Oracle recursive performance prompt

Oracle uses recursive performance prompts that when you use start with connect by nocycle prior for Recursive data search, www.2cto.com, then the performance of the following two sections of code must be significantly different. Please note that the Code does not look at the following to view my summary // query the number of layers in A folder ID = 12 and the number of files: for the relationship between files B: For the file in the folder positive solution: www.2cto.com select count (0) cou, max (levels) + 1 as levels select C. a1, C. a2, C. levels... from (Select. a1,. a2, level levels // hierarchy from A where. a1 =, and. a2 = .... start with. a1 = 12 connect by nocylce prior. ID =. parentID) C left join B on C. file ID = B. file ID and C. file type = folder error: select count (0) cou, max (levels) + 1 as levels select C. a1, C. a2, C. levels... from (Select. a1,. a2, level levels // hierarchy from A left join B on C. file ID = B. file ID where C. file type = folder and. a1 =, and. a2 = .... start with. a1 = 12 connect by nocylce prior. ID =. parentID) C the difference between the above Code is that www.2cto.com is the correct way: First recursively loop out all the folders under a folder and the wrong way to find the file content in the associated file table is: first, find the folder and file under a folder, and then recursively loop out all the folders and files in the folder under it. This causes the redundant data after association to be cyclically recursive. it has nothing to do with the file. Shouldn't it? The file is also put in recursion.