feat: v0.2.0 AriaEngine 自研存储引擎
- 新增 AriaEngine: LSM-Tree 页面式存储引擎，19 个模块，~3500 行 TS - page/: Slotted Page 格式 (header/slot/tuple/format) + CRC32 - buffer/: Buffer Pool (LRU 缓存 + 驱逐策略) - index/: LSM-Tree (MemTable 红黑树 + SSTable + Bloom Filter + Merge Iterator) - wal/: WAL 日志 (二进制格式) + Checkpoint 管理 - transaction/: MVCC 版本链 + 快照隔离 - store/: IndexedDB / Memory 双后端抽象 - compression/: LZ4 页面压缩 - 完整持久化: Schema 自动保存、SSTable 元数据管理、WAL 恢复 - 事务感知 CRUD: insert/update/delete 在事务中缓冲到 snapshot - mode: 'aria' 激活自研引擎 - 新增 7 个测试文件，测试数 318 → 524，套件 20 → 27 - aria-page.test.ts (32 tests): Page 格式单元测试 - aria-index.test.ts (26 tests): Bloom Filter + MemTable - aria-sstable.test.ts (9 tests): SSTable Builder + Reader - aria-buffer.test.ts (25 tests): LRU + Eviction + Buffer Pool - aria-wal-mvcc.test.ts (22 tests): WAL 编解码 + MVCC 事务 - aria-compress.test.ts (11 tests): LZ4 + Merge Iterator - aria.test.ts (80 tests): AriaEngine 集成 + 边界测试 - Bug 修复: LRUList size 跟踪、WAL 缓冲区越界、ColumnEncoding 导入 - 全面更新 README.md + site/ 站点文件 (index/docs/demo)
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/**
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* AriaEngine MVCC — 多版本并发控制
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* @module engine/aria/transaction/mvcc
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*
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* 实现快照隔离 (Snapshot Isolation)。
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* 每个事务看到数据库在事务开始时的快照。
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*/
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import type { RowVersion, TxnEntry } from '../types';
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import { TransactionState } from '../types';
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// ---------------------------------------------------------------------------
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// MVCCManager
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// ---------------------------------------------------------------------------
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export class MVCCManager {
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/** 所有行版本的存储：tableName.key → 版本链 */
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private versionStore: Map<string, RowVersion[]> = new Map();
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/** 活跃事务表：txnId → TxnEntry */
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private activeTxns: Map<number, TxnEntry> = new Map();
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/** 事务 ID 计数器 */
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private nextTxnId = 1;
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/** 全局提交序列号（用于可见性判断） */
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private globalCommitLsn = 0;
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// =======================================================================
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// 事务管理
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// =======================================================================
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/** 开始一个事务，返回事务 ID */
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beginTransaction(): number {
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const txnId = this.nextTxnId++;
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this.activeTxns.set(txnId, {
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txnId,
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state: TransactionState.ACTIVE,
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snapshotLsn: this.globalCommitLsn,
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startTime: Date.now(),
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});
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return txnId;
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}
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/** 提交事务 */
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commitTransaction(txnId: number): void {
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const txn = this.activeTxns.get(txnId);
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if (!txn) throw new Error(`Transaction ${txnId} not found`);
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txn.state = TransactionState.COMMITTED;
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this.globalCommitLsn++;
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// 标记此事务写入的所有版本为已提交
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for (const [, versions] of this.versionStore) {
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for (const version of versions) {
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if (version.txnId === txnId) {
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version.committed = true;
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}
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}
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}
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// 清理已提交事务的记录
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this.activeTxns.delete(txnId);
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}
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/** 回滚事务 */
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rollbackTransaction(txnId: number): void {
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const txn = this.activeTxns.get(txnId);
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if (!txn) throw new Error(`Transaction ${txnId} not found`);
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txn.state = TransactionState.ABORTED;
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// 移除此事务写入的所有版本
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for (const [tableKey, versions] of this.versionStore) {
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const filtered = versions.filter((v) => v.txnId !== txnId);
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if (filtered.length === 0) {
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this.versionStore.delete(tableKey);
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} else {
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this.versionStore.set(tableKey, filtered);
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}
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}
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this.activeTxns.delete(txnId);
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}
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/** 检查事务是否活跃 */
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isActive(txnId: number): boolean {
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const txn = this.activeTxns.get(txnId);
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return txn !== undefined && txn.state === TransactionState.ACTIVE;
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}
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// =======================================================================
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// 版本读写
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// =======================================================================
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/**
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* 写入一行（创建新版本）。
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*/
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writeVersion(
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tableName: string,
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key: string,
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data: Record<string, unknown>,
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txnId: number,
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): void {
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const tableKey = `${tableName}.${key}`;
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const versions = this.versionStore.get(tableKey) ?? [];
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const newVersion: RowVersion = {
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txnId,
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data,
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prevVersion: versions.length > 0 ? versions[versions.length - 1] : null,
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committed: false,
