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author | Alexis Reigel <alexis.reigel.ext@siemens.com> | 2018-09-13 14:45:11 +0300 |
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committer | Alexis Reigel <alexis.reigel.ext@siemens.com> | 2018-09-13 14:45:11 +0300 |
commit | f7ef78a7b5529a345d06b31df067f73c0b6c5833 (patch) | |
tree | bca3527ea6667f03539853e64d187590a5ee2bbe /app | |
parent | b4e2cc4421c8a836ae26867ac3eec35be079590a (diff) |
add a comment to the usage of a anti-pattern query
Diffstat (limited to 'app')
-rw-r--r-- | app/models/ci/runner.rb | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/app/models/ci/runner.rb b/app/models/ci/runner.rb index a041ea1a1c8..45fd15a6211 100644 --- a/app/models/ci/runner.rb +++ b/app/models/ci/runner.rb @@ -31,6 +31,12 @@ module Ci scope :active, -> { where(active: true) } scope :paused, -> { where(active: false) } scope :online, -> { where('contacted_at > ?', contact_time_deadline) } + # The following query using negation is cheaper than using `contacted_at <= ?` + # because there are less runners online than have been created. The + # resulting query is quickly finding online ones and then uses the regular + # indexed search and rejects the ones that are in the previous set. If we + # did `contacted_at <= ?` the query would effectively have to do a seq + # scan. scope :offline, -> { where.not(id: online) } scope :ordered, -> { order(id: :desc) } |