Oracle occi 批量插入数据
在用OCCI 向Oracle中插入数据时，效率不高，使用自动提交数据的情况（默认）下一秒钟只能插入1000条数据左右。因为插入数据库这块是影响系统中效率最明显的地方，因此很有必要提高数据插入这块的效率。在网上找了一些资料后发现，可以重用statement对象，使用批量插入的方法，先把数据保存在内存中，积累到一定数值之后批量插入Oracle，这样平均下来一秒钟可以插入5000多条数据，性能有所提高，不错，这里做一个记录。
#include <iostream>
#include <string.h>
#include <time.h>
#include <sys/time.h>
#define WIN32COMMON //避免函数重定义错误
#include <occi.h>
#include <cstdlib>
#include <map>
#define ArraySize 10000 //内存中数据满1000条批量插入到oracle中
using namespace oracle::occi;
using namespace std;
/*
*返回当前时间，用于计算两个操作的时间差
*/
long getCurrentTime()
{
struct timeval tv;
gettimeofday(&tv,NULL);
return tv.tv_sec * 1000 + tv.tv_usec / 1000;
}
/*
* @author: roger
*/
int main(void)
{
string username = "XX";
string pass = "XXX";
string srvName = "XXX";
Environment *env ;
Connection *conn;
Statement *stmt;
try
{
env = Environment::createEnvironment(Environment::THREADED_MUTEXED);
conn = env->createConnection(username, pass, srvName);
string sql = "insert into instant_infor (motor_id, lat, lon, uploadTime, receivetime, state_id, sys_state_id) values(:fld1,:fld2,:fld3,to_timestamp(:fld4,'yyyy-mm-dd hh24:mi:ss'),to_timestamp(:fld5,'yyyy-mm-dd hh24:mi:ss'),:fld6,:fld7)";
stmt = conn->createStatement(sql);
} catch(SQLException e)
{
env = NULL;
conn = NULL;
cout<<e.what()<<endl;
}
char motorid[ArraySize][12];
char lat[ArraySize][20];
char lon[ArraySize][20];
char uploadTime[ArraySize][20];
char createTime[ArraySize][20];
char state_id[ArraySize][50];
char sys_state_id[ArraySize][50];
ub2 motor_idLen[ArraySize] ;
ub2 uploadTimeLen[ArraySize] ;
ub2 createTimeLen[ArraySize];
ub2 state_idLen[ArraySize];
ub2 sys_state_idLen[ArraySize];
ub2 latLen[ArraySize] ;
ub2 lonLen[ArraySize] ;
long a1 = getCurrentTime();
for(int i=0;i<ArraySize;i++){
strcpy(motorid[i],"10000100000");
strcpy(lat[i] , "30.123");
strcpy(lon[i] , "120.123");
strcpy(uploadTime[i] , "2015-11-11 11:11:11");
strcpy(createTime[i] , "2015-11-11 11:11:11");
strcpy(state_id[i] ,"1");
strcpy(sys_state_id[i],"1");
motor_idLen[i] = strlen( motorid[i] ) + 1;
uploadTimeLen[i] = strlen( uploadTime[i] ) + 1;
createTimeLen[i] = strlen( createTime[i] ) + 1;
state_idLen[i] = strlen( state_id[i] ) + 1;
sys_state_idLen[i] = strlen( sys_state_id[i] ) + 1;
latLen[i] = strlen( lat[i] ) + 1;
lonLen[i] = strlen( lon[i] ) + 1;
}
stmt->setDataBuffer(1, (dvoid*)motorid, OCCI_SQLT_STR,sizeof( motorid[0] ), motor_idLen);
stmt->setDataBuffer(2, (dvoid*)lat, OCCI_SQLT_STR, sizeof( lat[0] ), latLen);
stmt->setDataBuffer(3, (dvoid*)lon, OCCI_SQLT_STR, sizeof( lon[0] ), lonLen);
stmt->setDataBuffer(4, (dvoid*)uploadTime, OCCI_SQLT_STR, sizeof( uploadTime[0] ), uploadTimeLen);
stmt->setDataBuffer(5, (dvoid*)createTime, OCCI_SQLT_STR, sizeof( createTime[0] ), createTimeLen);
stmt->setDataBuffer(6, (dvoid*)state_id, OCCI_SQLT_STR,sizeof( state_id[0] ), state_idLen);
stmt->setDataBuffer(7, (dvoid*)sys_state_id, OCCI_SQLT_STR, sizeof( sys_state_id[0] ), sys_state_idLen);
stmt->executeArrayUpdate(ArraySize);
conn->terminateStatement(stmt);
conn->commit();
long a2= getCurrentTime();
cout<<"插入"<<ArraySize<<"条数据完成"<<endl;
cout<<"花费时间： "<<(a2-a1)<<endl;
}
测试中是访问本地的Oracle数据库，用到的Makefile文件如下：
