Draft/POC for SQLite support in Core

.gitignore

@@ -102,3 +102,7 @@ wp-tests-config.php
 
 # Visual regression test diffs
 tests/visual-regression/specs/__snapshots__
+
+src/wp-content/database/.ht.sqlite
+
+src/wp-content/database/

phpcs.xml.dist

@@ -229,7 +229,7 @@
  #############################################################################
  SELECTIVE EXCLUSIONS
  Exclude specific files for specific sniffs and/or exclude sub-groups in sniffs.
- 
+
  These exclusions are listed ordered by alphabetic sniff name.
  #############################################################################
  -->
@@ -295,6 +295,10 @@
  <exclude-pattern>/tests/phpunit/tests/db/charset\.php</exclude-pattern>
  </rule>
 
+ <rule ref="WordPress.DB.RestrictedClasses">
+ <exclude-pattern>/src/wp-includes/sqlite/*\.php</exclude-pattern>
+ </rule>
+
  <!-- Allow the WP DB related tests for issues with prepared SQL placeholders
  (as the handling of those are being tested). -->
  <rule ref="WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare">

src/wp-admin/includes/class-wp-debug-data.php

@@ -279,6 +279,11 @@ public static function debug_data() {
  'label' => 'WP_MAX_MEMORY_LIMIT',
  'value' => WP_MAX_MEMORY_LIMIT,
  ),
+ 'DB_ENGINE' => array(
+ 'label' => 'DB_ENGINE',
+ 'value' => ( defined( 'DB_ENGINE' ) ? DB_ENGINE : __( 'Undefined' ) ),
+ 'debug' => ( defined( 'DB_ENGINE' ) ? DB_ENGINE : 'undefined' ),
+ ),
  'WP_DEBUG' => array(
  'label' => 'WP_DEBUG',
  'value' => WP_DEBUG ? __( 'Enabled' ) : __( 'Disabled' ),
@@ -879,79 +884,105 @@ public static function debug_data() {
  'value' => wp_date( 'c', $_SERVER['REQUEST_TIME'] ),
  );
 
- // Populate the database debug fields.
- if ( is_object( $wpdb->dbh ) ) {
- // mysqli or PDO.
- $extension = get_class( $wpdb->dbh );
- } else {
- // Unknown sql extension.
- $extension = null;
+ $db_engine = defined( 'DB_ENGINE' ) && 'sqlite' === DB_ENGINE ? 'sqlite' : 'mysql';
+ $extension = null;
+ if ( 'mysql' === $db_engine ) {
+ // Populate the database debug fields.
+ if ( is_object( $wpdb->dbh ) ) {
+ // mysqli or PDO.
+ $extension = get_class( $wpdb->dbh );
+ }
  }
 
  $server = $wpdb->get_var( 'SELECT VERSION()' );
 
  $client_version = $wpdb->dbh->client_info;
 
- $info['wp-database']['fields']['extension'] = array(
- 'label' => __( 'Extension' ),
- 'value' => $extension,
+ $info['wp-database']['fields']['db_engine'] = array(
+ 'label' => __( 'Database engine' ),
+ 'value' => 'sqlite' === $db_engine ? 'SQLite' : 'MySQL/MariaDB',
  );
 
- $info['wp-database']['fields']['server_version'] = array(
- 'label' => __( 'Server version' ),
- 'value' => $server,
- );
+ if ( 'mysql' === $db_engine ) {
+ $info['wp-database']['fields']['extension'] = array(
+ 'label' => __( 'Extension' ),
+ 'value' => $extension,
+ );
 
- $info['wp-database']['fields']['client_version'] = array(
- 'label' => __( 'Client version' ),
- 'value' => $client_version,
- );
+  $info['wp-database']['fields']['server_version'] = array(
+  'label' => __( 'Server version' ),
+  'value' => $server,
+  );
 
- $info['wp-database']['fields']['database_user'] = array(
- 'label' => __( 'Database username' ),
- 'value' => $wpdb->dbuser,
- 'private' => true,
- );
+ $info['wp-database']['fields']['client_version'] = array(
+ 'label' => __( 'Client version' ),
+ 'value' => $client_version,
+ );
 
- $info['wp-database']['fields']['database_host'] = array(
- 'label' => __( 'Database host' ),
- 'value' => $wpdb->dbhost,
- 'private' => true,
- );
+  $info['wp-database']['fields']['database_user'] = array(
+  'label' => __( 'Database username' ),
+  'value' => $wpdb->dbuser,
+  'private' => true,
+  );
 
- $info['wp-database']['fields']['database_name'] = array(
- 'label' => __( 'Database name' ),
- 'value' => $wpdb->dbname,
- 'private' => true,
- );
+ $info['wp-database']['fields']['database_host'] = array(
+ 'label' => __( 'Database host' ),
+ 'value' => $wpdb->dbhost,
+ 'private' => true,
+ );
+
+ $info['wp-database']['fields']['database_name'] = array(
+ 'label' => __( 'Database name' ),
+ 'value' => $wpdb->dbname,
+ 'private' => true,
+ );
+ } elseif ( 'sqlite' === $db_engine ) {
+ $info['wp-database']['fields']['database_version'] = array(
+ 'label' => __( 'SQLite version' ),
+ 'value' => class_exists( 'SQLite3' ) ? SQLite3::version()['versionString'] : null,
+ );
+
+ $info['wp-database']['fields']['database_file'] = array(
+ 'label' => __( 'Database file' ),
+ 'value' => FQDB,
+ 'private' => true,
+ );
+
+ $info['wp-database']['fields']['database_size'] = array(
+ 'label' => __( 'Database size' ),
+ 'value' => size_format( filesize( FQDB ) ),
+ );
+ }
 
