Draft: Add Migration to Drop Trace Section Tables

⚠ Do not merge. Marked as Draft until re-name is complete. Re-naming the tables first to mitigate the risk of dropping the table. ⚠

What does this MR do?

Currently the GitLab application only creates records in the ci_build_trace_sections table and ci_build_trace_section_names does not read from those tables. See #32565 (closed). Because these are large un-used tables we want to drop them to free up database space.

!66574 (merged) removes the application code that creates the trace sections as well as any trace section-related code (models and factories). See a summary of why we want to remove this code.

We Re-named the tables first to mitigate the risk of dropping the table.

This MR introduces a migration to drop the tables. The up method of this migration drops dep_ci_build_trace_section_names and dep_ci_build_trace_sections. The down method of this migration rebuilds the tables with any indexes and constraints. Related issue: #337209 (closed)

Migration Output

up

▶ rake db:migrate
== 20210909202853 DropTablesCiBuildTraceSection: migrating ====================
-- table_exists?(:dep_ci_build_trace_sections)
   -> 0.0005s
-- drop_table(:dep_ci_build_trace_sections)
   -> 0.0035s
-- table_exists?(:dep_ci_build_trace_section_names)
   -> 0.0006s
-- drop_table(:dep_ci_build_trace_section_names)
   -> 0.0027s
-- execute("DROP FUNCTION IF EXISTS trigger_91dc388a5fe6()")
   -> 0.0012s
== 20210909202853 DropTablesCiBuildTraceSection: migrated (4.1071s) ===========

down

▶ rake db:rollback
== 20210909202853 DropTablesCiBuildTraceSection: reverting ====================
-- table_exists?(:dep_ci_build_trace_section_names)
   -> 0.0007s
-- create_table(:dep_ci_build_trace_section_names, {:id=>:serial, :force=>:cascade})
   -> 0.0106s
-- table_exists?(:dep_ci_build_trace_sections)
   -> 0.0005s
-- create_table(:dep_ci_build_trace_sections, {:id=>false, :primary_key=>[:build_id, :section_name_id], :force=>:cascade})
   -> 0.0059s
-- transaction_open?()
   -> 0.0000s
-- foreign_keys(:dep_ci_build_trace_sections)
   -> 0.0046s
-- execute("ALTER TABLE dep_ci_build_trace_sections\nADD CONSTRAINT fk_19de4e8b30\nFOREIGN KEY (section_name_id)\nREFERENCES dep_ci_build_trace_section_names (id)\nON DELETE CASCADE\nNOT VALID;\n")
   -> 0.0020s
-- execute("SET statement_timeout TO 0")
   -> 0.0009s
-- execute("ALTER TABLE dep_ci_build_trace_sections VALIDATE CONSTRAINT fk_19de4e8b30;")
   -> 0.0022s
-- execute("RESET statement_timeout")
   -> 0.0007s
-- transaction_open?()
   -> 0.0000s
-- foreign_keys(:dep_ci_build_trace_sections)
   -> 0.0028s
-- execute("ALTER TABLE dep_ci_build_trace_sections\nADD CONSTRAINT fk_0ce77d63f1\nFOREIGN KEY (project_id)\nREFERENCES projects (id)\nON DELETE CASCADE\nNOT VALID;\n")
   -> 0.0016s
-- execute("ALTER TABLE dep_ci_build_trace_sections VALIDATE CONSTRAINT fk_0ce77d63f1;")
   -> 0.0109s
-- transaction_open?()
   -> 0.0000s
-- foreign_keys(:dep_ci_build_trace_sections)
   -> 0.0027s
-- execute("ALTER TABLE dep_ci_build_trace_sections\nADD CONSTRAINT fk_6ad94e233b\nFOREIGN KEY (build_id)\nREFERENCES ci_builds (id)\nON DELETE CASCADE\nNOT VALID;\n")
   -> 0.0016s
-- execute("ALTER TABLE dep_ci_build_trace_sections VALIDATE CONSTRAINT fk_6ad94e233b;")
   -> 0.0061s
-- transaction_open?()
   -> 0.0000s
-- foreign_keys(:dep_ci_build_trace_section_names)
   -> 0.0023s
-- execute("ALTER TABLE dep_ci_build_trace_section_names\nADD CONSTRAINT fk_1927c1a7e2\nFOREIGN KEY (project_id)\nREFERENCES projects (id)\nON DELETE CASCADE\nNOT VALID;\n")
   -> 0.0015s
-- execute("ALTER TABLE dep_ci_build_trace_section_names VALIDATE CONSTRAINT fk_1927c1a7e2;")
   -> 0.0021s
-- table_exists?(:dep_ci_build_trace_sections)
   -> 0.0005s
-- column_exists?(:dep_ci_build_trace_sections, :build_id)
   -> 0.0014s
-- column_exists?(:dep_ci_build_trace_sections, :build_id)
   -> 0.0010s
-- columns(:dep_ci_build_trace_sections)
   -> 0.0012s
-- add_column(:dep_ci_build_trace_sections, "build_id_convert_to_bigint", :bigint, {:default=>0, :null=>false})
   -> 0.0013s
== 20210909202853 DropTablesCiBuildTraceSection: reverted (0.1493s) ===========

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