CC=g++ OBJS=TestOracle.o LIB=-L/opt/oracle/oracle11g/product/11.2.0/dbhome_1/lib -L/opt/oracle/oracle11g/product/11.2.0/dbhome_1/rdbms/lib/ INCLUDE=-I/opt/oracle/oracle11g/product/11.2.0/dbhome_1/precomp/public -I/opt/oracle/oracle11g/product/11.2.0/dbhome_1/rdbms/public Test: $(OBJS) $(CC) -o Test $(OBJS) $(LIB) -locci -lclntsh TestOracle.o: TestOracle.cpp $(CC) -c TestOracle.cpp $(INCLUDE) clean: rm -rf *.o & rm Test
程序的编写是参考网上的一篇文章，写的很好，这里作为参考： http://rgyq.blog.163.com/blog/static/3161253820131695957501/
- 重用statement对象
每次创建statement对象时，需要在客户端和服务端分配资源，如内存和游标(cursor)，用于存储对象及数据。为了不必要的内存重分配，应重用statement对象。statement对象创建后，可以使用setSQL方法进行重用，例如：
Connection* conn = env->createConnection(); Statement* stmt = conn->createStatement(); stmt->setSQL(“INSERT INTO fruit_basket_tab VALUES(‘Apples’, 3)”); stmt->executeUpdate(); stmt->setSQL(“INSERT INTO fruit_basket_tab VALUES(‘Oranges’, 4)”); stmt->executeUpdate(); stmt->setSQL(“INSERT INTO fruit_basket_tab VALUES(‘Bananas’, 1)”); stmt->executeUpdate();' stmt->setSQL(“SELECT * FROM fruit_basket_tab WHERE quantity > 2”); ResultSet* rs = stmt->executeQuery();
- statement参数化
stmt->setSQL(“INSERT INTO fruit_basket_tab VALUES(:1, :2)”); stmt->setString( 1, “Apples” ); stmt->setInt( 2, 3 ); stmt->executeUpdate(); stmt->setString( 1, “Oranges” ); stmt->setInt( 2, 4 ); stmt->executeUpdate(); stmt->setString( 1, “Bananas” ); stmt->setInt( 2, 1 ); stmt->executeUpdate();
- 批量更新
//prepare the batching process stmt->setMaxIterations( 3 ); stmt->setMaxParamSize( 1, 8 ); //”Bananas” is longest param //batch the statements stmt->setSQL(“INSERT INTO fruit_basket_tab VALUES(:1, :2)”); stmt->setString( 1, “Apples” ); stmt->setInt( 2, 3 ); stmt->addIteration(); stmt->setString( 1, “Oranges” ); stmt->setInt( 2, 4 ); stmt->addIteration(); stmt->setString( 1, “Bananas” ); stmt->setInt( 2, 1 ); //execute the statements stmt->executeUpdate();
- Statement::setDataBuffer方法
虽然许多OCI开发者使用OCCI简明的创建environments和statement对象，但仍然使用许多OCI中的类型。 setDataBuffer方法允许OCI开发者执行数组更新，最小化网络通信次数。setDataBuffer方法与setXXX方法工作方法不同。一般说来，setXXX方法会将传过来的数据拷贝到内部缓冲区中，只要setXXX返回后参数值就可以被改变。然而，使用setDataBuffer方法可以避免将数据拷贝到内部缓冲区中。代价是应用程序在执行完statement之前不可以修改缓冲区。例如：
// insert Bananas char buf[BUF_SIZE] = "Bananas"; int quantity = 1; ub2 buflen = strlen( buf ) + 1; ub2 quantlen = sizeof(int); stmt->setDataBuffer(1, (dvoid*)buf, OCCI_SQLT_STR, buflen, &buflen); stmt->setDataBuffer(2, (dvoid*)&quantity, OCCIINT, quantlen, &quantlen); stmt->executeUpdate(); // executeArrayUpdate(1) also would work. // insert Apples strcpy( buf, “Apples” ); quantity = 3; buflen = strlen( buf ) + 1; quantlen = sizeof( int ); stmt->setDataBuffer(1, (dvoid*)buf, OCCI_SQLT_STR, buflen, &buflen); stmt->setDataBuffer(2, (dvoid*)&quantity, OCCIINT, quantlen, &quantlen); stmt->executeUpdate(); // executeArrayUpdate(1) also would work. //commit the transaction conn->commit();setDataBuffer方法可以与迭代执行(iterative executes)和executeArrayUpdate方法结合使用。
- executeArrayUpdate方法
char fruit[][BUF_SIZE] = { "Apples","Oranges","Bananas","Grapes" };
int int_arr[]={ 3,4,1,5 };
ub2 fruitlen[4]; // array of size of individual elements
ub2 intsize[4];
for(int i=0 ; i<4 ; i++)
{
intsize[i] = sizeof(int);
fruitlen[i] = strlen( fruit[i] ) + 1 ; // include the null
}
stmt->setDataBuffer(1, (dvoid*)fruit, OCCI_SQLT_STR, BUF_SIZE,
fruitlen);
stmt->setDataBuffer(2, (dvoid*)int_arr, OCCIINT, sizeof(int), intsize);
stmt->executeArrayUpdate(4);
