README.md

@@ -117,7 +117,7 @@ routewatch/
     - Signal handlers registered for graceful shutdown
 
 2. **Initialization** (`internal/routewatch/app.go`)
-    - Database created with SQLite schema (WAL mode, 3GB cache)
+    - Database created with SQLite schema (WAL mode, page caches as in "Memory")
     - Message handlers registered with the streamer
     - HTTP server started on configured port
 
@@ -170,8 +170,8 @@ routewatch/
 ```sql
 -- Core tables
 asns(id, number, handle, description, first_seen, last_seen)
-prefixes_v4(id, prefix, mask_length, first_seen, last_seen)
-prefixes_v6(id, prefix, mask_length, first_seen, last_seen)
+prefixes_v4(prefix, first_seen)
+prefixes_v6(prefix, first_seen)
 
 -- Live routing tables (one per IP version)
 live_routes_v4(id, prefix, mask_length, origin_asn, peer_ip, as_path,
@@ -215,8 +215,12 @@ data it tracks. The image sets ceilings that keep it inside a 5 GiB container.
 Budget:
 
 - Go heap: a 1.5 GiB soft limit (`GOMEMLIMIT=1536MiB`, set in the image).
-- SQLite: at most 640 MiB of page cache across the connection pool (64 MiB per
-  connection, 10 connections) and a 1.5 GiB hard heap limit for the C library.
+- SQLite: 1 GiB of page cache for the one connection every write uses, which
+  keeps the pages the route writes touch from one batch to the next, and 16 MiB
+  for each of the 9 reading connections, whose cache SQLite empties whenever
+  another connection has written: about 1.15 GiB in all. A 1.5 GiB soft heap
+  limit sits above the caches, so it does not shrink them, and a 2 GiB hard heap
+  limit caps the C library.
 - glibc allocator: the SQLite C library runs on glibc `malloc`, which frees
   page-cache chunks back to per-arena free lists rather than to the kernel, so
   process RSS tracks the high-water mark of those arenas, not SQLite's live
@@ -226,6 +230,9 @@ Budget:
   database writes are already serialized.
 - About 0.2 GiB for everything else in the runtime.
 
+The ceilings add up to 3.7 GiB: the Go heap's 1.5 GiB, SQLite's 2 GiB and the
+0.2 GiB for the rest.
+
 Run the container with a memory limit of 5 GiB and swap disabled:
 
 ```bash
@@ -244,8 +251,8 @@ What happens at each limit:
 
 - Go soft limit: as the heap approaches `GOMEMLIMIT`, the runtime runs garbage
   collection more aggressively rather than growing further.
-- SQLite: at a 1 GiB soft heap limit it recycles its page cache instead of
-  allocating more; at the 1.5 GiB hard heap limit a statement fails with an
+- SQLite: at the 1.5 GiB soft heap limit it recycles its page cache instead of
+  allocating more; at the 2 GiB hard heap limit a statement fails with an
   out-of-memory error, and the handler logs it and drops that batch. The process
   keeps running.
 - Handler queues: each of the four handler queues holds at most 20,000 messages.

internal/database/counts_internal_test.go

@@ -29,7 +29,6 @@ func mkV4Route(t *testing.T, prefix string, asn int, ts time.Time) *LiveRoute {
 	}
 
 	return &LiveRoute{
-		ID:          uuid.New(),
 		Prefix:      prefix,
 		MaskLength:  maskLength,
 		IPVersion:   ipVersionV4,
@@ -44,7 +43,6 @@ func mkV4Route(t *testing.T, prefix string, asn int, ts time.Time) *LiveRoute {
 // mkV6Route builds an IPv6 live route.
 func mkV6Route(prefix string, asn int, ts time.Time) *LiveRoute {
 	return &LiveRoute{
-		ID:          uuid.New(),
 		Prefix:      prefix,
 		MaskLength:  32,
 		IPVersion:   ipVersionV6,

internal/database/database.go

@@ -1,25 +1,27 @@
 package database
 
 import (
+	"cmp"
 	"context"
 	"database/sql"
 	_ "embed"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"maps"
 	"math/rand/v2"
 	"net"
 	"net/netip"
 	"os"
 	"path/filepath"
 	"runtime"
+	"slices"
 	"sync"
 	"time"
 
 	"git.eeqj.de/sneak/routewatch/internal/config"
 	"git.eeqj.de/sneak/routewatch/internal/logger"
 	"git.eeqj.de/sneak/routewatch/pkg/asinfo"
-	"github.com/google/uuid"
 	_ "github.com/mattn/go-sqlite3" // CGO SQLite driver
 )
 
@@ -52,20 +54,31 @@ const (
 	minLookupMaskLengthV6 = 16
 )
 
-// SQLite memory tuning. cache_size and busy_timeout go in the DSN so every
-// pooled connection gets them; the heap limits are process-wide and set once.
+// SQLite memory tuning (README "Memory"). cache_size and busy_timeout go in the
+// DSN so every pooled connection gets them; the connection kept for writing
+// then sets its own cache size. The heap limits are process-wide and set once.
 const (
-	// sqliteCacheSizeKiB is the per-connection page cache; negative means KiB.
-	// -65536 = 64 MiB, so at most 640 MiB across the 10-connection pool.
-	sqliteCacheSizeKiB = -65536
+	// maxConns is the size of the connection pool: the connection kept for
+	// writing and 9 reading connections.
+	maxConns = 10
+	// sqliteReadCacheSizeKiB is the page cache of each reading connection;
+	// negative means KiB. -16384 = 16 MiB, at most 144 MiB for the 9. A reading
+	// connection's cache is emptied whenever another connection has written
+	// since its last read, many times a minute, so a large one is wasted.
+	sqliteReadCacheSizeKiB = -16384
+	// sqliteWriteCacheSizeKiB is the page cache of the connection kept for
+	// writing, -1048576 = 1 GiB. It keeps its pages from one write to the next,
+	// so the index pages the route writes touch stay in memory.
+	sqliteWriteCacheSizeKiB = -1048576
 	// sqliteBusyTimeoutMs is how long a connection waits on a locked database.
 	sqliteBusyTimeoutMs = 5000
-	// sqliteSoftHeapLimitBytes (1 GiB) makes SQLite recycle its cache rather
-	// than allocate once its C heap passes this size.
-	sqliteSoftHeapLimitBytes = 1073741824
-	// sqliteHardHeapLimitBytes (1.5 GiB) fails a statement with SQLITE_NOMEM
+	// sqliteSoftHeapLimitBytes (1.5 GiB) makes SQLite recycle its cache rather
+	// than allocate once its C heap passes this size. It is above the caches
+	// together, so it does not shrink them.
+	sqliteSoftHeapLimitBytes = 1610612736
+	// sqliteHardHeapLimitBytes (2 GiB) fails a statement with SQLITE_NOMEM
 	// instead of growing the C heap without bound.
-	sqliteHardHeapLimitBytes = 1610612736
+	sqliteHardHeapLimitBytes = 2147483648
 )
 
 // Settings of the ANALYZE that Analyze runs.
@@ -106,7 +119,10 @@ var (
 
 // Database manages the SQLite database connection and operations.
 type Database struct {
-	db       *sql.DB
+	db *sql.DB
+	// writer is the connection kept for writing, taken from db when the
+	// database opens. Every write uses it while holding mu.
+	writer   *sql.Conn
 	logger   *logger.Logger
 	path     string
 	mu       sync.Mutex
@@ -144,7 +160,7 @@ func New(cfg *config.Config, logger *logger.Logger) (*Database, error) {
 		"file:%s?_cache_size=%d&_synchronous=OFF&_busy_timeout=%d"+
 			"&_auto_vacuum=incremental&_journal_mode=WAL&_txlock=immediate",
 		dbPath,
-		sqliteCacheSizeKiB,
+		sqliteReadCacheSizeKiB,
 		sqliteBusyTimeoutMs,
 	)
 
@@ -153,20 +169,34 @@ func New(cfg *config.Config, logger *logger.Logger) (*Database, error) {
 		return nil, fmt.Errorf("failed to open database: %w", err)
 	}
 
-	err = db.PingContext(context.Background())
+	ctx := context.Background()
+
+	err = db.PingContext(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("failed to ping database: %w", err)
 	}
 
 	// Set connection pool parameters
 	// Multiple connections allow concurrent reads while writes are serialized
-	const maxConns = 10
 	db.SetMaxOpenConns(maxConns)
 	db.SetMaxIdleConns(maxConns)
 	db.SetConnMaxLifetime(0)
 
