Изменение Laravel MYSQL на utf8mb4 для поддержки Emoji в существующей базе данных

для тех, кто хочет достичь этого во всей базе данных, мне понадобился такой script:

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Config;

class ChangeDbCharset extends Migration
{

    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        $charset = "utf8mb4";
        $collate = $charset."_unicode_ci";
        $dbName = Config::get('database.connections.'.Config::get('database.default').'.database');
        $query = "ALTER SCHEMA $dbName DEFAULT CHARACTER SET $charset DEFAULT COLLATE $collate;\n"; 
        DB::connection()->getPdo()->exec($query);

        $dbName = Config::get('database.connections.'.Config::get('database.default').'.database');
        $result = DB::select(DB::raw('show tables'));
        $test = DB::select(DB::raw("select * from INFORMATION_SCHEMA.COLUMNS where DATA_TYPE = 'varchar' AND TABLE_SCHEMA = '$dbName';"));
        //var_dump($test);
        foreach($test as $t)
        {
            $query = "ALTER TABLE $t->TABLE_NAME CHANGE $t->COLUMN_NAME $t->COLUMN_NAME VARCHAR(191) CHARACTER SET $charset COLLATE $collate; \n";
            echo $query;
            DB::connection()->getPdo()->exec($query);
        }
        $test = DB::select(DB::raw("select * from INFORMATION_SCHEMA.COLUMNS where DATA_TYPE = 'text' AND TABLE_SCHEMA = '$dbName';"));
        foreach($test as $t)
        {
            $query = "ALTER TABLE $t->TABLE_NAME CHANGE $t->COLUMN_NAME $t->COLUMN_NAME TEXT CHARACTER SET $charset COLLATE $collate; \n";
            echo $query;
            DB::connection()->getPdo()->exec($query);
        }


        $result = DB::select(DB::raw('show tables'));
        foreach($result as $r)
        {
            foreach($r as $k => $t)
            {
                $query = "ALTER TABLE `$t` CONVERT TO CHARACTER SET $charset COLLATE $collate; \n";
                echo $query;
                DB::connection()->getPdo()->exec($query);
            }
        }
        echo "DB CHARSET set to $charset , $collate";
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        $charset = "utf8";
        $collate = $charset."_unicode_ci";
        $dbName = Config::get('database.connections.'.Config::get('database.default').'.database');
        $query = "ALTER SCHEMA $dbName DEFAULT CHARACTER SET $charset DEFAULT COLLATE $collate;\n"; 
        DB::connection()->getPdo()->exec($query);

        $dbName = Config::get('database.connections.'.Config::get('database.default').'.database');
        $result = DB::select(DB::raw('show tables'));
        $test = DB::select(DB::raw("select * from INFORMATION_SCHEMA.COLUMNS where DATA_TYPE = 'varchar' AND TABLE_SCHEMA = '$dbName';"));
        //var_dump($test);
        foreach($test as $t)
        {
            $query = "ALTER TABLE $t->TABLE_NAME CHANGE $t->COLUMN_NAME $t->COLUMN_NAME VARCHAR(255) CHARACTER SET $charset COLLATE $collate; \n";
            echo $query;
            DB::connection()->getPdo()->exec($query);
        }
        $test = DB::select(DB::raw("select * from INFORMATION_SCHEMA.COLUMNS where DATA_TYPE = 'text' AND TABLE_SCHEMA = '$dbName';"));
        foreach($test as $t)
        {
            $query = "ALTER TABLE $t->TABLE_NAME CHANGE $t->COLUMN_NAME $t->COLUMN_NAME TEXT CHARACTER SET $charset COLLATE $collate; \n";
            echo $query;
            DB::connection()->getPdo()->exec($query);
        }


        $result = DB::select(DB::raw('show tables'));
        foreach($result as $r)
        {
            foreach($r as $k => $t)
            {
                $query = "ALTER TABLE `$t` CONVERT TO CHARACTER SET $charset COLLATE $collate; \n";
                echo $query;
                DB::connection()->getPdo()->exec($query);
            }
        }
        echo "DB CHARSET set to $charset , $collate";
    }

}

На основе ответа @insomniak-dev, но будет только сжимать varchar, когда они превышают пределы И используются в индексе. В противном случае они преобразуются, но размер остается как есть. Если столбец будет сокращен, тогда он проверяет, будут ли урезаны какие-либо данные.

Это также обрабатывает все типы текста и пакеты всех преобразований для каждой таблицы в один оператор для скорости.

Флаг Dryrun выводит полезный sql вместо прямого применения.

/**
 * Run the migrations.
 *
 * @return void
 */
public function up()
{
    $dryRun = true;
    $this->convertDb('mysql', 'utf8mb4', 'utf8mb4_unicode_ci', $dryRun);
    $this->convertDb('archive', 'utf8mb4', 'utf8mb4_unicode_ci', $dryRun);
}

/**
 * Reverse the migrations.
 *
 * @return void
 */
public function down()
{
    $dryRun = true;
    $this->convertDb('archive', 'utf8', 'utf8_unicode_ci', $dryRun);
    $this->convertDb('mysql', 'utf8', 'utf8_unicode_ci', $dryRun);
}

private function convertDb($connection, $charset, $collate, $dryRun)
{
    $dbName = config("database.connections.{$connection}.database");

