#3840 (ok 4.1.4) When exporting to gzip format, the data is compressed 2 times

[Gemorroj]

When exporting to gzip format, the data is compressed 2 times.
As I see it is because of option "onfly_compression".

[Gurutharshan]

I couldn't extract that .sql.gz file with gunzip... help me on how to extract..?

[Gemorroj]

I use 7-zip on Windows..
Try using http://sourceforge.net/projects/p7zip/

[Gurutharshan]

I was bugging into the code but couldnt find... But I tried to import the file again into seperate db, it was correctly inserted.. :^)

[Gemorroj]

See this screenshot. I think it will help.

[Marc Delisle]

The reason for the double compression is that your web server itself has a module to gzip what it sends, and phpMyAdmin is not able to detect it.

Is the web server using mod_deflate?

[Gurutharshan]

I think it's enabled.. mod_deflate shows under loaded modules under apache2handler in phpinfo

[Marc Delisle]

Gemorroj,
I believe you found the cause of the bug, however I have difficulty reproducing it. Could you try this commit from my bug_3840 branch ?

https://github.com/lem9/phpmyadmin/commit/b26895ed59c9a4b1742cf76e1e49d83e4db80d5f

[Gemorroj]

Yes, of course, as soon as I get to a working computer. (Weekend.. =))

[Gemorroj]

It did not work.
I spent more thorough investigation of the problem. If I remove the browser header Accept-Encoding, then the problem can not be played.
But, in the settings Apache, I not found that can automatically compress the data based on the header Accept-Encoding (mod_deflate module is disabled).
In the setting of php, zlib compression in the same off.
My initial assumption is that the problem is due to the option onfly_compression, probably wrong.

In an attachment - phpinfo and httpd.conf

[Marc Delisle]

Thanks for the investigation; sorry I have no further ideas. I have pushed my patch (without the ChangeLog part) to master because I believe it's needed, but not necessarily to solve this bug.

[Gemorroj]

I added this code to function PMA_gzencodeNeeded:

<?php
while (ob_get_level()) {
    file_put_contents('/log.log', print_r(ob_get_status(), true), FILE_APPEND);
    ob_end_clean();
}

Output:

Array
(
    [name] => default output handler
    [type] => 0
    [flags] => 112
    [level] => 1
    [chunk_size] => 0
    [buffer_size] => 16384
    [buffer_used] => 0
)
Array
(
    [name] => ob_gzhandler
    [type] => 0
    [flags] => 112
    [level] => 0
    [chunk_size] => 0
    [buffer_size] => 16384
    [buffer_used] => 0
)

The problem disappeared.

---

Perhaps this is not the correct code, but I think it is clear that the problem is due to handler ob_gzhandler. You may need to check for it, too.

[Marc Delisle]

Fixed by your https://github.com/phpmyadmin/phpmyadmin/pull/214, thanks.

[Marc Delisle]

[aommundsen]

This same problem is happening again on my servers. I am running phpMyAdmin 4.1.2, when I export as gzipped the data is compressed two times, so I will not be able to import it unles I first unpack the .gz file and then rename the unpacked file to .gz and unpack it one more time. Please confirm.

(I am running Apache 2.4.7, PHP 5.57 (mod_php).)

[Marc Delisle]

What about version 4.1.3?

[aommundsen]

Where can I download it? Because 4.1.2 seem to be the newest. Can you instead provide a patch patch from the change in 4.1.3 wich I can test in 4.1.2?

[Marc Delisle]

Download from https://sourceforge.net/projects/phpmyadmin/files/phpMyAdmin/.

Or maybe https://github.com/phpmyadmin/phpmyadmin/commit/8021f31e36f95afde4d05be7ecab7d1db08ba63c can help, however it seems to be the opposite problem.

Was there a previous 4.0 or 4.1 version that worked for you?

[aommundsen]

Yes, previous it has been working correctly. However I do not know at what time/version the problem returned. Only yesterday one of my customers complained, so I noticed it again. I will test the new version and give feedback, however I don't see anything in the changelog that indicate that this would be fixed.

[Marc Delisle]

Is your server running Apache + mod_deflate?

[Marc Delisle]

Might be the same problem as https://sourceforge.net/p/phpmyadmin/bugs/3673.