diff --git a/core/lib/Drupal/Core/Database/database.api.php b/core/lib/Drupal/Core/Database/database.api.php
index ab7041088737d5987ec804c6c416f19697aabce7..e4e5a0b9be08397da3a45a63b25e485344cb5d27 100644
--- a/core/lib/Drupal/Core/Database/database.api.php
+++ b/core/lib/Drupal/Core/Database/database.api.php
@@ -340,6 +340,9 @@
*
* A key column specifier is either a string naming a column or an array of two
* elements, column name and length, specifying a prefix of the named column.
+ * Note that some DBMS drivers may opt to ignore the prefix length configuration
+ * and still use the whole field value for the key. Code should therefore not
+ * rely on this functionality.
*
* As an example, this is the schema definition for the 'users_data' table. It
* shows five fields ('uid', 'module', 'name', 'value', and 'serialized'), the
diff --git a/core/modules/pgsql/src/Driver/Database/pgsql/Schema.php b/core/modules/pgsql/src/Driver/Database/pgsql/Schema.php
index 4843e076f08fd6b543a98f5527e157b8685ebd30..ed852c622ba0b20512d3a93bb6dcbffd93f0f110 100644
--- a/core/modules/pgsql/src/Driver/Database/pgsql/Schema.php
+++ b/core/modules/pgsql/src/Driver/Database/pgsql/Schema.php
@@ -286,7 +286,11 @@ protected function createTableSql($name, $table) {
}
if (isset($table['unique keys']) && is_array($table['unique keys'])) {
foreach ($table['unique keys'] as $key_name => $key) {
- $sql_keys[] = 'CONSTRAINT ' . $this->ensureIdentifiersLength($name, $key_name, 'key') . ' UNIQUE (' . implode(', ', $key) . ')';
+ // Use the createPrimaryKeySql(), which already discards any prefix
+ // lengths passed as part of the key column specifiers. (Postgres
+ // doesn't support setting a prefix length for PRIMARY or UNIQUE
+ // indices.)
+ $sql_keys[] = 'CONSTRAINT ' . $this->ensureIdentifiersLength($name, $key_name, 'key') . ' UNIQUE (' . $this->createPrimaryKeySql($key) . ')';
}
}
@@ -471,7 +475,7 @@ protected function _createKeySql($fields) {
}
/**
- * Create the SQL expression for primary keys.
+ * Create the SQL expression for primary and unique keys.
*
* Postgresql does not support key length. It does support fillfactor, but
* that requires a separate database lookup for each column in the key. The
@@ -794,8 +798,10 @@ public function addUniqueKey($table, $name, $fields) {
throw new SchemaObjectExistsException("Cannot add unique key '$name' to table '$table': unique key already exists.");
}
- $fields = array_map([$this->connection, 'escapeField'], $fields);
- $this->connection->query('ALTER TABLE {' . $table . '} ADD CONSTRAINT ' . $this->ensureIdentifiersLength($table, $name, 'key') . ' UNIQUE (' . implode(',', $fields) . ')');
+ // Use the createPrimaryKeySql(), which already discards any prefix lengths
+ // passed as part of the key column specifiers. (Postgres doesn't support
+ // setting a prefix length for PRIMARY or UNIQUE indices.)
+ $this->connection->query('ALTER TABLE {' . $table . '} ADD CONSTRAINT ' . $this->ensureIdentifiersLength($table, $name, 'key') . ' UNIQUE (' . $this->createPrimaryKeySql($fields) . ')');
$this->resetTableInformation($table);
}
diff --git a/core/tests/Drupal/KernelTests/Core/Database/SchemaUniquePrefixedKeysIndexTest.php b/core/tests/Drupal/KernelTests/Core/Database/SchemaUniquePrefixedKeysIndexTest.php
new file mode 100644
index 0000000000000000000000000000000000000000..b21543c13cd9cb3f8893696bea537a35f13d04a7
--- /dev/null
+++ b/core/tests/Drupal/KernelTests/Core/Database/SchemaUniquePrefixedKeysIndexTest.php
@@ -0,0 +1,135 @@
+<?php
+
+namespace Drupal\KernelTests\Core\Database;
+
+use Drupal\Core\Database\DatabaseException;
+
+/**
+ * Tests adding UNIQUE keys to tables.
