Write batches through one connection with a 1 GiB cache, in key order (closes #96)

Every write now uses one connection taken from the pool when the
database opens and used under the database lock. Its 1 GiB page cache
keeps the pages the route writes touch from one batch to the next. A
reading connection's cache is emptied whenever another connection has
written, so the 9 reading connections drop to 16 MiB each. The soft
and hard heap limits rise to 1.5 and 2 GiB so they do not shrink the
caches, and README "Memory" adds up the new budget. Batch writes sort
their rows by peer, then prefix. The benchmark also times the largest
prefix handler batch, 250,000 updates.

Model: opus-5-5

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
 
@@ -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
+- SQLite: 1 GiB of page cache for the one connection every write uses, which
-  connection, 10 connections) and a 1.5 GiB hard heap limit for the C library.
+  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
+- SQLite: at the 1.5 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
+  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
+// SQLite memory tuning (README "Memory"). cache_size and busy_timeout go in the
-// pooled connection gets them; the heap limits are process-wide and set once.
+// 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.
+	// maxConns is the size of the connection pool: the connection kept for
-	// -65536 = 64 MiB, so at most 640 MiB across the 10-connection pool.
+	// writing and 9 reading connections.
-	sqliteCacheSizeKiB = -65536
+	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
+	// sqliteSoftHeapLimitBytes (1.5 GiB) makes SQLite recycle its cache rather
-	// than allocate once its C heap passes this size.
+	// than allocate once its C heap passes this size. It is above the caches
-	sqliteSoftHeapLimitBytes = 1073741824
+	// together, so it does not shrink them.
-	// sqliteHardHeapLimitBytes (1.5 GiB) fails a statement with SQLITE_NOMEM
+	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
+	// synchronous, busy_timeout, journal_mode) live in the DSN, and New sets the
-	// left at its default so DISTINCT temp B-trees spill to disk instead of C
+	// writing connection's cache_size; temp_store is left at its default so
-	// heap. The heap limits below are process-wide, so setting them once here is
+	// DISTINCT temp B-trees spill to disk instead of C heap. The heap limits
-	// enough for the whole pool.
+	// 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
+// A live-route upsert sets the origin AS of the peer's route for the prefix
-// INSERT. A live route is keyed by prefix and peer, so an announcement replaces
+// when the announcement changes it, then updates the rest of the route, and
-// the peer's route for the prefix whatever its origin AS. The UPDATE's
+// inserts the route only when that update matched no row. A live route is keyed
-// rows-affected count (1 for an existing key, 0 for a new one) is what lets the
+// by prefix and peer, so an announcement replaces the peer's route for the
-// in-memory route counters stay exact without a COUNT(*). Callers hold the
+// prefix whatever its origin AS. The update's rows-affected count (1 for an
-// database write lock, so no other writer can insert the same key between the
+// existing key, 0 for a new one) is what lets the in-memory route counters stay
-// two statements. The id column is set only on INSERT, so an updated route
+// exact without a COUNT(*). Callers hold the database write lock, so no other
-// keeps its original id, exactly as the previous ON CONFLICT upsert did.
+// 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 = ?,
+		SET as_path = ?, next_hop = ?, last_updated = ?
-		last_updated = ? WHERE prefix = ? AND peer_ip = ?`
+		WHERE prefix = ? AND peer_ip = ?`
 
 	insertLiveRouteV4SQL = `INSERT INTO live_routes_v4
-		(id, prefix, mask_length, origin_asn, peer_ip, as_path, next_hop,
+		(prefix, mask_length, origin_asn, peer_ip, as_path, next_hop,
-		last_updated) VALUES (?, ?, ?, ?, ?, ?, ?, ?)`
+		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 = ?,
+		SET as_path = ?, next_hop = ?, last_updated = ?
-		last_updated = ? WHERE prefix = ? AND peer_ip = ?`
+		WHERE prefix = ? AND peer_ip = ?`
 
