atoti.Session.create_table()#
- Session.create_table(name, *, types, keys=frozenset({}), partitioning=None, default_values={}, **kwargs)#
Create an empty table with columns of the given types.
- Parameters:
name (str) – The name of the table.
types (Mapping[str, DataType]) – The table column names and their corresponding
data type
.keys (Set[str] | Sequence[str]) –
The columns that will become
keys
of the table.If a
Set
is given, the keys will be ordered as the table columns.partitioning (str | None) –
The description of how the data will be split across partitions of the table.
Default rules:
Only non-joined tables are automatically partitioned.
Tables are automatically partitioned by hashing their key columns. If there are no key columns, all the dictionarized columns are hashed.
Joined tables can only use a sub-partitioning of the table referencing them.
Automatic partitioning is done modulo the number of available cores.
Example
modulo4(country)
splits the data across 4 partitions based on the country column’s dictionarized value.default_values (Mapping[str, bool | date | datetime | float | int | Sequence[int] | Sequence[float] | str | time | None]) – Mapping from column name to column
default_value
.
- Return type:
Example
>>> from datetime import date >>> table = session.create_table( ... "Product", ... keys={"Date", "Product"}, ... types={"Date": tt.LOCAL_DATE, "Product": tt.STRING, "Quantity": tt.DOUBLE}, ... ) >>> table.head() Empty DataFrame Columns: [Quantity] Index: [] >>> table.append( ... (date(2021, 5, 19), "TV", 15.0), ... (date(2022, 8, 17), "Car", 2.0), ... ) >>> table.head() Quantity Date Product 2021-05-19 TV 15.0 2022-08-17 Car 2.0
Inserting a row with the same key values as an existing row replaces the latter:
>>> table += (date(2021, 5, 19), "TV", 8.0) >>> table.head() Quantity Date Product 2021-05-19 TV 8.0 2022-08-17 Car 2.0