+ *
+ * @coversDefaultClass \Drupal\Core\Database\Schema
+ *
+ * @group Database
+ */
+class SchemaUniquePrefixedKeysIndexTest extends DatabaseTestBase {
+
+ /**
+ * Tests UNIQUE keys put directly on the table definition.
+ *
+ * @covers ::createTable
+ */
+ public function testCreateTable(): void {
+ $this->connection->schema()->createTable('test_unique', [
+ 'fields' => [
+ 'field' => [
+ 'type' => 'varchar',
+ 'length' => 50,
+ ],
+ ],
+ 'unique keys' => [
+ 'field' => [['field', 10]],
+ ],
+ ]);
+
+ $this->checkUniqueConstraintException('test_unique', 'field');
+ }
+
+ /**
+ * Tests adding a UNIQUE key to an existing table.
+ *
+ * @covers ::addUniqueKey
+ */
+ public function testAddUniqueKey(): void {
+ $this->connection->schema()
+ ->addUniqueKey('test_people', 'job', [['job', 10]]);
+
+ $this->checkUniqueConstraintException('test_people', 'job');
+ }
+
+ /**
+ * Tests adding a new field with UNIQUE key.
+ *
+ * @covers ::addField
+ */
+ public function testAddField(): void {
+ $field_spec = [
+ 'type' => 'varchar',
+ 'length' => 50,
+ ];
+ $keys_spec = [
+ 'unique keys' => [
+ 'field' => [['field', 10]],
+ ],
+ ];
+ $this->connection->schema()
+ ->addField('test', 'field', $field_spec, $keys_spec);
+
+ $this->checkUniqueConstraintException('test', 'field');
+ }
+
+ /**
+ * Tests changing a field to add a UNIQUE key.
+ *
+ * @covers ::changeField
+ */
+ public function testChangeField(): void {
+ $field_spec = [
+ 'description' => "The person's job",
+ 'type' => 'varchar_ascii',
+ 'length' => 50,
+ 'not null' => TRUE,
+ 'default' => '',
+ ];
+ $keys_spec = [
+ 'unique keys' => [
+ 'job' => [['job', 10]],
+ ],
+ ];
+ $this->connection->schema()
+ ->changeField('test_people', 'job', 'job', $field_spec, $keys_spec);
+
+ $this->checkUniqueConstraintException('test_people', 'job');
+ }
+
+ /**
+ * Verifies that inserting the same value/prefix twice causes an exception.
+ *
+ * @param string $table
+ * The table to insert into.
+ * @param string $column
+ * The column on that table that has a UNIQUE index. If prefix lengths are
+ * accepted for UNIQUE keys on the current database, the prefix length for
+ * the field is expected to be set to 10 characters.
+ */
+ protected function checkUniqueConstraintException(string $table, string $column): void {
+ $this->connection->insert($table)
+ ->fields([
+ $column => '1234567890 foo',
+ ])
+ ->execute();
+
+ $this->expectException(DatabaseException::class);
+ $value = '1234567890 ' . ($this->supportsPrefixLength() ? 'bar' : 'foo');
+ $this->connection->insert($table)
+ ->fields([
+ $column => $value,
+ ])
+ ->execute();
+ }
+
+ /**
+ * Determines whether the current database supports prefix lengths for keys.
+ *
+ * The basic syntax of passing an array (field, prefix length) as a key column
+ * specifier must always be accepted by the driver. However, due to technical
+ * limitations, some drivers may choose to ignore them.
+ *
+ * @return bool
+ * TRUE if the current database (driver) will conform to the prefix length
+ * specified as part of a key column specifier, FALSE if it will be ignored.
+ */
+ protected function supportsPrefixLength(): bool {
+ return $this->connection->driver() === 'mysql';
+ }
+
+}