此示例说明如何使用 NDB 扫描 API。NdbScanFilter它展示了如何使用和
类执行扫描、如何扫描更新以及如何扫描删除
NdbScanOperation。
这个例子的源代码可以在 NDB Cluster 源树中找到，在文件中
storage/ndb/ndbapi-examples/ndbapi_scan/ndbapi_scan.cpp。
此示例使用以下类和方法：
/*
Copyright (c) 2005, 2017, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*
* ndbapi_scan.cpp:
* Illustrates how to use the scan api in the NDBAPI.
* The example shows how to do scan, scan for update and scan for delete
* using NdbScanFilter and NdbScanOperation
*
* Classes and methods used in this example:
*
* Ndb_cluster_connection
* connect()
* wait_until_ready()
*
* Ndb
* init()
* getDictionary()
* startTransaction()
* closeTransaction()
*
* NdbTransaction
* getNdbScanOperation()
* execute()
*
* NdbScanOperation
* getValue()
* readTuples()
* nextResult()
* deleteCurrentTuple()
* updateCurrentTuple()
*
* const NdbDictionary::Dictionary
* getTable()
*
* const NdbDictionary::Table
* getColumn()
*
* const NdbDictionary::Column
* getLength()
*
* NdbOperation
* insertTuple()
* equal()
* setValue()
*
* NdbScanFilter
* begin()
* eq()
* end()
*
*/
#ifdef _WIN32
#include <winsock2.h>
#endif
#include <mysql.h>
#include <mysqld_error.h>
#include <NdbApi.hpp>
// Used for cout
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <config.h>
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
/**
* Helper sleep function
*/
static void
milliSleep(int milliseconds){
struct timeval sleeptime;
sleeptime.tv_sec = milliseconds / 1000;
sleeptime.tv_usec = (milliseconds - (sleeptime.tv_sec * 1000)) * 1000000;
select(0, 0, 0, 0, &sleeptime);
}
/**
* Helper debugging macros
*/
#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); }
struct Car
{
/**
* Note memset, so that entire char-fields are cleared
* as all 20 bytes are significant (as type is char)
*/
Car() { memset(this, 0, sizeof(* this)); }
unsigned int reg_no;
char brand[20];
char color[20];
};
/**
* Function to drop table
*/
void drop_table(MYSQL &mysql)
{
if (mysql_query(&mysql, "DROP TABLE IF EXISTS api_scan"))
MYSQLERROR(mysql);
}
/**
* Function to create table
*/
void create_table(MYSQL &mysql)
{
while (mysql_query(&mysql,
"CREATE TABLE"
" api_scan"
" (REG_NO INT UNSIGNED NOT NULL,"
" BRAND CHAR(20) NOT NULL,"
" COLOR CHAR(20) NOT NULL,"
" PRIMARY KEY USING HASH (REG_NO))"
" ENGINE=NDB"))
{
if (mysql_errno(&mysql) != ER_TABLE_EXISTS_ERROR)
MYSQLERROR(mysql);
std::cout << "NDB Cluster already has example table: api_scan. "
<< "Dropping it..." << std::endl;
drop_table(mysql);
}
}
int populate(Ndb * myNdb)
{
int i;
Car cars[15];
const NdbDictionary::Dictionary* myDict= myNdb->getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("api_scan");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
/**
* Five blue mercedes
*/
for (i = 0; i < 5; i++)
{
cars[i].reg_no = i;
sprintf(cars[i].brand, "Mercedes");
sprintf(cars[i].color, "Blue");
}
/**
* Five black bmw
*/
for (i = 5; i < 10; i++)
{
cars[i].reg_no = i;
sprintf(cars[i].brand, "BMW");
sprintf(cars[i].color, "Black");
}
/**
* Five pink toyotas
*/
for (i = 10; i < 15; i++)
{
cars[i].reg_no = i;
sprintf(cars[i].brand, "Toyota");
sprintf(cars[i].color, "Pink");
}
NdbTransaction* myTrans = myNdb->startTransaction();
if (myTrans == NULL)
APIERROR(myNdb->getNdbError());
for (i = 0; i < 15; i++)
{
NdbOperation* myNdbOperation = myTrans->getNdbOperation(myTable);
if (myNdbOperation == NULL)
APIERROR(myTrans->getNdbError());
myNdbOperation->insertTuple();
myNdbOperation->equal("REG_NO", cars[i].reg_no);
myNdbOperation->setValue("BRAND", cars[i].brand);
myNdbOperation->setValue("COLOR", cars[i].color);
}
int check = myTrans->execute(NdbTransaction::Commit);
myTrans->close();
return check != -1;
}
int scan_delete(Ndb* myNdb,
int column,
const char * color)
{
// Scan all records exclusive and delete
// them one by one
int retryAttempt = 0;
const int retryMax = 10;
int deletedRows = 0;
int check;
NdbError err;
NdbTransaction *myTrans;
NdbScanOperation *myScanOp;
const NdbDictionary::Dictionary* myDict= myNdb->getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("api_scan");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
/**
* Loop as long as :
* retryMax not reached
* failed operations due to TEMPORARY erros
*
* Exit loop;
* retyrMax reached
* Permanent error (return -1)
*/
while (true)
{
if (retryAttempt >= retryMax)
{
std::cout << "ERROR: has retried this operation " << retryAttempt
<< " times, failing!" << std::endl;
return -1;
}
myTrans = myNdb->startTransaction();
if (myTrans == NULL)
{
const NdbError err = myNdb->getNdbError();
if (err.status == NdbError::TemporaryError)
{
milliSleep(50);
retryAttempt++;
continue;
}
std::cout << err.message << std::endl;
return -1;
}
/**
* Get a scan operation.
