Summary

Batch together operations for a SQLite table rebuild.

Review Request #11084 — Created July 16, 2020 and submitted July 17, 2020, 4:16 p.m.

Information

Owner

chipx86

Repository

Django Evolution

Branch

master

Bugs

Depends On

Reviewers

Groups

django-evolution

People

Description

A while back, Django Evolution introduced AlterTableSQLResult, which
worked with the mutation optimizer to reduce the number of ALTER TABLE
statements required for traditional databases when applying several
evolutions at once. That didn't work with SQLite, though, since SQLite
required a full table rebuild to make most changes.

This change enables these optimized operations through a new
SQLiteAlterTableSQLResult, which is a specialization of
AlterTableSQLResult that supports its own internal operations for
adding/deleting/renaming/changing columns, setting up state that's used
to construct the destination table when rebuilding.

That reduces the number of table rebuilds significantly, making it less
likely that something can go wrong and speeding up a chain of
evolutions.

Testing Done

Unit tests passed on all supported versions of Django, all databases,
and with SQLite 3.24.0 and 3.28.0 (which both handle table alterations
in subtly different ways).

Commits

Summary	ID
Batch together operations for a SQLite table rebuild. A while back, Django Evolution introduced `AlterTableSQLResult`, which worked with the mutation optimizer to reduce the number of `ALTER TABLE` statements required for traditional databases when applying several evolutions at once. That didn't work with SQLite, though, since SQLite required a full table rebuild to make most changes. This change enables these optimized operations through a new `SQLiteAlterTableSQLResult`, which is a specialization of `AlterTableSQLResult` that supports its own internal operations for adding/deleting/renaming/changing columns, setting up state that's used to construct the destination table when rebuilding. That reduces the number of table rebuilds significantly, making it less likely that something can go wrong and speeding up a chain of evolutions.	06d4f831015a3e766080d0c641bb1f372fd464fa

Summary

Batch together operations for a SQLite table rebuild.

A while back, Django Evolution introduced `AlterTableSQLResult`, which worked with the mutation optimizer to reduce the number of `ALTER TABLE` statements required for traditional databases when applying several evolutions at once. That didn't work with SQLite, though, since SQLite required a full table rebuild to make most changes. This change enables these optimized operations through a new `SQLiteAlterTableSQLResult`, which is a specialization of `AlterTableSQLResult` that supports its own internal operations for adding/deleting/renaming/changing columns, setting up state that's used to construct the destination table when rebuilding. That reduces the number of table rebuilds significantly, making it less likely that something can go wrong and speeding up a chain of evolutions.

06d4f831015a3e766080d0c641bb1f372fd464fa

Issues

Description	From	Last Updated
F401 'django_evolution.db.common.SQLResult' imported but unused	reviewbot	July 16, 2020, 11:51 p.m.
F841 local variable 'database_state' is assigned to but never used	reviewbot	July 16, 2020, 11:51 p.m.
F812 list comprehension redefines 'field' from line 87	reviewbot	July 16, 2020, 11:52 p.m.
F841 local variable 'create_indexes' is assigned to but never used	reviewbot	July 16, 2020, 11:53 p.m.

flake8 failed.

JSHint passed.

flake8

django_evolution/db/sqlite3.py (Diff revision 1)
The issue has been resolved. Show all issues
```
F401 'django_evolution.db.common.SQLResult' imported but unused
```
django_evolution/db/sqlite3.py (Diff revision 1)
The issue has been resolved. Show all issues
```
F841 local variable 'database_state' is assigned to but never used
```
django_evolution/db/sqlite3.py (Diff revision 1)
The issue has been resolved. Show all issues
```
F812 list comprehension redefines 'field' from line 87
```
django_evolution/db/sqlite3.py (Diff revision 1)
The issue has been resolved. Show all issues
```
F841 local variable 'create_indexes' is assigned to but never used
```

Change Summary:


Removed unused imports and variables.
Renamed some variables in a list comprehension to avoid a warning about reused variables.

Commits:

	Summary	ID
	Batch together operations for a SQLite table rebuild. A while back, Django Evolution introduced `AlterTableSQLResult`, which worked with the mutation optimizer to reduce the number of `ALTER TABLE` statements required for traditional databases when applying several evolutions at once. That didn't work with SQLite, though, since SQLite required a full table rebuild to make most changes. This change enables these optimized operations through a new `SQLiteAlterTableSQLResult`, which is a specialization of `AlterTableSQLResult` that supports its own internal operations for adding/deleting/renaming/changing columns, setting up state that's used to construct the destination table when rebuilding. That reduces the number of table rebuilds significantly, making it less likely that something can go wrong and speeding up a chain of evolutions.	e91775aa836ef7b321f548656b7870b66bbd167a
	Batch together operations for a SQLite table rebuild. A while back, Django Evolution introduced `AlterTableSQLResult`, which worked with the mutation optimizer to reduce the number of `ALTER TABLE` statements required for traditional databases when applying several evolutions at once. That didn't work with SQLite, though, since SQLite required a full table rebuild to make most changes. This change enables these optimized operations through a new `SQLiteAlterTableSQLResult`, which is a specialization of `AlterTableSQLResult` that supports its own internal operations for adding/deleting/renaming/changing columns, setting up state that's used to construct the destination table when rebuilding. That reduces the number of table rebuilds significantly, making it less likely that something can go wrong and speeding up a chain of evolutions.	06d4f831015a3e766080d0c641bb1f372fd464fa

Diff:

Revision 2 (+616 -830)

Show changes

	django_evolution/db/common.py
	django_evolution/db/sql_result.py
	django_evolution/db/sqlite3.py
	django_evolution/tests/db/sqlite3.py

Checks run (2 succeeded)

flake8 passed.

JSHint passed.

Ship it!

```
Ship It!
```

Status:: Completed
Change Summary:: Pushed to master (5288425)