I'm passing a large dataset into a MySQL table via PHP using insert commands and I'm wondering if it's possible to insert approximately 1000 rows at a time via a query other than appending each value on the end of a mile-long string and then executing it. I am using the CodeIgniter framework so its functions are also available to me.
13 Answers
Assembling one INSERT
statement with multiple rows is much faster in MySQL than one INSERT
statement per row.
That said, it sounds like you might be running into string-handling problems in PHP, which is really an algorithm problem, not a language one. Basically, when working with large strings, you want to minimize unnecessary copying. Primarily, this means you want to avoid concatenation. The fastest and most memory efficient way to build a large string, such as for inserting hundreds of rows at one, is to take advantage of the implode()
function and array assignment.
$sql = array();
foreach( $data as $row ) {
$sql[] = '("'.mysql_real_escape_string($row['text']).'", '.$row['category_id'].')';
}
mysql_query('INSERT INTO table (text, category) VALUES '.implode(',', $sql));
The advantage of this approach is that you don't copy and re-copy the SQL statement you've so far assembled with each concatenation; instead, PHP does this once in the implode()
statement. This is a big win.
If you have lots of columns to put together, and one or more are very long, you could also build an inner loop to do the same thing and use implode()
to assign the values clause to the outer array.
Multiple insert/ batch insert is now supported by CodeIgniter.
$data = array(
array(
'title' => 'My title' ,
'name' => 'My Name' ,
'date' => 'My date'
),
array(
'title' => 'Another title' ,
'name' => 'Another Name' ,
'date' => 'Another date'
)
);
$this->db->insert_batch('mytable', $data);
// Produces: INSERT INTO mytable (title, name, date) VALUES ('My title', 'My name', 'My date'), ('Another title', 'Another name', 'Another date')
You could prepare the query for inserting one row using the mysqli_stmt class, and then iterate over the array of data. Something like:
$stmt = $db->stmt_init();
$stmt->prepare("INSERT INTO mytbl (fld1, fld2, fld3, fld4) VALUES(?, ?, ?, ?)");
foreach($myarray as $row)
{
$stmt->bind_param('idsb', $row['fld1'], $row['fld2'], $row['fld3'], $row['fld4']);
$stmt->execute();
}
$stmt->close();
Where 'idsb' are the types of the data you're binding (int, double, string, blob).
mysqli in PHP 5 is an object with some good functions that will allow you to speed up the insertion time for the answer above:
$mysqli->autocommit(FALSE);
$mysqli->multi_query($sqlCombined);
$mysqli->autocommit(TRUE);
Turning off autocommit when inserting many rows greatly speeds up insertion, so turn it off, then execute as mentioned above, or just make a string (sqlCombined) which is many insert statements separated by semi-colons and multi-query will handle them fine.
Well, you don't want to execute 1000 query calls, but doing this is fine:
$stmt= array( 'array of statements' );
$query= 'INSERT INTO yourtable (col1,col2,col3) VALUES ';
foreach( $stmt AS $k => $v ) {
$query.= '(' .$v. ')'; // NOTE: you'll have to change to suit
if ( $k !== sizeof($stmt)-1 ) $query.= ', ';
}
$r= mysql_query($query);
Depending on your data source, populating the array might be as easy as opening a file and dumping the contents into an array via file()
.
You can do it with several ways in codeigniter e.g.
First By loop
foreach($myarray as $row)
{
$data = array("first"=>$row->first,"second"=>$row->sec);
$this->db->insert('table_name',$data);
}
Second -- By insert batch
$data = array(
array(
'first' => $myarray[0]['first'] ,
'second' => $myarray[0]['sec'],
),
array(
'first' => $myarray[1]['first'] ,
'second' => $myarray[1]['sec'],
),
);
$this->db->insert_batch('table_name', $data);
Third way -- By multiple value pass
$sql = array();
foreach( $myarray as $row ) {
$sql[] = '("'.mysql_real_escape_string($row['first']).'", '.$row['sec'].')';
}
mysql_query('INSERT INTO table (first, second) VALUES '.implode(',', $sql));
Although it is too late to answer this question. Here are my answer on the same.
If you are using CodeIgniter then you can use inbuilt methods defined in query_builder class.
$this->db->insert_batch()
Generates an insert string based on the data you supply, and runs the query. You can either pass an array or an object to the function. Here is an example using an array:
$data = array(
array(
'title' => 'My title',
'name' => 'My Name',
'date' => 'My date'
),
array(
'title' => 'Another title',
'name' => 'Another Name',
'date' => 'Another date'
)
);
$this->db->insert_batch('mytable', $data);
// Produces: INSERT INTO mytable (title, name, date) VALUES ('My title', 'My name', 'My date'), ('Another title', 'Another name', 'Another date')
The first parameter will contain the table name, the second is an associative array of values.
You can find more details about query_builder here
I have created a class that performs multi-line that is used as follows:
$pdo->beginTransaction();
$pmi = new PDOMultiLineInserter($pdo, "foo", array("a","b","c","e"), 10);
$pmi->insertRow($data);
// ....
$pmi->insertRow($data);
$pmi->purgeRemainingInserts();
$pdo->commit();
where the class is defined as follows:
class PDOMultiLineInserter {
private $_purgeAtCount;
private $_bigInsertQuery, $_singleInsertQuery;
private $_currentlyInsertingRows = array();
private $_currentlyInsertingCount = 0;
private $_numberOfFields;
private $_error;
private $_insertCount = 0;
/**
* Create a PDOMultiLine Insert object.
