pkey is not used on productive database

Hi,

I need help to understand the issue on a productive database for a select that takes more time than expected.

1-      On a development database I ran the query (select) and I can see on Explain Analyze pgAdmin use all the indexes and primary keys defined. Dev db has almost 10% of productive data.

2-      On productive database the same query on Explain Analyze from pgAdmin shows a diferent planning, not using a pkey index and instead uses the progressive scan on a million of rows. I can see Primary key is defined for the table on pgAdmin.

What could be the issue on a productive for not use the pkey index for the SELECT?

Cristian C. Bittel