Why doesn't it return content-length for gzip?

Question

PHP

Good afternoon.
htaccess settings

<IfModule mod_deflate.c>
    AddOutputFilterByType DEFLATE text/html application/json text/plain text/css application/javascript
    php_flag zlib.output_compression 1
    FileETag none
</IfModule>

With small amounts of json, the content-length header is returned correctly.
However, when the size of the output reaches several megabytes, there is no content-length.

Answer 1

In order to always give content-lenght, in the Apache config you need to increase the buffer size for mod_deflate

<IfModule mod_deflate.c>
    DeflateBufferSize тут-значение-побольше
</IfModule>