conn->commit();
executeArrayUpdate方法不会执行，直到所有缓冲区均通过setDataBuffer方法设置。如果有参数需要调用setXXX方法赋值，可以调用setMaxIterations和setMaxParamSize方法，以及addIteration方法。具体如下：
char fruits[][BUF_SIZE] = {“Apples”, “Oranges”, “Bananas”};
ub2 fruitLen[3];
for( int j=0; j<3; j++ )
{
fruitLen[j] = strlen( fruits[j] ) + 1; //include the null
}
stmt->setMaxIterations(3);
//setDataBuffer only needs to be executed once
//while all the other variables need to be set for each iteration
stmt->setDataBuffer( 1, fruits, OCCI_SQLT_STR, sizeof(fruits[0]),
fruitLen );
stmt->setInt(2, 3); //Apple’s quantity
stmt->addIteration();
stmt->setInt(2, 4); //Orange’s quantity
stmt->addIteration();
stmt->setInt(2, 1); //Banana’s quantity
//execute the iterative update
stmt->executeUpdate(3);
- 使用合适的Accessors和字符集
对操作的列使用合适的setXXX和getXXX方法，而非统一作为string处理，可以省去不必要的转换。
在NLS_LANG环境设置中使用合适的字符集，以避免获取字符串时不必要的字符集转换。
自动提交模式
由于所有的SQL DML都是在事务中执行，所以需要确认所有的DML。可以根据具体情况使用“Connection::commit”和“Connection::rollback”方法。“Statement::setAutoCommit”方法可以用来确认其后的每条语句。使用该方法可节省网络传输时间。
//code with AutoCommit //transaction 1 stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Apples”,3)); stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Oranges”,4)); stmt->setAutoCommit( TRUE ); stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Bananas”,1)); stmt->setAutoCommit( FALSE ); //transaction 2 stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Apples”,5)); stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Oranges”,6)); stmt->setAutoCommit( TRUE ); stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Bananas”,2)); stmt->setAutoCommit( FALSE );
这与下面的语句是等价的，但是2次网络传输，每个事务1次
//code without AutoCommit //transaction 1 stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Apples”,3)); stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Oranges”,4)); stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Bananas”,1)); conn->commit(); //transaction 2 stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Apples”,5)); stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Oranges”,6)); stmt->executeUpdate(“INSERT INTO fruit_basket_tab VALUES(“Bananas”,2)); conn->commit();
建议AutoCommit只在每个事务的最后一条SQL语句前面使用。
- 结果集对象的优化
ResultSet* rs = stmt->executeQuery( “SELECT * FROM fruit_basket_tab” );
ResultSet::Status stat = rs->status(); //status is DATA_AVAILABLE
while( rs->next() ) { //process data }
setPrefetchRowCount and setPrefetchMemorySize
虽然rs->next()每次只能返回一行，但是可以在一次网络中预取多行放到客户端的缓存中。使用类Statement的setPrefetchRowCount方法和setPrefetchMemorySize方法，每次可以取得不止一行。上例优化后如下：
stmt->setPrefetchRowCount( 3 );
ResultSet* rs = stmt->executeQuery( “SELECT * FROM fruit_basket_tab” );
while ( rs->next() ) { //process data }
使用上述代码，在一次网络通信中就能取得3条记录。默认情形中，预取功能是启用的，每次多取一条。要想关闭预取功能，必须同时调用方法setPrefetchRowCount和setPrefetchMemorySize，参数为0。如果两个setPrefetchXXX方法都被调用了，那么实际预取的数目是这两个方法参数中较小的那个。
setMaxColumnSize
当取得的结果中有些列较大时，可以使用ResultSet::setMaxColumnSize方法限制从指定的列可以获取多少数据。当只对部分数据感兴趣或者缓存大小有限时，这就有用了。
ResultSet *rs = stmt->executeQuery( “SELECT description FROM
fruit_basket_tab” );
//want only first 80 characters from the description column
rs->setMaxColumnSize( 1, 80 );
- 关闭结果集
- 终止Statement
conn->terminateStatement( stmt );
参考资料
Using OCCI: Best Practices
http://www.stanford.edu/dept/itss/docs/oracle/10gR2/appdev.102/b14294/performance.htm