Question

I am attempting to update a boolean column in one table based upon the values in a second.

UPDATE channels
SET contains_photos = TRUE 
WHERE id IN (SELECT unnest(ancestors) 
    FROM channel_tree WHERE id = 11329);

The channel_tree.ancestors column contains an array of channel IDs. The above is failing with the following error:

ERROR: cannot TRUNCATE “channel_tree” because it is being used by active queries in this session

The overriding goal is to set the contains_photos column to true for all ancestors of a given channel. Any one know how best to alleviate this error, or even an alternative solution?

Answer 1

No idea why your error says TRUNCATE. It sounds like you have a trigger or rule that is doing a truncate that we can’t see.

Here’s some alternative ways of doing that same query:

UPDATE channels
SET contains_photos = TRUE 
WHERE id = ANY (SELECT ancestors 
    FROM channel_tree WHERE id = 11329);

Or with a join:

UPDATE channels
SET contains_photos = TRUE
FROM channel_tree
WHERE channels.id = ANY (channel_tree.ancestors)
      AND channel_tree.id = 11329;