hstorepostgresql 自带的一个模块，可以在字段内用 key/value 格式存储文档数据。

In choosing which index type to use, GiST or GIN, consider these performance differences:

GIN index lookups are about three times faster than GiST

GIN indexes take about three times longer to build than GiST

GIN indexes are moderately slower to update than GiST indexes, but about 10 times slower if fast-update support was disabled (see Section 54.3.1 for details)

GIN indexes are two-to-three times larger than GiST indexes

As a rule of thumb, GIN indexes are best for static data because lookups are faster. For dynamic data, GiST indexes are faster to update. Specifically, GiST indexes are very good for dynamic data and fast if the number of unique words (lexemes) is under 100,000, while GIN indexes will handle 100,000+ lexemes better but are slower to update.

Note that GIN index build time can often be improved by increasing maintenance_work_mem, while GiST index build time is not sensitive to that parameter.


GINGiST 索引快三倍，但也多花了三倍时间。

postgresql 的其他模块用法可以在官方文档找到

elixir 是运行在erlang vm上的， 结合了ruby的语法，和erlang的OTP机制，目前正在自虐中(^o^)/~

## 说明

rails-footnotes 是一个在development环境下调试rails用的插件， 可以在当前页面的页脚处显示当前的调试信息，如session、实例变量、数据库查询时间等等

## 注意

rails-footnotes默认使用textmate来编辑当前页面文件， 如果要自定义配置编辑器， 请看rails-footnotes文档