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1、理論來源于實踐

現(xiàn)象：于2025-08-13 21:45:35，事實邏輯表將自身的指標與維度同步到原子服務(wù)的實現(xiàn)時，出現(xiàn)同步過來的指標與維度丟失。

核心原因：兩次重復(fù)的事實邏輯表同步時間非常相近，導(dǎo)致同步過來的指標與維度丟失。

2、倒帶進事故現(xiàn)場

邏輯表向原子服務(wù)同步的核心邏輯是 “先刪后增”：刪除舊數(shù)據(jù)→對比新老數(shù)據(jù)→插入新增數(shù)據(jù)，具體流程如下：

整體業(yè)務(wù)代碼精簡邏輯如下：

@Transactional(rollbackFor = Exception.class)
public Map driveToAtomService(Map logicTableData, String erp) {
//獲得環(huán)境信息
String env = driveLogicTable.getString(DRIVE_LOGIC_TABLE_ENV);
//獲取/更新實現(xiàn)id
 Long logicTableId = getOrAddLogicTableId(atomicServiceId, driveLogicTable, erp, EnvType.of(env));
//刪除關(guān)聯(lián)指標
 metricImplMapper.deleteByLogicTableIds(Collections.singletonList(logicId));
//獲取請求中的所有的指標信息
List metricList = getMetricImpls(logicTableData, logicTableId);
//獲取需要新增的指標實現(xiàn)(包含了查詢庫里現(xiàn)有的指標實現(xiàn))
List metricImpls = metricImplMapper.getMetricImpls(logicTableId);
Set metricDefIdSet = metricImpls.stream()
            .map(MetricImplRelBO::getMetricDefId).collect(Collectors.toSet());
List addList = metricList.stream()
            .filter(s -> !metricDefIdSet.contains(s.getMetricDefId())).collect(Collectors.toList());
//將需要新增的指標實現(xiàn)插入數(shù)據(jù)庫
 addMetricImpl(addList);

}

用一個請求進行舉例：

{"header":{"appKey":null,"uuid":"ce7cef2d-c417-464a-a519-311599fddfca","serviceName":"driveToAtomService","context":{"PIN":"wanyue3"}},"body":{"dimList":[{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":72,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2501,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2484,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2502,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":4591,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":3822,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":4523,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":4524,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":76,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1767,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1907,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1598,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":4620,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":4621,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":4622,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2504,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2485,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2486,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2487,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2488,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":3077,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":3080,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":3081,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2483,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2482,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":3082,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":3083,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":4851,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2503,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5070,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5044,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5087,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5144,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5145,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":3089,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":3680,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2223,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5428,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5101,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1315,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5247,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":3318,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5262,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":4646,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2252,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2254,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2959,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2958,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2728,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":2618,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":5061,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":6032,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":6375,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":6388,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":6389,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1316,"type":"ALL"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1081,"type":"FILTER"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1351,"type":"FILTER"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1082,"type":"FILTER"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1499,"type":"COMBINE"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1596,"type":"FILTER"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1606,"type":"FILTER"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1083,"type":"FILTER"},{"isRequiredForFilter":0,"supportCrossTopic":0,"dimDefId":1108,"type":"FILTER"}],"dimCombineList":[],"metricList":[{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":19872,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":19873,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":19875,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":19945,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":17263,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"COUNT_DISTINCT","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":28017,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":20242,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":18450,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":20276,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":18452,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":18453,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":18456,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":19866,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":21691,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"},{"lightDecorateIdList":"","aggregationType":"toSql","middleAggregationType":"DEFAULT","extendDecorateIdList":"4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867","staticDecorateIdListCombination":"","metricDefId":19871,"nameEnAtomic":null,"extendFunctionIdList":"25,6,5,7,23,22,20,21,19,18,4,1,2,3,24"}],"driveLogicTable":"{"dimensionType":"DETAIL","oldNameCn":"七鮮實時交易_for地推中間態(tài)新老標志","atomicAliasProd":"prod","implServiceTypeKey":"realtime","originPhysicDataSourceId":0,"nameCn":"七鮮實時交易_for地推中間態(tài)新老標志","description":"七鮮實時交易_for地推中間態(tài)新老標志","driveLogicTableId":9881,"driveLogicTableEnv":"DEV","commonDecorateIdList":"9665,3269,3270,3271,4556,8012,8270,6030,7247,6031,7248,6032,7249,6033,7250,6034,6035,2134,7254,7255,2085,619,620,5997,1586,7867,6845","atomicAliasPre":"pre","committer":"panjingrong","physicDataSourceId":9494,"storageType":"ONLINE","atomicAliasDev":"pre"}","atomicServiceId":1088},"pin":"wanyue3"}

