99 lines
2.9 KiB
Python
99 lines
2.9 KiB
Python
#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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# SQLAlchemy helper functions
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import sqlalchemy
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from sqlalchemy.orm import exc
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import tenacity
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def clone_table(name, parent, meta, newcols=None, ignorecols=None,
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swapcols=None, ignorecons=None):
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"""Helper function that clones parent table schema onto new table.
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:param name: new table name
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:param parent: parent table to copy schema from
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:param newcols: names of new columns to be added
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:param ignorecols: names of columns to be ignored while cloning
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:param swapcols: alternative column schema
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:param ignorecons: names of constraints to be ignored
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:return: sqlalchemy.Table instance
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"""
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newcols = newcols or []
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ignorecols = ignorecols or []
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swapcols = swapcols or {}
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ignorecons = ignorecons or []
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cols = [c.copy() for c in parent.columns
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if c.name not in ignorecols
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if c.name not in swapcols]
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cols.extend(swapcols.values())
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cols.extend(newcols)
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new_table = sqlalchemy.Table(name, meta, *(cols))
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def _is_ignorable(cons):
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# consider constraints on columns only
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if hasattr(cons, 'columns'):
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for col in ignorecols:
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if col in cons.columns:
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return True
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return False
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constraints = [c.copy() for c in parent.constraints
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if c.name not in ignorecons
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if not _is_ignorable(c)]
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for c in constraints:
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new_table.append_constraint(c)
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new_table.create()
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return new_table
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def migrate_data(migrate_engine,
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table,
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new_table,
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skip_columns=None):
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table_name = table.name
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list_of_rows = list(table.select().execute())
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colnames = [c.name for c in table.columns]
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for row in list_of_rows:
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values = dict(zip(colnames,
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map(lambda colname: getattr(row, colname),
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colnames)))
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if skip_columns is not None:
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for column in skip_columns:
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del values[column]
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migrate_engine.execute(new_table.insert(values))
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table.drop()
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new_table.rename(table_name)
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def retry_on_stale_data_error(func):
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wrapper = tenacity.retry(
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stop=tenacity.stop_after_attempt(3),
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retry=tenacity.retry_if_exception_type(exc.StaleDataError),
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reraise=True)
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return wrapper(func)
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