GaussDB-典型应用场景配置
日志诊断场景
ODBC日志分为unixODBC驱动管理器日志和gsqlODBC驱动端日志。前者可以用于追溯应用程序API的执行成功与否，后者是底层实现过程中的一些DFX日志，用来帮助定位问题。
unixODBC日志需要在odbcinst.ini文件中配置：
| ``` [ODBC] Trace=Yes TraceFile=/path/to/odbctrace.log [GaussMPP] Driver64=/usr/local/lib/gsqlodbcw.so setup=/usr/local/lib/gsqlodbcw.so
| --------------------------------------------------------------------------------------------------------------------------------------------- |
gsqlODBC日志只需要在odbc.ini加上如下内容：
[gaussdb] Driver=GaussMPP Servername=10.10.0.13 #数据库Server IP ... Debug=1 #打开驱动端debug日志
unixODBC日志将会生成在TraceFile配置的路径下，gsqlODBC会在系统/tmp/下生成mylog_xxx.log。
#### 高性能场景
进行大量数据插入时，建议如下：
- 需要设置批量绑定：odbc.ini配置文件中设置UseBatchProtocol=1、数据库设置support_batch_bind=on。
- ODBC程序绑定类型要和数据库中类型一致。
- 客户端字符集和数据库字符集一致。
- 事务改成手动提交模式。
odbc.ini配置文件：
[gaussdb] Driver=GaussMPP Servername=10.10.0.13 #数据库Server IP ... UseBatchProtocol=1 #默认打开 ConnSettings=set client_encoding=UTF8 #设置客户端字符编码，保证和server端一致
绑定类型用例：
#ifdef WIN32 #include <windows.h> #endif #include <stdio.h> #include <stdlib.h> #include <sql.h> #include <sqlext.h> #include <string.h> #include <sys/time.h>
#define MESSAGE_BUFFER_LEN 128 SQLHANDLE h_env = NULL; SQLHANDLE h_conn = NULL; SQLHANDLE h_stmt = NULL; void print_error() { SQLCHAR Sqlstate[SQL_SQLSTATE_SIZE+1]; SQLINTEGER NativeError; SQLCHAR MessageText[MESSAGE_BUFFER_LEN]; SQLSMALLINT TextLength; SQLRETURN ret = SQL_ERROR;
ret = SQLGetDiagRec(SQL_HANDLE_STMT, h_stmt, 1, Sqlstate, &NativeError, MessageText, MESSAGE_BUFFER_LEN, &TextLength);
if ( SQL_SUCCESS == ret)
{
printf("\n STMT ERROR-%05d %s", NativeError, MessageText);
return;
}
ret = SQLGetDiagRec(SQL_HANDLE_DBC, h_conn, 1, Sqlstate, &NativeError, MessageText, MESSAGE_BUFFER_LEN, &TextLength);
if ( SQL_SUCCESS == ret)
{
printf("\n CONN ERROR-%05d %s", NativeError, MessageText);
return;
}
ret = SQLGetDiagRec(SQL_HANDLE_ENV, h_env, 1, Sqlstate, &NativeError, MessageText, MESSAGE_BUFFER_LEN, &TextLength);
if ( SQL_SUCCESS == ret)
{
printf("\n ENV ERROR-%05d %s", NativeError, MessageText);
return;
}
return;
}
/* 期盼函数返回SQL_SUCCESS */
#define RETURN_IF_NOT_SUCCESS(func)
{
SQLRETURN ret_value = (func);
if (SQL_SUCCESS != ret_value)
{
print_error();
printf("\n failed line = %u: expect SQL_SUCCESS, but ret = %d", LINE, ret_value);
return SQL_ERROR;
}
}
/* 期盼函数返回SQL_SUCCESS */
#define RETURN_IF_NOT_SUCCESS_I(i, func)
{
SQLRETURN ret_value = (func);
if (SQL_SUCCESS != ret_value)
{
print_error();
printf("\n failed line = %u (i=%d): : expect SQL_SUCCESS, but ret = %d", LINE, (i), ret_value);
return SQL_ERROR;
}
}
/* 期盼函数返回SQL_SUCCESS_WITH_INFO */
#define RETURN_IF_NOT_SUCCESS_INFO(func)
{
SQLRETURN ret_value = (func);
if (SQL_SUCCESS_WITH_INFO != ret_value)
{
print_error();
printf("\n failed line = %u: expect SQL_SUCCESS_WITH_INFO, but ret = %d", LINE, ret_value);
return SQL_ERROR;
}
}
/* 期盼数值相等 */
#define RETURN_IF_NOT(expect, value)
if ((expect) != (value))
{
printf("\n failed line = %u: expect = %u, but value = %u", LINE, (expect), (value));
return SQL_ERROR;
}
/* 期盼字符串相同 */
#define RETURN_IF_NOT_STRCMP_I(i, expect, value)
if (( NULL == (expect) ) || (NULL == (value)))
{
printf("\n failed line = %u (i=%u): input NULL pointer !", LINE, (i));
return SQL_ERROR;
}
else if (0 != strcmp((expect), (value)))
{
printf("\n failed line = %u (i=%u): expect = %s, but value = %s", LINE, (i), (expect), (value));
return SQL_ERROR;
}
