Drop an unused index on the namespaces table
What does this MR do and why?
Drops the index index_btree_namespaces_traversal_ids on namespaces, which is not used. Reducing the number of indexes on this table is important, as it should help with mitigating the risk of LWLock saturation incidents.
We can see this index has (almost) zero scans - https://thanos-query.ops.gitlab.net/graph?g0.expr=sum%20by%20(type)(rate(pg_stat_user_indexes_idx_scan%7Benv%3D%22gprd%22%2C%20type%3D%22patroni%22%2C%20indexrelname%3D%22index_btree_namespaces_traversal_ids%22%7D%5B30d%5D))&g0.tab=1&g0.stacked=0&g0.range_input=1h&g0.max_source_resolution=0s&g0.deduplicate=1&g0.partial_response=0&g0.store_matches=%5B%5D.
See #425973 (closed) for more details.
Rollback
In case we need to recreate this index manually, here i sth ecommand to do it:
create index concurrently index_btree_namespaces_traversal_ids on namespaces using btree (traversal_ids)It should take less than 8 minutes on production - https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/22809/commands/73596.
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Related to #425973 (closed)