Store metadata in dedicated columns

composer.json

@@ -18,7 +18,7 @@
   "require": {
     "php": "^7.1",
     "ext-pdo": "*",
-    "event-engine/php-persistence": "^0.3"
+    "event-engine/php-persistence": "^0.4"
   },
   "require-dev": {
     "roave/security-advisories": "dev-master",

src/Index/RawSqlIndexCmd.php

@@ -0,0 +1,54 @@
+<?php
+declare(strict_types=1);
+
+namespace EventEngine\DocumentStore\Postgres\Index;
+
+use EventEngine\DocumentStore\Index;
+use EventEngine\DocumentStore\Postgres\Exception\InvalidArgumentException;
+
+final class RawSqlIndexCmd implements Index
+{
+    /**
+     * @var string|null
+     */
+    private $name;
+
+    /**
+     * @var string
+     */
+    private $sql;
+
+    public static function fromArray(array $data): Index
+    {
+        if(!array_key_exists('sql', $data)) {
+            throw new InvalidArgumentException("Data array misses raw sql stmt!");
+        }
+
+        return new self($data['sql'], $data['name'] ?? null);
+    }
+
+    public function __construct(string $sql, string $name = null)
+    {
+        $this->sql = $sql;
+        $this->name = $name;
+    }
+
+
+    public function toArray()
+    {
+        return [
+            'sql' => $this->sql,
+            'name' => $this->name,
+        ];
+    }
+
+    public function sql(): string
+    {
+        return $this->sql;
+    }
+
+    public function name(): ?string
+    {
+        return $this->name;
+    }
+}

src/Metadata/Column.php

@@ -0,0 +1,19 @@
+<?php
+declare(strict_types=1);
+
+namespace EventEngine\DocumentStore\Postgres\Metadata;
+
+final class Column
+{
+    private $sql;
+
+    public function __construct(string $sql)
+    {
+        $this->sql = $sql;
+    }
+
+    public function sql(): string
+    {
+        return $this->sql;
+    }
+}

src/Metadata/MetadataColumnIndex.php

@@ -0,0 +1,75 @@
+<?php
+declare(strict_types=1);
+
+namespace EventEngine\DocumentStore\Postgres\Metadata;
+
+use EventEngine\DocumentStore\Index;
+use EventEngine\DocumentStore\Postgres\Exception\InvalidArgumentException;
+
+final class MetadataColumnIndex implements Index
+{
+    /**
+     * @var Column[]
+     */
+    private $columns;
+
+    /**
+     * @var Index
+     */
+    private $indexCmd;
+
+    public static function fromArray(array $data): Index
+    {
+        if(!array_key_exists('column', $data)) {
+            throw new InvalidArgumentException('Missing key columns in index data');
+        }
+
+        if(!array_key_exists('index', $data)) {
+            throw new InvalidArgumentException('Missing key index in data');
+        }
+
+        if(!array_key_exists('indexClass', $data)) {
+            throw new InvalidArgumentException('Missing key indexClass in data');
+        }
+
+        $indexClass = $data['indexClass'];
+        $index = $indexClass::fromArray($data['index']);
+
+        return new self($index, ...array_map(function (string $columnSql) {
+            return new Column($columnSql);
+        }, $data['columns']));
+    }
+
+    public function __construct(Index $indexCmd, Column ...$columns)
+    {
+        $this->columns = $columns;
+        $this->indexCmd = $indexCmd;
+    }
+
+    /**
+     * @return Column[]
+     */
+    public function columns(): array
+    {
+        return $this->columns;
+    }
+
+    /**
+     * @return Index
+     */
+    public function indexCmd(): Index
+    {
+        return $this->indexCmd;
+    }
+
+    public function toArray()
+    {
+        return [
+            'columns' => array_map(function (Column $column) {
+                return $column->sql();
+            }, $this->columns),
+            'index' => $this->indexCmd->toArray(),
+            'indexClass' => get_class($this->indexCmd),
+        ];
+    }
+}