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# 5.2.1. Comparison

There are many differences between groonga and groonga-httpd. Here is a comparison table.

| groonga | groonga-httpd
--- | --- | ---
Performance | o | o
Using multi CPU cores | o (by multi threading) | o (by multi process)
Configuration file | optional | required
Custom prefix path | x | o
Custom command version | o | o
Multi databases | x | o
Authentication | x | o
Gzip compression | x | o
POST | o | o
HTTPS | x | o
Access log | x | o
Upgrading without downtime | x | o

## 5.2.1.1. Performance

Both groonga and groonga-httpd are very fast. They can work with the same throughput.

## 5.2.1.2. Using multi CPU cores

Groonga scales on multi CPU cores. groonga scales by multi threading. groonga-httpd scales by multi processes.

groonga uses the same number of threads as CPU cores by default. If you have 8 CPU cores, 8 threads are used by default.

groonga-httpd uses 1 process by default. You need to set worker_processes directive to use CPU cores. If you have 8 CPU cores, specify `worker_processes 8` in configuration file like the following:

    worker_processes 8;

    http {
      # ...
    }

## 5.2.1.3. Configuration file

groonga can work without configuration file. All configuration items such as port number and the max number of threads can be specified by command line. Configuration file is also used to specify configuration items.

It’s very easy to run groonga HTTP server because groonga requires just a few options to run. Here is the most simple command line to start HTTP server by groonga:

    % groonga --protocol http -d /PATH/TO/DATABASE

groonga-httpd requires configuration file to run. Here is the most simple configuration file to start HTTP server by groonga-httpd:

    events {
    }

    http {
      server {
        listen 10041;

        location /d/ {
          groonga on;
          groonga_database /PATH/TO/DATABASE;
        }
      }
    }

## 5.2.1.4. Custom prefix path

groonga accepts a path that starts with `/d/` as command URL such as `http://localhost:10041/d/status`. You cannot change the prefix path `/d/`.

groonga-httpd can custom prefix path. For example, you can use `http://localhost:10041/api/status` as command URL. Here is a sample configuration to use `/api/` as prefix path:

    events {
    }

    http {
      server {
        listen 10041;

        location /api/ { # <- change this
          groonga on;
          groonga_database /PATH/TO/DATABASE;
        }
      }
    }

## 5.2.1.5. Custom command version

Groonga has Command version mechanism. It is for upgrading groonga commands with backward compatibility.

groonga can change the default command veresion by `--default-command-version` option. Here is a sample command line to use command version 2 as the default command version:

    % groonga --protocol http --default-command-version 2 -d /PATH/TO/DATABASE

groonga-httpd cannot custom the default command version yet. But it will be supported soon. If it is supported, you can provides different command version groonga commands in the same groonga-httpd process. Here is a sample configuration to provide command version 1 commands under `/api/1/` and command version 2 comamnds under `/api/2/`:

    events {
    }

    http {
      server {
        listen 10041;

        groonga_database /PATH/TO/DATABASE;

        location /api/1/ {
          groonga on;
          groonga_default_command_version 1;
        }

        location /api/2/ {
          groonga on;
          groonga_default_command_version 2;
        }
      }
    }

## 5.2.1.6. Multi databases

groonga can use only one database in a process.

groonga-httpd can use one or more databases in a process. Here is a sample configuration to provide `/tmp/db1` database under `/db1/` path and `/tmp/db2` database under `/db2/` path:

    events {
    }

    http {
      server {
        listen 10041;

        location /db1/ {
          groonga on;
          groonga_database /tmp/db1;
        }

        location /db2/ {
          groonga on;
          groonga_database /tmp/db2;
        }
      }
    }

## 5.2.1.7. Authentication

HTTP supports authentications such as basic authentication and digest authentication. It can be used for restricting use of danger command such as shutdown.

groonga doesn’t support any authentications. To restrict use of danger command, other tools such as iptables and reverse proxy are needed.

groonga-httpd supports basic authentication. Here is a sample configuration to restrict use of shutdown command:

    events {
    }

    http {
      server {
        listen 10041;

        groonga_database /PATH/TO/DATABASE;

        location /d/shutdown {
          groonga on;
          auth_basic           "manager is required!";
          auth_basic_user_file "/etc/managers.htpasswd";
        }

        location /d/ {
          groonga on;
        }
      }
    }

## 5.2.1.8. Gzip compression

HTTP supports response compression by gzip with `Content-Encoding: gzip` response header. It can reduce network flow. It is useful for large search response.

groonga doesn’t support compression. To support compression, reverse proxy is needed.

groonga-httpd supports gzip compression. Here is a sample configuration to compress response by gzip:

    events {
    }

    http {
      server {
        listen 10041;

        groonga_database /PATH/TO/DATABASE;

        location /d/ {
          groonga    on;
          gzip       on;
          gzip_types *;
        }
      }
    }

Note that gzip_types * is specified. It’s one of the important configuration. gzip_types specifies gzip target data formats by MIME types. groonga-httpd returns one of JSON, XML or MessagePack format data. But those formats aren’t included in the default value of gzip_types. The default value of gzip_types is text/html.

To compress response data from groonga-httpd by gzip, you need to specify gzip_types * or gzip_types application/json text/xml application/x-msgpack explicitly. gzip_types * is recommended. There are two reasons for it. The first, groonga may support more formats in the future. The second, all requests for the location are processed by groonga. You don’t need to consider about other modules.

## 5.2.1.9. POST

You can load your data by POST JSON data. You need follow the following rules to use loading by POST.

- Content-Type header value must be application/json.

- JSON data is sent as body.

- Table name is specified by query parameter such as `table=NAME`.

Here is an example curl command line that loads two users alice and bob to Users table:

    % curl --data-binary '[{"_key": "alice"}, {"_key": "bob"}]' -H "Content-Type: application/json" "http://localhost:10041/d/load?table=Users"

## 5.2.1.10. HTTPS

TODO

## 5.2.1.11. Access log

TODO

## 5.2.1.12. Upgrading without downtime

TODO