https://bugzilla.wikimedia.org/show_bug.cgi?id=65218
Bug ID: 65218
Summary: slow query
Flow\Formatter\ContributionsQuery::queryRevisions
Product: MediaWiki extensions
Version: master
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: Unprioritized
Component: Flow
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected],
[email protected], [email protected],
[email protected]
Web browser: ---
Mobile Platform: ---
The following query form is starting to run slow on the x1 cluster for flowdb:
flowdb> explain SELECT /* Flow\Formatter\ContributionsQuery::queryRevisions */
* FROM `flow_revision`,`flow_workflow`,`flow_tree_node` WHERE (rev_user_id >
1509667) AND (rev_id < '*�*�\0\0\0\0\0\0') AND workflow_wiki = 'mediawikiwiki'
AND rev_type = 'post-summary' ORDER BY rev_id DESC LIMIT 51\G
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: flow_revision
type: ref
possible_keys: PRIMARY,flow_revision_user,flow_revision_type_id
key: flow_revision_type_id
key_len: 18
ref: const
rows: 55
Extra: Using index condition; Using where; Using filesort
*************************** 2. row ***************************
id: 1
select_type: SIMPLE
table: flow_workflow
type: ref
possible_keys: flow_workflow_lookup
key: flow_workflow_lookup
key_len: 18
ref: const
rows: 649
Extra: Using index condition
*************************** 3. row ***************************
id: 1
select_type: SIMPLE
table: flow_tree_node
type: index
possible_keys: NULL
key: flow_tree_constraint
key_len: 13
ref: NULL
rows: 20065
Extra: Using index
3 rows in set (0.26 sec)
While tolerable now thanks to optimizer choosing index condition pushdown, it
looks like a candidate for future pain. Should it be possible to trigger a
three-way cross join?
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