Question

我不认为类型为DOUBLE的22 * 1000值的更新应该需要约4秒。然而，这就是我得到的。以下是查询完成22次。也许这实际上是相提并论？那时它并不能满足我的速度要求。

UPDATE [some table] SET [some column] = (CASE WHEN [column1] = i THEN [some number]

通过i = 1：1：1000连接，以END);

结尾

此声明需要约4/22秒。

我试过的补救措施：更新前锁定表，然后解锁。

帮助（尚未尝试）的想法：将更新减少为更小的更新查询。

其他信息：引擎：InnoDB， C ++连接器

编辑1

代码摘录：

Query ="LOCK TABLES CANS_SQL.SortingIndices WRITE;";
stmt = con->createStatement();
bool LOCKBIT = stmt->execute(Query);

delete stmt;
Query.clear();

Query = "UPDATE SortingIndices SET " + Objects.at(Typ).GetMetricNames().at(ObjMetIndex) + "_KVector = ( CASE  ";
for (int k = 0; k<kvector.size()-1; k++)
{
    while(true)
    {
        if(InsertCount<KvectorInsertPos.size())
        {
            if (KvectorInsertPos.at(InsertCount)==k)
            {
                Query += "WHEN Sort_ID = " + std::to_string(k+1+InsertCount) + " THEN " + std::to_string(KvectorInsertVal.at(InsertCount)+InsertCount) + " ";
                InsertCount++;
            }
            else
                break;
        }
        else
            break;
    }

    Query += "WHEN Sort_ID = " + std::to_string(k+1+InsertCount) + " THEN " + std::to_string(kvector.at(k)+InsertCount) + " ";
}
while(true)
{
    if(InsertCount<KvectorInsertPos.size())
    {
        if (KvectorInsertPos.at(InsertCount)==kvector.size()-1)
        {
            Query += "WHEN Sort_ID = " + std::to_string(kvector.size()+InsertCount) + " THEN " + std::to_string(KvectorInsertVal.at(InsertCount)+InsertCount) + " ";
            InsertCount++;
        }
        else
            break;
    }
    else
        break;
}
Query += "WHEN Sort_ID = " + std::to_string(kvector.size()+InsertCount) + " THEN " + std::to_string(kvector.at(kvector.size()-1)+InsertCount) + " END ) ";
stmt = con->createStatement();
stmt->executeUpdate(Query);

delete stmt;

编辑2

示例查询：

Query = "UPDATE SortingIndices 
    SET X_Centroid_Sort_Index = (CASE 
         WHEN Sort_ID = 1 THEN 1.4324 
         WHEN Sort_ID = 2 THEN 4.234 
         WHEN Sort_ID = 3 THEN 324
         ...
         WHEN Sort_ID = 1000 THEN 232.4 END);

加速MySQL更新 - InnoDB

0 个答案: