/*

A backend replacement for https://tools.wmflabs.org/grep/ 

The current implementation of grep is very slow.

But as I've discovered by experimenting with this query,

"REGEXP" is not paricularly fast on its own either.

No, I was actually mistaken; regex works fine if it's set up correctly.

Earlier, I forgot SQL uses C-style strings, 

and so I forgot to escape the "+" properly with 2 "\".

"LIKE" seemed much faster for some reason.

  Starts with "C+": 1 sec vs. 67 sec

  Starts with "N+": 0.36 sec vs. 47.94 sec

  Starts with "U+": 5.44 sec vs. 37.66 sec

*/

/*

SET @regex_pattern = "^U\+";

SET @like_pattern = "U+%";

​

ns = 10

SET @regex_pattern = "^WP";

SET @like_pattern = "WP%";

​

-- 80.59 seconds

SET @regex_pattern = "TV_series\)$";

SET @like_pattern = "%TV_series)";

*/

SET @regex_pattern = "\(";

SET @like_pattern = "%(%";

​

USE enwiki_p; /* "Language" and "Project" */

SELECT page_title

FROM page

WHERE 

  page_namespace = 0 /* Namespace */

  /* AND page_title REGEXP @regex_pattern /* "Pattern" */

  AND page_title LIKE @like_pattern /* More straightforward option for pattern-based searching */  

  /* AND NOT page_is_redirect - negate "Include redirects" */

/* LIMIT 100 /* "Limit the display to the first 100 results" */