 	insertLiveRouteV6SQL = `INSERT INTO live_routes_v6
-		(id, prefix, mask_length, origin_asn, peer_ip, as_path, next_hop,
+		(prefix, mask_length, origin_asn, peer_ip, as_path, next_hop,
-		last_updated) VALUES (?, ?, ?, ?, ?, ?, ?, ?)`
+		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
+// upsertRouteRow updates a live route with the origin and update statements of
-// version's table, inserting it when no row matched. It reports whether a new
+// its IP version's table, inserting it when no row matched. It reports whether
-// row was inserted and whether that row is the first live route for its prefix.
+// 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,
+	_, err := setOrigin.ExecContext(ctx, route.OriginASN, route.Prefix,
-		route.NextHop, route.LastUpdated, route.Prefix, route.PeerIP)
+		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,
+	_, err = ins.ExecContext(ctx, route.Prefix, route.MaskLength,
-		route.MaskLength, route.OriginASN, route.PeerIP, pathJSON,
+		route.OriginASN, route.PeerIP, pathJSON, route.NextHop,
-		route.NextHop, route.LastUpdated)
+		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,
+	family, originSQL, updateSQL := ipv4Family, updateLiveRouteOriginV4SQL,
-		insertLiveRouteV4SQL, prefixHasLiveRouteV4SQL
+		updateLiveRouteV4SQL
+	insertSQL, lookupSQL := insertLiveRouteV4SQL, prefixHasLiveRouteV4SQL
+
 	if ipVersion == ipVersionV6 {
-		family, updateSQL, insertSQL, lookupSQL = ipv6Family,
+		family, originSQL, updateSQL = ipv6Family, updateLiveRouteOriginV6SQL,
-			updateLiveRouteV6SQL, insertLiveRouteV6SQL, prefixHasLiveRouteV6SQL
+			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,
+		inserted, newPrefix, err := upsertRouteRow(ctx, setOrigin, upd, ins, has,
-			string(pathJSON))
+			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 {
@@ -684,39 +761,33 @@ func (d *Database) DeleteLiveRoutesOfPeer(peerIP string) (int, error) {
 }
 
 // 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
+// IP version's table, inserting the prefix when the update matched no row. It
-// it inserted it.
+// reports whether it inserted it.
 func upsertPrefix(
-	ctx context.Context, selectStmt, updateStmt, insertStmt *sql.Stmt,
+	ctx context.Context, updateStmt, insertStmt *sql.Stmt,
 	prefix string, timestamp time.Time,
 ) (bool, error) {
-	var id string
+	res, err := updateStmt.ExecContext(ctx, timestamp, prefix)
-
+	if err != nil {
-	err := selectStmt.QueryRowContext(ctx, prefix).Scan(&id)
+		return false, fmt.Errorf("failed to update prefix %s: %w", prefix, err)
-
-	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)
 	}
+
+	affected, err := res.RowsAffected()
+	if err != nil {
+		return false, fmt.Errorf("failed to count updated prefix %s: %w",
+			prefix, err)
+	}
+
+	if affected > 0 {
+		return false, nil
+	}
+
+	_, err = insertStmt.ExecContext(ctx, prefix, timestamp, timestamp)
+	if err != nil {
+		return false, fmt.Errorf("failed to insert prefix %s: %w", prefix, err)
+	}
+
+	return true, nil
 }
 
 // upsertPrefixesInTable updates the last_seen time of prefixes, all of one IP
@@ -731,26 +802,17 @@ 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) " +
+	insertSQL := "INSERT INTO prefixes_v4 (prefix, first_seen, last_seen) " +
-		"VALUES (?, ?, ?, ?)"
+		"VALUES (?, ?, ?)"
 
 	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) " +
+		insertSQL = "INSERT INTO prefixes_v6 (prefix, first_seen, last_seen) " +
-			"VALUES (?, ?, ?, ?)"
+			"VALUES (?, ?, ?)"
 	}
 
-	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",
@@ -767,9 +829,10 @@ func upsertPrefixesInTable(
 
 	var newPrefixes int
 
-	for prefix, timestamp := range prefixes {
+	// The rows are written in key order, as UpsertLiveRouteBatch writes routes.
-		inserted, err := upsertPrefix(ctx, selectStmt, updateStmt, insertStmt,
+	for _, prefix := range slices.Sorted(maps.Keys(prefixes)) {
-			prefix, timestamp)
+		inserted, err := upsertPrefix(ctx, updateStmt, insertStmt, prefix,
+			prefixes[prefix])
 		if err != nil {
 			return 0, err
 		}
@@ -1047,22 +1110,19 @@ func (d *Database) GetOrCreatePrefix(
 		tableName = "prefixes_v6"
 	}
 
-	var (
+	var p Prefix
-		p     Prefix
-		idStr string
-	)
 
-	query := fmt.Sprintf("SELECT id, prefix, first_seen, last_seen "+
+	query := fmt.Sprintf("SELECT prefix, first_seen, last_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, &p.LastSeen)
 	if err == nil {
 		// Prefix exists, update last_seen
-		p.ID, _ = uuid.Parse(idStr)
 		p.IPVersion = ipVersion
-		updateQuery := fmt.Sprintf("UPDATE %s SET last_seen = ? WHERE id = ?", tableName)
+		updateQuery := fmt.Sprintf("UPDATE %s SET last_seen = ? WHERE prefix = ?",
+			tableName)
 