*
* @param PDO $pdo The PDO connection
* @param type $tableName The table name
* @param type $fieldsAsArray An array of the fields being inserted
* @param type $bigInsertCount How many rows to collect before performing an insert.
*/
function __construct(PDO $pdo, $tableName, $fieldsAsArray, $bigInsertCount = 100) {
$this->_numberOfFields = count($fieldsAsArray);
$insertIntoPortion = "REPLACE INTO `$tableName` (`".implode("`,`", $fieldsAsArray)."`) VALUES";
$questionMarks = " (?".str_repeat(",?", $this->_numberOfFields - 1).")";
$this->_purgeAtCount = $bigInsertCount;
$this->_bigInsertQuery = $pdo->prepare($insertIntoPortion.$questionMarks.str_repeat(", ".$questionMarks, $bigInsertCount - 1));
$this->_singleInsertQuery = $pdo->prepare($insertIntoPortion.$questionMarks);
}
function insertRow($rowData) {
// @todo Compare speed
// $this->_currentlyInsertingRows = array_merge($this->_currentlyInsertingRows, $rowData);
foreach($rowData as $v) array_push($this->_currentlyInsertingRows, $v);
//
if (++$this->_currentlyInsertingCount == $this->_purgeAtCount) {
if ($this->_bigInsertQuery->execute($this->_currentlyInsertingRows) === FALSE) {
$this->_error = "Failed to perform a multi-insert (after {$this->_insertCount} inserts), the following errors occurred:".implode('<br/>', $this->_bigInsertQuery->errorInfo());
return false;
}
$this->_insertCount++;
$this->_currentlyInsertingCount = 0;
$this->_currentlyInsertingRows = array();
}
return true;
}
function purgeRemainingInserts() {
while ($this->_currentlyInsertingCount > 0) {
$singleInsertData = array();
// @todo Compare speed - http://www.evardsson.com/blog/2010/02/05/comparing-php-array_shift-to-array_pop/
// for ($i = 0; $i < $this->_numberOfFields; $i++) $singleInsertData[] = array_pop($this->_currentlyInsertingRows); array_reverse($singleInsertData);
for ($i = 0; $i < $this->_numberOfFields; $i++) array_unshift($singleInsertData, array_pop($this->_currentlyInsertingRows));
if ($this->_singleInsertQuery->execute($singleInsertData) === FALSE) {
$this->_error = "Failed to perform a small-insert (whilst purging the remaining rows; the following errors occurred:".implode('<br/>', $this->_singleInsertQuery->errorInfo());
return false;
}
$this->_currentlyInsertingCount--;
}
}
public function getError() {
return $this->_error;
}
}
I had to INSERT more than 14000 rows into a table and found that line for line with Mysqli prepared statements took more than ten minutes, while argument unpacking with string parameters for the same Mysqli prepared statements did it in less than 10 seconds. My data was very repetitive as it was multiples of id's and one constant integer.
10 minutes code:
$num = 1000;
$ent = 4;
$value = ['id' => 1,
'id' => 2,
'id' => 3,
'id' => 4,
'id' => 5,
'id' => 6,
'id' => 7,
'id' => 8,
'id' => 9,
'id' => 10,
'id' => 11,
'id' => 12,
'id' => 13,
'id' => 14];
$cnt = 0;
$query = "INSERT INTO table (col1, col2) VALUES (?,?)";
$stmt = $this->db->prepare($query);
$stmt->bind_param('ii', $arg_one,$arg_two);
foreach ($value as $k => $val) {
for ($i=0; $i < $num; $i++) {
$arg_one = $k;
$arg_two = $ent;
if($stmt->execute()) {
$cnt++;
}
}
}
10 second code:
$ent = 4;
$num = 1000;
$value = ['id' => 1,
'id' => 2,
'id' => 3,
'id' => 4,
'id' => 5,
'id' => 6,
'id' => 7,
'id' => 8,
'id' => 9,
'id' => 10,
'id' => 11,
'id' => 12,
'id' => 13,
'id' => 14];
$newdat = [];
foreach ($value as $k => $val) {
for ($i=0; $i < $num; $i++) {
$newdat[] = $val;
$newdat[] = $ent;
}
}
// create string of data types
$cnt = count($newdat);
$param = str_repeat('i',$cnt);
// create string of question marks
$rec = (count($newdat) == 0) ? 0 : $cnt / 2 - 1;
$id_q = str_repeat('(?,?),', $rec) . '(?,?)';
// insert
$query = "INSERT INTO table (col1, col2) VALUES $id_q";
$stmt = $db->prepare($query);
$stmt->bind_param($param, ...$newdat);
$stmt->execute();
I have created this simple function which you guys can use easily. You will need to pass the table-name ($tbl)
, table-field ($insertFieldsArr)
against your inserting data, data array ($arr)
.
insert_batch('table',array('field1','field2'),$dataArray);
function insert_batch($tbl,$insertFieldsArr,$arr){ $sql = array();
foreach( $arr as $row ) {
$strVals='';
$cnt=0;
foreach($insertFieldsArr as $key=>$val){
if(is_array($row)){
$strVals.="'".mysql_real_escape_string($row[$cnt]).'\',';
}
else{
$strVals.="'".mysql_real_escape_string($row).'\',';
}
$cnt++;
}
$strVals=rtrim($strVals,',');
$sql[] = '('.$strVals.')';
}
$fields=implode(',',$insertFieldsArr);
mysql_query('INSERT INTO `'.$tbl.'` ('.$fields.') VALUES '.implode(',', $sql));
}