共計15個指標，64個維度

請求1(事務(wù))		請求2(事務(wù))		?
21:06:17.262	進入同步方法	21:06:17.263	進入同步方法	?
21:06:17.063	select unify_metric_impl where logic_id = 3245 查詢出15條數(shù)據(jù)(快照讀，readview1)	21:06:17.363	select unify_metric_impl where logic_id = 3245 查詢出15條數(shù)據(jù)(快照讀，readview2)	?
21:06:17.363	delete from unify_metric_impl where logic_id = 3245	21:06:17.372	delete from unify_metric_impl where logic_id = 3245	?
21:06:17.459	select unify_metric_impl where logic_id = 3245 查詢出0條數(shù)據(jù)	?	delete 由于logic_id不是索引，會表鎖阻塞	?
21:06:18.459	insert into unify_metric_impl 插入的logic_id = 3245的數(shù)據(jù)，15條	?	?	?
21:06:19.408	方法結(jié)束	?	?	?
?	?	21:06:19.529	刪除成功	?
?	?	21:06:20.362	select unify_metric_impl where logic_id = 3245 得到 15條數(shù)據(jù)	?
?	?	21:06:20.435	讀出15條數(shù)據(jù)，比較本次是否有新增指標，得出沒有新增指標，因此不進行新增。addAtomicMetricNameForDrive addList empty	?
?	?	21:06:21.435	方法結(jié)束	?

核心結(jié)論點：

1.請求2的刪除操作被阻塞了，直到請求1執(zhí)行完整個方法。

2.請求2中去查看當前實現(xiàn)的指標的時候，發(fā)現(xiàn)庫里已經(jīng)存在所有指標不會進行新增，與上一步刪除的邏輯相悖。

3、結(jié)論點深度剖析

3.1 分析結(jié)論一

請求2的刪除操作被阻塞了，直到請求1執(zhí)行完整個方法。

3.1.1 復(fù)習(xí)mysql的InnoDB鎖機制

3.1.1.1 不是“一把鎖”，而是 “鎖矩陣”

鎖粒度	共享鎖（S 鎖）（讀鎖，允許多讀）	排他鎖（X 鎖）（寫鎖，獨占）	意向鎖（表級，輔助判斷）
表級	表 S 鎖（極少用，如LOCK TABLES ... READ）	表 X 鎖（極少用，如LOCK TABLES ... WRITE）	意向 S 鎖（IS）、意向 X 鎖（IX）
行級	行 S 鎖（SELECT ... FOR SHARE）	行 X 鎖（UPDATE/DELETE/INSERT默認加）	（行鎖無需意向鎖）
間隙級	間隙 S 鎖（無，間隙只防插入）	間隙 X 鎖（防其他事務(wù)插入相同間隙）	無
Next-Key	無	Next-Key 鎖（行鎖 + 間隙鎖，默認行鎖算法）	無

3.1.1.2 一張圖總結(jié)：InnoDB 鎖的 “決策邏輯”

