Mroonga 12.10 has been released!

2022-11-29

Mroonga 12.10 has been released!

Mroonga is a MySQL storage engine that supports fast fulltext search and geolocation search. It is CJK ready. It uses Groonga as a storage and fulltext search engine.

How to install: Install
How to upgrade: Upgrade guide

Changes

The main changes are as follows.

Improvements

CentOS, AlmaLinux Added support for MariaDB 10.3.37, 10.4.27, 10.5.18, 10.6.11, 10.7.7, 10.8.6, 10.9.4.
CentOS, AlmaLinux Added support for Percona Server 8.0.30-22.
CentOS Added support for Percona Server 5.7.40-43.
Windows Added support for MariaDB 10.7, 10.8, 10.9.
Windows Dropped support for 32bit versions.

Because recent MariaDB can't be built for 32bit Windows, and the official packages for 32bit don't exist.

mroonga_highlight_html() Added new parameters: open_tag and close_tag.

Now we can specify a tag for highlighting with open_tag and close_tag.

It was inconvinient for us to unable specifying different tags or changing class because the fixed tag <span class="keyword">...</span> was used. Now, this new parameter provides more convenience for us because it allows specifying tags to highlight, such as <mark>...</mark>.

SELECT mroonga_highlight_html('Mroonga is the Groonga based storage engine.', 'groonga',
                              '<mark>' AS open_tag, '</mark>' AS close_tag) AS highlighted;

-- +-----------------------------------------------------------+
-- | highlighted                                               |
-- +-----------------------------------------------------------+
-- | Mroonga is the <mark>Groonga</mark> based storage engine. |
-- +-----------------------------------------------------------+

Please refer to mroonga_highlight_html() for details.

Added support for reference count mode.

Though this feature can keep fixed memory usage, its performance would be dropped. Thus, memory increments should be first consideration before using this feature.

The reference count mode is used with table_open_cache of MySQL.

MySQL can cache specified number of tables with table_open_cache. Groonga's object would not be released because the cached tables are still in use.

The tables with low usage would be closed if number of open tables is larger than number specified with table_open_cache. Groonga objects would be released at the same time with table closing if the reference count mode is enabled.

These are how the reference count mode keep fixed memory usage.

For actual use, we need to adjust balance between memory usage and perfomance with value of table_open_cache while checking memory usage and value of status variables Open_tables. Because this feature can keep fixed memory usage, but its performance would be dropped.

There is how to check Open_tables as follows.
```
SHOW GLOBAL STATUS LIKE 'Open_tables';
-- +---------------+-------+
-- | Variable_name | Value |
-- +---------------+-------+
-- | Open_tables   | 643   |
-- +---------------+-------+
```
Normally, all of tables in use are cached by setting table_open_cache larger than Open_tables. However, if there is limited memory, memory usage would be decreased by releasing memory for tables with low usage dropping from the cache. In order to releasing tables with low usage from the cache, table_open_cache should be set smaller than Open_tables. The smaller Open Tables setting , the more tables dropping from the cache. As cache is released, memory usage decrease, yet performance become worse due to reopen tables. The smaller table_open_cache, the more necessary to reopen tables. table_open_cache should set as much value as only to reaching memory tolerance.

In order to enable reference count mode, we need to specify values in my.cnf as follows;
```
loose-mroonga-enable-reference-count = ON
```
Note: The reference count mode would not be enabled with variables after booting MySQL. It is necesarry to specify values in my.cnf.
```
SET GLOBAL mroonga_enable_reference_count = ON
```

Fixes

Fixed a bug that Mroonga for Windows does not bundle groonga-normalizer-mysql.

It was false announcement in 12.09 that groonga-normalizer-mysql is bundled in.

Conclusion

Please refer to release note about the detail of changes in this release.

Let's search by Mroonga!

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