*/
myScanOp = myTrans->getNdbScanOperation(myTable);
if (myScanOp == NULL)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* Define a result set for the scan.
*/
if(myScanOp->readTuples(NdbOperation::LM_Exclusive) != 0)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* Use NdbScanFilter to define a search critera
*/
NdbScanFilter filter(myScanOp) ;
if(filter.begin(NdbScanFilter::AND) < 0 ||
filter.cmp(NdbScanFilter::COND_EQ, column, color, 20) < 0 ||
filter.end() < 0)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* Start scan (NoCommit since we are only reading at this stage);
*/
if(myTrans->execute(NdbTransaction::NoCommit) != 0){
err = myTrans->getNdbError();
if(err.status == NdbError::TemporaryError){
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
milliSleep(50);
continue;
}
std::cout << err.code << std::endl;
std::cout << myTrans->getNdbError().code << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* start of loop: nextResult(true) means that "parallelism" number of
* rows are fetched from NDB and cached in NDBAPI
*/
while((check = myScanOp->nextResult(true)) == 0){
do
{
if (myScanOp->deleteCurrentTuple() != 0)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
deletedRows++;
/**
* nextResult(false) means that the records
* cached in the NDBAPI are modified before
* fetching more rows from NDB.
*/
} while((check = myScanOp->nextResult(false)) == 0);
/**
* NoCommit when all cached tuple have been marked for deletion
*/
if(check != -1)
{
check = myTrans->execute(NdbTransaction::NoCommit);
}
/**
* Check for errors
*/
err = myTrans->getNdbError();
if(check == -1)
{
if(err.status == NdbError::TemporaryError)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
milliSleep(50);
continue;
}
}
/**
* End of loop
*/
}
/**
* Commit all prepared operations
*/
if(myTrans->execute(NdbTransaction::Commit) == -1)
{
if(err.status == NdbError::TemporaryError){
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
milliSleep(50);
continue;
}
}
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return 0;
}
if(myTrans!=0)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
}
return -1;
}
int scan_update(Ndb* myNdb,
int update_column,
const char * before_color,
const char * after_color)
{
// Scan all records exclusive and update
// them one by one
int retryAttempt = 0;
const int retryMax = 10;
int updatedRows = 0;
int check;
NdbError err;
NdbTransaction *myTrans;
NdbScanOperation *myScanOp;
const NdbDictionary::Dictionary* myDict= myNdb->getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("api_scan");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
/**
* Loop as long as :
* retryMax not reached
* failed operations due to TEMPORARY erros
*
* Exit loop;
* retryMax reached
* Permanent error (return -1)
*/
while (true)
{
if (retryAttempt >= retryMax)
{
std::cout << "ERROR: has retried this operation " << retryAttempt
<< " times, failing!" << std::endl;
return -1;
}
myTrans = myNdb->startTransaction();
if (myTrans == NULL)
{
const NdbError err = myNdb->getNdbError();
if (err.status == NdbError::TemporaryError)
{
milliSleep(50);
retryAttempt++;
continue;
}
std::cout << err.message << std::endl;
return -1;
}
/**
* Get a scan operation.
