Gzip-support for backups

[alexgit2k]

For backups CraftCMS dumps the database and then compresses it, if the zip-option is set:

cms/src/console/controllers/DbController.php

Line 168 in 203ebf0

public function actionBackup(?string $path = null): int

As the database dump can be quite big this can require a lot of diskspace. A better solution would be gzip, where the compression can be made on the fly. Therefore I suggest an additional option --gzip for dumps with gzip-compression.

For example for MySQL:

• Backup: mysqldump ... | gzip -c > backup.sql.gz
• Restore: zcat backup.sql.gz | mysql ...

For MySQL first the schema is dumped and then the data. With gzip the compressed output can simply be concatenated:
mysqldump ... | gzip -c > backup.sql.gz && mysqldump ... | gzip -c >> backup.sql.gz

cms/src/db/mysql/Schema.php

Lines 200 to 214 in 203ebf0

	$schemaDump = 'mysqldump' .
	$defaultArgs .
	' --single-transaction' .
	' --no-data' .
	' --result-file="{file}"' .
	' {database}';
	$dataDump = 'mysqldump' .
	$defaultArgs .
	' --no-create-info' .
	' ' . implode(' ', $ignoreTableArgs) .
	' {database}' .
	' >> "{file}"';
	return $schemaDump . ' && ' . $dataDump;