Batch together operations for a SQLite table rebuild.

Review Request #11084 — Created July 16, 2020 and submitted

chipx86
Django Evolution
master
django-evolution

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.

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).

Summary
Batch together operations for a SQLite table rebuild.
Description From Last Updated

F401 'django_evolution.db.common.SQLResult' imported but unused

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F841 local variable 'database_state' is assigned to but never used

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F812 list comprehension redefines 'field' from line 87

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F841 local variable 'create_indexes' is assigned to but never used

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Checks run (1 failed, 1 succeeded)
flake8 failed.
JSHint passed.

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chipx86
david
  1. Ship It!
  2. 
      
chipx86
Review request changed

Status: Closed (submitted)

Change Summary:

Pushed to master (5288425)
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