Question

I want to examine an index (and other objects) from psql.

I created the index with:

CREATE INDEX my_index on "my_table" (iso_country_code, type_name, UPPER(name) varchar_pattern_ops);

In psql I used the describe command:

db=> \d+ my_index
Index "public.my_index"
      Column      |          Type          | Storage  | Description 
------------------+------------------------+----------+-------------
 iso_country_code | character varying(3)   | extended | 
 type_name        | character varying(300) | extended | 
 pg_expression_3  | text                   | extended | 
btree, for table "public.my_table"

The expression in the last field of the index says only pg_expression_3. Why does the expression not show up in the psql output?

I can retrieve the table schema including the CREATE INDEX statements using pg_dump:

pg_dump --table my_table --schema-only my_db

Answer 1

It’s clearly pre-9.0 behaviour, take a look into E.5. Release 9.0:

• Show definitions of index columns in \d index_name (Khee Chin)

  The definition is useful for expression indexes.

For previous versions you can still fetch expression manually traversing system catalogs and using pg_get_indexdef(index_oid, column_no, pretty_bool) function, e.g.:

=> SELECT oid FROM pg_catalog.pg_class c WHERE c.relname LIKE 'my_index';
  oid  
-------
 25240
(1 row)
=> SELECT attname, attnum FROM pg_attribute a WHERE a.attrelid = '25240';
     attname      | attnum 
------------------+--------
 iso_country_code |      1
 type_name        |      2
 pg_expression_3  |      3
(3 rows)
=> SELECT pg_get_indexdef(25240, 3, true);
 pg_get_indexdef 
-----------------
 upper(name)
(1 row)