// prepare + execute SQL语句 int execute_cmd(SQLCHAR *sql) { if ( NULL == sql ) { return SQL_ERROR; }
if ( SQL_SUCCESS != SQLPrepare(h_stmt, sql, SQL_NTS))
{
return SQL_ERROR;
}
if ( SQL_SUCCESS != SQLExecute(h_stmt))
{
return SQL_ERROR;
}
return SQL_SUCCESS;
} // execute + commit 句柄 int commit_exec() { if ( SQL_SUCCESS != SQLExecute(h_stmt)) { return SQL_ERROR; }
// 手动提交
if ( SQL_SUCCESS != SQLEndTran(SQL_HANDLE_DBC, h_conn, SQL_COMMIT))
{
return SQL_ERROR;
}
return SQL_SUCCESS;
}
int begin_unit_test() { SQLINTEGER ret;
/* 申请环境句柄 */
ret = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &h_env);
if ((SQL_SUCCESS != ret) && (SQL_SUCCESS_WITH_INFO != ret))
{
printf("\n begin_unit_test::SQLAllocHandle SQL_HANDLE_ENV failed ! ret = %d", ret);
return SQL_ERROR;
}
/* 进行连接前必须要先设置版本号 */
if (SQL_SUCCESS != SQLSetEnvAttr(h_env, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0))
{
print_error();
printf("\n begin_unit_test::SQLSetEnvAttr SQL_ATTR_ODBC_VERSION failed ! ret = %d", ret);
SQLFreeHandle(SQL_HANDLE_ENV, h_env);
return SQL_ERROR;
}
/* 申请连接句柄 */
ret = SQLAllocHandle(SQL_HANDLE_DBC, h_env, &h_conn);
if (SQL_SUCCESS != ret)
{
print_error();
printf("\n begin_unit_test::SQLAllocHandle SQL_HANDLE_DBC failed ! ret = %d", ret);
SQLFreeHandle(SQL_HANDLE_ENV, h_env);
return SQL_ERROR;
}
/* 建立连接 */
ret = SQLConnect(h_conn, (SQLCHAR*) "gaussdb", SQL_NTS, (SQLCHAR*) NULL, 0, NULL, 0); if (SQL_SUCCESS != ret) { print_error(); printf("\n begin_unit_test::SQLConnect failed ! ret = %d", ret); SQLFreeHandle(SQL_HANDLE_DBC, h_conn); SQLFreeHandle(SQL_HANDLE_ENV, h_env); return SQL_ERROR; }
/* 申请语句句柄 */
ret = SQLAllocHandle(SQL_HANDLE_STMT, h_conn, &h_stmt);
if (SQL_SUCCESS != ret)
{
print_error();
printf("\n begin_unit_test::SQLAllocHandle SQL_HANDLE_STMT failed ! ret = %d", ret);
SQLFreeHandle(SQL_HANDLE_DBC, h_conn);
SQLFreeHandle(SQL_HANDLE_ENV, h_env);
return SQL_ERROR;
}
return SQL_SUCCESS;
}
void end_unit_test() { /* 释放语句句柄 */ if (NULL != h_stmt) { SQLFreeHandle(SQL_HANDLE_STMT, h_stmt); }
/* 释放连接句柄 */
if (NULL != h_conn)
{
SQLDisconnect(h_conn);
SQLFreeHandle(SQL_HANDLE_DBC, h_conn);
}
/* 释放环境句柄 */
if (NULL != h_env)
{
SQLFreeHandle(SQL_HANDLE_ENV, h_env);
}
return;
}
int main() { // begin test if (begin_unit_test() != SQL_SUCCESS) { printf("\n begin_test_unit failed."); return SQL_ERROR; } // 句柄配置同前面用例 int i = 0; SQLCHAR* sql_drop = "drop table if exists test_bindnumber_001"; SQLCHAR* sql_create = "create table test_bindnumber_001(" "f4 number, f5 number(10, 2)" ")"; SQLCHAR* sql_insert = "insert into test_bindnumber_001 values(?, ?)"; SQLCHAR* sql_select = "select * from test_bindnumber_001"; SQLLEN RowCount; SQL_NUMERIC_STRUCT st_number; SQLCHAR getValue[2][MESSAGE_BUFFER_LEN];
/* step 1. 建表 */
RETURN_IF_NOT_SUCCESS(execute_cmd(sql_drop));
RETURN_IF_NOT_SUCCESS(execute_cmd(sql_create));
/* step 2.1 通过SQL_NUMERIC_STRUCT结构绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
//第一行: 1234.5678
memset(st_number.val, 0, SQL_MAX_NUMERIC_LEN);
st_number.precision = 8;
st_number.scale = 4;
st_number.sign = 1;
st_number.val[0] = 0x4E;
st_number.val[1] = 0x61;
st_number.val[2] = 0xBC;
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_NUMERIC, SQL_NUMERIC, sizeof(SQL_NUMERIC_STRUCT), 4, &st_number, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_NUMERIC, SQL_NUMERIC, sizeof(SQL_NUMERIC_STRUCT), 4, &st_number, 0, NULL));
// 关闭自动提交