  $info['wp-database']['fields']['database_prefix'] = array(
  'label' => __( 'Table prefix' ),
  'value' => $wpdb->prefix,
  'private' => true,
  );
 
- $info['wp-database']['fields']['database_charset'] = array(
- 'label' => __( 'Database charset' ),
- 'value' => $wpdb->charset,
- 'private' => true,
- );
+ if ( 'mysql' === $db_engine ) {
+ $info['wp-database']['fields']['database_charset'] = array(
+ 'label' => __( 'Database charset' ),
+ 'value' => $wpdb->charset,
+ 'private' => true,
+ );
 
- $info['wp-database']['fields']['database_collate'] = array(
- 'label' => __( 'Database collation' ),
- 'value' => $wpdb->collate,
- 'private' => true,
- );
+  $info['wp-database']['fields']['database_collate'] = array(
+  'label' => __( 'Database collation' ),
+  'value' => $wpdb->collate,
+  'private' => true,
+  );
 
- $info['wp-database']['fields']['max_allowed_packet'] = array(
- 'label' => __( 'Max allowed packet size' ),
- 'value' => self::get_mysql_var( 'max_allowed_packet' ),
- );
+  $info['wp-database']['fields']['max_allowed_packet'] = array(
+  'label' => __( 'Max allowed packet size' ),
+  'value' => self::get_mysql_var( 'max_allowed_packet' ),
+  );
 
- $info['wp-database']['fields']['max_connections'] = array(
- 'label' => __( 'Max connections number' ),
- 'value' => self::get_mysql_var( 'max_connections' ),
- );
+ $info['wp-database']['fields']['max_connections'] = array(
+ 'label' => __( 'Max connections number' ),
+ 'value' => self::get_mysql_var( 'max_connections' ),
+ );
+ }
 
  // List must use plugins if there are any.
  $mu_plugins = get_mu_plugins();

src/wp-admin/includes/class-wp-site-health.php

@@ -15,6 +15,7 @@ class WP_Site_Health {
  private $is_recommended_mysql_version;
 
  public $is_mariadb = false;
+ public $is_sqlite = false;
  private $mysql_server_version = '';
  private $mysql_required_version = '5.5';
  private $mysql_recommended_version = '8.0';
@@ -208,6 +209,7 @@ private function prepare_sql_data() {
  global $wpdb;
 
  $mysql_server_type = $wpdb->db_server_info();
+ $this->is_sqlite = defined( 'DB_ENGINE' ) && 'sqlite' === DB_ENGINE ? 'sqlite' : 'mysql';
 
  $this->mysql_server_version = $wpdb->get_var( 'SELECT VERSION()' );
 
@@ -1230,7 +1232,7 @@ public function get_test_sql_server() {
 
  $db_dropin = file_exists( WP_CONTENT_DIR . '/db.php' );
 
- if ( ! $this->is_recommended_mysql_version ) {
+ if ( ! $this->is_sqlite && ! $this->is_recommended_mysql_version ) {
  $result['status'] = 'recommended';
 
  $result['label'] = __( 'Outdated SQL server' );
@@ -1246,7 +1248,7 @@ public function get_test_sql_server() {
  );
  }
 
- if ( ! $this->is_acceptable_mysql_version ) {
+ if ( ! $this->is_sqlite && ! $this->is_acceptable_mysql_version ) {
  $result['status'] = 'critical';
 
  $result['label'] = __( 'Severely outdated SQL server' );

src/wp-admin/includes/upgrade.php

@@ -51,7 +51,12 @@ function wp_install( $blog_title, $user_name, $user_email, $is_public, $deprecat
 
  wp_check_mysql_version();
  wp_cache_flush();
- make_db_current_silent();
+
+ if ( defined( 'DB_ENGINE' ) && 'sqlite' === DB_ENGINE ) {
+ sqlite_make_db_sqlite(); // phpcs:ignore PHPCompatibility.Extensions.RemovedExtensions.sqliteRemoved
+ } else {
+ make_db_current_silent();
+ }
 
  /*
  * Ensure update checks are delayed after installation.
@@ -3279,6 +3284,57 @@ function make_db_current_silent( $tables = 'all' ) {
  dbDelta( $tables );
 }
 
+
+/**
+ * Function to create tables according to the schemas of WordPress.
+ *
+ * This is executed only once while installation.
+ *
+ * @since 1.0.0
+ *
+ * @return boolean
+ */
+function sqlite_make_db_sqlite() {
+ include_once ABSPATH . 'wp-admin/includes/schema.php';
+
+ $table_schemas = wp_get_db_schema();
+ $queries = explode( ';', $table_schemas );
+ try {
+ $pdo = new PDO( 'sqlite:' . FQDB, null, null, array( PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION ) ); // phpcs:ignore WordPress.DB.RestrictedClasses
+ } catch ( PDOException $err ) {
+ $err_data = $err->errorInfo; // phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase
+ wp_die( $err_data[2], 'Database Error!' );
+ }
+
+ $translator = new WP_SQLite_Translator( $pdo, $GLOBALS['table_prefix'] );
+ $query = null;
+
+ try {
+ $translator->begin_transaction();
+ foreach ( $queries as $query ) {
+ $query = trim( $query );
+ if ( empty( $query ) ) {
+ continue;
+ }
+
+ $result = $translator->query( $query );
+ if ( false === $result ) {
+ throw new PDOException( $translator->get_error_message() );
+ }
+ }
+ $translator->commit();
+ } catch ( PDOException $err ) {
+ $err_data = $err->errorInfo; // phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase
+ $err_code = $err_data[1];
+ $translator->rollback();
+ wp_die( $err_data[2], 'Database Error!' );
+ }
+
+ $pdo = null;
+
+ return true;
+}
+
 /**
  * Creates a site theme from an existing theme.
  *