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infi.clickhouse_orm/docs/class_reference.md
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Class Reference

infi.clickhouse_orm.database

Database

Database instances connect to a specific ClickHouse database for running queries, inserting data and other operations.

Database(db_name, db_url="http://localhost:8123/", username=None, password=None, readonly=False, autocreate=True)

Initializes a database instance. Unless it's readonly, the database will be created on the ClickHouse server if it does not already exist.

  • db_name: name of the database to connect to.
  • db_url: URL of the ClickHouse server.
  • username: optional connection credentials.
  • password: optional connection credentials.
  • readonly: use a read-only connection.
  • autocreate: automatically create the database if does not exist (unless in readonly mode).

count(model_class, conditions=None)

Counts the number of records in the model's table.

  • model_class: the model to count.
  • conditions: optional SQL conditions (contents of the WHERE clause).

create_database()

Creates the database on the ClickHouse server if it does not already exist.

create_table(model_class)

Creates a table for the given model class, if it does not exist already.

drop_database()

Deletes the database on the ClickHouse server.

drop_table(model_class)

Drops the database table of the given model class, if it exists.

insert(model_instances, batch_size=1000)

Insert records into the database.

  • model_instances: any iterable containing instances of a single model class.
  • batch_size: number of records to send per chunk (use a lower number if your records are very large).

migrate(migrations_package_name, up_to=9999)

Executes schema migrations.

  • migrations_package_name - fully qualified name of the Python package containing the migrations.
  • up_to - number of the last migration to apply.

paginate(model_class, order_by, page_num=1, page_size=100, conditions=None, settings=None)

Selects records and returns a single page of model instances.

  • model_class: the model class matching the query's table, or None for getting back instances of an ad-hoc model.
  • order_by: columns to use for sorting the query (contents of the ORDER BY clause).
  • page_num: the page number (1-based), or -1 to get the last page.
  • page_size: number of records to return per page.
  • conditions: optional SQL conditions (contents of the WHERE clause).
  • settings: query settings to send as HTTP GET parameters

The result is a namedtuple containing objects (list), number_of_objects, pages_total, number (of the current page), and page_size.

raw(query, settings=None, stream=False)

Performs a query and returns its output as text.

  • query: the SQL query to execute.
  • settings: query settings to send as HTTP GET parameters
  • stream: if true, the HTTP response from ClickHouse will be streamed.

select(query, model_class=None, settings=None)

Performs a query and returns a generator of model instances.

  • query: the SQL query to execute.
  • model_class: the model class matching the query's table, or None for getting back instances of an ad-hoc model.
  • settings: query settings to send as HTTP GET parameters

DatabaseException

Extends Exception

Raised when a database operation fails.

infi.clickhouse_orm.models

Model

A base class for ORM models. Each model class represent a ClickHouse table. For example:

class CPUStats(Model):
    timestamp = DateTimeField()
    cpu_id = UInt16Field()
    cpu_percent = Float32Field()
    engine = Memory()

Model(**kwargs)

Creates a model instance, using keyword arguments as field values. Since values are immediately converted to their Pythonic type, invalid values will cause a ValueError to be raised. Unrecognized field names will cause an AttributeError.

Model.create_table_sql(db)

Returns the SQL command for creating a table for this model.

Model.drop_table_sql(db)

Returns the SQL command for deleting this model's table.

Model.fields(writable=False)

Returns an OrderedDict of the model's fields (from name to Field instance). If writable is true, only writable fields are included. Callers should not modify the dictionary.

Model.from_tsv(line, field_names=None, timezone_in_use=UTC, database=None)

Create a model instance from a tab-separated line. The line may or may not include a newline. The field_names list must match the fields defined in the model, but does not have to include all of them. If omitted, it is assumed to be the names of all fields in the model, in order of definition.

  • line: the TSV-formatted data.
  • field_names: names of the model fields in the data.
  • timezone_in_use: the timezone to use when parsing dates and datetimes.
  • database: if given, sets the database that this instance belongs to.

get_database()

Gets the Database that this model instance belongs to. Returns None unless the instance was read from the database or written to it.

get_field(name)

Gets a Field instance given its name, or None if not found.

Model.objects_in(database)

Returns a QuerySet for selecting instances of this model class.

set_database(db)

Sets the Database that this model instance belongs to. This is done automatically when the instance is read from the database or written to it.

Model.table_name()

Returns the model's database table name. By default this is the class name converted to lowercase. Override this if you want to use a different table name.

to_dict(include_readonly=True, field_names=None)

Returns the instance's column values as a dict.

