gitlab-org--gitlab-foss/db/migrate/20180119160751_optimize_ci_job_artifacts.rb
Greg Stark 271e7a3253 Add indexes and change SQL for expired artifacts to deal with artifacts migration efficiently
Artifacts are in the middle of being migrated from ci_builds to
ci_job_artifacts. The expiration date is currently visible in both of
these tables and the test for whether an expired artifact is present
for a job is complex as it requires checking both the of the tables.

Add two new indexes, one on ci_builds.artifacts_expire_at and one on
ci_job_artifacts.expire_at to enable finding expired artifacts
efficiently.

And until the migration is finished, replace the SQL for finding
expired and non-expired artifacts with a hand-crafted UNION ALL based
query instead of using OR. This overcomes a database optimizer
limitation that prevents it from using these indexes.

When the migration is finished the next version should remove this
query and replace it with a much simpler query on just
ci_job_artifacts. See
https://gitlab.com/gitlab-org/gitlab-ce/issues/42561 for followup.
2018-02-08 10:08:52 +01:00

23 lines
851 B
Ruby

# See http://doc.gitlab.com/ce/development/migration_style_guide.html
# for more information on how to write migrations for GitLab.
class OptimizeCiJobArtifacts < ActiveRecord::Migration
include Gitlab::Database::MigrationHelpers
# Set this constant to true if this migration requires downtime.
DOWNTIME = false
disable_ddl_transaction!
def up
# job_id is just here to be a covering index for index only scans
# since we'll almost always be joining against ci_builds on job_id
add_concurrent_index(:ci_job_artifacts, [:expire_at, :job_id])
add_concurrent_index(:ci_builds, [:artifacts_expire_at], where: "artifacts_file <> ''")
end
def down
remove_concurrent_index(:ci_job_artifacts, [:expire_at, :job_id])
remove_concurrent_index(:ci_builds, [:artifacts_expire_at], where: "artifacts_file <> ''")
end
end