【MongoDB】4.0版本事務上手測試

時間 2019-11-09

原文原文鏈接

事務上手測試

基礎：

原來3版本的只能叫單文檔事務，即針對行的事務。因此不必顯式提供調用，多文檔事務因爲有損耗，照顧到性能的需求，提供了事務開啓關閉的接口。
多行，多集合，多庫之間讀確定會牽扯到一致性讀，因此多文檔事務確定是有必要的。
4.2版本可能會支持分片系統多文檔事務，4.0的多文檔事務最多隻面向複製集javascript

準備

集合：java

use dba;
[10.240.129.36:30001_primary@dba]> db.coll_2.find()
[10.240.129.36:30001_primary@dba]> db.coll_1.find()
{ "_id" : ObjectId("5b371e120d6160b73a9fcee6"), "test" : true }
{ "_id" : ObjectId("5b371e6d0d6160b73a9fcee7"), "test" : true }

精簡命令：mysql

// 顯式開啓一個會話（難道經過shell連接來自己不就是會話嗎？）
session=db.getMongo().startSession()
// 顯式開啓事務
session.startTransaction()
// 獲取表對象
coll_1=session.getDatabase('dba').coll_1
coll_2=session.getDatabase('dba').coll_2;
// 使用表對象的插入函數進行插入
coll_1.insertOne({'not_test':false})
coll_2.insertOne({'not_test':false})
// 提交事務
session.commitTransaction()
// 回滾事務
session.abortTransaction()
// 檢查事務準確性
db.coll_1.find()
db.coll_2.find()

超時參數怎麼設置？

默認事務生命週期爲60秒，超出後會被自動清理sql

// The minimum value for transactionLifetimeLimitSeconds is 1 second.
db.adminCommand( { setParameter: 1, transactionLifetimeLimitSeconds: 30 } )
// You can also set parameter transactionLifetimeLimitSeconds at startup time.
// 能夠考慮寫在配置文件中
mongod --setParameter "transactionLifetimeLimitSeconds=30"

第一次嘗試

由於忘記設置後向兼容性，執行失敗，在同一個shell中進行設置後，再次插入，提示事務不存在mongodb

[10.240.129.36:30001_primary@dba]> Session.startTransactions()
2018-06-30T14:17:10.670+0800 E QUERY    [js] ReferenceError: Session is not defined :
@(shell):1:1
[10.240.129.36:30001_primary@dba]> db.getMongo()
connection to 127.0.0.1:30001
[10.240.129.36:30001_primary@dba]> db.getMongo().startSession()
session { "id" : UUID("887f4564-4f8a-4783-886d-a55a536f41aa") }
[10.240.129.36:30001_primary@dba]> session=db.getMongo().startSession()
session { "id" : UUID("9b3e10b9-93cd-4010-b1a3-0e7b49796db3") }
[10.240.129.36:30001_primary@dba]> session.startTransaction()
[10.240.129.36:30001_primary@dba]> coll_1=session.getDatabase('dba').coll_1;
dba.coll_1
[10.240.129.36:30001_primary@dba]> coll_2=session.getDatabase('dba').coll_2;
dba.coll_2
[10.240.129.36:30001_primary@dba]> coll_1.insertOne({'not_test':false})
// 後向兼容性要求爲4，也就是說想開啓事務必須是mongod4以上的版本
2018-06-30T14:28:55.708+0800 E QUERY    [js] WriteCommandError: Transactions are only supported in featureCompatibilityVersion 4.0. See http://dochub.mongodb.org/core/4.0-feature-compatibility for more information. :
WriteCommandError({
    "ok" : 0,
    "errmsg" : "Transactions are only supported in featureCompatibilityVersion 4.0. See http://dochub.mongodb.org/core/4.0-feature-compatibility for more information.",
    "code" : 50773,
    "codeName" : "Location50773"
})
WriteCommandError@src/mongo/shell/bulk_api.js:420:48
Bulk/executeBatch@src/mongo/shell/bulk_api.js:902:1
Bulk/this.execute@src/mongo/shell/bulk_api.js:1150:21
DBCollection.prototype.insertOne@src/mongo/shell/crud_api.js:252:9
@(shell):1:1
[10.240.129.36:30001_primary@dba]> db.adminCommand({setFeatureCompatibilityVersion:'4.0'})
{ "ok" : 1 }