-		_, err = tx.Exec(updateQuery, timestamp, p.ID.String())
+		_, err = tx.Exec(updateQuery, timestamp, prefix)
 		if err != nil {
 			return nil, err
 		}
@@ -1085,12 +1145,12 @@ func (d *Database) GetOrCreatePrefix(
 	}
 
 	// Prefix doesn't exist, create it
-	p = Prefix{ID: generateUUID(), Prefix: prefix, IPVersion: ipVersion,
+	p = Prefix{Prefix: prefix, IPVersion: ipVersion,
 		FirstSeen: timestamp, LastSeen: timestamp}
 	insertQuery := fmt.Sprintf("INSERT INTO %s "+
-		"(id, prefix, first_seen, last_seen) VALUES (?, ?, ?, ?)", tableName)
+		"(prefix, first_seen, last_seen) VALUES (?, ?, ?)", tableName)
 
-	_, err = tx.Exec(insertQuery, p.ID.String(), p.Prefix, p.FirstSeen, p.LastSeen)
+	_, err = tx.Exec(insertQuery, p.Prefix, p.FirstSeen, p.LastSeen)
 	if err != nil {
 		return nil, err
 	}
@@ -1389,37 +1449,44 @@ func (d *Database) UpsertLiveRoute(route *LiveRoute) error {
 		return fmt.Errorf("failed to encode AS path: %w", err)
 	}
 
-	updateSQL, insertSQL, lookupSQL := updateLiveRouteV4SQL,
+	originSQL, updateSQL := updateLiveRouteOriginV4SQL, updateLiveRouteV4SQL
-		insertLiveRouteV4SQL, prefixHasLiveRouteV4SQL
+	insertSQL, lookupSQL := insertLiveRouteV4SQL, prefixHasLiveRouteV4SQL
+
 	if route.IPVersion == ipVersionV6 {
-		updateSQL, insertSQL, lookupSQL = updateLiveRouteV6SQL,
+		originSQL, updateSQL = updateLiveRouteOriginV6SQL, updateLiveRouteV6SQL
-			insertLiveRouteV6SQL, prefixHasLiveRouteV6SQL
+		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,
+	inserted, newPrefix, err := upsertRouteRow(ctx, setOrigin, upd, ins, has,
-		string(pathJSON))
+		route, string(pathJSON))
 	if err != nil {
 		return fmt.Errorf("failed to upsert route %s: %w", route.Prefix, err)
 	}
@@ -2008,7 +2075,7 @@ func (d *Database) UpdateASNWHOIS(
 		WHERE asn = ?
 	`
 
-	_, err := d.db.ExecContext(ctx, query,
+	_, err := d.writer.ExecContext(ctx, query,
 		update.ASName,
 		update.OrgName,
 		update.OrgID,
@@ -2174,7 +2241,7 @@ func (d *Database) Vacuum(ctx context.Context) error {
 	d.lock("Vacuum")
 	defer d.unlock()
 
-	rows, err := d.db.QueryContext(ctx,
+	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)
@@ -2206,7 +2273,7 @@ func (d *Database) Analyze(ctx context.Context) error {
 
 	// 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 +2290,7 @@ func (d *Database) Checkpoint(ctx context.Context) error {
 	d.lock("Checkpoint")
 	defer d.unlock()
 
-	_, err := d.db.ExecContext(ctx, "PRAGMA wal_checkpoint(TRUNCATE)")
+	_, err := d.writer.ExecContext(ctx, "PRAGMA wal_checkpoint(TRUNCATE)")
 	if err != nil {
 		return fmt.Errorf("failed to checkpoint WAL: %w", err)
 	}
@@ -2279,9 +2346,9 @@ 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),
@@ -337,8 +340,10 @@ 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.
+// incremental. The connection kept for writing must have the large cache, and
+// the soft heap limit must leave room for every connection's cache: SQLite
+// shrinks the caches to stay under it.
 func TestConnectionPoolPragmas(t *testing.T) {
 	t.Parallel()
 
