dosubot[bot] commented on issue #29915:
URL: https://github.com/apache/superset/issues/29915#issuecomment-2283422296
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To resolve the issue of a unique constraint on table names when importing an
example dataset in Superset, you can modify the uniqueness constraint to
include the `cluster_name` along with the `datasource_name`. This makes the
constraint relative to the database/source instead of globally on just the
table name.
Here is the relevant part of the migration script that addresses this:
```python
def upgrade():
bind = op.get_bind()
insp = sa.engine.reflection.Inspector.from_engine(bind)
# Add the new less restrictive uniqueness constraint.
with op.batch_alter_table("datasources", naming_convention=conv) as
batch_op:
batch_op.create_unique_constraint(
"uq_datasources_cluster_name", ["cluster_name",
"datasource_name"]
)
# Augment the tables which have a foreign key constraint related to the
# datasources.datasource_name column.
for foreign in ["columns", "metrics"]:
with op.batch_alter_table(foreign, naming_convention=conv) as
batch_op:
# Add the datasource_id column with the relevant constraints.
batch_op.add_column(sa.Column("datasource_id", sa.Integer))
batch_op.create_foreign_key(
f"fk_{foreign}_datasource_id_datasources",
"datasources",
["datasource_id"],
["id"],
)
# Helper table for database migration using minimal schema.
table = sa.Table(
foreign,
sa.MetaData(),
sa.Column("id", sa.Integer, primary_key=True),
sa.Column("datasource_name", sa.String(255)),
sa.Column("datasource_id", sa.Integer),
)
# Migrate the existing data.
for datasource in bind.execute(datasources.select()):
bind.execute(
table.update()
.where(table.c.datasource_name == datasource.datasource_name)
.values(datasource_id=datasource.id)
)
with op.batch_alter_table(foreign, naming_convention=conv) as
batch_op:
# Drop the datasource_name column and associated constraints.
names = generic_find_fk_constraint_names(
foreign, {"datasource_name"}, "datasources", insp
)
for name in names:
batch_op.drop_constraint(
name or f"fk_{foreign}_datasource_name_datasources",
type_="foreignkey",
)
batch_op.drop_column("datasource_name")
try:
# Drop the old more restrictive uniqueness constraint.
with op.batch_alter_table("datasources", naming_convention=conv) as
batch_op:
batch_op.drop_constraint(
generic_find_uq_constraint_name(
"datasources", {"datasource_name"}, insp
)
or "uq_datasources_datasource_name",
type_="unique",
)
except Exception as ex:
logging.warning(
"Constraint drop failed, you may want to do this "
"manually on your database. For context, this is a known "
"issue around nondeterministic constraint names on Postgres "
"and perhaps more databases through SQLAlchemy."
)
logging.exception(ex)
```
Additionally, when loading example datasets such as the "birth_names"
dataset, ensure that the table name is unique within the context of the
database. The `load_data` function in the `superset/examples/birth_names.py`
script handles the loading of data into the specified table name, ensuring it
is unique within the database schema:
```python
def load_data(tbl_name: str, database: Database, sample: bool = False) ->
None:
url = get_example_url("birth_names2.json.gz")
pdf = pd.read_json(url, compression="gzip")
if database.backend == "presto":
pdf.ds = pd.to_datetime(pdf.ds, unit="ms")
pdf.ds = pdf.ds.dt.strftime("%Y-%m-%d %H:%M:%S")
else:
pdf.ds = pd.to_datetime(pdf.ds, unit="ms")
pdf = pdf.head(100) if sample else pdf
with database.get_sqla_engine() as engine:
schema = inspect(engine).default_schema_name
pdf.to_sql(
tbl_name,
engine,
schema=schema,
if_exists="replace",
chunksize=500,
dtype={
"ds": DateTime if database.backend != "presto" else
String(255),
"gender": String(16),
"state": String(10),
"name": String(255),
},
method="multi",
index=False,
)
print("Done loading table!")
print("-" * 80)
```
This script ensures that the table name `tbl_name` is unique within the
specified database schema, thus avoiding conflicts with other tables
<sup>[[1]](https://github.com/apache/superset/blob/master/superset/migrations/versions/2017-10-03_14-37_4736ec66ce19_.py)</sup><sup>[[2]](https://github.com/apache/superset/blob/master/superset/migrations/versions/2015-09-21_17-30_4e6a06bad7a8_init.py)</sup><sup>[[3]](https://github.com/apache/superset/blob/master/superset/examples/birth_names.py)</sup>.
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