[CLI] database:export "Allowed memory size bytes exhausted", php 7.4, J4

[bato3]

Steps to reproduce the issue

Default php 7.4 configuration from XAMMP,
389597 rows in #_finder_terms (127.9 MB on disk)

php cli\joomla.php -vvv --table=jos37_finder_terms database:export

Actual result

Exporting Database
==================

 Processing the jos37_finder_terms table
PHP Fatal error:  Allowed memory size of 536870912 bytes exhausted (tried to allocate 67108872 bytes) in C:\xampp\htdocs\libraries\vendor\joomla\database\src\DatabaseExporter.php on line 299

Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 67108872 bytes) in C:\xampp\htdocs\libraries\vendor\joomla\database\src\DatabaseExporter.php on line 299
Symfony\Component\ErrorHandler\Error\OutOfMemoryError^ {#390689
  -error: array:4 [
    "type" => 1
    "message" => "Allowed memory size of 536870912 bytes exhausted (tried to allocate 67108872 bytes)"
    "file" => "C:\xampp\htdocs\libraries\vendor\joomla\database\src\DatabaseExporter.php"
    "line" => 299
  ]
  #message: "Error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 67108872 bytes)"
  #code: 0
  #file: "C:\xampp\htdocs\libraries\vendor\joomla\database\src\DatabaseExporter.php"
  #line: 299
}

System information (as much as possible)

• PHP 7.4.9 (cli) (built: Aug 4 2020 11:52:41) ( ZTS Visual C++ 2017 x64 )
• Joomla! 4.0.0-beta3 (debug: No) (not fully upgraded, but i put files by FTP, and database version: 4.0.0-2020-05-29 )

Additional comments

I know, that I can reconfigure server, but I think we should find a solution that requires less memory.

[Hackwar]

I've opened an issue on the database repo: joomla-framework/database#287

[Hackwar]

So the solution to this issue would be to stagger reading and writing the data from the table during export. Limit the number of rows to read, then write them to a file resource, read the next batch and write it again until done. This is a bigger refactoring and I'm unsure if our Filesystem package properly supports this.