[wp-trac] [WordPress Trac] #63503: Exporting in high data instances results in empty file download

[WordPress Trac]

#63503: Exporting in high data instances results in empty file download
--------------------------+-----------------------------
 Reporter:  bor0          |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Export        |    Version:  6.8
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 When attempting to export products or documentation on a large WP instance
 with a lot of data, an empty .xml file is downloaded. This causes problems
 when we need to export updated content from production for use on our dev
 environments.

 In our investigation, we found out that the query gets stopped because it
 runs for too long.

 It comes from WP core:
 https://github.com/WordPress/WordPress/blob/2879b85136044a56fdd908a56c79c85a0ed7a39e
 /wp-admin/includes/export.php#L415. The query is also super long as it
 contains 23794 entries in the `$post_ids` array, though:


 {{{
 $ time vip wp -a woocommerce -e production -y -- db query "SELECT count(*)
 FROM wp_posts WHERE post_type = 'product'"
 +----------+
 | count(*) |
 +----------+
 |     2105 |
 +----------+
 }}}


 It likely happens because it also includes post attachments here:
 https://github.com/WordPress/WordPress/blob/2879b85136044a56fdd908a56c79c85a0ed7a39e
 /wp-admin/includes/export.php#L190).

 In that code block there's chunking, which is why it works, however, in
 the code where it fails there's no chunking.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/63503>
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