该程序说明了如何在 NDB API 中使用二级索引。
此示例的源代码可以在 NDB Cluster 源代码树中找到,在
storage/ndb/ndbapi-examples/ndbapi_simple_index/main.cpp
.
笔记
此文件以前命名为
ndbapi_simple_index.cpp
.
该程序的正确输出如下所示:
ATTR1 ATTR2
0 10
1 1
2 12
Detected that deleted tuple doesn't exist!
4 14
5 5
6 16
7 7
8 18
9 9
该程序的清单显示如下:
#include <mysql.h>
#include <mysqld_error.h>
#include <NdbApi.hpp>
// Used for cout
#include <stdio.h>
#include <iostream>
#define PRINT_ERROR(code,msg) \
std::cout << "Error in " << __FILE__ << ", line: " << __LINE__ \
<< ", code: " << code \
<< ", msg: " << msg << "." << std::endl
#define MYSQLERROR(mysql) { \
PRINT_ERROR(mysql_errno(&mysql),mysql_error(&mysql)); \
exit(-1); }
#define APIERROR(error) { \
PRINT_ERROR(error.code,error.message); \
exit(-1); }
int main(int argc, char** argv)
{
if (argc != 3)
{
std::cout << "Arguments are <socket mysqld> <connect_string cluster>.\n";
exit(-1);
}
char * mysqld_sock = argv[1];
const char *connection_string = argv[2];
ndb_init();
/**************************************************************
* Connect to mysql server and create table *
**************************************************************/
MYSQL mysql;
{
if ( !mysql_init(&mysql) ) {
std::cout << "mysql_init failed\n";
exit(-1);
}
if ( !mysql_real_connect(&mysql, "localhost", "root", "", "",
0, mysqld_sock, 0) )
MYSQLERROR(mysql);
mysql_query(&mysql, "CREATE DATABASE ndb_examples_1");
if (mysql_query(&mysql, "USE ndb_examples") != 0) MYSQLERROR(mysql);
while (mysql_query(&mysql,
"CREATE TABLE"
" api_simple_index"
" (ATTR1 INT UNSIGNED,"
" ATTR2 INT UNSIGNED NOT NULL,"
" PRIMARY KEY USING HASH (ATTR1),"
" UNIQUE MYINDEXNAME USING HASH (ATTR2))"
" ENGINE=NDB"))
{
if (mysql_errno(&mysql) == ER_TABLE_EXISTS_ERROR)
{
std::cout << "NDB Cluster already has example table: api_scan. "
<< "Dropping it..." << std::endl;
mysql_query(&mysql, "DROP TABLE api_simple_index");
}
else MYSQLERROR(mysql);
}
mysql_close(&mysql);
}
/**************************************************************
* Connect to ndb cluster *
**************************************************************/
Ndb_cluster_connection *cluster_connection=
new Ndb_cluster_connection(connection_string); // Object representing the cluster
if (cluster_connection->connect(5,3,1))
{
std::cout << "Connect to cluster management server failed.\n";
exit(-1);
}
if (cluster_connection->wait_until_ready(30,30))
{
std::cout << "Cluster was not ready within 30 secs.\n";
exit(-1);
}
Ndb* myNdb = new Ndb( cluster_connection,
"ndb_examples" ); // Object representing the database
if (myNdb->init() == -1) {
APIERROR(myNdb->getNdbError());
exit(-1);
}
const NdbDictionary::Dictionary* myDict= myNdb->getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("api_simple_index");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
const NdbDictionary::Index *myIndex= myDict->getIndex("MYINDEXNAME$unique","api_simple_index");
if (myIndex == NULL)
APIERROR(myDict->getNdbError());
/**************************************************************************
* Using 5 transactions, insert 10 tuples in table: (0,0),(1,1),...,(9,9) *
**************************************************************************/
for (int i = 0; i < 5; i++) {
NdbTransaction *myTransaction= myNdb->startTransaction();
if (myTransaction == NULL) APIERROR(myNdb->getNdbError());
NdbOperation *myOperation= myTransaction->getNdbOperation(myTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());
myOperation->insertTuple();
myOperation->equal("ATTR1", i);
myOperation->setValue("ATTR2", i);
