Best way to compress string in PHP

Question

I am compressing the array with gzcompress(json_encode($arr),9). So I am converting array into string with json_encode and then compress with gzcompress. But I could not find the much difference in the size of the resulted string. Before compression size is 488 KB and after compression size is 442 KB.

Is there any way I can compress the string further?

Thanks in advance.

Answer 1

Im not sure your numbers are right, tho you could use gzdeflate instead of gzcompress as gzcompress adds 6 bytes to the output (2 extra bytes at the beginning and 4 extra bytes at the end).

A simple test shows a 1756800 length string compressed to 99 bytes by double compressing it, 5164 bytes if compressed once.

$string = str_repeat('1234567890' . implode('', range('a', 'z')), 48800);

echo strlen($string); //1756800 bytes

$compressed = gzdeflate($string,  9);
$compressed = gzdeflate($compressed, 9);

echo strlen($compressed); //99 bytes

echo gzinflate(gzinflate($compressed));

Answer 2

How good the compression of your string will be depends on the data you want to compress. If it consists mainly of random data you won't achieve that much improvements in size. There are many algorithms out there which have been designed for specific usage.

You should try to determine what your data to compress mainly consists of and then select a proper compression.

Just now I can only refer you to bzcompress, bzip has usually highter compression rates than gzip.