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:
Press CTRL+C to copyATTR1 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:
Press CTRL+C to copy#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; }