同樣是工作中遇到的問題，寫下來留個紀念。
一個老系統已經跑了一年多了，最近報出這個問題的，具體問題貼出來給大家看
org.springframework.jdbc.BadSqlGrammarException:
### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Row size too large (> 8126).
Changing some columns to TEXT or BLOB or using ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED may help. In current row format,
BLOB prefix of 768 bytes is stored inline.
### The error occurred while setting parameters
### SQL: update test SET product_id=?, sp_id=?, key1=?, key2=?, key3=?, key4=?, key5=?, key6=?, key7=?, key8=?, key9=?, key10=?, key11=?, key12=?, key13=?, key14=?, key15=?, key16=?, key17=?, key18=?, key19=?, key20=?, key21=?, key22=?, key23=?, key24=?, key25=?, key26=?, key27=?, key28=?, key29=?, key30=?, gmt_modify=?, json_data=?, record_no=?, hash_no=?, gmt_create=?, is_repack=? where ID=?
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Row size too large (> 8126). Changing some columns to TEXT or BLOB or using ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED may help. In current row format, BLOB prefix of 768 bytes is stored inline.
; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Row size too large (> 8126). Changing some columns to TEXT or BLOB or using ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED may help. In current row format, BLOB prefix of 768 bytes is stored inline.
at org.springframework.jdbc.support.SQLExceptionSubclassTranslator.doTranslate(SQLExceptionSubclassTranslator.java:95)
at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:73)
at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:81)
at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:73)
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:371)
at com.sun.proxy.$Proxy18.update(Unknown Source)
at org.mybatis.spring.SqlSessionTemplate.update(SqlSessionTemplate.java:254)
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:49)
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:43)
at com.sun.proxy.$Proxy27.update(Unknown Source)
at com.ancun.webank.biz.service.TestRowSize.testCompBqData(TestRowSize.java:109)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
at org.springframework.test.context.junit4.SpringJUnit4Cla***unner.runChild(SpringJUnit4Cla***unner.java:232)
at org.springframework.test.context.junit4.SpringJUnit4Cla***unner.runChild(SpringJUnit4Cla***unner.java:89)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
at org.springframework.test.context.junit4.SpringJUnit4Cla***unner.run(SpringJUnit4Cla***unner.java:175)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
由於test表中存儲了一個text字段用於接收非結構化數據，並且預留了30個字段用於解析這個非結構化數據。在解析這個text字段時報上述錯誤，行大小超過限制8192。
通過SHOW VARIABLES LIKE '%engine%'，確認目前數據庫用的是innodb的引擎。
通過innodb_page_size可以確認每頁大小爲16k；
INNODB存儲引擎是索引組織的，即每頁中至少有兩行記錄，因此如果頁中只能存放一行記錄，INNODB會自動將行數據放到溢出頁中。當發生溢出行的時候，實際數據保存在BLOB頁中，數據頁只保存數據的前768字節（老的文件格式），新的文件格式（Barracuda）採用完全行溢出的方式，數據頁只保存20個字節的指針，BLOB也保存所有數據。
所以每個row的zise不能大於8k，即8192個字節。