// 能夠看到，報錯，從新設置版本兼容性後，原先的事務出現了問題
[10.240.129.36:30001_primary@dba]> coll_1.insertOne({'not_test':false})
2018-06-30T14:31:16.706+0800 E QUERY    [js] WriteCommandError: Given transaction number 0 does not match any in-progress transactions. :
WriteCommandError({
    "errorLabels" : [
        "TransientTransactionError"
    ],
    "ok" : 0,
    "errmsg" : "Given transaction number 0 does not match any in-progress transactions.",
    "code" : 251,
    "codeName" : "NoSuchTransaction"
})
WriteCommandError@src/mongo/shell/bulk_api.js:420:48
Bulk/executeBatch@src/mongo/shell/bulk_api.js:902:1
Bulk/this.execute@src/mongo/shell/bulk_api.js:1150:21
DBCollection.prototype.insertOne@src/mongo/shell/crud_api.js:252:9
@(shell):1:1

// 事務怎麼也調很差了

[10.240.129.36:30001_primary@dba]> session.startTransaction()
2018-06-30T14:33:53.293+0800 E QUERY    [js] Error: Transaction already in progress on this session. :
startTransaction@src/mongo/shell/session.js:732:1
startTransaction@src/mongo/shell/session.js:925:17
@(shell):1:1
[10.240.129.36:30001_primary@dba]> db.getMongo().abortTransaction
[10.240.129.36:30001_primary@dba]> db.getMongo().abortTransaction
[10.240.129.36:30001_primary@dba]> db.getMongo().abortTransaction
[10.240.129.36:30001_primary@dba]> db.getMongo().abortTransaction
[10.240.129.36:30001_primary@dba]> db.getMongo().abortTransaction
[10.240.129.36:30001_primary@dba]>
[10.240.129.36:30001_primary@dba]> db.getMongo().abortTransaction
[10.240.129.36:30001_primary@dba]> db.getMongo().abortTransaction
[10.240.129.36:30001_primary@dba]> exit
// 直接退出當前鏈接

第二次嘗試：

[10.240.129.36:30001_primary@admin]> session=db.getMongo().startSession()
session { "id" : UUID("b82d71b0-b698-4909-b5b8-a7845dba98b2") }
[10.240.129.36:30001_primary@admin]>  session.startTransaction()
[10.240.129.36:30001_primary@admin]> coll_1=session.getDatabase('dba').coll_1
dba.coll_1
[10.240.129.36:30001_primary@admin]> coll_2=session.getDatabase('dba').coll_2;
dba.coll_2
[10.240.129.36:30001_primary@admin]> coll_1.insertOne({'not_test':false})
{
    "acknowledged" : true,
    "insertedId" : ObjectId("5b37270429c5c0c486b4b17b")
}
[10.240.129.36:30001_primary@admin]> coll_2.insertOne({'not_test':false})

// 這裏的事務回滾多是由於超時引發的，默認事務生命週期最大值爲1分鐘

2018-06-30T15:00:50.629+0800 E QUERY    [js] WriteCommandError: Transaction 0 has been aborted. :
WriteCommandError({
    "errorLabels" : [
        "TransientTransactionError"
    ],
    "ok" : 0,
    "errmsg" : "Transaction 0 has been aborted.",
    "code" : 251,
    "codeName" : "NoSuchTransaction"
})
WriteCommandError@src/mongo/shell/bulk_api.js:420:48
Bulk/executeBatch@src/mongo/shell/bulk_api.js:902:1
Bulk/this.execute@src/mongo/shell/bulk_api.js:1150:21
DBCollection.prototype.insertOne@src/mongo/shell/crud_api.js:252:9
@(shell):1:1
[10.240.129.36:30001_primary@admin]> coll_2.insertOne({'not_test':false})
2018-06-30T15:00:59.308+0800 E QUERY    [js] WriteCommandError: Transaction 0 has been aborted. :
WriteCommandError({
    "errorLabels" : [
        "TransientTransactionError"
    ],
    "ok" : 0,
    "errmsg" : "Transaction 0 has been aborted.",
    "code" : 251,
    "codeName" : "NoSuchTransaction"
})
WriteCommandError@src/mongo/shell/bulk_api.js:420:48
Bulk/executeBatch@src/mongo/shell/bulk_api.js:902:1
Bulk/this.execute@src/mongo/shell/bulk_api.js:1150:21
DBCollection.prototype.insertOne@src/mongo/shell/crud_api.js:252:9
@(shell):1:1

// 事務超時回滾以後，應該還能夠重開新的事務纔對，這裏總是報錯

[10.240.129.36:30001_primary@admin]> session.startTransaction()
2018-06-30T15:01:04.932+0800 E QUERY    [js] Error: Transaction already in progress on this session. :
startTransaction@src/mongo/shell/session.js:732:1
startTransaction@src/mongo/shell/session.js:925:17
@(shell):1:1

