2.4.5 NDB API Example: Using Secondary Indexes in Scans

This program illustrates how to use secondary indexes in the NDB API.

The source code for this example may be found in the MySQL Cluster source tree, in storage/ndb/ndbapi-examples/ndbapi_simple_index/main.cpp.

Note

This file was previously named ndbapi_simple_index.cpp.

The correct output from this program is shown here:

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

The listing for this program is shown here:

#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();
  MYSQL mysql;

  /**************************************************************
   * Connect to mysql server and create table                   *
   **************************************************************/
  {
    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 << "MySQL Cluster already has example table: api_scan. "
        << "Dropping it..." << std::endl; 
        mysql_query(&mysql, "DROP TABLE api_simple_index");
      }
      else MYSQLERROR(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;
}