  • include_readonly: if false, returns only fields that can be inserted into database.
  • field_names: an iterable of field names to return (optional)

to_tsv(include_readonly=True)

Returns the instance's column values as a tab-separated line. A newline is not included.

  • include_readonly: if false, returns only fields that can be inserted into database.

BufferModel

Extends Model

BufferModel(**kwargs)

Creates a model instance, using keyword arguments as field values. Since values are immediately converted to their Pythonic type, invalid values will cause a ValueError to be raised. Unrecognized field names will cause an AttributeError.

BufferModel.create_table_sql(db)

Returns the SQL command for creating a table for this model.

BufferModel.drop_table_sql(db)

Returns the SQL command for deleting this model's table.

BufferModel.fields(writable=False)

Returns an OrderedDict of the model's fields (from name to Field instance). If writable is true, only writable fields are included. Callers should not modify the dictionary.

BufferModel.from_tsv(line, field_names=None, timezone_in_use=UTC, database=None)

Create a model instance from a tab-separated line. The line may or may not include a newline. The field_names list must match the fields defined in the model, but does not have to include all of them. If omitted, it is assumed to be the names of all fields in the model, in order of definition.

  • line: the TSV-formatted data.
  • field_names: names of the model fields in the data.
  • timezone_in_use: the timezone to use when parsing dates and datetimes.
  • database: if given, sets the database that this instance belongs to.

get_database()

Gets the Database that this model instance belongs to. Returns None unless the instance was read from the database or written to it.

get_field(name)

Gets a Field instance given its name, or None if not found.

BufferModel.objects_in(database)

Returns a QuerySet for selecting instances of this model class.

set_database(db)

Sets the Database that this model instance belongs to. This is done automatically when the instance is read from the database or written to it.

BufferModel.table_name()

Returns the model's database table name. By default this is the class name converted to lowercase. Override this if you want to use a different table name.

to_dict(include_readonly=True, field_names=None)

Returns the instance's column values as a dict.

  • include_readonly: if false, returns only fields that can be inserted into database.
  • field_names: an iterable of field names to return (optional)

to_tsv(include_readonly=True)

Returns the instance's column values as a tab-separated line. A newline is not included.

  • include_readonly: if false, returns only fields that can be inserted into database.

DistributedModel

Extends Model

Model for Distributed engine

DistributedModel(**kwargs)

Creates a model instance, using keyword arguments as field values. Since values are immediately converted to their Pythonic type, invalid values will cause a ValueError to be raised. Unrecognized field names will cause an AttributeError.

DistributedModel.create_table_sql(db)

DistributedModel.drop_table_sql(db)

Returns the SQL command for deleting this model's table.

DistributedModel.fields(writable=False)

Returns an OrderedDict of the model's fields (from name to Field instance). If writable is true, only writable fields are included. Callers should not modify the dictionary.

DistributedModel.fix_engine_table()

Remember: Distributed table does not store any data, just provides distributed access to it.

So if we define a model with engine that has no defined table for data storage (see FooDistributed below), that table cannot be successfully created. This routine can automatically fix engine's storage table by finding the first non-distributed model among your model's superclasses.

class Foo(Model): ... id = UInt8Field(1) ... class FooDistributed(Foo, DistributedModel): ... engine = Distributed('my_cluster') ... FooDistributed.engine.table None FooDistributed.fix_engine() FooDistributed.engine.table <class 'main.Foo'>

However if you prefer more explicit way of doing things, you can always mention the Foo model twice without bothering with any fixes:

class FooDistributedVerbose(Foo, DistributedModel): ... engine = Distributed('my_cluster', Foo) FooDistributedVerbose.engine.table <class 'main.Foo'>

See tests.test_engines:DistributedTestCase for more examples

DistributedModel.from_tsv(line, field_names=None, timezone_in_use=UTC, database=None)

Create a model instance from a tab-separated line. The line may or may not include a newline. The field_names list must match the fields defined in the model, but does not have to include all of them. If omitted, it is assumed to be the names of all fields in the model, in order of definition.

  • line: the TSV-formatted data.
  • field_names: names of the model fields in the data.
  • timezone_in_use: the timezone to use when parsing dates and datetimes.
  • database: if given, sets the database that this instance belongs to.

get_database()

Gets the Database that this model instance belongs to. Returns None unless the instance was read from the database or written to it.

get_field(name)

Gets a Field instance given its name, or None if not found.