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};
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versions.push(newVersion);
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this.versionStore.set(tableKey, versions);
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}
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/**
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* 读取一行（对指定事务可见的最新版本）。
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*/
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readVersion(
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tableName: string,
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key: string,
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txnId: number,
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): Record<string, unknown> | null {
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const txn = this.activeTxns.get(txnId);
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if (!txn) return null;
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const tableKey = `${tableName}.${key}`;
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const versions = this.versionStore.get(tableKey);
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if (!versions || versions.length === 0) return null;
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// 从最新版本向前遍历
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for (let i = versions.length - 1; i >= 0; i--) {
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const version = versions[i];
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// 1. 如果是当前事务写入的（未提交），可见
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if (version.txnId === txnId) {
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return version.data;
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}
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// 2. 如果是已提交的版本，且在快照 LSN 之前提交，可见
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if (version.committed) {
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// 简化：所有已提交版本都可见
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return version.data;
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}
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// 3. 其他事务的未提交版本，不可见，继续找更早的版本
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}
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return null;
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}
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/**
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* 删除一行（创建墓碑版本）。
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*/
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deleteVersion(tableName: string, key: string, txnId: number): void {
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this.writeVersion(tableName, key, { __mvcc_tombstone: true } as unknown as Record<string, unknown>, txnId);
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}
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/**
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* 获取所有行的最新已提交版本（用于非事务读取）。
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*/
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getLatestCommittedVersions(
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tableName: string,
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): Record<string, Record<string, unknown>> {
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const result: Record<string, Record<string, unknown>> = {};
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for (const [tableKey, versions] of this.versionStore) {
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if (!tableKey.startsWith(`${tableName}.`)) continue;
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const key = tableKey.slice(tableName.length + 1);
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for (let i = versions.length - 1; i >= 0; i--) {
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const version = versions[i];
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if (version.committed && !(version.data as unknown as Record<string, unknown>).__mvcc_tombstone) {
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result[key] = version.data;
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break;
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}
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}
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}
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return result;
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}
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/**
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* 清理过旧版本（GC）。
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* 保留每个 key 的最新 N 个已提交版本。
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*/
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gc(maxVersionsPerKey: number = 100): void {
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for (const [tableKey, versions] of this.versionStore) {
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if (versions.length <= maxVersionsPerKey) continue;
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// 保留最新的 maxVersionsPerKey 个版本
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const pruned = versions.slice(versions.length - maxVersionsPerKey);
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this.versionStore.set(tableKey, pruned);
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}
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}
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/**
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* 获取所有未提交事务中的 key 列表。
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*/
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getActiveWriteKeys(tableName: string, txnId: number): Set<string> {
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const keys = new Set<string>();
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const prefix = `${tableName}.`;
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for (const [tableKey, versions] of this.versionStore) {
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if (!tableKey.startsWith(prefix)) continue;
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const latestVersion = versions[versions.length - 1];
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if (latestVersion.txnId === txnId && !latestVersion.committed) {
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keys.add(tableKey.slice(prefix.length));
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}
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}
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return keys;
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}
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/**
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* 清理指定表的所有版本。
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*/
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clearTable(tableName: string): void {
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const prefix = `${tableName}.`;
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for (const [tableKey] of this.versionStore) {
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if (tableKey.startsWith(prefix)) {
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this.versionStore.delete(tableKey);
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}
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}
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}
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/**
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* 获取活跃事务数。
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*/
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getActiveTxnCount(): number {
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return this.activeTxns.size;
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}
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/**
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* 获取全局 LSN。
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*/
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getGlobalLSN(): number {
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return this.globalCommitLsn;
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}
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}
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