Added support of functional indexes for MySQL and Postgres

src/Driver/AbstractMySQLDriver.php

@@ -12,6 +12,7 @@
 use Doctrine\DBAL\Platforms\MariaDB1052Platform;
 use Doctrine\DBAL\Platforms\MariaDB1060Platform;
 use Doctrine\DBAL\Platforms\MariaDBPlatform;
+use Doctrine\DBAL\Platforms\MySQL8013Platform;
 use Doctrine\DBAL\Platforms\MySQL80Platform;
 use Doctrine\DBAL\Platforms\MySQLPlatform;
 use Doctrine\DBAL\ServerVersionProvider;
@@ -46,7 +47,14 @@ public function getDatabasePlatform(ServerVersionProvider $versionProvider): Abs
             return new MariaDBPlatform();
         }
 
-        if (version_compare($version, '8.0.0', '>=')) {
+        if (version_compare($version, '8.0.13', '>=')) {
+            return new MySQL8013Platform();
+        }
+
+        if (
+            version_compare($version, '8.0.0', '>=')
+            && version_compare($version, '8.0.13', '<')
+        ) {
             return new MySQL80Platform();
         }
 

src/Platforms/AbstractMySQLPlatform.php

@@ -43,6 +43,11 @@ abstract class AbstractMySQLPlatform extends AbstractPlatform
     final public const LENGTH_LIMIT_BLOB       = 65535;
     final public const LENGTH_LIMIT_MEDIUMBLOB = 16777215;
 
+    public function getColumnNameForIndexFetch(): string
+    {
+        return 'COLUMN_NAME';
+    }
+
     protected function doModifyLimitQuery(string $query, ?int $limit, int $offset): string
     {
         if ($limit !== null) {

src/Platforms/AbstractPlatform.php

@@ -55,8 +55,10 @@
 use function str_contains;
 use function str_replace;
 use function strlen;
+use function strrpos;
 use function strtolower;
 use function strtoupper;
+use function substr;
 
 /**
  * Base class for all DatabasePlatforms. The DatabasePlatforms are the central
@@ -794,6 +796,16 @@ private function buildCreateTableSQL(Table $table, bool $createForeignKeys): arr
         $options['primary']           = [];
 
         foreach ($table->getIndexes() as $index) {
+            if ($index->isFunctional() && ! $this->supportsFunctionalIndex()) {
+                throw new InvalidArgumentException(sprintf(
+                    'Index "%s" on table "%s" contains a functional part, ' .
+                    'but platform "%s" does not support functional indexes.',
+                    $index->getName(),
+                    $table->getName(),
+                    substr(static::class, (int) strrpos(static::class, '\\') + 1),
+                ));
+            }
+
             if (! $index->isPrimary()) {
                 $options['indexes'][$index->getQuotedName($this)] = $index;
 
@@ -1082,6 +1094,16 @@ public function getCreateIndexSQL(Index $index, string $table): string
             ));
         }
 
+        if ($index->isFunctional() && ! $this->supportsFunctionalIndex()) {
+            throw new InvalidArgumentException(sprintf(
+                'Index "%s" on table "%s" contains a functional part, ' .
+                'but platform "%s" does not support functional indexes.',
+                $name,
+                $table,
+                substr(static::class, (int) strrpos(static::class, '\\') + 1),
+            ));
+        }
+
         if ($index->isPrimary()) {
             return $this->getCreatePrimaryKeySQL($index, $table);
         }
@@ -1534,6 +1556,15 @@ public function getIndexDeclarationSQL(Index $index): string
             throw new InvalidArgumentException('Incomplete definition. "columns" required.');
         }
 
+        if ($index->isFunctional() && ! $this->supportsFunctionalIndex()) {
+            throw new InvalidArgumentException(sprintf(
+                'Index "%s" contains a functional part, ' .
+                'but platform "%s" does not support functional indexes.',
+                $index->getName(),
+                substr(static::class, (int) strrpos(static::class, '\\') + 1),
+            ));
+        }
+
         return $this->getCreateIndexSQLFlags($index) . 'INDEX ' . $index->getQuotedName($this)
             . ' (' . implode(', ', $index->getQuotedColumns($this)) . ')' . $this->getPartialIndexSQL($index);
     }
@@ -1974,6 +2005,14 @@ public function supportsColumnCollation(): bool
         return false;
     }
 
+    /**
+     * A flag that indicates whether the platform supports functional indexes.
+     */
+    public function supportsFunctionalIndex(): bool
+    {
+        return false;
+    }
+
     /**
      * Gets the format string, as accepted by the date() function, that describes
      * the format of a stored datetime value of this platform.

