DenozordecandCursor
44b94caacf
Runbook для оценки размеров таблиц, seq scan и EXPLAIN перед/после миграций схемы. Co-authored-by: Cursor <cursoragent@cursor.com>
91 lines
2.7 KiB
Markdown
91 lines
2.7 KiB
Markdown
# Диагностика схемы PostgreSQL (EvoBGP)
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Runbook для оценки объёма БД и узких мест **перед** и **после** миграций оптимизации схемы. Выполнять на staging или production read-only сессией.
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## Подключение
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```bash
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psql "$EVOBGP_DATABASE_URL"
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```
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## 1. Размеры таблиц и индексов
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```sql
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SELECT relname,
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pg_size_pretty(pg_total_relation_size(relid)) AS total,
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pg_size_pretty(pg_relation_size(relid)) AS heap,
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pg_size_pretty(pg_indexes_size(relid)) AS indexes
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FROM pg_catalog.pg_statio_user_tables
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ORDER BY pg_total_relation_size(relid) DESC;
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```
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**Ожидание:** лидеры — `revision_materialized_prefix`, `config_revision` (TOAST от preview), JSONB-кэши.
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## 2. Seq scan (горячие таблицы)
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```sql
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SELECT schemaname, relname, seq_scan, seq_tup_read, idx_scan
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FROM pg_stat_user_tables
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WHERE schemaname = 'public'
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ORDER BY seq_tup_read DESC;
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```
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Сброс статистики после деплоя: `SELECT pg_stat_reset();` (только осознанно, теряется baseline).
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## 3. Неиспользуемые индексы
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```sql
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SELECT indexrelname, idx_scan, pg_size_pretty(pg_relation_size(indexrelid)) AS size
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FROM pg_stat_user_indexes
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WHERE schemaname = 'public' AND idx_scan = 0
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ORDER BY pg_relation_size(indexrelid) DESC;
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```
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## 4. Дубликаты в materialized prefixes
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Перед UNIQUE `(revision_id, prefix, community_id, source)`:
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```sql
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SELECT revision_id, prefix, community_id, source, COUNT(*) AS n
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FROM revision_materialized_prefix
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GROUP BY 1, 2, 3, 4
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HAVING COUNT(*) > 1
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LIMIT 20;
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```
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## 5. Шаблон отчёта staging
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| Метрика | До | После | Дата |
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|---------|-----|-------|------|
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| `revision_materialized_prefix` total | | | |
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| `config_revision` total | | | |
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| `module_prefix_snapshot` total | | | |
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| `asn_prefix_cache` total | | | |
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| Top seq_scan table | | | |
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| Unused indexes (count) | | | |
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## 6. EXPLAIN для типовых запросов
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```sql
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-- Список префиксов ревизии (keyset)
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EXPLAIN (ANALYZE, BUFFERS)
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SELECT prefix::text, community_id::text, source
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FROM revision_materialized_prefix
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WHERE revision_id = '<revision-uuid>'::uuid
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ORDER BY id
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LIMIT 51;
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-- Diff added (anti-join)
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EXPLAIN (ANALYZE, BUFFERS)
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SELECT b.prefix::text
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FROM revision_materialized_prefix b
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LEFT JOIN revision_materialized_prefix a
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ON a.revision_id = '<rev-a>'::uuid AND a.prefix = b.prefix
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WHERE b.revision_id = '<rev-b>'::uuid
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AND a.prefix IS NULL
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ORDER BY b.prefix
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LIMIT 5001;
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```
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Цель: Index Scan / Bitmap Index Scan по `(revision_id, …)`, без Seq Scan на больших таблицах.
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