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Note concerning ngx.location.capture buffering all subrequest c… #607

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Note concerning ngx.location.capture buffering all subrequest c… #607

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Expand Up @@ -3120,6 +3120,7 @@ Nginx's subrequests provide a powerful way to make non-blocking internal request
`ngx_postgres`, `ngx_drizzle`, and even ngx_lua itself and etc etc etc.

Also note that subrequests just mimic the HTTP interface but there is *no* extra HTTP/TCP traffic *nor* IPC involved. Everything works internally, efficiently, on the C level.
This also mean that subrequests are fully performed and buffered before being returned to Lua: making a subrequest call to a location that can return or stream a large amount of data (including by using sendfile) is probably a bad idea.
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Hmm, I'm afraid there is no causal relationship here. The real reason behind the always-fully-buffering behaviour is that this API just does not support streaming.


Subrequests are completely different from HTTP 301/302 redirection (via [ngx.redirect](#ngxredirect)) and internal redirection (via [ngx.exec](#ngxexec)).

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