Does YugaByte’s SQL support index attributes inside a JSONB column?

Question

I was looking for index attributes inside a JSONB column but was unable to find this in the documentation.

Answer 1

Yes, this is supported, I am adding an example inline here. But unfortunately, we do not seem to have documented this yet. Could you please open a GitHub issue against us? https://github.com/YugaByte/yugabyte-db

I had installed YB on my machine and used ysqlsh to connect to it (you can use psql also) before doing the following.

1. Create a table with a JSONB column

postgres=# CREATE TABLE orders (
                ID serial NOT NULL PRIMARY KEY,
                info json NOT NULL
                );

CREATE TABLE
Time: 1706.060 ms (00:01.706)

2. Create an index on a JSONB attribute

postgres=# CREATE INDEX ON orders((info->'items'->>'product'));

CREATE INDEX
Time: 519.093 ms

Describing the table should show the indexes now:

postgres=# \d+ orders;
                                                Table "public.orders"
 Column |  Type   | Collation | Nullable |              Default               | Storage  | Stats target | Description
--------+---------+-----------+----------+------------------------------------+----------+--------------+-------------
 id     | integer |           | not null | nextval('orders_id_seq'::regclass) | plain    |              |
 info   | json    |           | not null |                                    | extended |              |
Indexes:
    "orders_pkey" PRIMARY KEY, lsm (id HASH)
    "orders_expr_idx" lsm (((info -> 'items'::text) ->> 'product'::text) HASH)

Notice the presence of the following line which shows the index: "orders_expr_idx" lsm (((info -> 'items'::text) ->> 'product'::text) HASH)

3. Insert some data

postgres=# INSERT INTO orders (info)
  VALUES
  ('{ "customer": "John Doe", "items": {"product": "Beer"  ,"qty": 6}}'),
  ('{ "customer": "Lily Bush", "items": {"product": "Diaper","qty": 24}}'),
  ('{ "customer": "Josh William", "items": {"product": "Toy Car","qty": 1}}'),
  ('{ "customer": "Mary Clark", "items": {"product": "Toy Train","qty": 2}}')
  );

4. Query with explain plan

postgres=# EXPLAIN SELECT * from orders WHERE info->'items'->>'product'='Beer';

                                  QUERY PLAN
-------------------------------------------------------------------------------
 Index Scan using orders_expr_idx on orders  (cost=0.00..4.12 rows=1 width=36)
   Index Cond: (((info -> 'items'::text) ->> 'product'::text) = 'Beer'::text)
(2 rows)

Note that per the query plan, this query will use the index to perform the lookup.