https://bugzilla.wikimedia.org/show_bug.cgi?id=2170
--- Comment #16 from Aryeh Gregor <simetrical+wikib...@gmail.com> 2010-04-15
15:08:36 UTC ---
AFAICT, that will have to scan the entire page_random index in the worst case,
e.g., if there are no actual pages in the category. You left out part of the
EXPLAIN -- this is full thing for me on enwiki (on toolserver).
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: page
type: range
possible_keys: page_random
key: page_random
key_len: 8
ref: NULL
rows: 10001064
Extra: Using where
*************************** 2. row ***************************
id: 1
select_type: SIMPLE
table: categorylinks
type: eq_ref
possible_keys: cl_from,cl_timestamp,cl_sortkey
key: cl_from
key_len: 261
ref: enwiki.page.page_id,const
rows: 1
Extra: Using where; Using index
Note rows: 10001064. Try running that on a large database with 'GFDL' replaced
by 'Nonexistent category' and you'll see it takes forever. It's O(N) in number
of pages in the worst case, only acceptable for very small sites.
--
Configure bugmail: https://bugzilla.wikimedia.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
You are on the CC list for the bug.
_______________________________________________
Wikibugs-l mailing list
Wikibugs-l@lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
