Inlude index on hypertable

TimescaleDB and PostgreSQL
1

I need to create index on hypertable that also includes time.

  1. Create table
    create table public.tab1 (mytime timestamptz not null, company int, value int);

  2. Create index with include option
    create index on public.tab1 (mytime desc) include (company);

  3. Convert table to hypertable
    SELECT create_hypertable('public.tab1', 'mytime');

  4. Check table definition and indexes
    \d public.tab1

Output:

                         Table "public.tab1"
 Column  |           Type           | Collation | Nullable | Default
---------+--------------------------+-----------+----------+---------
 mytime  | timestamp with time zone |           | not null |
 company | integer                  |           |          |
 value   | integer                  |           |          |
Indexes:
    "tab1_mytime_company_idx" btree (mytime DESC) INCLUDE (company)
    "tab1_mytime_idx" btree (mytime DESC)
Triggers:
    ts_insert_blocker BEFORE INSERT ON tab1
       FOR EACH ROW EXECUTE FUNCTION _timescaledb_internal.insert_blocker()

TimescaleDB created a new index despite my index already contains exactly the same time column as first column. I expected TimescaleDB to use my index instead of creating new one.

Is there an option TimescaleDB to force usage of already created index?

Now I have:

  • chunks: 5 TB of data
  • timescale index: 1 TB of data
  • my index: 3 TB of data.

If I can force TimescaleDB to use already created index, I could spare 1 TB of data.

EDIT: Instead of “include” index I also tried:
create index on public.tab1 (mytime desc, company);
and TimescaleDB also does not uses already created index.