+	writer, err := db.Conn(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open the writing connection: %w", err)
+	}
+
+	_, err = writer.ExecContext(ctx,
+		fmt.Sprintf("PRAGMA cache_size=%d", sqliteWriteCacheSizeKiB))
+	if err != nil {
+		return nil, fmt.Errorf("failed to set the writing connection's cache: %w",
+			err)
+	}
+
 	database := &Database{
-		db: db, logger: logger, path: dbPath, counts: &liveCounts{},
+		db: db, writer: writer, logger: logger, path: dbPath,
+		counts: &liveCounts{},
 	}
 
 	err = database.Initialize()
@@ -188,10 +218,11 @@ func New(cfg *config.Config, logger *logger.Logger) (*Database, error) {
 // Initialize creates the database schema if it doesn't exist.
 func (d *Database) Initialize() error {
 	// Set SQLite pragmas for performance. Per-connection settings (cache_size,
-	// synchronous, busy_timeout, journal_mode) live in the DSN; temp_store is
-	// left at its default so DISTINCT temp B-trees spill to disk instead of C
-	// heap. The heap limits below are process-wide, so setting them once here is
-	// enough for the whole pool.
+	// synchronous, busy_timeout, journal_mode) live in the DSN, and New sets the
+	// writing connection's cache_size; temp_store is left at its default so
+	// DISTINCT temp B-trees spill to disk instead of C heap. The heap limits
+	// below are process-wide, so setting them once here is enough for the whole
+	// pool.
 	pragmas := []string{
 		"PRAGMA journal_mode=WAL", // Write-Ahead Logging
 		fmt.Sprintf("PRAGMA soft_heap_limit=%d", sqliteSoftHeapLimitBytes),
@@ -208,7 +239,7 @@ func (d *Database) Initialize() error {
 	// Run WAL checkpoint on startup to consolidate any existing WAL
 	var walPages, checkpointedPages, movedPages int
 
-	err := d.db.QueryRowContext(context.Background(),
+	err := d.writer.QueryRowContext(context.Background(),
 		"PRAGMA wal_checkpoint(TRUNCATE)",
 	).Scan(&walPages, &checkpointedPages, &movedPages)
 	if err != nil {
@@ -229,35 +260,47 @@ func (d *Database) Initialize() error {
 	return nil
 }
 
-// Close closes the database connection.
+// Close closes the writing connection and then the connection pool.
 func (d *Database) Close() error {
-	return d.db.Close()
+	return errors.Join(d.writer.Close(), d.db.Close())
 }
 
-// A live-route upsert is an UPDATE followed, only when no row matched, by an
-// INSERT. A live route is keyed by prefix and peer, so an announcement replaces
-// the peer's route for the prefix whatever its origin AS. The UPDATE's
-// rows-affected count (1 for an existing key, 0 for a new one) is what lets the
-// in-memory route counters stay exact without a COUNT(*). Callers hold the
-// database write lock, so no other writer can insert the same key between the
-// two statements. The id column is set only on INSERT, so an updated route
-// keeps its original id, exactly as the previous ON CONFLICT upsert did.
+// A live-route upsert sets the origin AS of the peer's route for the prefix
+// when the announcement changes it, then updates the rest of the route, and
+// inserts the route only when that update matched no row. A live route is keyed
+// by prefix and peer, so an announcement replaces the peer's route for the
+// prefix whatever its origin AS. The update's rows-affected count (1 for an
+// existing key, 0 for a new one) is what lets the in-memory route counters stay
+// exact without a COUNT(*). Callers hold the database write lock, so no other
+// writer can insert the same key between the statements.
+//
+// SQLite rewrites a row's entry in every index on a column an UPDATE sets, even
+// when the value stays the same, so the update sets only the columns that
+// change: mask_length follows from the prefix, and origin_asn has a statement
+// of its own that changes nothing when the origin AS stays the same, as it
+// mostly does.
 const (
+	updateLiveRouteOriginV4SQL = `UPDATE live_routes_v4 SET origin_asn = ?
+		WHERE prefix = ? AND peer_ip = ? AND origin_asn != ?`
+
 	updateLiveRouteV4SQL = `UPDATE live_routes_v4
-		SET mask_length = ?, origin_asn = ?, as_path = ?, next_hop = ?,
-		last_updated = ? WHERE prefix = ? AND peer_ip = ?`
+		SET as_path = ?, next_hop = ?, last_updated = ?
+		WHERE prefix = ? AND peer_ip = ?`
 
 	insertLiveRouteV4SQL = `INSERT INTO live_routes_v4
-		(id, prefix, mask_length, origin_asn, peer_ip, as_path, next_hop,
-		last_updated) VALUES (?, ?, ?, ?, ?, ?, ?, ?)`
+		(prefix, mask_length, origin_asn, peer_ip, as_path, next_hop,
+		last_updated) VALUES (?, ?, ?, ?, ?, ?, ?)`
+
+	updateLiveRouteOriginV6SQL = `UPDATE live_routes_v6 SET origin_asn = ?
+		WHERE prefix = ? AND peer_ip = ? AND origin_asn != ?`
 
 	updateLiveRouteV6SQL = `UPDATE live_routes_v6
-		SET mask_length = ?, origin_asn = ?, as_path = ?, next_hop = ?,
-		last_updated = ? WHERE prefix = ? AND peer_ip = ?`
+		SET as_path = ?, next_hop = ?, last_updated = ?
+		WHERE prefix = ? AND peer_ip = ?`
 
 	insertLiveRouteV6SQL = `INSERT INTO live_routes_v6
-		(id, prefix, mask_length, origin_asn, peer_ip, as_path, next_hop,
-		last_updated) VALUES (?, ?, ?, ?, ?, ?, ?, ?)`
+		(prefix, mask_length, origin_asn, peer_ip, as_path, next_hop,
+		last_updated) VALUES (?, ?, ?, ?, ?, ?, ?)`
 )
 
 // Before a new route is inserted and after a route is deleted, the write looks
@@ -278,15 +321,22 @@ const (
 		WHERE prefix = ? AND peer_ip = ?`
 )
 
-// upsertRouteRow updates a live route with the update statement of its IP
-// version's table, inserting it when no row matched. It reports whether a new
-// row was inserted and whether that row is the first live route for its prefix.
+// upsertRouteRow updates a live route with the origin and update statements of
+// its IP version's table, inserting it when no row matched. It reports whether
+// a new row was inserted and whether that row is the first live route for its
+// prefix.
 func upsertRouteRow(
-	ctx context.Context, upd, ins, has *sql.Stmt, route *LiveRoute,
+	ctx context.Context, setOrigin, upd, ins, has *sql.Stmt, route *LiveRoute,
 	pathJSON string,
 ) (bool, bool, error) {
-	res, err := upd.ExecContext(ctx, route.MaskLength, route.OriginASN, pathJSON,
-		route.NextHop, route.LastUpdated, route.Prefix, route.PeerIP)
+	_, err := setOrigin.ExecContext(ctx, route.OriginASN, route.Prefix,
+		route.PeerIP, route.OriginASN)
+	if err != nil {
+		return false, false, err
+	}
+
+	res, err := upd.ExecContext(ctx, pathJSON, route.NextHop, route.LastUpdated,
+		route.Prefix, route.PeerIP)
 	if err != nil {
 		return false, false, err
 	}
@@ -307,9 +357,9 @@ func upsertRouteRow(
 		return false, false, err
 	}
 
-	_, err = ins.ExecContext(ctx, route.ID.String(), route.Prefix,
-		route.MaskLength, route.OriginASN, route.PeerIP, pathJSON,
-		route.NextHop, route.LastUpdated)
+	_, err = ins.ExecContext(ctx, route.Prefix, route.MaskLength,
+		route.OriginASN, route.PeerIP, pathJSON, route.NextHop,
+		route.LastUpdated)
 	if err != nil {
 		return false, false, err
 	}
@@ -327,13 +377,23 @@ func upsertRoutesInTable(
 		return 0, nil, nil
 	}
 
-	family, updateSQL, insertSQL, lookupSQL := ipv4Family, updateLiveRouteV4SQL,
-		insertLiveRouteV4SQL, prefixHasLiveRouteV4SQL
+	family, originSQL, updateSQL := ipv4Family, updateLiveRouteOriginV4SQL,
+		updateLiveRouteV4SQL
+	insertSQL, lookupSQL := insertLiveRouteV4SQL, prefixHasLiveRouteV4SQL
+
 	if ipVersion == ipVersionV6 {
-		family, updateSQL, insertSQL, lookupSQL = ipv6Family,
-			updateLiveRouteV6SQL, insertLiveRouteV6SQL, prefixHasLiveRouteV6SQL
+		family, originSQL, updateSQL = ipv6Family, updateLiveRouteOriginV6SQL,
+			updateLiveRouteV6SQL
+		insertSQL, lookupSQL = insertLiveRouteV6SQL, prefixHasLiveRouteV6SQL
 	}
 
+	setOrigin, err := tx.PrepareContext(ctx, originSQL)
+	if err != nil {
+		return 0, nil, fmt.Errorf("failed to prepare %s origin statement: %w",
+			family, err)
+	}
+	defer func() { _ = setOrigin.Close() }()
+
 	upd, err := tx.PrepareContext(ctx, updateSQL)
 	if err != nil {
 		return 0, nil, fmt.Errorf("failed to prepare %s update statement: %w",
@@ -365,8 +425,8 @@ func upsertRoutesInTable(
 			return 0, nil, fmt.Errorf("failed to encode AS path: %w", err)
 		}
 