3.1.2 理論應(yīng)用實踐

3.1.2.1 本次事故的物料：

mysql表：

CREATE TABLE `unify_metric_impl` (
  `id` bigint(50) unsigned NOT NULL AUTO_INCREMENT COMMENT '自增ID',
  `metric_def_id` bigint(11) unsigned NOT NULL DEFAULT '0' COMMENT '指標定義id',
  `logic_table_id` bigint(11) unsigned NOT NULL DEFAULT '0' COMMENT '邏輯表id',
  `name_en_atomic` varchar(256) NOT NULL DEFAULT '' COMMENT '真實指標名',
  `committer` varchar(64) NOT NULL DEFAULT '' COMMENT '負責人',
  `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '開始時間',
  `update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '修改時間',
  `metric_atomic_name_temp` varchar(32) NOT NULL DEFAULT '' COMMENT '原子指標id',
  `decorate_id_list_temp` varchar(32) NOT NULL DEFAULT '' COMMENT '修飾列表',
  `name_cn_alias_temp` varchar(32) NOT NULL DEFAULT '' COMMENT '中文別名',
  `metric_type_temp` varchar(32) NOT NULL DEFAULT '' COMMENT '指標類型：DERIVE 衍生指標，F(xiàn)ORMULA 復(fù)合指標',
  `description_temp` varchar(64) NOT NULL DEFAULT '' COMMENT '指標說明',
  `data_type_temp` varchar(16) NOT NULL DEFAULT '' COMMENT '數(shù)據(jù)類型：STRING，DOUBLE, LONG, INT',
  `data_accuracy_temp` tinyint(4) NOT NULL DEFAULT '2' COMMENT '數(shù)據(jù)精度-小數(shù)點后幾位',
  `security_level_temp` varchar(16) DEFAULT '-1' COMMENT '安全等級',
  `logic_table_id_excel_temp` varchar(16) DEFAULT '-1' COMMENT '模型excelId',
  `implement_type` varchar(32) NOT NULL DEFAULT '' COMMENT '指標實現(xiàn)類型：APP、ATOMIC 原子服務(wù)',
  `app_ori_metric_name_temp` varchar(16) DEFAULT '' COMMENT '所依賴的app層原始名字（適用于導(dǎo)數(shù)任務(wù)改變字段的情況）',
  `name_en_depend_atomic` varchar(256) NOT NULL DEFAULT '' COMMENT '指標依賴字段',
  `name_en_depend_app` varchar(16) DEFAULT '' COMMENT '所依賴的app層原始名字（適用于導(dǎo)數(shù)任務(wù)改變字段的情況）',
  `update_status` tinyint(4) NOT NULL DEFAULT '0' COMMENT '信息更新狀態(tài) 0-未完成更新，1-完成更新',
  `status` tinyint(4) NOT NULL DEFAULT '0' COMMENT '信息更新狀態(tài) 0-未完成更新，1-完成更新',
  `light_decorate_id_list` varchar(1024) NOT NULL DEFAULT '' COMMENT '點燈修飾id列表',
  `extend_decorate_id_list` varchar(1024) NOT NULL DEFAULT '' COMMENT '支持的動態(tài)修飾id列表',
  `extend_function_id_list` varchar(1024) NOT NULL DEFAULT '' COMMENT '支持的原子服務(wù)函數(shù)id列表',
  `aggregation_type` varchar(64) NOT NULL DEFAULT '' COMMENT '聚合類型:ORIGINAL 原值 COUNT 計數(shù) DISTINCT 指定字段去重 SUM 求和 AVG  均值 MIN 求最大值 MAX 求最小值 QUANTITLE 求分位數(shù)',
  `middle_aggregation_type` varchar(30) NOT NULL DEFAULT '' COMMENT '中間層類型,UNKNOWN:未知,AGG_BY_FIELD:按聚合字段分組后聚合,AGG_BY_DAY:按天去重后累加',
  `static_decorate_id_list_combination` varchar(1024) NOT NULL DEFAULT '' COMMENT '支持的固化修飾id列表組合,[[d1,d2],[d2]]',
  PRIMARY KEY (`id`),
  KEY `idx_metric_def_id` (`metric_def_id`,`logic_table_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='指標實現(xiàn)';

3.1.2.2 實踐分析

通過mysql的innoDB的鎖決策，可以得出

//刪除關(guān)聯(lián)指標
 metricImplMapper.deleteByLogicTableIds(Collections.singletonList(logicId));

delete from unify_metric_impl where logic_table_id in (45631);

mysql的索引：KEY `idx_metric_def_id` (`metric_def_id`,`logic_table_id`)

刪除寫操作，不符合最左匹配原則，因此為表x鎖。

因此請求2的刪除操作需要等待請求1的事務(wù)釋放表鎖后才可繼續(xù)進行，符合當時場景。

3.2 分析結(jié)論二

請求2中去查看當前實現(xiàn)的指標的時候，發(fā)現(xiàn)庫里已經(jīng)存在所有指標不會進行新增，與上一步刪除的邏輯相悖。

3.2.1 復(fù)習(xí)Mysql的事務(wù)

