初始化集群，建库，建表，建索引，sort | compare QUERY时都可以指定COLLATE。
用法参考
https://www.postgresql.org/docs/9.5/static/sql-createtable.html
https://www.postgresql.org/docs/9.5/static/collation.html
CREATE DATABASE name
[ [ WITH ] [ OWNER [=] user_name ]
[ TEMPLATE [=] template ]
[ ENCODING [=] encoding ]
[ LC_COLLATE [=] lc_collate ]
[ LC_CTYPE [=] lc_ctype ]
[ TABLESPACE [=] tablespace_name ]
[ ALLOW_CONNECTIONS [=] allowconn ]
[ CONNECTION LIMIT [=] connlimit ] ]
[ IS_TEMPLATE [=] istemplate ]CREATE TABLE test1 (
a text COLLATE "de_DE",
b text COLLATE "es_ES",
...
);CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ [ IF NOT EXISTS ] name ] ON table_name [ USING method ]
( { column_name | ( expression ) } [ COLLATE collation ] [ opclass ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] )
[ WITH ( storage_parameter = value [, ... ] ) ]
[ TABLESPACE tablespace_name ]
[ WHERE predicate ]Character-string data is sorted according to the collation that applies to the column being sorted.
That can be overridden at need by including a COLLATE clause in the expression, for example
ORDER BY mycolumn COLLATE "en_US".
如果你要在一个集群中创建不同的或者与模板库不兼容的LC怎么做呢？
通过template0创建即可，建议你这样做：
新建所有需求的lc库，以它们为模板再创建其他的库。
创建模板库，指定collate
ps PostgreSQL 9.5以下的版本不支持is_template选项，不加即可。
postgres=# create database tmpdb_zh_cn with template template0 lc_collate 'zh_CN.UTF8' lc_ctype 'zh_CN.UTF8' is_template=true;在模板库中创建一些你需要预定义的东西，包括数据等等。
tmpdb_zh_cn=# create extension hstore;
CREATE EXTENSION基于模板库创建数据库。
postgres=# create database db1_zh_cn with template tmpdb_zh_cn;
CREATE DATABASE
tmp | postgres | UTF8 | zh_CN.utf8 | zh_CN.utf8 | | 7360 kB | pg_default |
tmpdb_zh_cn | postgres | UTF8 | zh_CN.UTF8 | zh_CN.UTF8 | | 7360 kB | pg_default |
(8 rows)如果你要删除模板库，需要先把模板库改成普通库再删除。
postgres=# alter database tmpdb_zh_cn is_template false;
ALTER DATABASE
postgres=# drop database tmpdb_zh_cn ;
DROP DATABASE查询PG支持的collate
postgres=# select * from pg_collation ;
collname | collnamespace | collowner | collencoding | collcollate | collctype
-----------------------+---------------+-----------+--------------+-----------------------+-----------------------
default | 11 | 10 | -1 | |
C | 11 | 10 | -1 | C | C
POSIX | 11 | 10 | -1 | POSIX | POSIX
aa_DJ | 11 | 10 | 6 | aa_DJ.utf8 | aa_DJ.utf8
aa_DJ | 11 | 10 | 8 | aa_DJ | aa_DJ
aa_DJ.iso88591 | 11 | 10 | 8 | aa_DJ.iso88591 | aa_DJ.iso88591
......查询列对应的collate
pg_catalog.pg_attribute.attcollation
对应 pg_collation.oid
