Merge branch 'compress-db' into 'master'

Compress database backup

Restore handles both cases: uncompressed and compressed backup. As an improvement `IO.popen` can be used.

/cc @jacobvosmaer

See merge request !873

CHANGELOG

@@ -53,6 +53,8 @@ v 7.12.1
   - Fix closed merge request scope at milestone page (Dmitriy Zaporozhets)
   - Revert merge request states renaming 
   - Fix hooks for web based events with external issue references (Daniel Gerhardt)
+  - Improve performance for issue and merge request pages
+  - Compress database dumps to reduce backup size
 
 v 7.12.0
   - Fix Error 500 when one user attempts to access a personal, internal snippet (Stan Hu)

doc/update/mysql_to_postgresql.md

@@ -57,12 +57,15 @@ sudo -u git -H git clone https://github.com/gitlabhq/mysql-postgresql-converter.
 sudo -u git -H mkdir db
 sudo -u git -H python mysql-postgresql-converter/db_converter.py gitlabhq_production.mysql db/database.sql
 
+# Compress database backup
+sudo -u git -H gzip db/database.sql
+
 # Replace the MySQL dump in TIMESTAMP_gitlab_backup.tar.
 
 # Warning: if you forget to replace TIMESTAMP below, tar will create a new file
 # 'TIMESTAMP_gitlab_backup.tar' without giving an error.
 
-sudo -u git -H tar rf TIMESTAMP_gitlab_backup.tar db/database.sql
+sudo -u git -H tar rf TIMESTAMP_gitlab_backup.tar db/database.sql.gz
 
 # Done! TIMESTAMP_gitlab_backup.tar can now be restored into a Postgres GitLab
 # installation. Remember to recreate the indexes after the import.

lib/backup/database.rb

@@ -22,9 +22,19 @@ module Backup
       end
       report_success(success)
       abort 'Backup failed' unless success
+
+      $progress.print 'Compressing database ... '
+      success = system('gzip', db_file_name)
+      report_success(success)
+      abort 'Backup failed: compress error' unless success
     end
 
     def restore
+      $progress.print 'Decompressing database ... '
+      success = system('gzip', '-d', db_file_name_gz)
+      report_success(success)
+      abort 'Restore failed: decompress error' unless success
+
       success = case config["adapter"]
       when /^mysql/ then
         $progress.print "Restoring MySQL database #{config['database']} ... "
@@ -48,6 +58,10 @@ module Backup
       File.join(db_dir, 'database.sql')
     end
 
+    def db_file_name_gz
+      File.join(db_dir, 'database.sql.gz')
+    end
+
     def mysql_args
       args = {
         'host'      => '--host',