*/
myScanOp = myTrans->getNdbScanOperation(myTable);
if (myScanOp == NULL)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* Define a result set for the scan.
*/
if( myScanOp->readTuples(NdbOperation::LM_Exclusive) )
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* Use NdbScanFilter to define a search critera
*/
NdbScanFilter filter(myScanOp) ;
if(filter.begin(NdbScanFilter::AND) < 0 ||
filter.cmp(NdbScanFilter::COND_EQ, update_column, before_color, 20) <0||
filter.end() <0)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* Start scan (NoCommit since we are only reading at this stage);
*/
if(myTrans->execute(NdbTransaction::NoCommit) != 0)
{
err = myTrans->getNdbError();
if(err.status == NdbError::TemporaryError){
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
milliSleep(50);
continue;
}
std::cout << myTrans->getNdbError().code << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* start of loop: nextResult(true) means that "parallelism" number of
* rows are fetched from NDB and cached in NDBAPI
*/
while((check = myScanOp->nextResult(true)) == 0){
do {
/**
* Get update operation
*/
NdbOperation * myUpdateOp = myScanOp->updateCurrentTuple();
if (myUpdateOp == 0)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
updatedRows++;
/**
* do the update
*/
myUpdateOp->setValue(update_column, after_color);
/**
* nextResult(false) means that the records
* cached in the NDBAPI are modified before
* fetching more rows from NDB.
*/
} while((check = myScanOp->nextResult(false)) == 0);
/**
* NoCommit when all cached tuple have been updated
*/
if(check != -1)
{
check = myTrans->execute(NdbTransaction::NoCommit);
}
/**
* Check for errors
*/
err = myTrans->getNdbError();
if(check == -1)
{
if(err.status == NdbError::TemporaryError){
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
milliSleep(50);
continue;
}
}
/**
* End of loop
*/
}
/**
* Commit all prepared operations
*/
if(myTrans->execute(NdbTransaction::Commit) == -1)
{
if(err.status == NdbError::TemporaryError){
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
milliSleep(50);
continue;
}
}
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return 0;
}
if(myTrans!=0)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
}
return -1;
}
int scan_print(Ndb * myNdb)
{
// Scan all records exclusive and update
// them one by one
int retryAttempt = 0;
const int retryMax = 10;
int fetchedRows = 0;
int check;
NdbError err;
NdbTransaction *myTrans;
NdbScanOperation *myScanOp;
/* Result of reading attribute value, three columns:
REG_NO, BRAND, and COLOR
*/
NdbRecAttr * myRecAttr[3];
const NdbDictionary::Dictionary* myDict= myNdb->getDictionary();
const NdbDictionary::Table *myTable= myDict->getTable("api_scan");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
/**
* Loop as long as :
* retryMax not reached
* failed operations due to TEMPORARY erros
*
* Exit loop;
* retyrMax reached
* Permanent error (return -1)
*/
while (true)
{
if (retryAttempt >= retryMax)
{
std::cout << "ERROR: has retried this operation " << retryAttempt
<< " times, failing!" << std::endl;
return -1;
}
myTrans = myNdb->startTransaction();
if (myTrans == NULL)
{
const NdbError err = myNdb->getNdbError();
if (err.status == NdbError::TemporaryError)
{
milliSleep(50);
retryAttempt++;
continue;
}
std::cout << err.message << std::endl;
return -1;
}
/*
* Define a scan operation.
* NDBAPI.
*/
myScanOp = myTrans->getNdbScanOperation(myTable);
if (myScanOp == NULL)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* Read without locks, without being placed in lock queue
*/
if( myScanOp->readTuples(NdbOperation::LM_CommittedRead) == -1)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* Define storage for fetched attributes.
* E.g., the resulting attributes of executing
* myOp->getValue("REG_NO") is placed in myRecAttr[0].
* No data exists in myRecAttr until transaction has commited!
