diff --git a/UPGRADING.md b/UPGRADING.md index c75c4fddb..95f87f7ee 100644 --- a/UPGRADING.md +++ b/UPGRADING.md @@ -13,8 +13,188 @@ limitations under the License. # 3.0.0 Migration Guide -TODO +## New Required Dependencies +Some of the previously optional dependencies are now *required* in `3.x` versions of the +library, namely +[google-cloud-bigquery-storage](https://pypi.org/project/google-cloud-bigquery-storage/) +(minimum version `2.0.0`) and [pyarrow](https://pypi.org/project/pyarrow/) (minimum +version `3.0.0`). + +The behavior of some of the package "extras" has thus also changed: + * The `pandas` extra now requires the [db-types](https://pypi.org/project/db-dtypes/) + package. + * The `bqstorage` extra has been preserved for comaptibility reasons, but it is now a + no-op and should be omitted when installing the BigQuery client library. + + **Before:** + ``` + $ pip install google-cloud-bigquery[bqstorage] + ``` + + **After:** + ``` + $ pip install google-cloud-bigquery + ``` + + * The `bignumeric_type` extra has been removed, as `BIGNUMERIC` type is now + automatically supported. That extra should thus not be used. + + **Before:** + ``` + $ pip install google-cloud-bigquery[bignumeric_type] + ``` + + **After:** + ``` + $ pip install google-cloud-bigquery + ``` + + +## Type Annotations + +The library is now type-annotated and declares itself as such. If you use a static +type checker such as `mypy`, you might start getting errors in places where +`google-cloud-bigquery` package is used. + +It is recommended to update your code and/or type annotations to fix these errors, but +if this is not feasible in the short term, you can temporarily ignore type annotations +in `google-cloud-bigquery`, for example by using a special `# type: ignore` comment: + +```py +from google.cloud import bigquery # type: ignore +``` + +But again, this is only recommended as a possible short-term workaround if immediately +fixing the type check errors in your project is not feasible. + +## Re-organized Types + +The auto-generated parts of the library has been removed, and proto-based types formerly +found in `google.cloud.bigquery_v2` have been replaced by the new implementation (but +see the [section](#legacy-types) below). + +For example, the standard SQL data types should new be imported from a new location: + +**Before:** +```py +from google.cloud.bigquery_v2 import StandardSqlDataType +from google.cloud.bigquery_v2.types import StandardSqlField +from google.cloud.bigquery_v2.types.standard_sql import StandardSqlStructType +``` + +**After:** +```py +from google.cloud.bigquery import StandardSqlDataType +from google.cloud.bigquery.standard_sql import StandardSqlField +from google.cloud.bigquery.standard_sql import StandardSqlStructType +``` + +The `TypeKind` enum defining all possible SQL types for schema fields has been renamed +and is not nested anymore under `StandardSqlDataType`: + + +**Before:** +```py +from google.cloud.bigquery_v2 import StandardSqlDataType + +if field_type == StandardSqlDataType.TypeKind.STRING: + ... +``` + +**After:** +```py + +from google.cloud.bigquery import StandardSqlTypeNames + +if field_type == StandardSqlTypeNames.STRING: + ... +``` + + +## Issuing queries with `Client.create_job` preserves destination table + +The `Client.create_job` method no longer removes the destination table from a +query job's configuration. Destination table for the query can thus be +explicitly defined by the user. + + +## Changes to data types when reading a pandas DataFrame + +The default dtypes returned by the `to_dataframe` method have changed. + +* Now, the BigQuery `BOOLEAN` data type maps to the pandas `boolean` dtype. + Previously, this mapped to the pandas `bool` dtype when the column did not + contain `NULL` values and the pandas `object` dtype when `NULL` values are + present. +* Now, the BigQuery `INT64` data type maps to the pandas `Int64` dtype. + Previously, this mapped to the pandas `int64` dtype when the column did not + contain `NULL` values and the pandas `float64` dtype when `NULL` values are + present. +* Now, the BigQuery `DATE` data type maps to the pandas `dbdate` dtype, which + is provided by the + [db-dtypes](https://googleapis.dev/python/db-dtypes/latest/index.html) + package. If any date value is outside of the range of + [pandas.Timestamp.min](https://pandas.pydata.org/docs/reference/api/pandas.Timestamp.min.html) + (1677-09-22) and + [pandas.Timestamp.max](https://pandas.pydata.org/docs/reference/api/pandas.Timestamp.max.html) + (2262-04-11), the data type maps to the pandas `object` dtype. The + `date_as_object` parameter has been removed. +* Now, the BigQuery `TIME` data type maps to the pandas `dbtime` dtype, which + is provided by the + [db-dtypes](https://googleapis.dev/python/db-dtypes/latest/index.html) + package. + + +## Changes to data types loading a pandas DataFrame + +In the absence of schema information, pandas columns with naive +`datetime64[ns]` values, i.e. without timezone information, are recognized and +loaded using the `DATETIME` type. On the other hand, for columns with +timezone-aware `datetime64[ns, UTC]` values, the `TIMESTAMP` type is continued +to be used. + +## Changes to `Model`, `Client.get_model`, `Client.update_model`, and `Client.list_models` + +The types of several `Model` properties have been changed. + +- `Model.feature_columns` now returns a sequence of `google.cloud.bigquery.standard_sql.StandardSqlField`. +- `Model.label_columns` now returns a sequence of `google.cloud.bigquery.standard_sql.StandardSqlField`. +- `Model.model_type` now returns a string. +- `Model.training_runs` now returns a sequence of dictionaries, as recieved from the [BigQuery REST API](https://cloud.google.com/bigquery/docs/reference/rest/v2/models#Model.FIELDS.training_runs). + + +## Legacy Protocol Buffers Types + +For compatibility reasons, the legacy proto-based types still exists as static code +and can be imported: + +```py +from google.cloud.bigquery_v2 import Model # a sublcass of proto.Message +``` + +Mind, however, that importing them will issue a warning, because aside from +being importable, these types **are not maintained anymore**. They may differ +both from the types in `google.cloud.bigquery`, and from the types supported on +the backend. + +### Maintaining compatibility with `google-cloud-bigquery` version 2.0 + +If you maintain a library or system that needs to support both +`google-cloud-bigquery` version 2.x and 3.x, it is recommended that you detect +when version 2.x is in use and convert properties that use the legacy protocol +buffer types, such as `Model.training_runs`, into the types used in 3.x. + +Call the [`to_dict` +method](https://proto-plus-python.readthedocs.io/en/latest/reference/message.html#proto.message.Message.to_dict) +on the protocol buffers objects to get a JSON-compatible dictionary. + +```py +from google.cloud.bigquery_v2 import Model + +training_run: Model.TrainingRun = ... +training_run_dict = training_run.to_dict() +``` # 2.0.0 Migration Guide diff --git a/docs/index.rst b/docs/index.rst index 3f8ba2304..4ab0a298d 100644 --- a/docs/index.rst +++ b/docs/index.rst @@ -30,7 +30,8 @@ API Reference Migration Guide --------------- -See the guide below for instructions on migrating to the 2.x release of this library. +See the guides below for instructions on migrating from older to newer *major* releases +of this library (from ``1.x`` to ``2.x``, or from ``2.x`` to ``3.x``). .. toctree:: :maxdepth: 2