-		inserted, newPrefix, err := upsertRouteRow(ctx, upd, ins, has, route,
-			string(pathJSON))
+		inserted, newPrefix, err := upsertRouteRow(ctx, setOrigin, upd, ins, has,
+			route, string(pathJSON))
 		if err != nil {
 			return 0, nil, fmt.Errorf("failed to upsert route %s: %w",
 				route.Prefix, err)
@@ -400,9 +460,18 @@ func (d *Database) UpsertLiveRouteBatch(routes []*LiveRoute) error {
 	}
 	defer d.rollback(tx)
 
+	// The rows are written in key order, peer then prefix, so consecutive writes
+	// land on the same index pages. The sort is stable, so of two updates of
+	// one route the later one is still written last.
+	sorted := slices.SortedStableFunc(slices.Values(routes),
+		func(a, b *LiveRoute) int {
+			return cmp.Or(cmp.Compare(a.PeerIP, b.PeerIP),
+				cmp.Compare(a.Prefix, b.Prefix))
+		})
+
 	var routesV4, routesV6 []*LiveRoute
 
-	for _, route := range routes {
+	for _, route := range sorted {
 		if route.IPVersion == ipVersionV4 {
 			routesV4 = append(routesV4, route)
 		} else {
@@ -546,9 +615,17 @@ func (d *Database) DeleteLiveRouteBatch(deletions []LiveRouteDeletion) error {
 	}
 	defer d.rollback(tx)
 
+	// The rows are deleted in key order, peer then prefix, as
+	// UpsertLiveRouteBatch writes them.
+	sorted := slices.SortedFunc(slices.Values(deletions),
+		func(a, b LiveRouteDeletion) int {
+			return cmp.Or(cmp.Compare(a.PeerIP, b.PeerIP),
+				cmp.Compare(a.Prefix, b.Prefix))
+		})
+
 	var deletionsV4, deletionsV6 []LiveRouteDeletion
 
-	for _, del := range deletions {
+	for _, del := range sorted {
 		if del.IPVersion == ipVersionV4 {
 			deletionsV4 = append(deletionsV4, del)
 		} else {
@@ -683,46 +760,11 @@ func (d *Database) DeleteLiveRoutesOfPeer(peerIP string) (int, error) {
 	return int(deletedV4 + deletedV6), nil
 }
 
-// upsertPrefix updates the last_seen time of prefix with the statements of its
-// IP version's table, inserting the prefix when it is new. It reports whether
-// it inserted it.
-func upsertPrefix(
-	ctx context.Context, selectStmt, updateStmt, insertStmt *sql.Stmt,
-	prefix string, timestamp time.Time,
-) (bool, error) {
-	var id string
-
-	err := selectStmt.QueryRowContext(ctx, prefix).Scan(&id)
-
-	switch {
-	case err == nil:
-		// Prefix exists, update last_seen
-		_, err = updateStmt.ExecContext(ctx, timestamp, prefix)
-		if err != nil {
-			return false, fmt.Errorf("failed to update prefix %s: %w",
-				prefix, err)
-		}
-
-		return false, nil
-	case errors.Is(err, sql.ErrNoRows):
-		// Prefix doesn't exist, create it
-		_, err = insertStmt.ExecContext(ctx, generateUUID().String(), prefix,
-			timestamp, timestamp)
-		if err != nil {
-			return false, fmt.Errorf("failed to insert prefix %s: %w",
-				prefix, err)
-		}
-
-		return true, nil
-	default:
-		return false, fmt.Errorf("failed to query prefix %s: %w", prefix, err)
-	}
-}
-
-// upsertPrefixesInTable updates the last_seen time of prefixes, all of one IP
-// version, in the prefix table of that version, inserting the ones that are
-// new. It returns how many it inserted.
-func upsertPrefixesInTable(
+// insertPrefixesInTable inserts the prefixes, all of one IP version, that the
+// prefix table of that version does not hold yet, each first seen at its time
+// in prefixes. A prefix already stored is left as it is. It returns how many it
+// inserted.
+func insertPrefixesInTable(
 	ctx context.Context, tx *loggingTx, prefixes map[string]time.Time,
 	ipVersion int,
 ) (int, error) {
@@ -731,33 +773,15 @@ func upsertPrefixesInTable(
 	}
 
 	family := ipv4Family
-	selectSQL := "SELECT id FROM prefixes_v4 WHERE prefix = ?"
-	updateSQL := "UPDATE prefixes_v4 SET last_seen = ? WHERE prefix = ?"
-	insertSQL := "INSERT INTO prefixes_v4 (id, prefix, first_seen, last_seen) " +
-		"VALUES (?, ?, ?, ?)"
+	insertSQL := "INSERT INTO prefixes_v4 (prefix, first_seen) VALUES (?, ?) " +
+		"ON CONFLICT (prefix) DO NOTHING"
 
 	if ipVersion == ipVersionV6 {
 		family = ipv6Family
-		selectSQL = "SELECT id FROM prefixes_v6 WHERE prefix = ?"
-		updateSQL = "UPDATE prefixes_v6 SET last_seen = ? WHERE prefix = ?"
-		insertSQL = "INSERT INTO prefixes_v6 (id, prefix, first_seen, last_seen) " +
-			"VALUES (?, ?, ?, ?)"
+		insertSQL = "INSERT INTO prefixes_v6 (prefix, first_seen) VALUES (?, ?) " +
+			"ON CONFLICT (prefix) DO NOTHING"
 	}
 
-	selectStmt, err := tx.PrepareContext(ctx, selectSQL)
-	if err != nil {
-		return 0, fmt.Errorf("failed to prepare %s select statement: %w",
-			family, err)
-	}
-	defer func() { _ = selectStmt.Close() }()
-
-	updateStmt, err := tx.PrepareContext(ctx, updateSQL)
-	if err != nil {
-		return 0, fmt.Errorf("failed to prepare %s update statement: %w",
-			family, err)
-	}
-	defer func() { _ = updateStmt.Close() }()
-
 	insertStmt, err := tx.PrepareContext(ctx, insertSQL)
 	if err != nil {
 		return 0, fmt.Errorf("failed to prepare %s insert statement: %w",
@@ -767,14 +791,21 @@ func upsertPrefixesInTable(
 
 	var newPrefixes int
 
-	for prefix, timestamp := range prefixes {
-		inserted, err := upsertPrefix(ctx, selectStmt, updateStmt, insertStmt,
-			prefix, timestamp)
+	// The rows are written in key order, as UpsertLiveRouteBatch writes routes.
+	for _, prefix := range slices.Sorted(maps.Keys(prefixes)) {
+		res, err := insertStmt.ExecContext(ctx, prefix, prefixes[prefix])
 		if err != nil {
-			return 0, err
+			return 0, fmt.Errorf("failed to insert prefix %s: %w", prefix, err)
 		}
 
-		if inserted {
+		// One row for a new prefix, none for one already stored.
+		inserted, err := res.RowsAffected()
+		if err != nil {
+			return 0, fmt.Errorf("failed to count inserted prefix %s: %w",
+				prefix, err)
+		}
+
+		if inserted > 0 {
 			newPrefixes++
 		}
 	}
@@ -782,8 +813,9 @@ func upsertPrefixesInTable(
 	return newPrefixes, nil
 }
 
-// UpdatePrefixesBatch updates the last_seen time for multiple prefixes in a
-// single transaction, the IPv4 prefixes first and then the IPv6 prefixes.
+// UpdatePrefixesBatch stores, in a single transaction, the prefixes that are
+// not stored yet, each first seen at its time in prefixes: the IPv4 prefixes
+// first and then the IPv6 prefixes.
 func (d *Database) UpdatePrefixesBatch(prefixes map[string]time.Time) error {
 	if len(prefixes) == 0 {
 		return nil
@@ -811,12 +843,12 @@ func (d *Database) UpdatePrefixesBatch(prefixes map[string]time.Time) error {
 
 	ctx := context.Background()
 
-	newV4, err := upsertPrefixesInTable(ctx, tx, prefixesV4, ipVersionV4)
+	newV4, err := insertPrefixesInTable(ctx, tx, prefixesV4, ipVersionV4)
 	if err != nil {
 		return err
 	}
 
-	newV6, err := upsertPrefixesInTable(ctx, tx, prefixesV6, ipVersionV6)
+	newV6, err := insertPrefixesInTable(ctx, tx, prefixesV6, ipVersionV6)
 	if err != nil {
 		return err
 	}
@@ -1047,35 +1079,15 @@ func (d *Database) GetOrCreatePrefix(
 		tableName = "prefixes_v6"
 	}
 
-	var (
-		p     Prefix
-		idStr string
-	)
+	var p Prefix
 
-	query := fmt.Sprintf("SELECT id, prefix, first_seen, last_seen "+
-		"FROM %s WHERE prefix = ?", tableName)
+	query := fmt.Sprintf("SELECT prefix, first_seen FROM %s WHERE prefix = ?",
+		tableName)
 
