On PostgreSQL 10.4 on Ubuntu 10.4-2.pgdg16.04+1

select to_tsvector('simple', 'БОЛЬШИЕ БУКВЫ');

returns 'большие':1 'буквы':2

But on postgres 10.3 (installed by brew) on Mac Os High Sierra version 10.13.3 it returns 'БОЛЬШИЕ':1 'БУКВЫ':2 for not english letters

How can I fix it on Mac os?

  • For people who are not literate enough to understand Cyrillic letters, you're questions seems strange. You are inputting capital Cyrillic letters (or so it seems) and are receiving a lower-case result set. But on Mac OS you are receiving an exact match of what you "selected". Why should the result set on the PostgreSQL/Ubuntu combination be better than the PostgreSQL\MacOS combination? Could you explain a bit?
    – John K. N.
    May 28, 2018 at 6:21
  • The same function has to give the same result regardless of OS. Now results are different and I want to understand why. For english letters both versions give lowercased result, but for russian - only ubuntu make it lowercased.
    – Sviatoslav
    May 28, 2018 at 6:59

1 Answer 1


The ability to identify the case of characters depend on the LC_CTYPE of your database, which by default, depends on the environment in which the PostgreSQL instance has been created (with initdb).

For instance, on Ubuntu with PostgreSQL11:

tstc=# show lc_ctype;

tstc=# select to_tsvector('simple', 'БОЛЬШИЕ БУКВЫ');
(1 row)

That's the result you got on your db on MacOS.

But when I'm logged to a different database, with an UTF-8 locale this time:

postgres=# show lc_ctype;
(1 row)

postgres=# select to_tsvector('simple', 'БОЛЬШИЕ БУКВЫ');
 'большие':1 'буквы':2
(1 row)

Now letters are put in lower case.

The fix is to create the database with the correct LC_CTYPE. It cannot be changed afterwards. By default, this setting comes from template1, but it can be overriden by choosing template0, if template1 does not suit you, for instance:

CREATE DATABASE newDB lc_ctype='C.UTF-8' template template0;

The locale specified with lc_ctype must also be supported by the system. Check with locale -a or some equivalent if that doesn't work on MacOS.


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