3.2.1.1 ACID 不是 "四個獨立特性"，而是 "因果鏈"

?一句話：ACID 的核心是一致性，其他三個特性都是為了實現(xiàn)它的手段。

?一致性（Consistency）：一致性確保事務(wù)將數(shù)據(jù)庫從一個一致的狀態(tài)轉(zhuǎn)變到另一個一致的狀態(tài)。即使在多個事務(wù)同時執(zhí)行的情況下，數(shù)據(jù)庫也能保持數(shù)據(jù)的一致性。

?原子性（Atomicity）：事務(wù)是 "不可分割的工作單元"（要么全成，要么全?。?，是一致性的前提（如果步驟能拆分，中間失敗就會破壞一致性）。

?隔離性（Isolation）：通過控制多事務(wù)并發(fā)規(guī)則，避免互相干擾，是一致性的保障（并發(fā)混亂會直接破壞一致性）。

?耐久性（Durability）：事務(wù)提交后結(jié)果永久保存，是一致性的最終落點（否則重啟后數(shù)據(jù)丟失，之前的一致性白搭）。

3.2.1.2 隔離級別：不是 "越嚴越好"，而是 "成本與需求的平衡術(shù)"

InnoDB 的 4 種隔離級別，本質(zhì)是用 "數(shù)據(jù)可見性" 換 "并發(fā)性能"的選擇：

隔離級別	解決的問題	無法解決的問題	性能消耗	典型場景
讀未提交（RU）	無	臟讀、不可重復(fù)讀、幻讀	極低	實時監(jiān)控（允許臟數(shù)據(jù)）
讀已提交（RC）	臟讀	不可重復(fù)讀、幻讀	低	互聯(lián)網(wǎng)普通業(yè)務(wù)
可重復(fù)讀（RR，默認）	臟讀、不可重復(fù)讀	幻讀（被 Next-Key 鎖解決）	中	金融交易、庫存管理
串行化（Serializable）	所有并發(fā)問題	無	極高	銀行對賬（無并發(fā)需求）

3.2.1.3 MVCC：事務(wù)的 "平行宇宙" 機制（為什么讀寫不沖突？）

InnoDB 的多版本并發(fā)控制是 "無鎖讀" 的核心，它讓讀和寫像在平行宇宙中運行：

底層邏輯（用 "時間戳" 理解）：

?每個事務(wù)啟動時，會拿到一個全局遞增的事務(wù) ID（trx_id）。

?每行數(shù)據(jù)隱藏 3 個字段：

?DB_TRX_ID：最后修改該行的事務(wù) ID；

?DB_ROLL_PTR：指向 undo 日志的指針（存儲歷史版本）；

?DB_DELETED：標記是否刪除（邏輯刪除）。

讀操作的 "幻術(shù)"：

?快照讀（普通 SELECT）：只看 "事務(wù) ID ≤ 自己 ID" 且 "未被刪除" 的版本，完全不加鎖。例：事務(wù) A（ID=100）查詢時，會忽略所有被 ID>100 的事務(wù)修改的數(shù)據(jù)。

包含 4 個核心字段：

?m_ids：生成 Read View 時，當前活躍的事務(wù) ID 列表（未提交的事務(wù)）。

?min_trx_id：m_ids中最小的事務(wù) ID。

?max_trx_id：下一個將要分配的事務(wù) ID（非活躍事務(wù) ID，僅用于判斷 “未來事務(wù)”）。

?creator_trx_id：生成該 Read View 的事務(wù)自身 ID。

可見性判斷規(guī)則（一條記錄是否對當前事務(wù)可見，取決于其 “最后修改事務(wù) ID”，記為db_trx_id）：

1.若db_trx_id == creator_trx_id：可見（自己修改的自己可見）。

2.若db_trx_id < min_trx_id：可見（修改記錄的事務(wù)在當前快照生成前已提交）。

3.若db_trx_id >= max_trx_id：不可見（修改記錄的事務(wù)在當前快照生成后才啟動）。

4.若min_trx_id ≤ db_trx_id < max_trx_id：

?若db_trx_id在m_ids中：不可見（該事務(wù)仍活躍，未提交）。

?若db_trx_id不在m_ids中：可見（該事務(wù)已提交）。

5.當前讀（加鎖讀 / 寫操作）：讀取最新版本，并加鎖防止其他事務(wù)修改。

3.2.1.4 事務(wù)日志：InnoDB 的 "安全與性能" 平衡術(shù)

