WAL والاستعادة إلى نقطة زمنية

في هذا الدرس

explain how WAL enables recovery to any moment.

الموضوعات المخطط لها

• WAL (write-ahead log): every change is written to the log before the data files; used for crash recovery and replication.
• WAL archiving copies finished WAL segments to safe storage (archive_mode, archive_command).
• PITR: restore a base backup, then replay archived WAL up to a target time (recovery_target_time).
• Recovery time depends on the base backup age and the WAL volume since.
• Settings and signal files changed over versions (recovery.signal since PostgreSQL 12); verify version before recording.