@@ -372,9 +377,9 @@ 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 +394,12 @@ 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",
@@ -401,6 +412,29 @@ func TestConnectionPoolPragmas(t *testing.T) {
 				i, autoVacuum, autoVacuumIncremental)
 		}
 	}
+
+	var writeCacheSize 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)
+	}
+
+	readCacheSize := readPragma(ctx, t, conns[0], 0, "cache_size")
+	softHeapLimit := readPragma(ctx, t, conns[0], 0, "soft_heap_limit")
+	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.
@@ -1090,3 +1124,372 @@ 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 counted, and the known one keeps its
+// first_seen time while its last_seen time moves on.
+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, lastSeen time.Time
+	}{
+		{
+			query:  "SELECT first_seen, last_seen FROM prefixes_v4 WHERE prefix = ?",
+			prefix: known, firstSeen: first, lastSeen: later,
+		},
+		{
+			query:  "SELECT first_seen, last_seen FROM prefixes_v6 WHERE prefix = ?",
+			prefix: testV6Prefix, firstSeen: later, lastSeen: later,
+		},
+	} {
+		var firstSeen, lastSeen time.Time
+
+		err := db.db.QueryRowContext(t.Context(), tt.query, tt.prefix).
+			Scan(&firstSeen, &lastSeen)
+		if err != nil {
+			t.Fatalf("reading %s: %v", tt.prefix, err)
+		}
+
+		if !firstSeen.Equal(tt.firstSeen) || !lastSeen.Equal(tt.lastSeen) {
+			t.Errorf("%s: first seen %s, last seen %s; want %s, %s", tt.prefix,
+				firstSeen, lastSeen, tt.firstSeen, tt.lastSeen)
+		}
+	}
+}
+
+// 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
+
+	type row struct {
+		peer, prefix string
+		origin       int
+	}
+
+	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
+
+	var routes []*LiveRoute
+
+	for _, announced := range []row{
+		{secondV4PeerIP, "198.51.100.0/24", firstOrigin},
+		{testV4PeerIP, "203.0.113.0/24", firstOrigin},
+		{secondV4PeerIP, "192.0.2.0/24", firstOrigin},
+		{testV4PeerIP, "198.51.100.0/24", firstOrigin},
+		{secondV4PeerIP, "198.51.100.0/24", laterOrigin},
+	} {
+		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, "198.51.100.0/24", firstOrigin},
+		{testV4PeerIP, "203.0.113.0/24", firstOrigin},
+		{secondV4PeerIP, "192.0.2.0/24", firstOrigin},
+		{secondV4PeerIP, "198.51.100.0/24", 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 the last-seen time of every prefix
+// the batch names.
+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

@@ -37,7 +37,6 @@ type ASN struct {
 // Prefix represents an IP prefix (CIDR block) with its IP version (4 or 6)
 // and first/last seen timestamps.
 type Prefix struct {
-	ID        uuid.UUID
 	Prefix    string
 	IPVersion int // 4 or 6
 	FirstSeen time.Time
@@ -71,7 +70,6 @@ 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 +27,20 @@ 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 PRIMARY KEY,
-	prefix TEXT UNIQUE NOT NULL,
 	first_seen DATETIME NOT NULL,
 	last_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 PRIMARY KEY,
-	prefix TEXT UNIQUE NOT NULL,
 	first_seen DATETIME NOT NULL,
 	last_seen DATETIME NOT NULL
-);
+) WITHOUT ROWID;
 
 CREATE TABLE IF NOT EXISTS announcements (
 	id TEXT PRIMARY KEY,
@@ -75,11 +74,6 @@ 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 +91,14 @@ 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 +106,15 @@ 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
+	-- A peer has at most one route for a prefix. This key finds the route a
-	-- this key also finds all of a peer's routes, when its BGP session goes
+	-- write updates or deletes and, peer_ip coming first, all of a peer's
-	-- down; lookups by prefix use the prefix index below.
+	-- 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 +122,29 @@ 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
+-- Indexes for both live route tables, and the queries that use each.
--- Finds a prefix's newest route in one search, whatever the number of peers.
+--
+-- 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);
-CREATE INDEX IF NOT EXISTS idx_live_routes_v6_origin_asn ON live_routes_v6(origin_asn);
+-- mask_length, prefix: the prefix-length pages' list of a mask length's
-CREATE INDEX IF NOT EXISTS idx_live_routes_v6_last_updated ON live_routes_v6(last_updated);
+-- prefixes in text order, and the prefix distribution read at startup.
--- Index to optimize prefix distribution queries
+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);
+-- 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
@@ -97,7 +96,6 @@ func (m *mockStore) UpdatePrefixesBatch(prefixes map[string]time.Time) error {
 			}
 
 			m.Prefixes[prefix] = &database.Prefix{
-				ID:        uuid.New(),
 				Prefix:    prefix,
 				IPVersion: ipVersion,
 				FirstSeen: timestamp,
@@ -133,7 +131,6 @@ func (m *mockStore) GetOrCreatePrefix(
 	}
 
 	p := &database.Prefix{
-		ID:        uuid.New(),
 		Prefix:    prefix,
 		IPVersion: ipVersion,
 		FirstSeen: timestamp,
@@ -370,7 +367,6 @@ 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,

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),
 	}})