It's a query fingerprint (percona calls them query hashes) thing....

WP does queries like

SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN (627329,627330,627331,627332,627333,627334,627335,627336,627337,627338,627339,627340,627341,627342,627343,627344,627345,627346,627347,627348,627349,627350,627351,627352,627353,627354,627355,627356,627357,627358,627359,627360,627361,627362,627363,627364,627365,627366,627367,627368,627369,627370,627371,627372,627373,627374,627375,627376,627377,627378,627379,627380,627381,627382,627383,627384,627385,627386,627387,627388,627389,627390,627391,627392,627393,627394,627395,627396,627397,627398,627399,627400,627401,627402,627403,627404,627405,627406,627407,627408,627409,627410,627411,627412,627413,627414,627415,627416,627417,627418,627419,627420,627421,627422,627423,627424,627425,627426,627427,627428,627429,627430,627431,627432,627433,627434,627435,627436,627437,627438,627439,627440,627441,627442,627443,627444,627445,627446,627447,627448,627449) ORDER BY meta_id ASC

The fingerprint for that is

SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN (?ilonglist?) ORDER BY meta_id ASC

For shorter lists it's ?ilist? instead. The longlists should start at length 21, because WP does a lot of pagination with 20 rows at a time.

And we sometimes get stuff like this, with strings rather than numbers in the queries.

SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN ('627329','627330','627331','627332','627333') ORDER BY meta_id ASC

Right now the fingerprinting turns that into

SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN ('?s?','?s?','?s?','?s?','?s?') ORDER BY meta_id ASC

which means the fingerprint scheme doesn't consolidate similar queries very well.

slist like ilist #12

Description

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions