How to use index in simple select

Hi!

Table has index on name column:

        CREATE TABLE firma2.klient
        (
            kood character(12) primary key,
             nimi character(100),
           ...
        );

       CREATE INDEX IF NOT EXISTS klient_nimi_idx
        ON firma2.klient USING btree
        (nimi COLLATE pg_catalog."default" ASC NULLS LAST)
        TABLESPACE pg_default;

Database settings have default values:

    enable_indexonlyscan       on
    enable_indexscan           on
    enable_indexonlyscan       on
    enable_indexscan           on

Query

    SELECT * FROM firma2.klient WHERE nimi='John';

Runs slowly.

    analyze firma2.klient;
    explain analyze select * from firma2.klient where nimi='John'

Shows that index is not used:

    "Seq Scan on klient  (cost=0.00..2287976.20 rows=1 width=4002)
(actual time=12769.987..12769.988 rows=0 loops=1)"
    "  Filter: (nimi = 'John'::bpchar)"
    "  Rows Removed by Filter: 849971"
    "Planning Time: 4.751 ms"
    "Execution Time: 12770.029 ms"

How to force Postgres to use index? It probably worked long time but
suddenly stopped working today.
Re-started whole windows server but problem persists.

Using

PostgreSQL 17.5 on x86_64-windows, compiled by msvc-19.43.34808, 64-bit

in Windows Server 2022 vers 21H2

Andrus.

Posted also in

https://stackoverflow.com/questions/79832965/how-to-use-index-in-simple-select