The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/10/static/gin-tips.html
Description:
I fail to create multi-column index use following statements:
create table t_gin3 (id int, c1 int, c2 int, c3 int, c4 int, c5 int, c6 int,
c7 int, c8 int, c9 int);
create index idx_t_gin3_1 on t_gin3 using GIN
(c1,c2,c3,c4,c5,c6,c7,c8,c9);
but the document says gin supports multi-columns