Reason: I was assigned to run some script that advances a website,it's a fantasy football site and there are several instants of the site located into different domains. Some has more than 80k users and each users supposed to have a team that consists of 15 players. Hence some tables have No.users x No.players rows.
However Sometimes the script fails and the result gets corrupted, therefore I must backup 10 tables in question before i execute the script. Nevertheless, I still need to backup the tables to keep historical record of users action. Because football matches may last for 50+ game weeks.
Task: To duplicate db tables using php script. When i started i used to backup the tables using sqlyog. it's works but it's time consuming since I have to wait for each table to be duplicated. Besides, for large tables the sqlyog application crashes during the duplicating of large tables which may be very annoying.
Current solution: I have created a simple application with interface that does the job and it works great. It consist of three files, one for db connection, 2nd for db manipulation, 3rd for user interface and to use the 2nd file's code. The thing is, sometimes it get stuck at the middle of duplicating tables process.
Objective: To create an application to be used by admin to facilitate database backing up using mysql+php.
My Question: How to ensure that the duplicating script will definitely backup the table completely without hanging the server or interrupting the script.
Down here I will include my code for duplicating function, but basically these are the two crucial lines that i think the problem is located in them:
//duplicate tables structure
$query = "CREATE TABLE $this->dbName.`$newTableName` LIKE $this->dbName.`$oldTable`";
//duplicate tables data
$query = "INSERT INTO $this->dbName.`$newTableName` SELECT * FROM $this->dbName.`$oldTable`";
The rest of the code is solely for validation in case error occur. If you wish to take a look at the whole code, be my guest. Here's the function:
private function duplicateTable($oldTable, $newTableName) {
if ($this->isExistingTable($oldTable))
{
$this->printLogger("Original Table is valid -table exists- : $oldTable ");
}
else
{
$this->printrR("Original Table is invalid -table does not exist- : $oldTable ");
return false;
}
if (!$this->isExistingTable($newTableName))// make sure new table does not exist alrady
{
$this->printLogger("Distination Table name is valid -no table with this name- : $newTableName");
$query = "CREATE TABLE $this->dbName.`$newTableName` LIKE $this->dbName.`$oldTable`";
$result = mysql_query($query) or $this->printrR("Error in query. Query:\n $query\n Error: " . mysql_error());
}
else
{
$this->printrR("Distination Table is invalid. -table already exists- $newTableName");
$this->printr("Now checking if tables actually match,: $oldTable => $newTableName \n");
$varifyStatus = $this->varifyDuplicatedTables($oldTable, $newTableName);
if ($varifyStatus >= 0)
{
$this->printrG("Tables match, it seems they were duplicated before $oldTable => $newTableName");
}
else
{
$this->printrR("The duplicate table exists, yet, doesn't match the original! $oldTable => $newTableName");
}
return false;
}
if ($result)
{
$this->printLogger("Query executed 1/2");
}
else
{
$this->printrR("Something went wrong duplicateTable\nQuery: $query\n\n\nMySql_Error: " . mysql_error());
return false;
}
if (!$this->isExistingTable($newTableName))//validate table has been created
{
$this->printrR("Attemp to duplicate table structure failed $newTableName table was not found after creating!");
return false;
}
else
{
$this->printLogger("Table created successfully: $newTableName");
//Now checking table structure
$this->printLogger("Now comparing indexes ... ");
$autoInc = $this->checkAutoInc($oldTable, $newTableName);
if ($autoInc == 1)
{
$this->printLogger("Auto inc seems ok");
}
elseif ($autoInc == 0)
{
$this->printLogger("No inc key for both tables. Continue anyways");
}
elseif ($autoInc == -1)
{
$this->printLogger("No match inc key!");
}
$time = $oldTable == 'team_details' ? 5 : 2;
$msg = $oldTable == 'team_details' ? "This may take a while for team_details. Please wait." : "Please wait.";
$this->printLogger("Sleep for $time ...\n");
sleep($time);
$this->printLogger("Preparing for copying data ...\n");
$query = "INSERT INTO $this->dbName.`$newTableName` SELECT * FROM $this->dbName.`$oldTable`";
$this->printLogger("Processing copyign data query.$msg...\n\n\n");
$result = mysql_query($query) or $this->printrR("Error in query. Query:\n $query\n Error: " . mysql_error());
// ERROR usually happens here if large tables
sleep($time); //to make db process current requeste.
$this->printLogger("Query executed 2/2");
sleep($time); //to make db process current requeste.
if ($result)
{
$this->printLogger("Table created ($newTableName) and data has been copied!");
$this->printLogger("Confirming number of rows ... ");
/////////////////////////////////
// start checking count
$numRows = $this->checkCountRows($oldTable, $newTableName);
if ($numRows)
{
$this->printLogger("Table duplicated successfully ");
return true;
}
else
{
$this->printLogger("Table duplicated, but, please check num rows $newTableName");
return -3;
}
// end of checking count
/////////////////////////////////
}//end of if(!$result) query 2/2
else
{
$this->printrR("Something went wrong duplicate Table\nINSERT INTO $oldTable -> $newTableName\n\n$query\n mysql_error() \n " . mysql_error());
return false;
}
}
}
AS you noticed the function is only to duplicate one table, that's why there is another function that that takes an array of tables from the user and pass the tables names array one by one to duplicateTable(). Any other function should be included for this question, please let me know.
One solution pops into my mind, would duplicating tables by part by part add any improvement, I'm not sure how Insert into works, but maybe if I could insert let's say 25% at a time it may help?
However Sometimes the script fails and the result gets corrupted, therefore I must backup 10 tables in question before i execute the script.
Probably you need to use another solution here: transactions. You need to wrap up all queries you are using in failing script into transaction. If transaction fails all data will be the same as in the beginning of the operation. If queries got executed correctly - you are OK.
why are you every time duplicating the table.. CLUSTERS are good option which can make duplicate copies of your table in distributed manner and is much more reliable and secure.
来源：https://stackoverflow.com/questions/14038348/copy-duplicate-backup-database-tables-effectively-mysql