PGroonga 4.0.0 - Multilingual fast full text search

Hi,

PGroonga 4.0.0 has been released!

This is the 4th major release of PGroonga! This release has one backward incompatible change.
It removes API (`pgroonga` schema) that was deprecated by PGroonga 2.0.0 released on 2017-08-17.
If you don't use `pgroonga` schema, you can upgrade to 4.0.0 by `ALTER EXTENSION pgroonga UPDATE`
without backward incompatibility. If you are still using `pgroonga` schema, you need to migrate
to the current `pgroonga_XXX` API from `pgroonga.XXX`.

4.0.0 also includes parallel index build support. You can build an index 2x-10x faster.

### About PGroonga

[https://pgroonga.github.io/](https://pgroonga.github.io/)

PGroonga is a PostgreSQL extension that makes PostgreSQL
fast full text search platform for all languages!
It's released under PostgreSQL license.

There are some PostgreSQL extensions that improves full text
search feature of PostgreSQL such as [pg_trgm](https://www.postgresql.org/docs/current/pgtrgm.html).

pg_trgm doesn't support languages that use non-alphanumerics
characters such as Japanese and Chinese.

PGroonga supports all languages, provides rich full text
search related features and is very fast. Because PGroonga
uses [Groonga](https://groonga.org/) that is a full-fledged full text search
engine as backend.

See the following benchmark results for performance:

* [Benchmark result for PGroonga, textsearch and pg_trgm with English Wikipedia](https://pgroonga.github.io/reference/pgroonga-versus-textsearch-and-pg-trgm.html)
* [Benchmark result for PGroonga and pg_bigm with Japanese Wikipedia](https://pgroonga.github.io/reference/pgroonga-versus-pg-bigm.html)

PGroonga also supports JSON search. You can use each value
for condition. You can also perform full text search against
all texts in JSON.

### Users

[https://pgroonga.github.io/users/](https://pgroonga.github.io/users/) lists PGroonga users.
If you're a PGroonga user, please send us your use case!

### Usage

You can use PGroonga without full text search knowledge. You
just create an index and puts a condition into WHERE:

`CREATE INDEX index_name ON table USING pgroonga (column);`
`SELECT * FROM table WHERE column &@~ 'PostgreSQL';`

You can also use `LIKE` to use PGroonga. PGroonga provides a
feature that performs `LIKE` with index. `LIKE` with PGroonga
index is faster than `LIKE` without index. It means that you
can improve performance without changing your application
that uses the following SQL:

`SELECT * FROM table WHERE column LIKE '%PostgreSQL%';`

Are you interested in PGroonga? Please [install](https://pgroonga.github.io/install/) and try
[tutorial](https://pgroonga.github.io/tutorial/). You can know all PGroonga features.

You can install PGroonga easily. Because PGroonga provides
packages for major platforms. There are binaries for
Windows.

Thanks,

--

kou