devot:eeDevoted to ExpressionEngine

In one case exp_category_posts table is not updated when one would expect it to be updated. Say you have a category which has category id 260. Then you post into that category an entry, which has entry id 3377. Then if you run the code

{exp:query sql="SELECT cat_id FROM exp_category_posts WHERE entry_id = '3377'"}
{cat_id}
{/exp:query}

the category id of the entry will be displayed.

Now say you create a category which has category id 261 and after that you make this category the parent of the category 260.

Having made such changes you would expect that the code above will display both category ids - 260 and 261. But instead it will display only 260 as earlier.

Both category ids will be displayed only in case the entry 3377 will be updated after category 261 was made the parent of the category 260.

I think that such behavior is not good since it goes against the principle that all entries posted into child category are considered to be entries posted into its parent category. I even thought that this behavior might be considered a bug, but Robin disagreed. 

Bug or not, it seems that after some category was made a parent of some other category, the table exp_category_posts should be updated accordingly to reflect the change.

As it is, when you make this kind of category relationship change the change doesn’t “take” in individual entries unless you go through and update every single one.

Now using Retroactive Parents extension you have a means to make your changes retroactive if you choose, that is this extension will make what is needed that for selected parent categories all entries posted into any child category will also be posted into relevant parent category.