// 內部已經回滾掉了，結果居然須要我手動回滾才行，暈

[10.240.129.36:30001_primary@admin]> session.abortTransaction()
[10.240.129.36:30001_primary@admin]> session.startTransaction()
[10.240.129.36:30001_primary@admin]> coll_1.insertOne({'not_test':false})
{
    "acknowledged" : true,
    "insertedId" : ObjectId("5b372ac229c5c0c486b4b17e")
}
[10.240.129.36:30001_primary@admin]> coll_2.insertOne({'not_test':false})
{
    "acknowledged" : true,
    "insertedId" : ObjectId("5b372ac529c5c0c486b4b17f")
}

// 試試能不能進行explain操做

[10.240.129.36:30001_primary@admin]> coll_1.explain().find({'test_explain':1})
2018-06-30T15:03:09.375+0800 E QUERY    [js] Error: explain failed: {
    "ok" : 0,
    "errmsg" : "Cannot run 'explain' in a multi-document transaction.",
    "code" : 50767,
    "codeName" : "Location50767"
} :  // 果真是報錯了呢，在事務中不能進行explain操做
_getErrorWithCode@src/mongo/shell/utils.js:25:13
throwOrReturn@src/mongo/shell/explainable.js:31:1
constructor/this.finish@src/mongo/shell/explain_query.js:171:24
constructor/this.shellPrint@src/mongo/shell/explain_query.js:210:26
shellPrintHelper@src/mongo/shell/utils.js:594:1
@(shell2):1:1

// 嘗試提交時報錯
[10.240.129.36:30001_primary@admin]> session.commitTransaction()
2018-06-30T15:04:21.985+0800 E QUERY    [js] Error: command failed: {
    "errorLabels" : [
        "TransientTransactionError"
    ],
    "ok" : 0,
    "errmsg" : "Transaction 1 has been aborted.",
    "code" : 251,
    "codeName" : "NoSuchTransaction"
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
doassert@src/mongo/shell/assert.js:18:14
_assertCommandWorked@src/mongo/shell/assert.js:534:17
assert.commandWorked@src/mongo/shell/assert.js:618:16
commitTransaction@src/mongo/shell/session.js:929:17
@(shell):1:1

[10.240.129.36:30001_primary@dba]> db.coll_1.find()
{ "_id" : ObjectId("5b371e120d6160b73a9fcee6"), "test" : true }
{ "_id" : ObjectId("5b371e6d0d6160b73a9fcee7"), "test" : true }
[10.240.129.36:30001_primary@dba]> db.coll_2.find()
// 這邊能夠看到，插入語句並無真正被執行

[10.240.129.36:30001_primary@dba]> session.commitTransaction()
2018-06-30T15:05:46.288+0800 E QUERY    [js] Error: command failed: {
    "errorLabels" : [
        "TransientTransactionError"
    ],
    "ok" : 0,
    "errmsg" : "Transaction 1 has been aborted.",
    "code" : 251,
    "codeName" : "NoSuchTransaction"
} :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
doassert@src/mongo/shell/assert.js:18:14
_assertCommandWorked@src/mongo/shell/assert.js:534:17
assert.commandWorked@src/mongo/shell/assert.js:618:16
commitTransaction@src/mongo/shell/session.js:929:17
@(shell):1:1

// 這兒又抽風了，內部回滾以後禁止提交操做，嘗試進行回滾，結果說已經提交了，不能回滾，真是暈死

[10.240.129.36:30001_primary@dba]> session.abortTransaction()
2018-06-30T15:06:04.162+0800 E QUERY    [js] Error: Cannot call abortTransaction after calling commitTransaction. :
abortTransaction@src/mongo/shell/session.js:764:1
abortTransaction@src/mongo/shell/session.js:934:17
@(shell):1:1

