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Writing Tables

Use the :func:`pandas_gbq.to_gbq` function to write a :class:`pandas.DataFrame` object to a BigQuery table.

.. literalinclude:: ../samples/snippets/to_gbq_simple.py
   :language: python
   :dedent: 4
   :start-after: [START bigquery_pandas_gbq_to_gbq_simple]
   :end-before: [END bigquery_pandas_gbq_to_gbq_simple]

The destination table and destination dataset will automatically be created if they do not already exist.

Writing to an Existing Table

Use the if_exists argument to dictate whether to 'fail', 'replace' or 'append' if the destination table already exists. The default value is 'fail'.

For example, assume that if_exists is set to 'fail'. The following snippet will raise a TableCreationError if the destination table already exists.

import pandas_gbq
pandas_gbq.to_gbq(
    df, 'my_dataset.my_table', project_id=projectid, if_exists='fail',
)

If the if_exists argument is set to 'append', the destination dataframe will be written to the table using the defined table schema and column types. The dataframe must contain fields (matching name and type) currently in the destination table.

Inferring the Table Schema

The :func:`~pandas_gbq.to_gbq` method infers the BigQuery table schema based on the dtypes of the uploaded :class:`~pandas.DataFrame`.

dtype BigQuery Data Type
i (integer) INTEGER
b (boolean) BOOLEAN
f (float) FLOAT
O (object) STRING
S (zero-terminated bytes) STRING
U (Unicode string) STRING
M (datetime) TIMESTAMP

If the data type inference does not suit your needs, supply a BigQuery schema as the table_schema parameter of :func:`~pandas_gbq.to_gbq`.

Troubleshooting Errors

If an error occurs while writing data to BigQuery, see Troubleshooting BigQuery Errors.