DistributedModel.objects_in(database)

Returns a QuerySet for selecting instances of this model class.

set_database(db)

DistributedModel.table_name()

Returns the model's database table name. By default this is the class name converted to lowercase. Override this if you want to use a different table name.

to_dict(include_readonly=True, field_names=None)

Returns the instance's column values as a dict.

  • include_readonly: if false, returns only fields that can be inserted into database.
  • field_names: an iterable of field names to return (optional)

to_tsv(include_readonly=True)

Returns the instance's column values as a tab-separated line. A newline is not included.

  • include_readonly: if false, returns only fields that can be inserted into database.

infi.clickhouse_orm.fields

Field

Abstract base class for all field types.

Field(default=None, alias=None, materialized=None, readonly=None)

StringField

Extends Field

StringField(default=None, alias=None, materialized=None, readonly=None)

DateField

Extends Field

DateField(default=None, alias=None, materialized=None, readonly=None)

DateTimeField

Extends Field

DateTimeField(default=None, alias=None, materialized=None, readonly=None)

BaseIntField

Extends Field

Abstract base class for all integer-type fields.

BaseIntField(default=None, alias=None, materialized=None, readonly=None)

BaseFloatField

Extends Field

Abstract base class for all float-type fields.

BaseFloatField(default=None, alias=None, materialized=None, readonly=None)

BaseEnumField

Extends Field

Abstract base class for all enum-type fields.

BaseEnumField(enum_cls, default=None, alias=None, materialized=None, readonly=None)

ArrayField

Extends Field

ArrayField(inner_field, default=None, alias=None, materialized=None, readonly=None)

NullableField

Extends Field

NullableField(inner_field, default=None, alias=None, materialized=None, extra_null_values=None)

FixedStringField

Extends StringField

FixedStringField(length, default=None, alias=None, materialized=None, readonly=None)

UInt8Field

Extends BaseIntField

UInt8Field(default=None, alias=None, materialized=None, readonly=None)

UInt16Field

Extends BaseIntField

UInt16Field(default=None, alias=None, materialized=None, readonly=None)

UInt32Field

Extends BaseIntField

UInt32Field(default=None, alias=None, materialized=None, readonly=None)

UInt64Field

Extends BaseIntField

UInt64Field(default=None, alias=None, materialized=None, readonly=None)

Int8Field

Extends BaseIntField

Int8Field(default=None, alias=None, materialized=None, readonly=None)

Int16Field

Extends BaseIntField

Int16Field(default=None, alias=None, materialized=None, readonly=None)

Int32Field

Extends BaseIntField

Int32Field(default=None, alias=None, materialized=None, readonly=None)

Int64Field

Extends BaseIntField

Int64Field(default=None, alias=None, materialized=None, readonly=None)

Float32Field

Extends BaseFloatField

Float32Field(default=None, alias=None, materialized=None, readonly=None)

Float64Field

Extends BaseFloatField

Float64Field(default=None, alias=None, materialized=None, readonly=None)

Enum8Field

Extends BaseEnumField

Enum8Field(enum_cls, default=None, alias=None, materialized=None, readonly=None)

Enum16Field

Extends BaseEnumField

Enum16Field(enum_cls, default=None, alias=None, materialized=None, readonly=None)

infi.clickhouse_orm.engines

Engine

TinyLog

Extends Engine

Log

Extends Engine

Memory

Extends Engine

MergeTree

Extends Engine

MergeTree(date_col=None, order_by=(), sampling_expr=None, index_granularity=8192, replica_table_path=None, replica_name=None, partition_key=None)

Buffer

Extends Engine

Buffers the data to write in RAM, periodically flushing it to another table. Must be used in conjuction with a BufferModel. Read more here.

Buffer(main_model, num_layers=16, min_time=10, max_time=100, min_rows=10000, max_rows=1000000, min_bytes=10000000, max_bytes=100000000)

Merge

Extends Engine

The Merge engine (not to be confused with MergeTree) does not store data itself, but allows reading from any number of other tables simultaneously. Writing to a table is not supported https://clickhouse.yandex/docs/en/single/index.html#document-table_engines/merge

Merge(table_regex)

Distributed

Extends Engine

The Distributed engine by itself does not store data, but allows distributed query processing on multiple servers. Reading is automatically parallelized. During a read, the table indexes on remote servers are used, if there are any.