第三次嘗試（成功提交）：

[10.240.129.36:30001_primary@admin]> session=db.getMongo().startSession()
session { "id" : UUID("e7935985-160d-4969-adfe-3bae401e155f") }
[10.240.129.36:30001_primary@admin]> session.startTransaction()
[10.240.129.36:30001_primary@admin]> coll_1=session.getDatabase('dba').coll_1
dba.coll_1
[10.240.129.36:30001_primary@admin]> coll_2=session.getDatabase('dba').coll_2;
dba.coll_2
[10.240.129.36:30001_primary@admin]> coll_1.insertOne({'not_test':false})
{
    "acknowledged" : true,
    "insertedId" : ObjectId("5b373202d0b208b7386e9c20")
}
[10.240.129.36:30001_primary@admin]> coll_2.insertOne({'not_test':false})
{
    "acknowledged" : true,
    "insertedId" : ObjectId("5b373202d0b208b7386e9c21")
}
[10.240.129.36:30001_primary@admin]> session.commitTransaction()
[10.240.129.36:30001_primary@admin]> use dba
switched to db dba
[10.240.129.36:30001_primary@dba]> db.coll_1.find()
{ "_id" : ObjectId("5b371e120d6160b73a9fcee6"), "test" : true }
{ "_id" : ObjectId("5b371e6d0d6160b73a9fcee7"), "test" : true }
{ "_id" : ObjectId("5b373202d0b208b7386e9c20"), "not_test" : false }
[10.240.129.36:30001_primary@dba]> db.coll_2.find()
{ "_id" : ObjectId("5b373202d0b208b7386e9c21"), "not_test" : false }

第四次嘗試（測試回滾）：

[10.240.129.36:30001_primary@admin]> session=db.getMongo().startSession()
session { "id" : UUID("e7935985-160d-4969-adfe-3bae401e155f") }
[10.240.129.36:30001_primary@admin]> session.startTransaction()
[10.240.129.36:30001_primary@admin]> coll_1=session.getDatabase('dba').coll_1
dba.coll_1
[10.240.129.36:30001_primary@admin]> coll_2=session.getDatabase('dba').coll_2;
dba.coll_2
[10.240.129.36:30001_primary@admin]> coll_1.insertOne({'not_test':false})
{
    "acknowledged" : true,
    "insertedId" : ObjectId("5b373202d0b208b7386e9c20")
}
[10.240.129.36:30001_primary@admin]> coll_2.insertOne({'not_test':false})
{
    "acknowledged" : true,
    "insertedId" : ObjectId("5b373202d0b208b7386e9c21")
}
[10.240.129.36:30001_primary@admin]> session.commitTransaction()
[10.240.129.36:30001_primary@admin]> use dba
switched to db dba
[10.240.129.36:30001_primary@dba]> db.coll_1.find()
{ "_id" : ObjectId("5b371e120d6160b73a9fcee6"), "test" : true }
{ "_id" : ObjectId("5b371e6d0d6160b73a9fcee7"), "test" : true }
{ "_id" : ObjectId("5b373202d0b208b7386e9c20"), "not_test" : false }
[10.240.129.36:30001_primary@dba]> db.coll_2.find()
{ "_id" : ObjectId("5b373202d0b208b7386e9c21"), "not_test" : false }
[10.240.129.36:30001_primary@dba]> session=db.getMongo().startSession()
session { "id" : UUID("cc0e2d23-1766-4ea5-87a5-957efcae28ad") }
[10.240.129.36:30001_primary@dba]> session.startTransaction()
[10.240.129.36:30001_primary@dba]> coll_1=session.getDatabase('dba').coll_1
dba.coll_1
[10.240.129.36:30001_primary@dba]> coll_2=session.getDatabase('dba').coll_2;
dba.coll_2
[10.240.129.36:30001_primary@dba]> coll_1.insertOne({'not_test':false})
{
    "acknowledged" : true,
    "insertedId" : ObjectId("5b3732f0d0b208b7386e9c22")
}
[10.240.129.36:30001_primary@dba]> coll_2.insertOne({'not_test':false})
{
    "acknowledged" : true,
    "insertedId" : ObjectId("5b3732f1d0b208b7386e9c23")
}
[10.240.129.36:30001_primary@dba]> session.abortTransaction()
[10.240.129.36:30001_primary@dba]> db.coll_2.find()
{ "_id" : ObjectId("5b373202d0b208b7386e9c21"), "not_test" : false }
[10.240.129.36:30001_primary@dba]> db.coll_1.find()
{ "_id" : ObjectId("5b371e120d6160b73a9fcee6"), "test" : true }
{ "_id" : ObjectId("5b371e6d0d6160b73a9fcee7"), "test" : true }
{ "_id" : ObjectId("5b373202d0b208b7386e9c20"), "not_test" : false }

注意

默認事務超時時間有點短，1分鐘
默認鎖等待時間短，5毫秒
事務的操做有些繁瑣，不如RDS的 begin commit rollback方便（指SHELL操做）
一個事務的對應的oplog不能超過16M（指BSON格式的文件大小)
顯式事務功能的開啓對WT緩存提出了新的要求。相似於IBP事務不按時提交，相似undo用於存放快照或者舊版本的東西確定會佔用大量WT的空間。shell