def preview(self, tables: Optional[TableInfo]) -> PreviewResult:
# Preview data in tables mounted by this FDW / data source
# Local import here since this data source gets imported by the commandline entry point
from splitgraph.core.common import get_temporary_table_id
tmp_schema = get_temporary_table_id()
try:
# Seed the result with the tables that failed to mount
result = PreviewResult({
e.table_name: e
for e in self.mount(tmp_schema, tables=tables) or []
})
# Commit so that errors don't cancel the mount
self.engine.commit()
for t in self.engine.get_all_tables(tmp_schema):
if t in result:
continue
try:
result[t] = self._preview_table(tmp_schema, t)
except psycopg2.DatabaseError as e:
logging.warning("Could not preview data for table %s",
t,
exc_info=e)
result[t] = MountError(table_name=t,
error=get_exception_name(e),
error_text=str(e).strip())
return result
finally:
self.engine.rollback()
self.engine.delete_schema(tmp_schema)
self.engine.commit()
def introspect(self) -> IntrospectionResult:
# Ability to override introspection by e.g. contacting the remote database without having
# to mount the actual table. By default, just call out into mount()
# Local import here since this data source gets imported by the commandline entry point
from splitgraph.core.common import get_temporary_table_id
import jsonschema
tmp_schema = get_temporary_table_id()
try:
mount_errors = self.mount(tmp_schema) or []
table_options = dict(self._get_foreign_table_options(tmp_schema))
# Sanity check for adapters: validate the foreign table options that we get back
# to make sure they're still appropriate.
for v in table_options.values():
jsonschema.validate(v, self.table_params_schema)
result = IntrospectionResult({
t: (
self.engine.get_full_table_schema(tmp_schema, t),
cast(TableParams, table_options.get(t, {})),
)
for t in self.engine.get_all_tables(tmp_schema)
})
# Add errors to the result as well
for error in mount_errors:
result[error.table_name] = error
return result
finally:
self.engine.rollback()
self.engine.delete_schema(tmp_schema)
self.engine.commit()
def _create_staging_table(self) -> str:
staging_table = get_temporary_table_id()
logging.debug("Using staging table %s", staging_table)
self.repository.object_engine.create_table(
schema=SPLITGRAPH_META_SCHEMA,
table=staging_table,
schema_spec=self.table_schema,
unlogged=True,
)
return staging_table
def _load(self, schema: str, tables: Optional[TableInfo] = None):
from splitgraph.core.common import get_temporary_table_id
tmp_schema = get_temporary_table_id()
try:
self.mount(tmp_schema, tables=tables)
self.engine.commit()
for t in self.engine.get_all_tables(tmp_schema):
try:
self.engine.copy_table(tmp_schema, t, schema, t)
self.engine.commit()
except psycopg2.DatabaseError as e:
logging.warning("Error ingesting table %s", t, exc_info=e)
finally:
self.engine.rollback()
self.engine.delete_schema(tmp_schema)
self.engine.commit()