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Preserve composite UNIQUE constraints in transforms

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Simon Willison 2026-08-12 18:46:18 -07:00
commit 75ba588462
5 changed files with 425 additions and 10 deletions
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119
sqlite_utils/db.py
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@ -32,10 +32,13 @@ from .create_table_parser import (
Check,
ColumnComments,
ParseError,
Unique,
UniqueColumn,
check_references_identifier,
parse_autoincrement,
parse_checks,
parse_column_comments,
parse_uniques,
rewrite_check_expression,
sql_ends_in_line_comment,
)
@ -104,6 +107,24 @@ def _check_constraint_sql(check: Check) -> str:
return f"{prefix}CHECK ({check.check}{newline})"
def _unique_constraint_sql(unique: Unique) -> str:
prefix = f"CONSTRAINT {quote_identifier(unique.name)} " if unique.name else ""
if unique.column:
constraint = "UNIQUE"
else:
columns = []
for column in unique.columns:
column_sql = quote_identifier(column.name)
if column.collation:
column_sql += f" COLLATE {quote_identifier(column.collation)}"
if column.order:
column_sql += f" {column.order}"
columns.append(column_sql)
constraint = "UNIQUE ({})".format(", ".join(columns))
conflict = f" ON CONFLICT {unique.conflict}" if unique.conflict else ""
return f"{prefix}{constraint}{conflict}"
def _column_definition_with_comments(
definition: str, comments: ColumnComments | None
) -> str:
@ -1424,6 +1445,7 @@ class Database:
_checks: Iterable[Check] | None = None,
_column_comments: Mapping[str, ColumnComments] | None = None,
_autoincrement: str | None = None,
_uniques: Iterable[Unique] | None = None,
) -> str:
"""
Returns the SQL ``CREATE TABLE`` statement for creating the specified table.
@ -1486,6 +1508,60 @@ class Database:
checks_by_column.setdefault(column, []).append(check)
else:
table_checks.append(check)
uniques_by_column: dict[str, list[Unique]] = {}
table_uniques: list[Unique] = []
for unique in _uniques or ():
resolved_unique = Unique(
tuple(
UniqueColumn(
resolve_casing(column.name, columns),
collation=column.collation,
order=column.order,
)
for column in unique.columns
),
name=unique.name,
column=(
resolve_casing(unique.column, columns) if unique.column else ""
),
conflict=unique.conflict,
)
missing = [
column.name
for column in resolved_unique.columns
if column.name not in columns
]
if missing:
raise AlterError(
"No such column for UNIQUE constraint: {}".format(
", ".join(missing)
)
)
if resolved_unique.column:
if (
len(resolved_unique.columns) != 1
or resolved_unique.columns[0].name != resolved_unique.column
):
raise AlterError("Invalid column-level UNIQUE constraint")
if any(
column.collation or column.order
for column in resolved_unique.columns
):
# Render this as a table constraint so the collation or sort
# order that governs uniqueness can be represented explicitly.
table_uniques.append(
Unique(
resolved_unique.columns,
name=resolved_unique.name,
conflict=resolved_unique.conflict,
)
)
else:
uniques_by_column.setdefault(resolved_unique.column, []).append(
resolved_unique
)
else:
table_uniques.append(resolved_unique)
if not columns:
raise ValueError("Tables must have at least one column")
if not all(n in columns for n in not_null):
@ -1554,6 +1630,10 @@ class Database:
column_extras.append(
f"REFERENCES {quote_identifier(fk.other_table)}({quote_identifier(cast(str, fk.other_column))}){_fk_actions_sql(fk)}"
)
column_extras.extend(
_unique_constraint_sql(unique)
for unique in uniques_by_column.get(column_name, ())
)
column_extras.extend(
_check_constraint_sql(check)
for check in checks_by_column.get(column_name, ())
@ -1600,6 +1680,9 @@ class Database:
actions=_fk_actions_sql(fk),
)
)
column_defs.extend(
f" {_unique_constraint_sql(unique)}" for unique in table_uniques
)
column_defs.extend(
f" {_check_constraint_sql(check)}" for check in table_checks
)
@ -2763,6 +2846,7 @@ class Table(Queryable):
existing_checks = self.checks
existing_column_comments = parse_column_comments(self.schema)
existing_autoincrement = parse_autoincrement(self.schema)
existing_uniques = parse_uniques(self.schema)
except ParseError as ex:
raise TransformError(
f"Could not parse table schema for table {self.name!r}: {ex}"
@ -2789,6 +2873,37 @@ class Table(Queryable):
)
)
create_table_uniques: list[Unique] = []
for unique in existing_uniques:
columns = tuple(
UniqueColumn(
resolve_casing(column.name, existing_columns),
collation=column.collation,
order=column.order,
)
for column in unique.columns
)
if any(column.name in drop for column in columns):
continue
owner = (
resolve_casing(unique.column, existing_columns) if unique.column else ""
)
create_table_uniques.append(
Unique(
tuple(
UniqueColumn(
rename.get(column.name) or column.name,
collation=column.collation,
order=column.order,
)
for column in columns
),
name=unique.name,
column=rename.get(owner) or owner,
conflict=unique.conflict,
)
)
create_table_column_comments: dict[str, ColumnComments] = {}
for column, comments in existing_column_comments.items():
owner = resolve_casing(column, existing_columns)
@ -2974,6 +3089,7 @@ class Table(Queryable):
_checks=create_table_checks,
_column_comments=create_table_column_comments,
_autoincrement=create_table_autoincrement,
_uniques=create_table_uniques,
).strip()
)
@ -3008,6 +3124,9 @@ class Table(Queryable):
{"index_name": index.name},
).fetchall()[0][0]
if index_sql is None:
if index.origin == "u":
# UNIQUE constraints are reproduced in CREATE TABLE above.
continue
raise TransformError(
f"Index '{index.name}' on table '{self.name}' does not have a "
"CREATE INDEX statement. You must manually drop this index prior to running this "