# 4.3 Database Lifecycle

_Peios / Advanced Peios / eventd / Log Storage_

> The log store is a file rather than a directory — its path, creation, opening, concurrency and checkpointing.

## 4.3.1 Path

The log store is the file named by `LogStorePath` (§A) — a file path,
unlike the event store's directory. There is no compiled-in default: a
missing or invalid value is a startup failure.

eventd creates the file and any absent parent directories.

## 4.3.2 Creation

A log store that does not exist is created with:

1. WAL mode, `PRAGMA journal_mode=WAL`
2. `PRAGMA synchronous=NORMAL`
3. the `logs` and `metadata` tables (§4.2)
4. the `idx_logs_timestamp`, `idx_logs_origin` and `idx_logs_job_id`
   indexes
5. the `schema_version` and `created_at` entries

## 4.3.3 Opening

1. Open in WAL mode.
2. Set synchronous to NORMAL.
3. Verify the schema version. Missing or unrecognised is a **startup
   failure**; no migration is attempted.
4. Verify structural integrity — required tables and indexes present.
   Failing this, with SQLite reporting no corruption, is a **startup
   failure**.
5. On SQLite reporting corruption, quarantine and replace.

Quarantine works exactly as for a shard (§3.3): the database, `-wal` and
`-shm` files are renamed with a shared `.corrupt.<timestamp_ns>` suffix,
`.N` appended with the lowest positive integer if the name is taken, and
a fresh empty log store is created at the configured path.

The log store is a **required** store. There is no degraded mode in
which eventd runs without one (§8.2), which is why steps 3 and 4 fail
startup rather than proceeding without logs.

## 4.3.4 Concurrency

One read-write connection owned by the log writer thread, and any number
of read-only connections owned by query handlers. WAL mode lets them run
concurrently.

## 4.3.5 Checkpointing

The log writer checkpoints when its write-ahead log reaches
`WalCheckpointPages` (§A), in passive mode, and does not block if
readers hold pages — it keeps writing and retries after a later commit.

Checkpointing matters more here than in the event store, because
`synchronous=NORMAL` makes the checkpoint the durability boundary rather
than merely a space-reclamation event: data committed since the last
checkpoint is what a power cut takes (§9.5).