[TYPO3-core] RFC #9803: getTreeList causes duplicate entry sql error in cache_treelist

[Christian Kuhn]

Christian Kuhn wrote:
> Problem:
> With revision 3947 a new cache for getTreeList() was added to cache the 
> expensive operation of finding recursive pidlists. The test for an 
> existing cache entry fails if a page has no subpages:
> The "select where identifier=" query returns one row and the field 
> treelist is an empty string. The check for "if 
> (!empty($cacheEntry[0]['treelist'])) {" fails, a new treelist is 
> calculated and the following insert to cache fails with an "Duplicate 
> entry" error.
> 
> Solution:
> Check Select result set for 0 rows instead of empty string of "treelist" 
> field.

FYI: This was solved by #14149 / #14128 / #14129. So this one is dropped.

Thanks
Christian