See full documentation here https://clickhouse.yandex/docs/en/table_engines/distributed.html

Distributed(cluster, table=None, sharding_key=None)

:param cluster: what cluster to access data from :param table: underlying table that actually stores data. If you are not specifying any table here, ensure that it can be inferred from your model's superclass (see models.DistributedModel.fix_engine_table) :param sharding_key: how to distribute data among shards when inserting straightly into Distributed table, optional

CollapsingMergeTree

Extends MergeTree

CollapsingMergeTree(date_col=None, order_by=(), sign_col="sign", sampling_expr=None, index_granularity=8192, replica_table_path=None, replica_name=None, partition_key=None)

SummingMergeTree

Extends MergeTree

SummingMergeTree(date_col=None, order_by=(), summing_cols=None, sampling_expr=None, index_granularity=8192, replica_table_path=None, replica_name=None, partition_key=None)

ReplacingMergeTree

Extends MergeTree

ReplacingMergeTree(date_col=None, order_by=(), ver_col=None, sampling_expr=None, index_granularity=8192, replica_table_path=None, replica_name=None, partition_key=None)

infi.clickhouse_orm.query

QuerySet

A queryset is an object that represents a database query using a specific Model. It is lazy, meaning that it does not hit the database until you iterate over its matching rows (model instances).

QuerySet(model_cls, database)

Initializer. It is possible to create a queryset like this, but the standard way is to use MyModel.objects_in(database).

aggregate(*args, **kwargs)

Returns an AggregateQuerySet over this query, with args serving as grouping fields and kwargs serving as calculated fields. At least one calculated field is required. For example:

    Event.objects_in(database).filter(date__gt='2017-08-01').aggregate('event_type', count='count()')

is equivalent to:

    SELECT event_type, count() AS count FROM event
    WHERE data > '2017-08-01'
    GROUP BY event_type

as_sql()

Returns the whole query as a SQL string.

conditions_as_sql()

Returns the contents of the query's WHERE clause as a string.

count()

Returns the number of matching model instances.

distinct()

Adds a DISTINCT clause to the query, meaning that any duplicate rows in the results will be omitted.

exclude(**filter_fields)

Returns a copy of this queryset that excludes all rows matching the conditions.

filter(*q, **filter_fields)

Returns a copy of this queryset that includes only rows matching the conditions. Add q object to query if it specified.

only(*field_names)

Returns a copy of this queryset limited to the specified field names. Useful when there are large fields that are not needed, or for creating a subquery to use with an IN operator.

order_by(*field_names)

Returns a copy of this queryset with the ordering changed.

order_by_as_sql()

Returns the contents of the query's ORDER BY clause as a string.

paginate(page_num=1, page_size=100)

Returns a single page of model instances that match the queryset. Note that order_by should be used first, to ensure a correct partitioning of records into pages.

  • page_num: the page number (1-based), or -1 to get the last page.
  • page_size: number of records to return per page.

The result is a namedtuple containing objects (list), number_of_objects, pages_total, number (of the current page), and page_size.

AggregateQuerySet

Extends QuerySet

A queryset used for aggregation.

AggregateQuerySet(base_qs, grouping_fields, calculated_fields)

Initializer. Normally you should not call this but rather use QuerySet.aggregate().

The grouping fields should be a list/tuple of field names from the model. For example:

    ('event_type', 'event_subtype')

The calculated fields should be a mapping from name to a ClickHouse aggregation function. For example:

    {'weekday': 'toDayOfWeek(event_date)', 'number_of_events': 'count()'}

At least one calculated field is required.

aggregate(*args, **kwargs)

This method is not supported on AggregateQuerySet.

as_sql()

Returns the whole query as a SQL string.

conditions_as_sql()

Returns the contents of the query's WHERE clause as a string.

count()

Returns the number of rows after aggregation.

distinct()

Adds a DISTINCT clause to the query, meaning that any duplicate rows in the results will be omitted.

exclude(**filter_fields)

Returns a copy of this queryset that excludes all rows matching the conditions.

filter(*q, **filter_fields)

Returns a copy of this queryset that includes only rows matching the conditions. Add q object to query if it specified.

group_by(*args)

This method lets you specify the grouping fields explicitly. The args must be names of grouping fields or calculated fields that this queryset was created with.

only(*field_names)

This method is not supported on AggregateQuerySet.

order_by(*field_names)

Returns a copy of this queryset with the ordering changed.

order_by_as_sql()

Returns the contents of the query's ORDER BY clause as a string.

paginate(page_num=1, page_size=100)

Returns a single page of model instances that match the queryset. Note that order_by should be used first, to ensure a correct partitioning of records into pages.

  • page_num: the page number (1-based), or -1 to get the last page.
  • page_size: number of records to return per page.

The result is a namedtuple containing objects (list), number_of_objects, pages_total, number (of the current page), and page_size.