-	err = tx.QueryRow(query, prefix).Scan(&idStr, &p.Prefix, &p.FirstSeen, &p.LastSeen)
+	err = tx.QueryRow(query, prefix).Scan(&p.Prefix, &p.FirstSeen)
 	if err == nil {
-		// Prefix exists, update last_seen
-		p.ID, _ = uuid.Parse(idStr)
+		// Prefix exists; the deferred rollback ends the read.
 		p.IPVersion = ipVersion
-		updateQuery := fmt.Sprintf("UPDATE %s SET last_seen = ? WHERE id = ?", tableName)
-
-		_, err = tx.Exec(updateQuery, timestamp, p.ID.String())
-		if err != nil {
-			return nil, err
-		}
-
-		p.LastSeen = timestamp
-
-		err = tx.Commit()
-		if err != nil {
-			d.logger.Error("Failed to commit transaction for prefix update",
-				"prefix", prefix, "error", err)
-
-			return nil, err
-		}
 
 		return &p, nil
 	}
@@ -1085,12 +1097,11 @@ func (d *Database) GetOrCreatePrefix(
 	}
 
 	// Prefix doesn't exist, create it
-	p = Prefix{ID: generateUUID(), Prefix: prefix, IPVersion: ipVersion,
-		FirstSeen: timestamp, LastSeen: timestamp}
+	p = Prefix{Prefix: prefix, IPVersion: ipVersion, FirstSeen: timestamp}
 	insertQuery := fmt.Sprintf("INSERT INTO %s "+
-		"(id, prefix, first_seen, last_seen) VALUES (?, ?, ?, ?)", tableName)
+		"(prefix, first_seen) VALUES (?, ?)", tableName)
 
-	_, err = tx.Exec(insertQuery, p.ID.String(), p.Prefix, p.FirstSeen, p.LastSeen)
+	_, err = tx.Exec(insertQuery, p.Prefix, p.FirstSeen)
 	if err != nil {
 		return nil, err
 	}
@@ -1389,37 +1400,44 @@ func (d *Database) UpsertLiveRoute(route *LiveRoute) error {
 		return fmt.Errorf("failed to encode AS path: %w", err)
 	}
 
-	updateSQL, insertSQL, lookupSQL := updateLiveRouteV4SQL,
-		insertLiveRouteV4SQL, prefixHasLiveRouteV4SQL
+	originSQL, updateSQL := updateLiveRouteOriginV4SQL, updateLiveRouteV4SQL
+	insertSQL, lookupSQL := insertLiveRouteV4SQL, prefixHasLiveRouteV4SQL
+
 	if route.IPVersion == ipVersionV6 {
-		updateSQL, insertSQL, lookupSQL = updateLiveRouteV6SQL,
-			insertLiveRouteV6SQL, prefixHasLiveRouteV6SQL
+		originSQL, updateSQL = updateLiveRouteOriginV6SQL, updateLiveRouteV6SQL
+		insertSQL, lookupSQL = insertLiveRouteV6SQL, prefixHasLiveRouteV6SQL
 	}
 
 	ctx := context.Background()
 
 	// The write lock is held, so no other writer can insert this key between the
 	// update and the insert even though they are separate autocommit statements.
-	upd, err := d.db.PrepareContext(ctx, updateSQL)
+	setOrigin, err := d.writer.PrepareContext(ctx, originSQL)
+	if err != nil {
+		return fmt.Errorf("failed to prepare origin statement: %w", err)
+	}
+	defer func() { _ = setOrigin.Close() }()
+
+	upd, err := d.writer.PrepareContext(ctx, updateSQL)
 	if err != nil {
 		return fmt.Errorf("failed to prepare update statement: %w", err)
 	}
 	defer func() { _ = upd.Close() }()
 
-	ins, err := d.db.PrepareContext(ctx, insertSQL)
+	ins, err := d.writer.PrepareContext(ctx, insertSQL)
 	if err != nil {
 		return fmt.Errorf("failed to prepare insert statement: %w", err)
 	}
 	defer func() { _ = ins.Close() }()
 
-	has, err := d.db.PrepareContext(ctx, lookupSQL)
+	has, err := d.writer.PrepareContext(ctx, lookupSQL)
 	if err != nil {
 		return fmt.Errorf("failed to prepare prefix lookup statement: %w", err)
 	}
 	defer func() { _ = has.Close() }()
 
-	inserted, newPrefix, err := upsertRouteRow(ctx, upd, ins, has, route,
-		string(pathJSON))
+	inserted, newPrefix, err := upsertRouteRow(ctx, setOrigin, upd, ins, has,
+		route, string(pathJSON))
 	if err != nil {
 		return fmt.Errorf("failed to upsert route %s: %w", route.Prefix, err)
 	}
@@ -2008,7 +2026,7 @@ func (d *Database) UpdateASNWHOIS(
 		WHERE asn = ?
 	`
 
-	_, err := d.db.ExecContext(ctx, query,
+	_, err := d.writer.ExecContext(ctx, query,
 		update.ASName,
 		update.OrgName,
 		update.OrgID,
@@ -2165,7 +2183,8 @@ func (d *Database) GetIPInfoContext(
 // Vacuum runs incremental vacuum to return up to 1000 unused pages to the
 // filesystem. Like Analyze and Checkpoint, it holds the database lock, so it
 // and the batch writes wait for each other instead of failing on SQLite's
-// write lock.
+// write lock, and returns ctx's error without running if ctx ended while it
+// waited: the writing connection it uses does not check ctx itself.
 func (d *Database) Vacuum(ctx context.Context) error {
 	// Free up to 1000 pages per call (~4MB with default 4KB page size)
 	// This keeps each vacuum operation quick
@@ -2174,7 +2193,12 @@ func (d *Database) Vacuum(ctx context.Context) error {
 	d.lock("Vacuum")
 	defer d.unlock()
 
-	rows, err := d.db.QueryContext(ctx,
+	err := ctx.Err()
+	if err != nil {
+		return fmt.Errorf("failed to run incremental vacuum: %w", err)
+	}
+
+	rows, err := d.writer.QueryContext(ctx,
 		fmt.Sprintf("PRAGMA incremental_vacuum(%d)", pagesToFree))
 	if err != nil {
 		return fmt.Errorf("failed to run incremental vacuum: %w", err)
@@ -2204,9 +2228,14 @@ func (d *Database) Analyze(ctx context.Context) error {
 	d.lock("Analyze")
 	defer d.unlock()
 
+	err := ctx.Err()
+	if err != nil {
+		return fmt.Errorf("failed to analyze database: %w", err)
+	}
+
 	// analysis_limit is a setting of the connection, so it is set in the same
 	// call as PRAGMA optimize, which runs both statements on one connection.
-	_, err := d.db.ExecContext(ctx, fmt.Sprintf(
+	_, err = d.writer.ExecContext(ctx, fmt.Sprintf(
 		"PRAGMA analysis_limit=%d; PRAGMA optimize=%#x",
 		analysisLimit, optimizeAllTables))
 	if err != nil {
@@ -2223,7 +2252,12 @@ func (d *Database) Checkpoint(ctx context.Context) error {
 	d.lock("Checkpoint")
 	defer d.unlock()
 
-	_, err := d.db.ExecContext(ctx, "PRAGMA wal_checkpoint(TRUNCATE)")
+	err := ctx.Err()
+	if err != nil {
+		return fmt.Errorf("failed to checkpoint WAL: %w", err)
+	}
+
+	_, err = d.writer.ExecContext(ctx, "PRAGMA wal_checkpoint(TRUNCATE)")
 	if err != nil {
 		return fmt.Errorf("failed to checkpoint WAL: %w", err)
 	}
@@ -2279,9 +2313,9 @@ func (d *Database) unlock() {
 		"held_by", lockedBy, "duration_ms", holdDuration.Milliseconds())
 }
 
-// beginTx starts a new transaction with logging
+// beginTx starts a new transaction on the writing connection, with logging
 func (d *Database) beginTx() (*loggingTx, error) {
-	tx, err := d.db.BeginTx(context.Background(), nil)
+	tx, err := d.writer.BeginTx(context.Background(), nil)
 	if err != nil {
 		return nil, err
 	}

internal/database/database_internal_test.go

@@ -6,15 +6,16 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"math/rand/v2"
 	"net/netip"
 	"slices"
+	"strconv"
 	"sync"
 	"testing"
 	"time"
 
 	"git.eeqj.de/sneak/routewatch/internal/config"
 	"git.eeqj.de/sneak/routewatch/internal/logger"
-	"github.com/google/uuid"
 	"github.com/mattn/go-sqlite3"
 )
 
@@ -33,6 +34,9 @@ const vacuumTestRoutes = 2000
 // once so each is a distinct SQLite connection that parsed the DSN.
 const heldConnections = 5
 
+// bytesPerKiB turns a cache_size in KiB into bytes.
+const bytesPerKiB = 1024
+
 // testPeerIP is the peer every route in the IP lookup test is learned from.
 const testPeerIP = "192.0.2.254"
 
