public String dataMigration()

in ignite-tc-helper-web/src/main/java/org/apache/ignite/ci/db/DbMigrations.java [120:238]
80 lines of code
7 McCabe index (conditional complexity)

    public String dataMigration() {
        doneMigrations = doneMigrationsCache();

        int sizeBefore = doneMigrations.size();

        applyDestroyCacheMigration(Old.COMPACT_VISAS_HISTORY_CACHE_NAME);

        applyMigration("InitialFillLatestRunsV3", () -> {
        });

        applyRemoveCache(Old.CURRENT_PR_FAILURES);


        Cache<IssueKey, Issue> issuesCache = IssuesStorage.botDetectedIssuesCache(ignite);
        applyMigration(Old.ISSUES + "-to-" + issuesCache.getName() + "V2", () -> {
            String cacheName = Old.ISSUES;
            IgniteCache<IssueKey, Issue> issuesOldCache = ignite.getOrCreateCache(cacheName);

            int size = issuesOldCache.size();
            if (size > 0) {
                int i = 0;

                Map<IssueKey, Issue> batch = new HashMap<>();

                IgniteDataStreamer<IssueKey, Issue> streamer = ignite.dataStreamer(issuesCache.getName());
                for (Cache.Entry<IssueKey, Issue> entry : issuesOldCache) {
                    batch.put(entry.getKey(), entry.getValue());

                    i++;

                    if (batch.size() >= 300)
                        saveOneBatch(cacheName, size, i, batch, streamer);
                }

                if (!batch.isEmpty())
                    saveOneBatch(cacheName, size, i, batch, streamer);

                System.err.println("Removing data from old cache " + issuesOldCache.getName());

                issuesOldCache.destroy();
            }
        });

        applyDestroyCacheMigration(BUILD_CONDITIONS_CACHE_NAME, BUILD_CONDITIONS_CACHE_NAME);
        applyDestroyCacheMigration(Old.TEAMCITY_BUILD_CACHE_NAME_OLD, Old.TEAMCITY_BUILD_CACHE_NAME_OLD);



        applyDestroyCacheMigration(Old.COMPACT_VISAS_HISTORY_CACHE_NAME, Old.COMPACT_VISAS_HISTORY_CACHE_NAME);


        applyDestroyCacheMigration(Old.SUITE_HIST_CACHE_NAME);
        applyDestroyCacheMigration(Old.BUILD_START_TIME_CACHE_NAME);
        applyDestroyCacheMigration(Old.TEST_HIST_CACHE_NAME);
        applyDestroyCacheMigration(Old.TEST_HIST_CACHE_NAME2);
        applyDestroyCacheMigration(Old.BUILD_START_TIME_CACHE_NAME);
        applyDestroyCacheMigration(Old.BUILD_START_TIME_CACHE_NAME2);

        for (String srvId : serverIds) {
            if(!DONE_MIGRATION_PREFIX.equals(srvId))
                applyDestroyIgnCacheMigration(DONE_MIGRATIONS, srvId);

            applyMigration("Remove-" + Old.RUN_STAT_CACHE, () -> {
                IgniteCache<String, Build> oldBuilds = ignite.getOrCreateCache(ignCacheNme(Old.RUN_STAT_CACHE, srvId));

                oldBuilds.clear();

                oldBuilds.destroy();
            });

            applyDestroyIgnCacheMigration(Old.TEST_OCCURRENCE_FULL, srvId);

            applyDestroyIgnCacheMigration(Old.PROBLEMS, srvId);

            applyDestroyIgnCacheMigration(Old.FINISHED_BUILDS_INCLUDE_FAILED, srvId);
            applyDestroyIgnCacheMigration(RUNNING_BUILDS, srvId);

            applyDestroyIgnCacheMigration(BUILD_QUEUE, srvId);

            applyDestroyIgnCacheMigration(Old.FINISHED_BUILDS_INCLUDE_FAILED, srvId);
            applyDestroyIgnCacheMigration(Old.TEST_OCCURRENCE_FULL, srvId);

            applyDestroyIgnCacheMigration(Old.TESTS, srvId);
            applyDestroyIgnCacheMigration(Old.STAT, srvId);
            applyDestroyIgnCacheMigration(BUILD_STATISTICS, srvId);

            applyDestroyIgnCacheMigration(Old.CHANGE_INFO_FULL, srvId);
            applyDestroyIgnCacheMigration(Old.CHANGES_LIST, srvId);

            applyDestroyIgnCacheMigration(Old.FINISHED_BUILDS, srvId);
            applyDestroyIgnCacheMigration(Old.BUILD_HIST_FINISHED, srvId);
            applyDestroyIgnCacheMigration(Old.BUILD_HIST_FINISHED_OR_FAILED, srvId);
            applyDestroyIgnCacheMigration(Old.BUILD_PROBLEMS, srvId);
            applyDestroyIgnCacheMigration(Old.TEST_FULL, srvId);

            applyDestroyIgnCacheMigration(Old.CONFIGURATIONS, srvId);
            applyDestroyIgnCacheMigration(Old.TESTS_OCCURRENCES, srvId);
            applyDestroyIgnCacheMigration(Old.TEST_REFS, srvId);

            applyDestroyIgnCacheMigration(Old.ISSUES_USAGES_LIST, srvId);
            applyDestroyIgnCacheMigration(Old.CALCULATED_STATISTIC, srvId);
            applyDestroyIgnCacheMigration(Old.BUILDS, srvId);
            applyDestroyIgnCacheMigration(Old.BUILD_RESULTS, srvId);
            applyDestroyIgnCacheMigration(Old.BUILDS_FAILURE_RUN_STAT, srvId);
            applyDestroyIgnCacheMigration(Old.TESTS_RUN_STAT, srvId);

            applyDestroyIgnCacheMigration(Old.LOG_CHECK_RESULT, srvId);
        }

        applyDestroyCacheMigration("issues");
        applyDestroyCacheMigration("digestHist");

        applyDestroyCacheMigration(Old.TEST_HIST_CACHE_NAME_V2_0);
        applyDestroyCacheMigration(Old.SUITE_HIST_CACHE_NAME_V2_0);

        int sizeAfter = doneMigrations.size();
        return (sizeAfter - sizeBefore) + " Migrations done from " + sizeAfter;

    }