From 6b6c11f3ea4b7ac5966f9f39ce3c2500c1740972 Mon Sep 17 00:00:00 2001
From: Matroskeen <matroskeen@3426249.no-reply.drupal.org>
Date: Sat, 23 Apr 2022 16:37:27 +0000
Subject: [PATCH] Issue #3276619 by Matroskeen: Document XML parsers and
explain the difference between them
---
src/Plugin/migrate_plus/data_parser/SimpleXml.php | 5 +++++
src/Plugin/migrate_plus/data_parser/Xml.php | 5 +++++
2 files changed, 10 insertions(+)
diff --git a/src/Plugin/migrate_plus/data_parser/SimpleXml.php b/src/Plugin/migrate_plus/data_parser/SimpleXml.php
index 0d6eb9ec..5f86b8bc 100644
--- a/src/Plugin/migrate_plus/data_parser/SimpleXml.php
+++ b/src/Plugin/migrate_plus/data_parser/SimpleXml.php
@@ -10,6 +10,11 @@ use Drupal\migrate_plus\DataParserPluginBase;
/**
* Obtain XML data for migration using the SimpleXML API.
*
+ * SimpleXML parses the whole file into memory, which allows using XPath
+ * expression in the item selector. For large XML sources it results in
+ * consuming lots of memory, which can be undesirable. If you run into memory
+ * issues, then consider using the 'xml' data parser.
+ *
* @DataParser(
* id = "simple_xml",
* title = @Translation("Simple XML")
diff --git a/src/Plugin/migrate_plus/data_parser/Xml.php b/src/Plugin/migrate_plus/data_parser/Xml.php
index ead05917..580df846 100644
--- a/src/Plugin/migrate_plus/data_parser/Xml.php
+++ b/src/Plugin/migrate_plus/data_parser/Xml.php
@@ -10,6 +10,11 @@ use Drupal\migrate_plus\DataParserPluginBase;
/**
* Obtain XML data for migration using the XMLReader pull parser.
*
+ * XMLReader reader performs incremental parsing of an XML file. This allows
+ * parsing very large XML sources (e.g. 200MB WordPress dumps), which reduces
+ * the memory usage and increases the performance. The disadvantage is that it's
+ * not possible to use XPath search across the entire source.
+ *
* @DataParser(
* id = "xml",
* title = @Translation("XML")
--
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