事務(wù)能既保證 durability 又不慢，全靠兩大日志：

1.redo log（重做日志）：

?作用：崩潰后恢復(fù)未寫入磁盤的數(shù)據(jù)（保證 durability）。

?反直覺：事務(wù)提交時，數(shù)據(jù)先寫 redo log（內(nèi)存 + 磁盤），再異步刷到數(shù)據(jù)文件（這叫 WAL 技術(shù)）。

?為什么快？redo log 是順序?qū)?/strong>（磁盤順序?qū)懕入S機寫快 100 倍 +）。

2.undo log（回滾日志）：

?作用：保存數(shù)據(jù)修改前的版本，用于事務(wù)回滾（保證 atomicity）和 MVCC 快照讀。

?注意：undo log 會被 purge 線程定期清理（當沒有事務(wù)需要舊版本時）。

3.2.1.5 終極心法：事務(wù)設(shè)計的 "3 個凡是"

1.凡是不需要事務(wù)的操作，堅決不用（如日志插入可關(guān)閉自動提交，批量提交）。

2.凡是能在 RC 解決的，絕不升 RR（互聯(lián)網(wǎng)業(yè)務(wù)優(yōu)先選 RC，用業(yè)務(wù)邏輯防不可重復(fù)讀）。

3.凡是大事務(wù)，必拆分成 "讀 - 算 - 寫" 三步（讀階段不加鎖，算階段在應(yīng)用層，寫階段用最短事務(wù)加鎖）。

記?。菏聞?wù)的本質(zhì)不是 "約束"，而是 "工具"—— 能解決問題的最簡單事務(wù)，才是最好的事務(wù)。

?

3.2.2 理論應(yīng)用實踐

3.2.2.1 本次事故的物料：

表的事務(wù)等級：

SELECT @@transaction_isolation;

?

需要刪除的指標實現(xiàn)(根據(jù)實現(xiàn)id):

delete from unify_metric_impl where logic_table_id in (45631);

需要插入的指標實現(xiàn)：

INSERT INTO `unify_metric_impl` (`id`, `metric_def_id`, `logic_table_id`, `name_en_atomic`, `committer`, `create_time`, `update_time`, `metric_atomic_name_temp`, `decorate_id_list_temp`, `name_cn_alias_temp`, `metric_type_temp`, `description_temp`, `data_type_temp`, `data_accuracy_temp`, `security_level_temp`, `logic_table_id_excel_temp`, `implement_type`, `app_ori_metric_name_temp`, `name_en_depend_atomic`, `name_en_depend_app`, `update_status`, `status`, `light_decorate_id_list`, `extend_decorate_id_list`, `extend_function_id_list`, `aggregation_type`, `middle_aggregation_type`, `static_decorate_id_list_combination`) VALUES (1358195, 19872, 45631, 'jdr_7fresh_trade_complete_ord_user_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358196, 19873, 45631, 'jdr_7fresh_trade_complete_ord_sku_dis_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358197, 19875, 45631, 'jdr_7fresh_trade_complete_ord_ord_dis_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358198, 19945, 45631, 'jdr_7fresh_sku_deal_ord_sku_dis_qtty_main_img_video_num', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358199, 17263, 45631, 'jdr_7fresh_trade_deal_ord_ord_dis_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358200, 28017, 45631, 'jdr_7fresh_bd_bd_attendance_offline__store_cnt_bd_attendance_cnt', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'COUNT_DISTINCT', 'DEFAULT', ''), (1358201, 20242, 45631, 'jdr_7fresh_trade_deal_ord_app__ord_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358202, 18450, 45631, 'jdr_7fresh_trade_deal_ord_ord_amt_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358203, 20276, 45631, 'jdr_7fresh_trade_deal_ord_app__ord_cnt_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358204, 18452, 45631, 'jdr_7fresh_trade_deal_ord_sku_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358205, 18453, 45631, 'jdr_7fresh_trade_deal_ord_user_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358206, 18456, 45631, 'jdr_7fresh_trade_deal_ord_sku_dis_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358207, 19866, 45631, 'jdr_7fresh_trade_complete_ord_ord_amt_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358208, 21691, 45631, 'jdr_7fresh_trade_deal_ord_ord_amt_include_moutai', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (1358209, 19871, 45631, 'jdr_7fresh_trade_complete_ord_sku_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', '');