@@ -293,7 +297,7 @@ func TestLiveRouteTablesHoldOneRoutePerPrefixAndPeer(t *testing.T) {
 			t.Fatalf("UpsertLiveRoute(%s): %v", tt.route.Prefix, err)
 		}
 
-		_, err = db.db.ExecContext(t.Context(), tt.insertSQL, uuid.NewString(),
+		_, err = db.db.ExecContext(t.Context(), tt.insertSQL,
 			tt.route.Prefix, tt.route.MaskLength, otherOriginASN,
 			tt.route.PeerIP, "[]", tt.route.NextHop, ts)
 
@@ -317,7 +321,6 @@ func writeOriginRoutes(t *testing.T, db *Database, origins map[string]int) {
 
 	for prefix, asn := range origins {
 		routes = append(routes, &LiveRoute{
-			ID:          uuid.New(),
 			Prefix:      prefix,
 			MaskLength:  netip.MustParsePrefix(prefix).Bits(),
 			IPVersion:   detectIPVersion(prefix),
@@ -337,7 +340,7 @@ func writeOriginRoutes(t *testing.T, db *Database, origins map[string]int) {
 
 // TestConnectionPoolPragmas holds several pooled connections open at once and
 // checks each one carries the per-connection settings from the DSN, plus the
-// process-wide hard heap limit, and sees the new file with auto_vacuum
+// process-wide heap limits, and sees the new file with auto_vacuum
 // incremental.
 func TestConnectionPoolPragmas(t *testing.T) {
 	t.Parallel()
@@ -372,9 +375,9 @@ func TestConnectionPoolPragmas(t *testing.T) {
 
 	for i, c := range conns {
 		cacheSize := readPragma(ctx, t, c, i, "cache_size")
-		if cacheSize != sqliteCacheSizeKiB {
+		if cacheSize != sqliteReadCacheSizeKiB {
 			t.Errorf("conn %d: cache_size = %d, want %d",
-				i, cacheSize, sqliteCacheSizeKiB)
+				i, cacheSize, sqliteReadCacheSizeKiB)
 		}
 
 		busyTimeout := readPragma(ctx, t, c, i, "busy_timeout")
@@ -389,6 +392,12 @@ func TestConnectionPoolPragmas(t *testing.T) {
 				i, tempStore, tempStoreMemory)
 		}
 
+		softHeapLimit := readPragma(ctx, t, c, i, "soft_heap_limit")
+		if softHeapLimit != sqliteSoftHeapLimitBytes {
+			t.Errorf("conn %d: soft_heap_limit = %d, want %d",
+				i, softHeapLimit, sqliteSoftHeapLimitBytes)
+		}
+
 		hardHeapLimit := readPragma(ctx, t, c, i, "hard_heap_limit")
 		if hardHeapLimit != sqliteHardHeapLimitBytes {
 			t.Errorf("conn %d: hard_heap_limit = %d, want %d",
@@ -403,6 +412,51 @@ func TestConnectionPoolPragmas(t *testing.T) {
 	}
 }
 
