Hackers, I've discovered that PostgreSQL is able to run following kind of queries in order to change statistic-gathering target for an indexed expression.
ALTER INDEX index_name ALTER COLUMN expr SET STATISTICS stat_target; It's been previously discussed in [1]. I think this should be fixed not just in docs. This is why I've started thread in pgsql-hackers. For me usage of internal column names "expr", "expr1", "expr2" etc. looks weird. And I think we should replace it with a better syntax. What do you think about these options? ALTER INDEX index_name ALTER EXPRESSION 0 SET STATISTICS stat_target; -- Refer expression by its number ALTER INDEX index_name ALTER EXPRESSION (x + y) SET STATISTICS stat_target; -- Refer expression by its definition 1. https://www.postgresql.org/message-id/flat/20150716143149.GO2301%40postgresql.org ------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