SQLSetConnectAttr(h_conn, SQL_ATTR_AUTOCOMMIT, (SQLPOINTER)SQL_AUTOCOMMIT_OFF, 0);
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
//第二行: 12345678
memset(st_number.val, 0, SQL_MAX_NUMERIC_LEN);
st_number.precision = 8;
st_number.scale = 0;
st_number.sign = 1;
st_number.val[0] = 0x4E;
st_number.val[1] = 0x61;
st_number.val[2] = 0xBC;
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_NUMERIC, SQL_NUMERIC, sizeof(SQL_NUMERIC_STRUCT), 0, &st_number, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_NUMERIC, SQL_NUMERIC, sizeof(SQL_NUMERIC_STRUCT), 0, &st_number, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
//第三行: 12345678
memset(st_number.val, 0, SQL_MAX_NUMERIC_LEN);
st_number.precision = 0;
st_number.scale = 4;
st_number.sign = 1;
st_number.val[0] = 0x4E;
st_number.val[1] = 0x61;
st_number.val[2] = 0xBC;
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_NUMERIC, SQL_NUMERIC, sizeof(SQL_NUMERIC_STRUCT), 4, &st_number, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_NUMERIC, SQL_NUMERIC, sizeof(SQL_NUMERIC_STRUCT), 4, &st_number, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
/* step 2.2 第四行通过SQL_C_CHAR字符串绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
SQLCHAR* szNumber = "1234.5678";
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_NUMERIC, strlen(szNumber), 0, szNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_NUMERIC, strlen(szNumber), 0, szNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
/* step 2.3 第五行通过SQL_C_FLOAT绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
SQLREAL fNumber = 1234.5678;
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_FLOAT, SQL_NUMERIC, sizeof(fNumber), 4, &fNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_FLOAT, SQL_NUMERIC, sizeof(fNumber), 4, &fNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
/* step 2.4 第六行通过SQL_C_DOUBLE绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
SQLDOUBLE dNumber = 1234.5678;
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_DOUBLE, SQL_NUMERIC, sizeof(dNumber), 4, &dNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_DOUBLE, SQL_NUMERIC, sizeof(dNumber), 4, &dNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
SQLBIGINT bNumber1 = 0xFFFFFFFFFFFFFFFF;
SQLBIGINT bNumber2 = 12345;
/* step 2.5 第七行通过SQL_C_SBIGINT绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_SBIGINT, SQL_NUMERIC, sizeof(bNumber1), 4, &bNumber1, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_SBIGINT, SQL_NUMERIC, sizeof(bNumber2), 4, &bNumber2, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
/* step 2.6 第八行通过SQL_C_UBIGINT绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_UBIGINT, SQL_NUMERIC, sizeof(bNumber1), 4, &bNumber1, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_UBIGINT, SQL_NUMERIC, sizeof(bNumber2), 4, &bNumber2, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
SQLLEN lNumber1 = 0xFFFFFFFFFFFFFFFF;
SQLLEN lNumber2 = 12345;
/* step 2.7 第九行通过SQL_C_LONG绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_LONG, SQL_NUMERIC, sizeof(lNumber1), 0, &lNumber1, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_LONG, SQL_NUMERIC, sizeof(lNumber2), 0, &lNumber2, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
/* step 2.8 第十行通过SQL_C_ULONG绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_ULONG, SQL_NUMERIC, sizeof(lNumber1), 0, &lNumber1, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_ULONG, SQL_NUMERIC, sizeof(lNumber2), 0, &lNumber2, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