+// TestWritingConnectionCache checks that the connection kept for writing has
+// the large cache, and that the soft heap limit is above the caches of all the
+// connections together: SQLite shrinks the caches to stay under it.
+func TestWritingConnectionCache(t *testing.T) {
+	t.Parallel()
+
+	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
+	if err != nil {
+		t.Fatalf("failed to create database: %v", err)
+	}
+	defer func() { _ = db.Close() }()
+
+	ctx := t.Context()
+
+	var writeCacheSize, readCacheSize, softHeapLimit int64
+
+	err = db.writer.QueryRowContext(ctx, "PRAGMA cache_size").
+		Scan(&writeCacheSize)
+	if err != nil {
+		t.Fatalf("failed to read the writing connection's cache_size: %v", err)
+	}
+
+	if writeCacheSize != sqliteWriteCacheSizeKiB {
+		t.Errorf("writing connection: cache_size = %d, want %d",
+			writeCacheSize, sqliteWriteCacheSizeKiB)
+	}
+
+	err = db.db.QueryRowContext(ctx, "PRAGMA cache_size").Scan(&readCacheSize)
+	if err != nil {
+		t.Fatalf("failed to read a reading connection's cache_size: %v", err)
+	}
+
+	err = db.db.QueryRowContext(ctx, "PRAGMA soft_heap_limit").
+		Scan(&softHeapLimit)
+	if err != nil {
+		t.Fatalf("failed to read soft_heap_limit: %v", err)
+	}
+
+	cachesBytes := -bytesPerKiB * (writeCacheSize + (maxConns-1)*readCacheSize)
+	if softHeapLimit <= cachesBytes {
+		t.Errorf("soft_heap_limit = %d, not above the %d bytes of the caches",
+			softHeapLimit, cachesBytes)
+	}
+}
+
 // readPragma reads the integer value of PRAGMA name on connection i, c.
 func readPragma(
 	ctx context.Context, t *testing.T, c *sql.Conn, i int, name string,
@@ -1090,3 +1144,380 @@ func TestGetRandomPrefixesByLengthSkipsWithdrawnRoutes(t *testing.T) {
 			routes, kept.Prefix)
 	}
 }
+
+// TestLiveRouteUpdateSetsOriginWhenItChanges announces a peer's route for a
+// prefix, then again with the same origin AS and a new path, then with a new
+// origin AS. Each time the route must carry the announced origin AS, path and
+// time, and the AS details must list the prefix under that origin AS only. The
+// update sets the origin AS with a statement of its own, which changes nothing
+// while the origin AS stays the same.
+func TestLiveRouteUpdateSetsOriginWhenItChanges(t *testing.T) {
+	t.Parallel()
+
+	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
+	if err != nil {
+		t.Fatalf("failed to create database: %v", err)
+	}
+	defer func() { _ = db.Close() }()
+
+	const firstOrigin, secondOrigin = 64500, 64501
+
+	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
+
+	for _, asn := range []int{firstOrigin, secondOrigin} {
+		_, err := db.GetOrCreateASN(asn, ts)
+		if err != nil {
+			t.Fatalf("GetOrCreateASN(%d): %v", asn, err)
+		}
+	}
+
+	route := mkV4Route(t, "198.51.100.0/24", firstOrigin, ts)
+
+	for _, announced := range []struct {
+		origin int
+		path   []int
+	}{
+		{firstOrigin, []int{firstOrigin}},
+		{firstOrigin, []int{secondOrigin, firstOrigin}},
+		{secondOrigin, []int{firstOrigin, secondOrigin}},
+	} {
+		ts = ts.Add(time.Minute)
+		route.OriginASN, route.ASPath, route.LastUpdated =
+			announced.origin, announced.path, ts
+
+		err := db.UpsertLiveRouteBatch([]*LiveRoute{route})
+		if err != nil {
+			t.Fatalf("UpsertLiveRouteBatch: %v", err)
+		}
+
+		routes, _, err := db.GetPrefixDetails(route.Prefix)
+		if err != nil {
+			t.Fatalf("GetPrefixDetails: %v", err)
+		}
+
+		if len(routes) != 1 || routes[0].OriginASN != announced.origin ||
+			!slices.Equal(routes[0].ASPath, announced.path) ||
+			!routes[0].LastUpdated.Equal(ts) {
+			t.Errorf("after announcing origin AS%d, path %v at %s: routes %+v",
+				announced.origin, announced.path, ts, routes)
+		}
+
+		for _, asn := range []int{firstOrigin, secondOrigin} {
+			_, prefixes, err := db.GetASDetails(asn)
+			if err != nil {
+				t.Fatalf("GetASDetails(%d): %v", asn, err)
+			}
+
+			listed := len(prefixes) == 1 && prefixes[0].Prefix == route.Prefix
+			if listed != (asn == announced.origin) {
+				t.Errorf("after announcing origin AS%d, AS%d lists %+v",
+					announced.origin, asn, prefixes)
+			}
+		}
+	}
+}
+
+// TestUpdatePrefixesBatchKeepsFirstSeen writes a prefix, then a batch with it
+// and a new prefix. Only the new prefix is inserted and counted, and the known
+// one keeps its first_seen time.
+func TestUpdatePrefixesBatchKeepsFirstSeen(t *testing.T) {
+	t.Parallel()
+
+	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
+	if err != nil {
+		t.Fatalf("failed to create database: %v", err)
+	}
+	defer func() { _ = db.Close() }()
+
+	const known = "198.51.100.0/24"
+
+	first := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
+	later := first.Add(time.Hour)
+
+	err = db.UpdatePrefixesBatch(map[string]time.Time{known: first})
+	if err != nil {
+		t.Fatalf("UpdatePrefixesBatch: %v", err)
+	}
+
+	err = db.UpdatePrefixesBatch(map[string]time.Time{
+		known: later, testV6Prefix: later,
+	})
+	if err != nil {
+		t.Fatalf("UpdatePrefixesBatch: %v", err)
+	}
+
+	stats, err := db.GetStats()
+	if err != nil {
+		t.Fatalf("GetStats: %v", err)
+	}
+
+	if stats.IPv4Prefixes != 1 || stats.IPv6Prefixes != 1 {
+		t.Errorf("prefix counts = (v4 %d, v6 %d), want (1, 1)",
+			stats.IPv4Prefixes, stats.IPv6Prefixes)
+	}
+
+	for _, tt := range []struct {
+		query, prefix string
+		firstSeen     time.Time
+	}{
+		{
+			query:  "SELECT first_seen FROM prefixes_v4 WHERE prefix = ?",
+			prefix: known, firstSeen: first,
+		},
+		{
+			query:  "SELECT first_seen FROM prefixes_v6 WHERE prefix = ?",
+			prefix: testV6Prefix, firstSeen: later,
+		},
+	} {
+		var firstSeen time.Time
+
+		err := db.db.QueryRowContext(t.Context(), tt.query, tt.prefix).
+			Scan(&firstSeen)
+		if err != nil {
+			t.Fatalf("reading %s: %v", tt.prefix, err)
+		}
+
+		if !firstSeen.Equal(tt.firstSeen) {
+			t.Errorf("%s: first seen %s, want %s", tt.prefix, firstSeen,
+				tt.firstSeen)
+		}
+	}
+}
+
+// TestUpsertLiveRouteBatchWritesInKeyOrder writes new routes of two peers out
+// of key order, the last one a second announcement of the first, and checks
+// that the rows were inserted in key order, peer then prefix (each new row's id
+// is one above the last), and that the route announced twice carries the later
+// announcement.
+func TestUpsertLiveRouteBatchWritesInKeyOrder(t *testing.T) {
+	t.Parallel()
+
+	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
+	if err != nil {
+		t.Fatalf("failed to create database: %v", err)
+	}
+	defer func() { _ = db.Close() }()
+
+	const (
+		firstOrigin, laterOrigin = 64500, 64501
+		// Three prefixes, in text order.
+		firstPrefix  = "192.0.2.0/24"
+		secondPrefix = "198.51.100.0/24"
+		thirdPrefix  = "203.0.113.0/24"
+	)
+
+	type row struct {
+		peer, prefix string
+		origin       int
+	}
+
+	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
+
+	announcements := []row{
+		{secondV4PeerIP, secondPrefix, firstOrigin},
+		{testV4PeerIP, thirdPrefix, firstOrigin},
+		{secondV4PeerIP, firstPrefix, firstOrigin},
+		{testV4PeerIP, secondPrefix, firstOrigin},
+		{secondV4PeerIP, secondPrefix, laterOrigin},
+	}
+
+	routes := make([]*LiveRoute, 0, len(announcements))
+
+	for _, announced := range announcements {
+		route := mkV4Route(t, announced.prefix, announced.origin, ts)
+		route.PeerIP = announced.peer
+		routes = append(routes, route)
+	}
+
+	err = db.UpsertLiveRouteBatch(routes)
+	if err != nil {
+		t.Fatalf("UpsertLiveRouteBatch: %v", err)
+	}
+
+	rows, err := db.db.QueryContext(t.Context(),
+		"SELECT peer_ip, prefix, origin_asn FROM live_routes_v4 ORDER BY id")
+	if err != nil {
+		t.Fatalf("reading the routes: %v", err)
+	}
+	defer func() { _ = rows.Close() }()
+
+	var stored []row
+
+	for rows.Next() {
+		var r row
+
+		err := rows.Scan(&r.peer, &r.prefix, &r.origin)
+		if err != nil {
+			t.Fatalf("reading a route: %v", err)
+		}
+
+		stored = append(stored, r)
+	}
+
+	err = rows.Err()
+	if err != nil {
+		t.Fatalf("reading the routes: %v", err)
+	}
+
+	want := []row{
+		{testV4PeerIP, secondPrefix, firstOrigin},
+		{testV4PeerIP, thirdPrefix, firstOrigin},
+		{secondV4PeerIP, firstPrefix, firstOrigin},
+		{secondV4PeerIP, secondPrefix, laterOrigin},
+	}
+
+	if !slices.Equal(stored, want) {
+		t.Errorf("routes in insertion order = %+v, want %+v", stored, want)
+	}
+}
+
+// Parameters for BenchmarkPrefixBatchOnFiveMillionRoutes.
+const (
+	// benchPeers and benchPrefixes size the table the batches are written to:
+	// every peer has a route for every prefix, 5 million routes in all.
+	benchPeers    = 10
+	benchPrefixes = 500000
+	// benchBatchSize is how many updates each batch holds, as many as a full
+	// prefix handler batch (prefixBatchSize in internal/routewatch).
+	benchBatchSize = 25000
+	// benchMaxBatchSize is the largest batch the prefix handler writes, the
+	// one it holds while a slow write runs (prefixBatchMaxSize in
+	// internal/routewatch).
+	benchMaxBatchSize = 250000
+	// benchWithdrawalEvery makes every fifth update of a timed batch a
+	// withdrawal; the others are announcements.
+	benchWithdrawalEvery = 5
+	// benchOrigins is how many origin ASes the prefixes are spread over.
+	benchOrigins = 50000
+	// benchFirstASN is the lowest AS number in the benchmark's AS paths.
+	benchFirstASN = 64500
+	// benchMaskLength is the mask length of every prefix in the benchmark.
+	benchMaskLength = 24
+)
+
+// BenchmarkPrefixBatchOnFiveMillionRoutes times the writes the prefix handler
+// makes for one batch of announcements and withdrawals of routes picked at
+// random, to a database that already holds 5 million live routes: 500,000
+// IPv4 prefixes, each from 10 peers. It times a full batch of 25,000 updates,
+// then the largest batch, 250,000. It builds that database first, one batch at
+// a time, which takes some minutes and a few GB of disk under TMPDIR. It is
+// run by hand, not by make test, for example in the test image:
+//
+//	go test -run '^$' -bench FiveMillion -benchtime 10x ./internal/database/
+func BenchmarkPrefixBatchOnFiveMillionRoutes(b *testing.B) {
+	db, err := New(&config.Config{StateDir: b.TempDir()}, logger.New())
+	if err != nil {
+		b.Fatalf("failed to create database: %v", err)
+	}
+	defer func() { _ = db.Close() }()
+
+	//nolint:gosec // The benchmark needs the same batches every run.
+	rng := rand.New(rand.NewPCG(1, 2))
+	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
+
+	// Each peer sends its whole table, as when its session comes up.
+	for peer := range benchPeers {
+		for first := 0; first < benchPrefixes; first += benchBatchSize {
+			routes := make([]*LiveRoute, 0, benchBatchSize)
+			for prefix := first; prefix < first+benchBatchSize; prefix++ {
+				routes = append(routes, benchRoute(rng, prefix, peer, ts))
+			}
+
+			writeBenchBatch(b, db, routes, nil, ts)
+		}
+	}
+
+	for _, batchSize := range []int{benchBatchSize, benchMaxBatchSize} {
+		b.Run(strconv.Itoa(batchSize), func(b *testing.B) {
+			for b.Loop() {
+				ts = ts.Add(time.Second)
+
+				var (
+					routes      []*LiveRoute
+					withdrawals []LiveRouteDeletion
+				)
+
+				for i := range batchSize {
+					route := benchRoute(rng, rng.IntN(benchPrefixes),
+						rng.IntN(benchPeers), ts)
+					if i%benchWithdrawalEvery == 0 {
+						withdrawals = append(withdrawals, LiveRouteDeletion{
+							Prefix: route.Prefix, PeerIP: route.PeerIP,
+							IPVersion: ipVersionV4,
+						})
+					} else {
+						routes = append(routes, route)
+					}
+				}
+
+				writeBenchBatch(b, db, routes, withdrawals, ts)
+			}
+		})
+	}
+}
+
+// benchRoute returns the route peer has for the prefix numbered prefix, a /24
+// from 1.0.0.0/24 on, with a new AS path of three to six ASes from the peer's
+// AS to the prefix's origin AS.
+func benchRoute(rng *rand.Rand, prefix, peer int, ts time.Time) *LiveRoute {
+	const minPathLength, extraPathLength = 3, 4
+
+	origin := benchFirstASN + prefix%benchOrigins
+	pathLength := minPathLength + rng.IntN(extraPathLength)
+
+	path := make([]int, 0, pathLength)
+	path = append(path, benchFirstASN+peer)
+
+	for len(path) < pathLength-1 {
+		path = append(path, benchFirstASN+rng.IntN(benchOrigins))
+	}
+
+	path = append(path, origin)
+	peerIP := fmt.Sprintf("198.51.100.%d", 1+peer)
+
+	return &LiveRoute{
+		Prefix: fmt.Sprintf("%d.%d.%d.0/%d",
+			1+prefix>>16, (prefix>>8)%256, prefix%256, benchMaskLength),
+		MaskLength:  benchMaskLength,
+		IPVersion:   ipVersionV4,
+		OriginASN:   origin,
+		PeerIP:      peerIP,
+		ASPath:      path,
+		NextHop:     peerIP,
+		LastUpdated: ts,
+	}
+}
+
+// writeBenchBatch writes what the prefix handler writes for a batch: the
+// announced routes, the withdrawals, and every prefix the batch names, of
+// which only the ones not stored yet are inserted.
+func writeBenchBatch(
+	b *testing.B, db *Database, routes []*LiveRoute,
+	withdrawals []LiveRouteDeletion, ts time.Time,
+) {
+	b.Helper()
+
+	prefixes := make(map[string]time.Time, len(routes)+len(withdrawals))
+	for _, route := range routes {
+		prefixes[route.Prefix] = ts
+	}
+
+	for _, withdrawal := range withdrawals {
+		prefixes[withdrawal.Prefix] = ts
+	}
+
+	err := db.UpsertLiveRouteBatch(routes)
+	if err != nil {
+		b.Fatalf("UpsertLiveRouteBatch: %v", err)
+	}
+
+	err = db.DeleteLiveRouteBatch(withdrawals)
+	if err != nil {
+		b.Fatalf("DeleteLiveRouteBatch: %v", err)
+	}
+
+	err = db.UpdatePrefixesBatch(prefixes)
+	if err != nil {
+		b.Fatalf("UpdatePrefixesBatch: %v", err)
+	}
+}

