zuul
/
zuul
Code Issues Proposed changes

Restore mysql hint conditional 

This restores the conditional around adding the mysql index hint
for the builds query.  It was thought (incorrectly) that the hint
is now safe in all cases, but it is still the case that it can
slow down the query if some columns appear in the where clause.

Change-Id: Ieafab7e529e305f084ebf8c7844c8fa78da86902
This commit is contained in:
James E. Blair 2024-04-07 09:06:48 -07:00
parent 4a7a534191
commit 014717bde6
1 changed files with 19 additions and 4 deletions
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23
zuul/driver/sql/sqlconnection.py
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@ -177,8 +177,20 @@ class DatabaseSession(object):
self.connection.buildModel.id.label('inner_id')).\
distinct().\
join(self.connection.buildSetModel).\
join(self.connection.refModel).\
with_hint(build_table, 'USE INDEX (PRIMARY)', 'mysql')
join(self.connection.refModel)
# If the query planner isn't able to reduce either the number
# of rows returned by the buildset or build tables, then it
# tends to produce a very slow query. This hint produces
# better results, but only in those cases. When we can narrow
# things down with indexes, it's better to omit the hint.
# job_name is a tricky one. It is indexed, but if there are a
# lot of rows, it is better to include the hint, but if there
# are few, it is better to not include it. We include the hint
# regardless of whether job_name is specified (optimizing for
# the more common case).
if not (project or change or uuid):
q = q.with_hint(build_table, 'USE INDEX (PRIMARY)', 'mysql')
# Avoid joining the provides table unless necessary; postgres
# has created some poor query plans in that case. Currently
@ -318,8 +330,11 @@ class DatabaseSession(object):
self.connection.buildModel.end_time.label('inner_end_time')).\
distinct().\
join(self.connection.buildSetModel).\
join(self.connection.refModel).\
with_hint(build_table, 'USE INDEX (PRIMARY)', 'mysql')
join(self.connection.refModel)
# See note above about the hint.
if not (project):
q = q.with_hint(build_table, 'USE INDEX (PRIMARY)', 'mysql')
q = self.listFilter(q, buildset_table.c.tenant, tenant)
q = self.listFilter(q, buildset_table.c.pipeline, pipeline)