在http://otl.sourceforge.net/otl3_stream_class.htm 中對buffer size 的說明是:The buffer size is defined in logical rows to inserted into a table, selected from a table / view in one round-trip to the database (a.k.a. batch size, array size).
為此做了如下例子進行了測試.

程式碼如下:

// TestOCT.cpp : Defines the entry point for the console application.
#include "stdafx.h"
#include <iostream>
using namespace std;

#include <stdio.h>
//#define OTL_ORA10G
#define OTL_ORA9I // Compile OTL 4.0/OCI9i
#define OTL_ORA_UTF8 // Enable UTF8 OTL for OCI9i
#include <otlv4.h> // include the OTL 4.0 header file
#pragma comment(lib, "oci.lib")
otl_connect db; // connect object
#define CONNECTSTRING "test/[email protected]"

char strSql[100]  = { "select f1,f2 from test_tab"};
void insert()
{
 otl_stream o(3,"INSERT INTO TEST_TAB(f1,f2)values(4,'b')",db);

int main()
{
    otl_connect::otl_initialize(); // initialize OCI environment
    try
 {
  db.rlogon(CONNECTSTRING); // connect to Oracle

  otl_cursor::direct_exec(db,"drop table test_tab",otl_exception::disabled); // drop table
  otl_cursor::direct_exec(db,"create table test_tab(f1 number, f2 nvarchar2(30))");  // create table
     insert(); // insert records into table
     select(); // select records from table
 }
 catch(otl_exception& p)
 { // intercept OTL exceptions
  cerr<<p.msg<<endl; // print out error message
  cerr<<p.stm_text<<endl; // print out SQL that caused the error
  cerr<<p.var_info<<endl; // print out the variable that caused the error
 }

 db.logoff(); // disconnect from Oracle
 return 0;
} 

插入資料: otl_stream o(3,"INSERT INTO TEST_TAB(f1,f2)values(4,'b')",db);中otl_stream的建構函式的第一個 引數表示要插入的資料條數.

查詢資料:otl_stream o(1,strSql,db);中otl_stream的建構函式的第一個引數表示查詢到的資料從伺服器傳遞到客戶端的往返次數

執行上面的程式，得到的結果就是:

f1: 4, f2: b, 當前行數1

f1: 4, f2: b, 當前行數1

f1: 4, f2: b, 當前行數1