENCE WITH ADMIN OPTION
CREATE PROCEDURE WITH ADMIN OPTION
CREATE TRIGGER WITH ADMIN OPTION
While the RESOURCE role has the required CREATE TABLE,\nCREATE SEQUENCE, CREATE PROCEDURE, and CREATE TRIGGER privileges,\nand a user granted RESOURCE WITH ADMIN OPTION can grant RESOURCE, such\na user cannot grant the individual privileges (e.g. CREATE TABLE), and thus\nRESOURCE WITH ADMIN OPTION is not usually sufficient for running tests.
Some test suites also create views or materialized views; to run these, the\nuser also needs CREATE VIEW WITH ADMIN OPTION and\nCREATE MATERIALIZED VIEW WITH ADMIN OPTION privileges. In particular, this\nis needed for Django’s own test suite.
All of these privileges are included in the DBA role, which is appropriate\nfor use on a private developer’s database.
\nThe Oracle database backend uses the SYS.DBMS_LOB and SYS.DBMS_RANDOM\npackages, so your user will require execute permissions on it. It’s normally\naccessible to all users by default, but in case it is not, you’ll need to grant\npermissions like so:
GRANT EXECUTE ON SYS.DBMS_LOB TO user;\nGRANT EXECUTE ON SYS.DBMS_RANDOM TO user;\nTo connect using the service name of your Oracle database, your settings.py\nfile should look something like this:
DATABASES = {\n "default": {\n "ENGINE": "django.db.backends.oracle",\n "NAME": "xe",\n "USER": "a_user",\n "PASSWORD": "a_password",\n "HOST": "",\n "PORT": "",\n }\n}\nIn this case, you should leave both HOST and PORT empty.\nHowever, if you don’t use a tnsnames.ora file or a similar naming method\nand want to connect using the SID („xe” in this example), then fill in both\nHOST and PORT like so:
DATABASES = {\n "default": {\n "ENGINE": "django.db.backends.oracle",\n "NAME": "xe",\n "USER": "a_user",\n "PASSWORD": "a_password",\n "HOST": "dbprod01ned.mycompany.com",\n "PORT": "1540",\n }\n}\nYou should either supply both HOST and PORT, or leave\nboth as empty strings. Django will use a different connect descriptor depending\non that choice.
A Full DSN or Easy Connect string can be used in NAME if both\nHOST and PORT are empty. This format is required when\nusing RAC or pluggable databases without tnsnames.ora, for example.
Example of an Easy Connect string:
\n"NAME": "localhost:1521/orclpdb1"\nExample of a full DSN string:
\n"NAME": (\n "(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521))"\n "(CONNECT_DATA=(SERVICE_NAME=orclpdb1)))"\n)\nTo use a connection pool with oracledb, set "pool" to True in the\nOPTIONS part of your database configuration. This uses the driver’s\ncreate_pool() default values:
DATABASES = {\n "default": {\n "ENGINE": "django.db.backends.oracle",\n # ...\n "OPTIONS": {\n "pool": True,\n },\n },\n}\nTo pass custom parameters to the driver’s create_pool() function, you can\nalternatively set "pool" to be a dict:
DATABASES = {\n "default": {\n "ENGINE": "django.db.backends.oracle",\n # ...\n "OPTIONS": {\n "pool": {\n "min": 1,\n "max": 10,\n # ...\n }\n },\n },\n}\nBy default, the Oracle backend uses a RETURNING INTO clause to efficiently\nretrieve the value of an AutoField when inserting new rows. This behavior\nmay result in a DatabaseError in certain unusual setups, such as when\ninserting into a remote table, or into a view with an INSTEAD OF trigger.\nThe RETURNING INTO clause can be disabled by setting the\nuse_returning_into option of the database configuration to False:
"OPTIONS": {\n "use_returning_into": False,\n}\nIn this case, the Oracle backend will use a separate SELECT query to\nretrieve AutoField values.
Oracle imposes a name length limit of 30 characters. To accommodate this, the\nbackend truncates database identifiers to fit, replacing the final four\ncharacters of the truncated name with a repeatable MD5 hash value.\nAdditionally, the backend turns database identifiers to all-uppercase.
\nTo prevent these transformations (this is usually required only when dealing\nwith legacy databases or accessing tables which belong to other users), use\na quoted name as the value for db_table:
class LegacyModel(models.Model):\n class Meta:\n db_table = '"name_left_in_lowercase"'\n\n\nclass ForeignModel(models.Model):\n class Meta:\n db_table = '"OTHER_USER"."NAME_ONLY_SEEMS_OVER_30"'\nQuoted names can also be used with Django’s other supported database\nbackends; except for Oracle, however, the quotes have no effect.
\nWhen running migrate, an ORA-06552 error may be encountered if\ncertain Oracle keywords are used as the name of a model field or the\nvalue of a db_column option. Django quotes all identifiers used\nin queries to prevent most such problems, but this error can still\noccur when an Oracle datatype is used as a column name. In\nparticular, take care to avoid using the names date,\ntimestamp, number or float as a field name.
Django generally prefers to use the empty string ('') rather than\nNULL, but Oracle treats both identically. To get around this, the\nOracle backend ignores an explicit null option on fields that\nhave the empty string as a possible value and generates DDL as if\nnull=True. When fetching from the database, it is assumed that\na NULL value in one of these fields really means the empty\nstring, and the data is silently converted to reflect this assumption.
TextField limitationsLink to this heading#The Oracle backend stores each TextField as an NCLOB column. Oracle\nimposes some limitations on the usage of such LOB columns in general:
LOB columns may not be used as primary keys.
LOB columns may not be used in indexes.
LOB columns may not be used in a SELECT DISTINCT list. This means that\nattempting to use the QuerySet.distinct method on a model that\nincludes TextField columns will result in an ORA-00932 error when\nrun against Oracle. As a workaround, use the QuerySet.defer method in\nconjunction with distinct() to prevent TextField columns from being\nincluded in the SELECT DISTINCT list.
Django comes with built-in database backends. You may subclass an existing\ndatabase backend to modify its behavior, features, or configuration.
\nConsider, for example, that you need to change a single database feature.\nFirst, you have to create a new directory with a base module in it. For\nexample:
mysite/\n ...\n mydbengine/\n __init__.py\n base.py\nThe base.py module must contain a class named DatabaseWrapper that\nsubclasses an existing engine from the django.db.backends module. Here’s an\nexample of subclassing the PostgreSQL engine to change a feature class\nallows_group_by_selected_pks_on_model:
mysite/mydbengine/base.pyfrom django.db.backends.postgresql import base, features\n\n\nclass DatabaseFeatures(features.DatabaseFeatures):\n def allows_group_by_selected_pks_on_model(self, model):\n return True\n\n\nclass DatabaseWrapper(base.DatabaseWrapper):\n features_class = DatabaseFeatures\nFinally, you must specify a DATABASE-ENGINE in your settings.py\nfile:
DATABASES = {\n "default": {\n "ENGINE": "mydbengine",\n # ...\n },\n}\nYou can see the current list of database engines by looking in\ndjango/db/backends.
\nIn addition to the officially supported databases, there are backends provided\nby 3rd parties that allow you to use other databases with Django:
\nThe Django versions and ORM features supported by these unofficial backends\nvary considerably. Queries regarding the specific capabilities of these\nunofficial backends, along with any support queries, should be directed to\nthe support channels provided by each 3rd party project.
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