myOperation = myTransaction->getNdbOperation(myTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());
myOperation->insertTuple();
myOperation->equal("ATTR1", i+5);
myOperation->setValue("ATTR2", i+5);
if (myTransaction->execute( NdbTransaction::Commit ) == -1)
APIERROR(myTransaction->getNdbError());
myNdb->closeTransaction(myTransaction);
}
/*****************************************
* Read and print all tuples using index *
*****************************************/
std::cout << "ATTR1 ATTR2" << std::endl;
for (int i = 0; i < 10; i++) {
NdbTransaction *myTransaction= myNdb->startTransaction();
if (myTransaction == NULL) APIERROR(myNdb->getNdbError());
NdbIndexOperation *myIndexOperation=
myTransaction->getNdbIndexOperation(myIndex);
if (myIndexOperation == NULL) APIERROR(myTransaction->getNdbError());
myIndexOperation->readTuple(NdbOperation::LM_Read);
myIndexOperation->equal("ATTR2", i);
NdbRecAttr *myRecAttr= myIndexOperation->getValue("ATTR1", NULL);
if (myRecAttr == NULL) APIERROR(myTransaction->getNdbError());
if(myTransaction->execute( NdbTransaction::Commit,
NdbOperation::AbortOnError ) != -1)
printf(" %2d %2d\n", myRecAttr->u_32_value(), i);
myNdb->closeTransaction(myTransaction);
}
/*****************************************************************
* Update the second attribute in half of the tuples (adding 10) *
*****************************************************************/
for (int i = 0; i < 10; i+=2) {
NdbTransaction *myTransaction= myNdb->startTransaction();
if (myTransaction == NULL) APIERROR(myNdb->getNdbError());
NdbIndexOperation *myIndexOperation=
myTransaction->getNdbIndexOperation(myIndex);
if (myIndexOperation == NULL) APIERROR(myTransaction->getNdbError());
myIndexOperation->updateTuple();
myIndexOperation->equal( "ATTR2", i );
myIndexOperation->setValue( "ATTR2", i+10);
if( myTransaction->execute( NdbTransaction::Commit ) == -1 )
APIERROR(myTransaction->getNdbError());
myNdb->closeTransaction(myTransaction);
}
/*************************************************
* Delete one tuple (the one with primary key 3) *
*************************************************/
{
NdbTransaction *myTransaction= myNdb->startTransaction();
if (myTransaction == NULL) APIERROR(myNdb->getNdbError());
NdbIndexOperation *myIndexOperation=
myTransaction->getNdbIndexOperation(myIndex);
if (myIndexOperation == NULL) APIERROR(myTransaction->getNdbError());
myIndexOperation->deleteTuple();
myIndexOperation->equal( "ATTR2", 3 );
if (myTransaction->execute(NdbTransaction::Commit) == -1)
APIERROR(myTransaction->getNdbError());
myNdb->closeTransaction(myTransaction);
}
/*****************************
* Read and print all tuples *
*****************************/
{
std::cout << "ATTR1 ATTR2" << std::endl;
for (int i = 0; i < 10; i++) {
NdbTransaction *myTransaction= myNdb->startTransaction();
if (myTransaction == NULL) APIERROR(myNdb->getNdbError());
NdbOperation *myOperation= myTransaction->getNdbOperation(myTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());
myOperation->readTuple(NdbOperation::LM_Read);
myOperation->equal("ATTR1", i);
NdbRecAttr *myRecAttr= myOperation->getValue("ATTR2", NULL);
if (myRecAttr == NULL) APIERROR(myTransaction->getNdbError());
if(myTransaction->execute( NdbTransaction::Commit,
NdbOperation::AbortOnError ) == -1)
if (i == 3) {
std::cout << "Detected that deleted tuple doesn't exist!\n";
} else {
APIERROR(myTransaction->getNdbError());
}
if (i != 3) {
printf(" %2d %2d\n", i, myRecAttr->u_32_value());
}
myNdb->closeTransaction(myTransaction);
}
}
delete myNdb;
delete cluster_connection;
ndb_end(0);
return 0;
}