SQLSMALLINT sNumber = 0xFFFF;
/* step 2.9 第十一行通过SQL_C_SHORT绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_SHORT, SQL_NUMERIC, sizeof(sNumber), 0, &sNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_SHORT, SQL_NUMERIC, sizeof(sNumber), 0, &sNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
/* step 2.10 第十二行通过SQL_C_USHORT绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_USHORT, SQL_NUMERIC, sizeof(sNumber), 0, &sNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_USHORT, SQL_NUMERIC, sizeof(sNumber), 0, &sNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
SQLCHAR cNumber = 0xFF;
/* step 2.11 第十三行通过SQL_C_TINYINT绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_TINYINT, SQL_NUMERIC, sizeof(cNumber), 0, &cNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_TINYINT, SQL_NUMERIC, sizeof(cNumber), 0, &cNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
/* step 2.12 第十四行通过SQL_C_UTINYINT绑定参数 */
RETURN_IF_NOT_SUCCESS(SQLPrepare(h_stmt, sql_insert, SQL_NTS));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 1, SQL_PARAM_INPUT, SQL_C_UTINYINT, SQL_NUMERIC, sizeof(cNumber), 0, &cNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(SQLBindParameter(h_stmt, 2, SQL_PARAM_INPUT, SQL_C_UTINYINT, SQL_NUMERIC, sizeof(cNumber), 0, &cNumber, 0, NULL));
RETURN_IF_NOT_SUCCESS(commit_exec());
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(1, RowCount);
/* 用字符串类型统一进行期盼 */
SQLCHAR* expectValue[14][2] = {{"1234.5678", "1234.57"},
{"12345678", "12345678"},
{"0", "0"},
{"1234.5678", "1234.57"},
{"1234.5677", "1234.57"},
{"1234.5678", "1234.57"},
{"-1", "12345"},
{"18446744073709551615", "12345"},
{"-1", "12345"},
{"4294967295", "12345"},
{"-1", "-1"},
{"65535", "65535"},
{"-1", "-1"},
{"255", "255"},
};
RETURN_IF_NOT_SUCCESS(execute_cmd(sql_select));
while ( SQL_NO_DATA != SQLFetch(h_stmt))
{
RETURN_IF_NOT_SUCCESS_I(i, SQLGetData(h_stmt, 1, SQL_C_CHAR, &getValue[0], MESSAGE_BUFFER_LEN, NULL));
RETURN_IF_NOT_SUCCESS_I(i, SQLGetData(h_stmt, 2, SQL_C_CHAR, &getValue[1], MESSAGE_BUFFER_LEN, NULL));
//RETURN_IF_NOT_STRCMP_I(i, expectValue[i][0], getValue[0]);
//RETURN_IF_NOT_STRCMP_I(i, expectValue[i][1], getValue[1]);
i++;
}
RETURN_IF_NOT_SUCCESS(SQLRowCount(h_stmt, &RowCount));
RETURN_IF_NOT(i, RowCount);
SQLCloseCursor(h_stmt); /* step final. 删除表还原环境 */ RETURN_IF_NOT_SUCCESS(execute_cmd(sql_drop));
end_unit_test();
}
上述用例中定义了number列，调用SQLBindParameter接口时，绑定SQL_NUMERIC会比SQL_LONG性能更高。因为如果是char，在数据库服务端插入数据时需要进行数据类型转换，从而引发性能瓶颈。
#### 负载均衡场景
当应用程序有大并发场景时可开启负载均衡：
- 负载均衡即为将并发连接随机分发到所有CN上，避免单个CN负载过大，达到提高性能的目的。
- 配置参数AutoBalance=1，开启负载均衡功能。
- 参数RefreshCNListTime=5可以选择性配置，默认刷新时间为10s。
- 参数Priority=1可以选择性配置，即为并发连接优先发送到配置文件中配置的CN上，当配置的CN全部不可连接时，连接才会被分发到剩余CN上。
示例场景：
集群环境有6个CN，CN1、CN2、CN3、CN4、CN5和CN6；配置文件配置4个CN，为CN1、CN2、CN3和CN4。
odbc.ini配置文件示例：
[gaussdb] Driver=GaussMPP Servername=10.145.130.26,10.145.130.27,10.145.130.28,10.145.130.29（数据库Server IP） Database=db1 #数据库名 Username=omm #数据库用户名 Password= #数据库用户密码 Port=8000 #数据库侦听端口 Sslmode=allow AutoBalance=1 RefreshCNListTime=3 Priority=1
当配置文件和集群环境如示例时，并发连接会随机、平均发送到CN1、CN2、CN3和CN4上，连接数均衡。当CN1、CN2、CN3和CN4全部不可用时，并发连接会随机、平均发送到CN5和CN6上。如果此时CN1、CN2、CN3和CN4中有CN重新可用时，连接则不会再发送到CN5和CN6上，而是重新发送到重新可用的CN上。
更多详情请参考GaussDB 文档中心：<https://doc.hcs.huawei.com/db/zh-cn/gaussdbqlh/24.1.30/productdesc/qlh_03_0001.html>
