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38 lines
1.7 KiB
Markdown
38 lines
1.7 KiB
Markdown
# Databases
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Direct usage of `Database` objects is not expected in this library. But in some cases, you may still need them.
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This section describes `Database` objects and there usage.
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`django_clickhouse.database.Database` is a class, describing a ClickHouse database connection.
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## Getting database objects
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To get a `Database` object by its alias name in [CLICKHOUSE_DATABASES](configuration.md#clickhouse_databases)
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use `django_clickhouse.database.connections` object.
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This object is a `django_clickhouse.database.ConnectionProxy` instance:
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it creates `Database` objects when they are used for the first time and stores them in memory.
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Example:
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```python
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from django_clickhouse.database import connections
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# Database objects are inited on first call
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db = connections['default']
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secondary = connections['secondary']
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# Already inited - object is returned from memory
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db_link = connections['default']
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```
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You can also get database objects from [QuerySet](queries.md) and [ClickHouseModel](models.md) instances by calling `get_database(for_write: bool = False)` method.
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This database may differ, depending on [routing](routing.md#router) you use.
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## Database object
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Database class is based on [infi.clickhouse_orm Database object](https://github.com/Infinidat/infi.clickhouse_orm/blob/develop/docs/models_and_databases.md#models-and-databases),
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but extends it with some extra attributes and methods:
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### Database migrations are restricted
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I expect this library [migration system](migrations.md) to be used.
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Direct database migration will lead to migration information errors.
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### `insert_tuples` and `select_tuples` methods
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Methods to work with [ClickHouseModel namedtuples](models.md#clickhousemodel-namedtuple-form).
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