src/Platforms/MySQL8013Platform.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\DBAL\Platforms;
+
+/**
+ * Provides features of the MySQL since 8.0.13 database platform.
+ *
+ * Note: Should not be used with versions prior to 8.0.13.
+ */
+class MySQL8013Platform extends MySQL80Platform
+{
+    public function getColumnNameForIndexFetch(): string
+    {
+        return "COALESCE(COLUMN_NAME, CONCAT('(', REPLACE(EXPRESSION, '\\\''', ''''), ')'))";
+    }
+
+    public function supportsFunctionalIndex(): bool
+    {
+        return true;
+    }
+}

src/Platforms/PostgreSQLPlatform.php

@@ -781,4 +781,9 @@ public function createSchemaManager(Connection $connection): PostgreSQLSchemaMan
     {
         return new PostgreSQLSchemaManager($connection, $this);
     }
+
+    public function supportsFunctionalIndex(): bool
+    {
+        return true;
+    }
 }

src/Platforms/SQLitePlatform.php

@@ -35,6 +35,7 @@
 use function sprintf;
 use function str_replace;
 use function strpos;
+use function strrpos;
 use function strtolower;
 use function substr;
 use function trim;
@@ -561,6 +562,16 @@ public function getCreateIndexSQL(Index $index, string $table): string
             ));
         }
 
+        if ($index->isFunctional() && ! $this->supportsFunctionalIndex()) {
+            throw new InvalidArgumentException(sprintf(
+                'Index "%s" on table "%s" contains a functional part, ' .
+                'but platform "%s" does not support functional indexes.',
+                $name,
+                $table,
+                substr(static::class, (int) strrpos(static::class, '\\') + 1),
+            ));
+        }
+
         if ($index->isPrimary()) {
             return $this->getCreatePrimaryKeySQL($index, $table);
         }

src/Schema/Index.php

@@ -12,6 +12,8 @@
 use function array_search;
 use function array_shift;
 use function count;
+use function str_ends_with;
+use function str_starts_with;
 use function strtolower;
 
 class Index extends AbstractAsset
@@ -27,6 +29,8 @@ class Index extends AbstractAsset
 
     protected bool $_isPrimary = false;
 
+    protected bool $_isFunctional = false;
+
     /**
      * Platform specific flags for indexes.
      *
@@ -58,6 +62,10 @@ public function __construct(
 
         foreach ($columns as $column) {
             $this->_addColumn($column);
+
+            $this->_isFunctional = $this->_isFunctional === true
+                ? $this->_isFunctional
+                : self::isFunctionalIndex($column);
         }
 
         foreach ($flags as $flag) {
@@ -101,10 +109,14 @@ public function getQuotedColumns(AbstractPlatform $platform): array
         foreach ($this->_columns as $column) {
             $length = array_shift($subParts);
 
-            $quotedColumn = $column->getQuotedName($platform);
+            if ($this->isFunctional()) {
+                $quotedColumn = $column->getName();
+            } else {
+                $quotedColumn = $column->getQuotedName($platform);
 
-            if ($length !== null) {
-                $quotedColumn .= '(' . $length . ')';
+                if ($length !== null) {
+                    $quotedColumn .= '(' . $length . ')';
+                }
             }
 
             $columns[] = $quotedColumn;
@@ -137,6 +149,11 @@ public function isPrimary(): bool
         return $this->_isPrimary;
     }
 
+    public function isFunctional(): bool
+    {
+        return $this->_isFunctional;
+    }
+
     public function hasColumnAtPosition(string $name, int $pos = 0): bool
     {
         $name         = $this->trimQuotes(strtolower($name));
@@ -283,6 +300,11 @@ public function getOptions(): array
         return $this->options;
     }
 
+    public static function isFunctionalIndex(string $name): bool
+    {
+        return str_starts_with($name, '(') && str_ends_with($name, ')');
+    }
+
     /**
      * Return whether the two indexes have the same partial index
      */

src/Schema/MySQLSchemaManager.php

@@ -390,10 +390,12 @@ protected function selectIndexColumns(string $databaseName, ?string $tableName =
             $sql .= ' TABLE_NAME,';
         }
 
-        $sql .= <<<'SQL'
+        $columnName = $this->getColumnNameForIndexFetch();
+
+        $sql .= <<<SQL
         NON_UNIQUE  AS Non_Unique,
         INDEX_NAME  AS Key_name,
-        COLUMN_NAME AS Column_Name,
+        {$columnName},
         SUB_PART    AS Sub_Part,
         INDEX_TYPE  AS Index_Type
 FROM information_schema.STATISTICS
@@ -539,4 +541,17 @@ private function getDefaultTableOptions(): DefaultTableOptions
 
         return $this->defaultTableOptions;
     }
+
+    /**
+     * EXPRESSION
+     *
+     * MySQL 8.0.13 and higher supports functional key parts (see Functional Key Parts), which affects both
+     * the COLUMN_NAME and EXPRESSION columns:
+     * For a nonfunctional key part, COLUMN_NAME indicates the column indexed by the key part and EXPRESSION is NULL.
+     * For a functional key part, COLUMN_NAME column is NULL and EXPRESSION indicates the expression for the key part.
+     */
+    private function getColumnNameForIndexFetch(): string
+    {
+        return $this->platform->getColumnNameForIndexFetch() . ' as Column_Name';
+    }
 }