internal/database/models.go

@@ -35,13 +35,11 @@ type ASN struct {
 }
 
 // Prefix represents an IP prefix (CIDR block) with its IP version (4 or 6)
-// and first/last seen timestamps.
+// and the time it was first seen.
 type Prefix struct {
-	ID        uuid.UUID
 	Prefix    string
 	IPVersion int // 4 or 6
 	FirstSeen time.Time
-	LastSeen  time.Time
 }
 
 // Announcement represents a BGP announcement or withdrawal event,
@@ -71,7 +69,6 @@ type ASNPeering struct {
 //
 //nolint:tagliatelle // field names are the existing JSON API
 type LiveRoute struct {
-	ID          uuid.UUID `json:"id"`
 	Prefix      string    `json:"prefix"`
 	MaskLength  int       `json:"mask_length"`
 	IPVersion   int       `json:"ip_version"`

internal/database/schema.sql

@@ -27,21 +27,18 @@ CREATE TABLE IF NOT EXISTS asns (
 	whois_updated_at DATETIME    -- when we last fetched WHOIS data
 );
 
--- IPv4 prefixes table
+-- IPv4 prefixes table. Every read and write finds a row by its prefix, so the
+-- rows are stored by prefix (WITHOUT ROWID) and need no index of their own.
 CREATE TABLE IF NOT EXISTS prefixes_v4 (
-	id TEXT PRIMARY KEY,
-	prefix TEXT UNIQUE NOT NULL,
-	first_seen DATETIME NOT NULL,
-	last_seen DATETIME NOT NULL
-);
+	prefix TEXT PRIMARY KEY,
+	first_seen DATETIME NOT NULL
+) WITHOUT ROWID;
 
--- IPv6 prefixes table
+-- IPv6 prefixes table, stored as prefixes_v4 is.
 CREATE TABLE IF NOT EXISTS prefixes_v6 (
-	id TEXT PRIMARY KEY,
-	prefix TEXT UNIQUE NOT NULL,
-	first_seen DATETIME NOT NULL,
-	last_seen DATETIME NOT NULL
-);
+	prefix TEXT PRIMARY KEY,
+	first_seen DATETIME NOT NULL
+) WITHOUT ROWID;
 
 CREATE TABLE IF NOT EXISTS announcements (
 	id TEXT PRIMARY KEY,
@@ -75,11 +72,6 @@ CREATE TABLE IF NOT EXISTS bgp_peers (
 	last_message_type TEXT
 );
 
--- Indexes for prefixes_v4 table
-CREATE INDEX IF NOT EXISTS idx_prefixes_v4_prefix ON prefixes_v4(prefix);
-
--- Indexes for prefixes_v6 table
-CREATE INDEX IF NOT EXISTS idx_prefixes_v6_prefix ON prefixes_v6(prefix);
 CREATE INDEX IF NOT EXISTS idx_announcements_timestamp ON announcements(timestamp);
 CREATE INDEX IF NOT EXISTS idx_announcements_prefix_id ON announcements(prefix_id);
 CREATE INDEX IF NOT EXISTS idx_announcements_peer_asn ON announcements(peer_asn);
@@ -97,9 +89,14 @@ CREATE INDEX IF NOT EXISTS idx_bgp_peers_asn ON bgp_peers(peer_asn);
 CREATE INDEX IF NOT EXISTS idx_bgp_peers_last_seen ON bgp_peers(last_seen);
 CREATE INDEX IF NOT EXISTS idx_bgp_peers_ip ON bgp_peers(peer_ip);
 
--- IPv4 routing table maintained by PrefixHandler
+-- IPv4 routing table maintained by PrefixHandler. A route write changes the
+-- table and its entry in every index on a column the write sets, so the table
+-- has only the indexes that the queries named with them use.
 CREATE TABLE IF NOT EXISTS live_routes_v4 (
-	id TEXT PRIMARY KEY,
+	-- The row id, which the prefix-length pages' sample draws through the
+	-- mask_length index. Declared as a column, it stays the same for as long
+	-- as the route is live, also through a VACUUM.
+	id INTEGER PRIMARY KEY,
 	prefix TEXT NOT NULL,
 	mask_length INTEGER NOT NULL, -- CIDR mask length (0-32)
 	origin_asn INTEGER NOT NULL,
@@ -107,15 +104,15 @@ CREATE TABLE IF NOT EXISTS live_routes_v4 (
 	as_path TEXT NOT NULL, -- JSON array
 	next_hop TEXT NOT NULL,
 	last_updated DATETIME NOT NULL,
-	-- A peer has at most one route for a prefix. peer_ip comes first so that
-	-- this key also finds all of a peer's routes, when its BGP session goes
-	-- down; lookups by prefix use the prefix index below.
+	-- A peer has at most one route for a prefix. This key finds the route a
+	-- write updates or deletes and, peer_ip coming first, all of a peer's
+	-- routes when its BGP session goes down.
 	UNIQUE(peer_ip, prefix)
 );
 
--- IPv6 routing table maintained by PrefixHandler
+-- IPv6 routing table maintained by PrefixHandler, as live_routes_v4.
 CREATE TABLE IF NOT EXISTS live_routes_v6 (
-	id TEXT PRIMARY KEY,
+	id INTEGER PRIMARY KEY,
 	prefix TEXT NOT NULL,
 	mask_length INTEGER NOT NULL, -- CIDR mask length (0-128)
 	origin_asn INTEGER NOT NULL,
@@ -123,24 +120,29 @@ CREATE TABLE IF NOT EXISTS live_routes_v6 (
 	as_path TEXT NOT NULL, -- JSON array
 	next_hop TEXT NOT NULL,
 	last_updated DATETIME NOT NULL,
-	-- As in live_routes_v4: peer_ip first, to find all of a peer's routes.
 	UNIQUE(peer_ip, prefix)
 );
 
--- Indexes for live_routes_v4 table
--- Finds a prefix's newest route in one search, whatever the number of peers.
+-- Indexes for both live route tables, and the queries that use each.
+--
+-- prefix, last_updated: a prefix's routes, for the prefix page and its API
+-- answer, the IP lookup and its peer count, and the check whether a prefix
+-- still has a live route; and a prefix's newest route for the prefix-length
+-- pages, in one search whatever the number of peers.
 CREATE INDEX IF NOT EXISTS idx_live_routes_v4_prefix_last_updated ON live_routes_v4(prefix, last_updated);
-CREATE INDEX IF NOT EXISTS idx_live_routes_v4_mask_length ON live_routes_v4(mask_length);
-CREATE INDEX IF NOT EXISTS idx_live_routes_v4_origin_asn ON live_routes_v4(origin_asn);
-CREATE INDEX IF NOT EXISTS idx_live_routes_v4_last_updated ON live_routes_v4(last_updated);
--- Index to optimize prefix distribution queries
-CREATE INDEX IF NOT EXISTS idx_live_routes_v4_mask_prefix ON live_routes_v4(mask_length, prefix);
-
--- Indexes for live_routes_v6 table
--- Finds a prefix's newest route in one search, whatever the number of peers.
 CREATE INDEX IF NOT EXISTS idx_live_routes_v6_prefix_last_updated ON live_routes_v6(prefix, last_updated);
+-- mask_length: the prefix-length pages' random sample, the row id range of a
+-- mask length and the first route of it at or after a row id.
+CREATE INDEX IF NOT EXISTS idx_live_routes_v4_mask_length ON live_routes_v4(mask_length);
 CREATE INDEX IF NOT EXISTS idx_live_routes_v6_mask_length ON live_routes_v6(mask_length);
+-- mask_length, prefix: the prefix-length pages' list of a mask length's
+-- prefixes in text order, and the prefix distribution read at startup.
+CREATE INDEX IF NOT EXISTS idx_live_routes_v4_mask_prefix ON live_routes_v4(mask_length, prefix);
+CREATE INDEX IF NOT EXISTS idx_live_routes_v6_mask_prefix ON live_routes_v6(mask_length, prefix);
+-- origin_asn: the prefixes an AS originates, for the AS page and its API answer.
+CREATE INDEX IF NOT EXISTS idx_live_routes_v4_origin_asn ON live_routes_v4(origin_asn);
 CREATE INDEX IF NOT EXISTS idx_live_routes_v6_origin_asn ON live_routes_v6(origin_asn);
-CREATE INDEX IF NOT EXISTS idx_live_routes_v6_last_updated ON live_routes_v6(last_updated);
--- Index to optimize prefix distribution queries
-CREATE INDEX IF NOT EXISTS idx_live_routes_v6_mask_prefix ON live_routes_v6(mask_length, prefix);
+-- last_updated: the oldest and newest route times in /api/v1/stats and
+-- /status.json.
+CREATE INDEX IF NOT EXISTS idx_live_routes_v4_last_updated ON live_routes_v4(last_updated);
+CREATE INDEX IF NOT EXISTS idx_live_routes_v6_last_updated ON live_routes_v6(last_updated);

