I need to use redirect map with quite a lot rules (2k+ lines, file size is ~200K)

I have the following settings in nginx:

map $uri $new_uri {
        include /etc/nginx/conf.d/redirects.map;

server {
        listen 80 default_server;
        listen [::]:80 default_server;

        # redirects
        if ($new_uri) {
                rewrite ^ $new_uri permanent;

as described here and found here. The problem : configtest fails:

nginx: [emerg] could not build map_hash, you should increase map_hash_bucket_size: 64

I tried to increase map_hash_max_size and map_hash_bucket_size to quite crazy values:

map $uri $new_uri {
        map_hash_max_size 262144;
        map_hash_bucket_size 262144;
        include /etc/nginx/conf.d/redirects.map;

but still have the same error (ending exactly with '64'). I selected those values so they are bigger than the file size. I made sure I'm editing live config by adding "blabla" and see 'unknown directive'

So, how those values should be set? There's not much details in the official doc, unfortunately.

3 Answers 3


map_hash_max_size and map_hash_bucket_size must be in http context, i.e. outside of map directive.

map_hash_max_size 262144;
map_hash_bucket_size 262144;
map $uri $new_uri {
    include /etc/nginx/conf.d/redirects.map;
  • 1
    I set up right above the map but still got the same error. It's really weird. Nov 19, 2018 at 12:47
  • @KevinNguyen what error?
    – Alexey Ten
    Nov 19, 2018 at 13:52
  • Nginx: could not build map_hash, you should increase map_hash_bucket_size: 64. I posted my answer btw. Nov 19, 2018 at 17:27
  • It is not obvious but it also needs to appear before the map directives. Apr 23, 2019 at 18:05
  • 2
    @AlexeyTen this solution works well in with nginx 1.16 but not with nginx 1.18. Jul 1, 2021 at 15:46

I put it on the top of the http {} and it worked. Don't put it outside http {}


Add to the top of the http block in the main configuration file (/etc/nginx/nginx.conf):

map_hash_bucket_size 128;
  • How does your answer differ from the existing answer? Nov 18, 2018 at 21:10
  • I got the following error: nginx: "map_hash_bucket_size" directive is duplicate in /etc/nginx/conf.d/my-redirect-map.conf:2 using the above answer. This answer indicates that map_hash_max_size is not required and this global setting is better suited to be placed in the main configuration file.
    – tread
    Nov 18, 2018 at 22:10
  • Well, having it twice in your config causes that problem. Nov 18, 2018 at 22:25
  • Yip. Another reason why it is better to put this setting in the main nginx config.
    – tread
    Nov 18, 2018 at 23:37

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