    $varchars = \DB::connection($connection)
        ->select(\DB::raw("select * from INFORMATION_SCHEMA.COLUMNS where DATA_TYPE = 'varchar' and (CHARACTER_SET_NAME != '{$charset}' or COLLATION_NAME != '{$collate}') AND TABLE_SCHEMA = '{$dbName}'"));
    // Check if shrinking field size will truncate!
    $skip = [];  // List of table.column that will be handled manually
    $indexed = [];
    if ($charset == 'utf8mb4') {
        $error = false;
        foreach($varchars as $t) {
            if ($t->CHARACTER_MAXIMUM_LENGTH > 191) {
                $key = "{$t->TABLE_NAME}.{$t->COLUMN_NAME}";

                // Check if column is indexed
                $index = \DB::connection($connection)
                    ->select(\DB::raw("SHOW INDEX FROM `{$t->TABLE_NAME}` where column_name = '{$t->COLUMN_NAME}'"));
                $indexed[$key] = count($index) ? true : false;

                if (count($index)) {
                    $result = \DB::connection($connection)
                        ->select(\DB::raw("select count(*) as `count` from `{$t->TABLE_NAME}` where length(`{$t->COLUMN_NAME}`) > 191"));
                    if ($result[0]->count > 0) {
                        echo "-- DATA TRUNCATION: {$t->TABLE_NAME}.{$t->COLUMN_NAME}({$t->CHARACTER_MAXIMUM_LENGTH}) => {$result[0]->count}" . PHP_EOL;
                        if (!in_array($key, $skip)) {
                            $error = true;
                        }
                    }
                }
            }
        }
        if ($error) {
            throw new \Exception('Aborting due to data truncation');
        }
    }

    $query = "SET FOREIGN_KEY_CHECKS = 0";
    $this->dbExec($query, $dryRun, $connection);

    $query = "ALTER SCHEMA {$dbName} DEFAULT CHARACTER SET {$charset} DEFAULT COLLATE {$collate}";
    $this->dbExec($query, $dryRun, $connection);

    $tableChanges = [];
    foreach($varchars as $t) {
        $key = "{$t->TABLE_NAME}.{$t->COLUMN_NAME}";
        if (!in_array($key, $skip)) {
            if ($charset == 'utf8mb4' && $t->CHARACTER_MAXIMUM_LENGTH > 191 && $indexed["{$t->TABLE_NAME}.{$t->COLUMN_NAME}"]) {
                $tableChanges["{$t->TABLE_NAME}"][] = "CHANGE `{$t->COLUMN_NAME}` `{$t->COLUMN_NAME}` VARCHAR(191) CHARACTER SET {$charset} COLLATE {$collate}";
                echo "-- Shrinking: {$t->TABLE_NAME}.{$t->COLUMN_NAME}({$t->CHARACTER_MAXIMUM_LENGTH})" . PHP_EOL;
            } else if ($charset == 'utf8' && $t->CHARACTER_MAXIMUM_LENGTH == 191) {
                $tableChanges["{$t->TABLE_NAME}"][] = "CHANGE `{$t->COLUMN_NAME}` `{$t->COLUMN_NAME}` VARCHAR(255) CHARACTER SET {$charset} COLLATE {$collate}";
                echo "-- Expanding: {$t->TABLE_NAME}.{$t->COLUMN_NAME}({$t->CHARACTER_MAXIMUM_LENGTH})";
            } else {
                $tableChanges["{$t->TABLE_NAME}"][] = "CHANGE `{$t->COLUMN_NAME}` `{$t->COLUMN_NAME}` VARCHAR({$t->CHARACTER_MAXIMUM_LENGTH}) CHARACTER SET {$charset} COLLATE {$collate}";
            }
        }
    }

    $texts = \DB::connection($connection)
        ->select(\DB::raw("select * from INFORMATION_SCHEMA.COLUMNS where DATA_TYPE like '%text%' and (CHARACTER_SET_NAME != '{$charset}' or COLLATION_NAME != '{$collate}') AND TABLE_SCHEMA = '{$dbName}'"));
    foreach($texts as $t) {
        $tableChanges["{$t->TABLE_NAME}"][] = "CHANGE `{$t->COLUMN_NAME}` `{$t->COLUMN_NAME}` {$t->DATA_TYPE} CHARACTER SET {$charset} COLLATE {$collate}";
    }

    $tables = \DB::connection($connection)
        ->select(\DB::raw("select * from INFORMATION_SCHEMA.TABLES where TABLE_COLLATION != '{$collate}' and TABLE_SCHEMA = '{$dbName}';"));
    foreach($tables as $t) {
        $tableChanges["{$t->TABLE_NAME}"][] = "CONVERT TO CHARACTER SET {$charset} COLLATE {$collate}";
        $tableChanges["{$t->TABLE_NAME}"][] = "DEFAULT CHARACTER SET={$charset} COLLATE={$collate}";
    }

    foreach ($tableChanges as $table => $changes) {
        $query = "ALTER TABLE `{$table}` ".implode(",\n", $changes);
        $this->dbExec($query, $dryRun, $connection);
    }

    $query = "SET FOREIGN_KEY_CHECKS = 1";
    $this->dbExec($query, $dryRun, $connection);

    echo "-- {$dbName} CONVERTED TO {$charset}-{$collate}" . PHP_EOL;
}

private function dbExec($query, $dryRun, $connection)
{
    if ($dryRun) {
        echo $query . ';' . PHP_EOL;
    } else {
        \DB::connection($connection)->getPdo()->exec($query);
    }
}