3.2.2.2 實踐分析：

用sql模擬兩個事務(wù)的執(zhí)行過程：

事務(wù)1：

begin; select * from unify_metric_impl umi where logic_table_id = 45631; delete from unify_metric_impl where logic_table_id in (45631); SELECT trx_id, trx_query FROM INFORMATION_SCHEMA.INNODB_TRX; select * from unify_metric_impl umi where logic_table_id = 45631; INSERT INTO `unify_metric_impl` ( `metric_def_id`, `logic_table_id`, `name_en_atomic`, `committer`, `create_time`, `update_time`, `metric_atomic_name_temp`, `decorate_id_list_temp`, `name_cn_alias_temp`, `metric_type_temp`, `description_temp`, `data_type_temp`, `data_accuracy_temp`, `security_level_temp`, `logic_table_id_excel_temp`, `implement_type`, `app_ori_metric_name_temp`, `name_en_depend_atomic`, `name_en_depend_app`, `update_status`, `status`, `light_decorate_id_list`, `extend_decorate_id_list`, `extend_function_id_list`, `aggregation_type`, `middle_aggregation_type`, `static_decorate_id_list_combination`) VALUES (19872, 45631, 'jdr_7fresh_trade_complete_ord_user_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (19873, 45631, 'jdr_7fresh_trade_complete_ord_sku_dis_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (19875, 45631, 'jdr_7fresh_trade_complete_ord_ord_dis_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (19945, 45631, 'jdr_7fresh_sku_deal_ord_sku_dis_qtty_main_img_video_num', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (17263, 45631, 'jdr_7fresh_trade_deal_ord_ord_dis_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (28017, 45631, 'jdr_7fresh_bd_bd_attendance_offline__store_cnt_bd_attendance_cnt', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'COUNT_DISTINCT', 'DEFAULT', ''), (20242, 45631, 'jdr_7fresh_trade_deal_ord_app__ord_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (18450, 45631, 'jdr_7fresh_trade_deal_ord_ord_amt_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (20276, 45631, 'jdr_7fresh_trade_deal_ord_app__ord_cnt_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (18452, 45631, 'jdr_7fresh_trade_deal_ord_sku_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (18453, 45631, 'jdr_7fresh_trade_deal_ord_user_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (18456, 45631, 'jdr_7fresh_trade_deal_ord_sku_dis_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (19866, 45631, 'jdr_7fresh_trade_complete_ord_ord_amt_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (21691, 45631, 'jdr_7fresh_trade_deal_ord_ord_amt_include_moutai', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''), (19871, 45631, 'jdr_7fresh_trade_complete_ord_sku_qtty_deal_7fresh', '', '2025-09-02 09:23:41', '2025-09-02 09:23:41', '', '', '', '', '', '', 2, '-1', '-1', '', '', '', '', 0, 0, '', '4556,8012,8270,7247,7248,7249,7250,2134,7254,7255,5997,7867', '25,6,5,7,23,22,20,21,19,18,4,1,2,3,24', 'toSql', 'DEFAULT', ''); commit;

?

事務(wù)2：

begin; select * from unify_metric_impl umi where logic_table_id = 45631; delete from unify_metric_impl where logic_table_id in (45631); select * from unify_metric_impl umi where logic_table_id = 45631; commit;

?

流程圖(用一行數(shù)據(jù)進行演示版本控制)：

?

