Unique indexes can be loaded in 3 different ways

[Tigrov]

Unique indexes can be loaded in 3 different ways:

• Schema::loadTableConstraints(): Constraint[] <- AbstractSchema::getTableUniques()
• Schema::loadTableIndexes(): IndexConstraint[] <- AbstractSchema::getTableIndexes() with check $index->isUnique()
• Schema::findUniqueIndexes(): array <- SchemaInterface::findUniqueIndexes()

PgSQL
https://github.com/yiisoft/db-pgsql/blob/535975396d865da6cb15ed7bee5648c27a9b7360/src/Schema.php#L894
https://github.com/yiisoft/db-pgsql/tree/535975396d865da6cb15ed7bee5648c27a9b7360/src/Schema.php#L357
https://github.com/yiisoft/db-pgsql/tree/535975396d865da6cb15ed7bee5648c27a9b7360/src/Schema.php#L630

MySQL
https://github.com/yiisoft/db-mysql/blob/4dd4e13502a0f047627c398854fc733a41054370/src/Schema.php#L618
https://github.com/yiisoft/db-mysql/blob/4dd4e13502a0f047627c398854fc733a41054370/src/Schema.php#L770
https://github.com/yiisoft/db-mysql/blob/4dd4e13502a0f047627c398854fc733a41054370/src/Schema.php#L158

Suggestion

• Load all unique indexes include primary key in getTableUniques()
• Mark as @deprecated SchemaInterface::findUniqueIndexes(): array use getTableUniques() instead
• Load all indexes loadTableIndexes() and unique indexes in one way
  • get uniques from getTableIndexes() with check $index->isUnique()
  • or load all indexes together with uniques as in SQLite Schema::loadTableConstraints() in one or more queries

[Tigrov]

Related with

db/src/QueryBuilder/AbstractDMLQueryBuilder.php

Lines 342 to 359 in 12b8927

	private function getTableUniqueColumnNames(string $name, array $columns, array &$constraints = []): array
	{
	$primaryKey = $this->schema->getTablePrimaryKey($name);
	if ($primaryKey !== null) {
	$constraints[] = $primaryKey;
	}
	/** @psalm-var IndexConstraint[] $tableIndexes */
	$tableIndexes = $this->schema->getTableIndexes($name);
	foreach ($tableIndexes as $constraint) {
	if ($constraint->isUnique()) {
	$constraints[] = $constraint;
	}
	}
	$constraints = array_merge($constraints, $this->schema->getTableUniques($name));