fix(backend): уменьшить лишние записи SQLite

Убрать WAL TRUNCATE с hot path NetFlow, не писать неизменённые UPDATE
и служебные INSERT, кэшировать карты topology/analytics.

Co-authored-by: Cursor <[email protected]>

backend/src/db/index.ts

@@ -8,18 +8,85 @@ import { env } from "../config.js"
 import * as schema from "./schema.js"
 
 export const SQLITE_BUSY_TIMEOUT_MS = 5000
+/** ~16 MiB page cache (negative = KiB). */
+export const SQLITE_CACHE_SIZE_KIB = 16_000
+export const SQLITE_WAL_AUTOCHECKPOINT_PAGES = 1000
+
+export interface SqliteWriteStats {
+  insert: number
+  update: number
+  delete: number
+  walCheckpoint: number
+}
+
+let writeTrace: SqliteWriteStats | null = null
+
+function classifyWriteSql(sql: string): keyof Omit<SqliteWriteStats, "walCheckpoint"> | null {
+  const head = sql.trimStart().slice(0, 12).toUpperCase()
+  if (head.startsWith("INSERT")) return "insert"
+  if (head.startsWith("UPDATE")) return "update"
+  if (head.startsWith("DELETE")) return "delete"
+  return null
+}
+
+function installSqliteWriteTrace(handle: SqliteHandle): SqliteHandle {
+  const origPrepare = handle.prepare.bind(handle)
+  handle.prepare = ((sql: string) => {
+    const stmt = origPrepare(sql)
+    const kind = classifyWriteSql(sql)
+    if (!kind) return stmt
+    const origRun = stmt.run.bind(stmt)
+    stmt.run = ((...args: unknown[]) => {
+      if (writeTrace) writeTrace[kind] += 1
+      return origRun(...args)
+    }) as typeof stmt.run
+    return stmt
+  }) as typeof handle.prepare
+
+  const origExec = handle.exec.bind(handle)
+  handle.exec = ((sql: string) => {
+    if (writeTrace) {
+      for (const part of sql.split(";")) {
+        const kind = classifyWriteSql(part)
+        if (kind) writeTrace[kind] += 1
+      }
+    }
+    return origExec(sql)
+  }) as typeof handle.exec
+
+  const origPragma = handle.pragma.bind(handle)
+  handle.pragma = ((source: string, options?: { simple?: boolean }) => {
+    if (writeTrace && /wal_checkpoint/i.test(source)) writeTrace.walCheckpoint += 1
+    return origPragma(source, options as never)
+  }) as typeof handle.pragma
+
+  return handle
+}
+
+export function countSqliteWrites<T>(fn: () => T): { result: T; stats: SqliteWriteStats } {
+  const stats: SqliteWriteStats = { insert: 0, update: 0, delete: 0, walCheckpoint: 0 }
+  writeTrace = stats
+  try {
+    return { result: fn(), stats }
+  } finally {
+    writeTrace = null
+  }
+}
 
 export function applySqlitePragmas(handle: SqliteHandle): void {
   handle.pragma("journal_mode = WAL")
   handle.pragma("foreign_keys = ON")
   handle.pragma(`busy_timeout = ${SQLITE_BUSY_TIMEOUT_MS}`)
   handle.pragma("synchronous = NORMAL")
+  handle.pragma(`wal_autocheckpoint = ${SQLITE_WAL_AUTOCHECKPOINT_PAGES}`)
+  handle.pragma("temp_store = MEMORY")
+  handle.pragma(`cache_size = -${SQLITE_CACHE_SIZE_KIB}`)
 }
 
 function openSqlite(): SqliteHandle {
   const handle = new Database(env.DATABASE_PATH)
   applySqlitePragmas(handle)
-  return handle
+  return installSqliteWriteTrace(handle)
 }
 
 let sqlite = openSqlite()