internal/database/slowquery.go

@@ -18,12 +18,12 @@ func logSlowQuery(logger *logger.Logger, query string, start time.Time) {
 	}
 }
 
-// exec wraps Exec with slow query logging
+// exec runs a statement on the writing connection, with slow query logging
 func (d *Database) exec(query string, args ...any) error {
 	start := time.Now()
 	defer logSlowQuery(d.logger, query, start)
 
-	_, err := d.db.ExecContext(context.Background(), query, args...)
+	_, err := d.writer.ExecContext(context.Background(), query, args...)
 
 	return err
 }

internal/routewatch/app_integration_internal_test.go

@@ -18,7 +18,6 @@ import (
 	"git.eeqj.de/sneak/routewatch/internal/ristypes"
 	"git.eeqj.de/sneak/routewatch/internal/server"
 	"git.eeqj.de/sneak/routewatch/internal/streamer"
-	"github.com/google/uuid"
 )
 
 // mockStore is a mock implementation of database.Store for testing
@@ -83,9 +82,7 @@ func (m *mockStore) UpdatePrefixesBatch(prefixes map[string]time.Time) error {
 	defer m.mu.Unlock()
 
 	for prefix, timestamp := range prefixes {
-		if p, exists := m.Prefixes[prefix]; exists {
-			p.LastSeen = timestamp
-		} else {
+		if _, exists := m.Prefixes[prefix]; !exists {
 			const (
 				ipVersionV4 = 4
 				ipVersionV6 = 6
@@ -97,11 +94,9 @@ func (m *mockStore) UpdatePrefixesBatch(prefixes map[string]time.Time) error {
 			}
 
 			m.Prefixes[prefix] = &database.Prefix{
-				ID:        uuid.New(),
 				Prefix:    prefix,
 				IPVersion: ipVersion,
 				FirstSeen: timestamp,
-				LastSeen:  timestamp,
 			}
 		}
 	}
@@ -117,8 +112,6 @@ func (m *mockStore) GetOrCreatePrefix(
 	defer m.mu.Unlock()
 
 	if p, exists := m.Prefixes[prefix]; exists {
-		p.LastSeen = timestamp
-
 		return p, nil
 	}
 
@@ -133,11 +126,9 @@ func (m *mockStore) GetOrCreatePrefix(
 	}
 
 	p := &database.Prefix{
-		ID:        uuid.New(),
 		Prefix:    prefix,
 		IPVersion: ipVersion,
 		FirstSeen: timestamp,
-		LastSeen:  timestamp,
 	}
 	m.Prefixes[prefix] = p
 	m.PrefixCount++
@@ -370,11 +361,9 @@ func (m *mockStore) UpsertLiveRouteBatch(routes []*database.LiveRoute) error {
 		// Track prefix
 		if _, exists := m.Prefixes[route.Prefix]; !exists {
 			m.Prefixes[route.Prefix] = &database.Prefix{
-				ID:        uuid.New(),
 				Prefix:    route.Prefix,
 				IPVersion: route.IPVersion,
 				FirstSeen: route.LastUpdated,
-				LastSeen:  route.LastUpdated,
 			}
 			m.PrefixCount++
 

internal/routewatch/prefixhandler.go

@@ -12,7 +12,6 @@ import (
 	"git.eeqj.de/sneak/routewatch/internal/logger"
 	"git.eeqj.de/sneak/routewatch/internal/metrics"
 	"git.eeqj.de/sneak/routewatch/internal/ristypes"
-	"github.com/google/uuid"
 )
 
 const (
@@ -461,7 +460,6 @@ func (h *PrefixHandler) createLiveRoute(update prefixUpdate) *database.LiveRoute
 
 	// Create live route record
 	liveRoute := &database.LiveRoute{
-		ID:          uuid.New(),
 		Prefix:      update.prefix,
 		MaskLength:  maskLength,
 		IPVersion:   ipVersion,

internal/server/handlers_internal_test.go

@@ -19,7 +19,6 @@ import (
 	"git.eeqj.de/sneak/routewatch/internal/metrics"
 	"git.eeqj.de/sneak/routewatch/internal/streamer"
 	"git.eeqj.de/sneak/routewatch/pkg/asinfo"
-	"github.com/google/uuid"
 )
 
 // The prefix and peer addresses the prefix page tests store routes for.
@@ -114,12 +113,12 @@ func TestStatsHandlersAnswerFromMemory(t *testing.T) {
 
 	err = db.UpsertLiveRouteBatch([]*database.LiveRoute{
 		{
-			ID: uuid.New(), Prefix: "198.51.100.0/24", MaskLength: 24, IPVersion: 4,
+			Prefix: "198.51.100.0/24", MaskLength: 24, IPVersion: 4,
 			OriginASN: 64500, PeerIP: "192.0.2.1", ASPath: []int{64500},
 			NextHop: "192.0.2.1", LastUpdated: ts,
 		},
 		{
-			ID: uuid.New(), Prefix: "2001:db8::/32", MaskLength: 32, IPVersion: 6,
+			Prefix: "2001:db8::/32", MaskLength: 32, IPVersion: 6,
 			OriginASN: 64501, PeerIP: testPeerV6, ASPath: []int{64501},
 			NextHop: testPeerV6, LastUpdated: ts,
 		},
@@ -204,12 +203,12 @@ func TestPrefixDetailHandlersParsePrefix(t *testing.T) {
 
 	err = db.UpsertLiveRouteBatch([]*database.LiveRoute{
 		{
-			ID: uuid.New(), Prefix: testPrefixV4, MaskLength: 24, IPVersion: 4,
+			Prefix: testPrefixV4, MaskLength: 24, IPVersion: 4,
 			OriginASN: 64500, PeerIP: testPeerV4, ASPath: []int{64500},
 			NextHop: testPeerV4, LastUpdated: ts,
 		},
 		{
-			ID: uuid.New(), Prefix: "2001:db8::/32", MaskLength: 32, IPVersion: 6,
+			Prefix: "2001:db8::/32", MaskLength: 32, IPVersion: 6,
 			OriginASN: 64501, PeerIP: testPeerV6, ASPath: []int{64501},
 			NextHop: testPeerV6, LastUpdated: ts,
 		},
@@ -287,12 +286,12 @@ func TestPrefixDetailShowsOriginNames(t *testing.T) {
 
 	err = db.UpsertLiveRouteBatch([]*database.LiveRoute{
 		{
-			ID: uuid.New(), Prefix: testPrefixV4, MaskLength: 24, IPVersion: 4,
+			Prefix: testPrefixV4, MaskLength: 24, IPVersion: 4,
 			OriginASN: origins[0], PeerIP: testPeerV4,
 			ASPath: []int{origins[0]}, NextHop: testPeerV4, LastUpdated: ts,
 		},
 		{
-			ID: uuid.New(), Prefix: testPrefixV4, MaskLength: 24, IPVersion: 4,
+			Prefix: testPrefixV4, MaskLength: 24, IPVersion: 4,
 			OriginASN: origins[1], PeerIP: "198.51.100.2",
 			ASPath: []int{origins[1]}, NextHop: "198.51.100.2", LastUpdated: ts,
 		},
@@ -347,7 +346,7 @@ func TestPagesSayOriginZeroIsNoKnownOrigin(t *testing.T) {
 	t.Cleanup(func() { _ = db.Close() })
 
 	err = db.UpsertLiveRouteBatch([]*database.LiveRoute{{
-		ID: uuid.New(), Prefix: testPrefixV4, MaskLength: 24, IPVersion: 4,
+		Prefix: testPrefixV4, MaskLength: 24, IPVersion: 4,
 		OriginASN: 0, PeerIP: testPeerV4, ASPath: []int{64500, 64501, 64502},
 		NextHop: testPeerV4, LastUpdated: time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC),
 	}})