Is there a way I can determine if index deduplication is active on the indexes?
I inherited a database that has been upgraded from v12 to 13 to 16. I checked the upgrade scripts used and there was not a reindex run during the upgrades. Someone may have run a reindex over the years.
Then I can reindex if needed those indexes created prior to v13.
I looked in pg_index but I did not find a field. Perhaps it is in a flag in indoption but I did not see that in the definition in src/include/catalog/pg_index.h. I see the allequalimage flag to protect the conditions described in the documentation. But I do not know if that flag is reused to signify this index has been evaluated for deduplication due to a reindex and it is safe. A comment in _bt_allequalimage in src/backend/access/nbtree/nbtutils.c says the flag is stored in the index meta page. Is there a way to find index deduplication is active for an index from a postgresql client?