為何事務(wù)1的select查詢出“為空”，事務(wù)2的select查詢出“不為空”：

對比維度事務(wù) 1 查詢（讀自己的刪除版本 V2）事務(wù) 2 查詢（讀readview前的V1版本）
自己生成的版本 V2（trx_id=17190，已刪除） V4（trx_id=17191，已刪除）
對自己版本的處理可見，且事務(wù)內(nèi)需反映自己的刪除操作，所以不追溯前驅(qū) V1 不可見，但當前刪除的版本是由其他事務(wù)得到(V3)，并非在readview之前的數(shù)據(jù)。
追溯的終止條件遇到自己生成的版本，即使已刪除，也終止追溯遇到自己生成的已刪除版本，但不符合"有效刪除"，需繼續(xù)追溯
最終返回結(jié)果 v2（已刪除版本，反映自己的刪除操作） V1（readview之前有效的版本）
?

4.解決辦法

為了解決事務(wù)2的查詢"不為空"的問題，分別列出以下方案：

?
解決辦法優(yōu)點缺點傾向
方式1 針對同一個邏輯表的同步添加分布式鎖實現(xiàn)成本低，影響范圍小存在長事務(wù)的問題短期解法
方式2 將事務(wù)2的select改為當前讀(使用slecet...for update)，這樣就能查詢出最新的數(shù)據(jù)為空實現(xiàn)成本低，存在長事務(wù)的問題，影響范圍大(長事務(wù)涉及邏輯多) 不推薦
方式3 將長事務(wù)拆分， "讀 - 算 - 寫" 三步 1. 讀：無鎖讀取原子服務(wù)與實現(xiàn)數(shù)據(jù)； 2. 算：在應(yīng)用層對比新增 / 刪除數(shù)據(jù)； 3. 寫：僅對差異數(shù)據(jù)執(zhí)行短事務(wù)操作從根源解決問題實現(xiàn)成本大，重構(gòu)該方法長期解法
當前落地情況：已通過 “分布式鎖控制同一邏輯表同步并發(fā)” 的短期方案解決事故，后續(xù)將在業(yè)務(wù)迭代中推進 “讀 - 算 - 寫” 拆分的長期優(yōu)化，進一步降低事務(wù)粒度與鎖沖突風險。

5.附錄

5.1名詞解釋

事實邏輯表：由物理數(shù)倉中的事實表和維度邏輯表關(guān)聯(lián)形成的語義表，可以描述業(yè)務(wù)過程的詳細信息，是指標的數(shù)據(jù)來源。

原子服務(wù)：指標的實現(xiàn)方式，一個指標可以有多個實現(xiàn)。

?
審核編輯黃宇

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評論

對比維度	事務(wù) 1 查詢（讀自己的刪除版本 V2）	事務(wù) 2 查詢（讀readview前的V1版本）
自己生成的版本	V2（trx_id=17190，已刪除）	V4（trx_id=17191，已刪除）
對自己版本的處理	可見，且事務(wù)內(nèi)需反映自己的刪除操作，所以不追溯前驅(qū) V1	不可見，但當前刪除的版本是由其他事務(wù)得到(V3)，并非在readview之前的數(shù)據(jù)。
追溯的終止條件	遇到自己生成的版本，即使已刪除，也終止追溯	遇到自己生成的已刪除版本，但不符合"有效刪除"，需繼續(xù)追溯
最終返回結(jié)果	v2（已刪除版本，反映自己的刪除操作）	V1（readview之前有效的版本）

?	解決辦法	優(yōu)點	缺點	傾向
方式1	針對同一個邏輯表的同步添加分布式鎖	實現(xiàn)成本低，影響范圍小	存在長事務(wù)的問題	短期解法
方式2	將事務(wù)2的select改為當前讀(使用slecet...for update)，這樣就能查詢出最新的數(shù)據(jù)為空	實現(xiàn)成本低，	存在長事務(wù)的問題，影響范圍大(長事務(wù)涉及邏輯多)	不推薦
方式3	將長事務(wù)拆分， "讀 - 算 - 寫" 三步 1. 讀：無鎖讀取原子服務(wù)與實現(xiàn)數(shù)據(jù)； 2. 算：在應(yīng)用層對比新增 / 刪除數(shù)據(jù)； 3. 寫：僅對差異數(shù)據(jù)執(zhí)行短事務(wù)操作	從根源解決問題	實現(xiàn)成本大，重構(gòu)該方法	長期解法