*/
myRecAttr[0] = myScanOp->getValue("REG_NO");
myRecAttr[1] = myScanOp->getValue("BRAND");
myRecAttr[2] = myScanOp->getValue("COLOR");
if(myRecAttr[0] ==NULL || myRecAttr[1] == NULL || myRecAttr[2]==NULL)
{
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* Start scan (NoCommit since we are only reading at this stage);
*/
if(myTrans->execute(NdbTransaction::NoCommit) != 0){
err = myTrans->getNdbError();
if(err.status == NdbError::TemporaryError){
std::cout << myTrans->getNdbError().message << std::endl;
myNdb->closeTransaction(myTrans);
milliSleep(50);
continue;
}
std::cout << err.code << std::endl;
std::cout << myTrans->getNdbError().code << std::endl;
myNdb->closeTransaction(myTrans);
return -1;
}
/**
* start of loop: nextResult(true) means that "parallelism" number of
* rows are fetched from NDB and cached in NDBAPI
*/
while((check = myScanOp->nextResult(true)) == 0){
do {
fetchedRows++;
/**
* print REG_NO unsigned int
*/
std::cout << myRecAttr[0]->u_32_value() << "\t";
/**
* print BRAND character string
*/
std::cout << myRecAttr[1]->aRef() << "\t";
/**
* print COLOR character string
*/
std::cout << myRecAttr[2]->aRef() << std::endl;
/**
* nextResult(false) means that the records
* cached in the NDBAPI are modified before
* fetching more rows from NDB.
*/
} while((check = myScanOp->nextResult(false)) == 0);
}
myNdb->closeTransaction(myTrans);
return 1;
}
return -1;
}
void mysql_connect_and_create(MYSQL & mysql, const char *socket)
{
bool ok;
ok = mysql_real_connect(&mysql, "localhost", "root", "", "", 0, socket, 0);
if(ok) {
mysql_query(&mysql, "CREATE DATABASE ndb_examples");
ok = ! mysql_select_db(&mysql, "ndb_examples");
}
if(ok) {
create_table(mysql);
}
if(! ok) MYSQLERROR(mysql);
}
void ndb_run_scan(const char * connectstring)
{
/**************************************************************
* Connect to ndb cluster *
**************************************************************/
Ndb_cluster_connection cluster_connection(connectstring);
if (cluster_connection.connect(4, 5, 1))
{
std::cout << "Unable to connect to cluster within 30 secs." << std::endl;
exit(-1);
}
// Optionally connect and wait for the storage nodes (ndbd's)
if (cluster_connection.wait_until_ready(30,0) < 0)
{
std::cout << "Cluster was not ready within 30 secs.\n";
exit(-1);
}
Ndb myNdb(&cluster_connection,"ndb_examples");
if (myNdb.init(1024) == -1) { // Set max 1024 parallel transactions
APIERROR(myNdb.getNdbError());
exit(-1);
}
/*******************************************
* Check table definition *
*******************************************/
int column_color;
{
const NdbDictionary::Dictionary* myDict= myNdb.getDictionary();
const NdbDictionary::Table *t= myDict->getTable("api_scan");
if(t == NULL)
{
std::cout << "Dictionary::getTable() failed.";
exit(-1);
}
Car car;
if (t->getColumn("COLOR")->getLength() != sizeof(car.color) ||
t->getColumn("BRAND")->getLength() != sizeof(car.brand))
{
std::cout << "Wrong table definition" << std::endl;
exit(-1);
}
column_color= t->getColumn("COLOR")->getColumnNo();
}
if(populate(&myNdb) > 0)
std::cout << "populate: Success!" << std::endl;
if(scan_print(&myNdb) > 0)
std::cout << "scan_print: Success!" << std::endl << std::endl;
std::cout << "Going to delete all pink cars!" << std::endl;
{
/**
* Note! color needs to be of exact the same size as column defined
*/
Car tmp;
sprintf(tmp.color, "Pink");
if(scan_delete(&myNdb, column_color, tmp.color) > 0)
std::cout << "scan_delete: Success!" << std::endl << std::endl;
}
if(scan_print(&myNdb) > 0)
std::cout << "scan_print: Success!" << std::endl << std::endl;
{
/**
* Note! color1 & 2 need to be of exact the same size as column defined
*/
Car tmp1, tmp2;
sprintf(tmp1.color, "Blue");
sprintf(tmp2.color, "Black");
std::cout << "Going to update all " << tmp1.color
<< " cars to " << tmp2.color << " cars!" << std::endl;
if(scan_update(&myNdb, column_color, tmp1.color, tmp2.color) > 0)
std::cout << "scan_update: Success!" << std::endl << std::endl;
}
if(scan_print(&myNdb) > 0)
std::cout << "scan_print: Success!" << std::endl << std::endl;
}
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 *connectstring = argv[2];
MYSQL mysql;
mysql_init(& mysql);
mysql_connect_and_create(mysql, mysqld_sock);
ndb_init();
ndb_run_scan(connectstring);
ndb_end(0);
mysql_close(&mysql);
return 0;
}