Best practice: Import mySQL file in PHP; split queries

Question

I have a situation where I have to update a web site on a shared hosting provider. The site has a CMS. Uploading the CMS's files is pretty straightforward using FTP.

I also have to import a big (relative to the confines of a PHP script) database file (Around 2-3 MB uncompressed). Mysql is closed for access from the outside, so I have to upload a file using FTP, and start a PHP script to import it. Sadly, I do not have access to the mysql command line function so I have to parse and query it using native PHP. I also can't use LOAD DATA INFILE. I also can't use any kind of interactive front-end like phpMyAdmin, it needs to run in an automated fashion. I also can't use mysqli_multi_query().

Does anybody know or have a already coded, simple solution that reliably splits such a file into single queries (there could be multi-line statements) and runs the query. I would like to avoid to start fiddling with it myself due to the many gotchas that I'm likely to come across (How to detect whether a field delimiter is part of the data; how to deal with line breaks in memo fields; and so on). There must be a ready made solution for this.

Answer 1

Here is a memory-friendly function that should be able to split a big file in individual queries without needing to open the whole file at once:

function SplitSQL($file, $delimiter = ';')
{
    set_time_limit(0);

    if (is_file($file) === true)
    {
        $file = fopen($file, 'r');

        if (is_resource($file) === true)
        {
            $query = array();

            while (feof($file) === false)
            {
                $query[] = fgets($file);

                if (preg_match('~' . preg_quote($delimiter, '~') . '\s*$~iS', end($query)) === 1)
                {
                    $query = trim(implode('', $query));

                    if (mysql_query($query) === false)
                    {
                        echo '<h3>ERROR: ' . $query . '</h3>' . "\n";
                    }

                    else
                    {
                        echo '<h3>SUCCESS: ' . $query . '</h3>' . "\n";
                    }

                    while (ob_get_level() > 0)
                    {
                        ob_end_flush();
                    }

                    flush();
                }

                if (is_string($query) === true)
                {
                    $query = array();
                }
            }

            return fclose($file);
        }
    }

    return false;
}

I tested it on a big phpMyAdmin SQL dump and it worked just fine.

---

Some test data:

CREATE TABLE IF NOT EXISTS "test" (
    "id" INTEGER PRIMARY KEY AUTOINCREMENT,
    "name" TEXT,
    "description" TEXT
);

BEGIN;
    INSERT INTO "test" ("name", "description")
    VALUES (";;;", "something for you mind; body; soul");
COMMIT;

UPDATE "test"
    SET "name" = "; "
    WHERE "id" = 1;

And the respective output:

SUCCESS: CREATE TABLE IF NOT EXISTS "test" ( "id" INTEGER PRIMARY KEY AUTOINCREMENT, "name" TEXT, "description" TEXT );
SUCCESS: BEGIN;
SUCCESS: INSERT INTO "test" ("name", "description") VALUES (";;;", "something for you mind; body; soul");
SUCCESS: COMMIT;
SUCCESS: UPDATE "test" SET "name" = "; " WHERE "id" = 1;

Answer 2

Single page PHPMyAdmin - Adminer - Just one PHP script file. check : http://www.adminer.org/en/

Answer 3

When StackOverflow released their monthly data dump in XML format, I wrote PHP scripts to load it into a MySQL database. I imported about 2.2 gigabytes of XML in a few minutes.

My technique is to prepare() an INSERT statement with parameter placeholders for the column values. Then use XMLReader to loop over the XML elements and execute() my prepared query, plugging in values for the parameters. I chose XMLReader because it's a streaming XML reader; it reads the XML input incrementally instead of requiring to load the whole file into memory.

You could also read a CSV file one line at a time with fgetcsv().

If you're inporting into InnoDB tables, I recommend starting and committing transactions explicitly, to reduce the overhead of autocommit. I commit every 1000 rows, but this is arbitrary.

I'm not going to post the code here (because of StackOverflow's licensing policy), but in pseudocode:

connect to database
open data file
PREPARE parameterizes INSERT statement
begin first transaction
loop, reading lines from data file: {
    parse line into individual fields
    EXECUTE prepared query, passing data fields as parameters
    if ++counter % 1000 == 0,
        commit transaction and begin new transaction
}
commit final transaction

Writing this code in PHP is not rocket science, and it runs pretty quickly when one uses prepared statements and explicit transactions. Those features are not available in the outdated mysql PHP extension, but you can use them if you use mysqli or PDO_MySQL.

I also added convenient stuff like error checking, progress reporting, and support for default values when the data file doesn't include one of the fields.

I wrote my code in an abstract PHP class that I subclass for each table I need to load. Each subclass declares the columns it wants to load, and maps them to fields in the XML data file by name (or by position if the data file is CSV).

Answer 4

Can't you install phpMyAdmin, gzip the file (which should make it much smaller) and import it using phpMyAdmin?

EDIT: Well, if you can't use phpMyAdmin, you can use the code from phpMyAdmin. I'm not sure about this particular part, but it's generaly nicely structured.

Answer 5

Export

The first step is getting the input in a sane format for parsing when you export it. From your question it appears that you have control over the exporting of this data, but not the importing.

~: mysqldump test --opt --skip-extended-insert | grep -v '^--' | grep . > test.sql

This dumps the test database excluding all comment lines and blank lines into test.sql. It also disables extended inserts, meaning there is one INSERT statement per line. This will help limit the memory usage during the import, but at a cost of import speed.

Import

The import script is as simple as this:

<?php

$mysqli = new mysqli('localhost', 'hobodave', 'p4ssw3rd', 'test');
$handle = fopen('test.sql', 'rb');
if ($handle) {
    while (!feof($handle)) {
        // This assumes you don't have a row that is > 1MB (1000000)
        // which is unlikely given the size of your DB
        // Note that it has a DIRECT effect on your scripts memory
        // usage.
        $buffer = stream_get_line($handle, 1000000, ";\n");
        $mysqli->query($buffer);
    }
}
echo "Peak MB: ",memory_get_peak_usage(true)/1024/1024;

This will utilize an absurdly low amount of memory as shown below:

daves-macbookpro:~ hobodave$ du -hs test.sql 
 15M    test.sql
daves-macbookpro:~ hobodave$ time php import.php 
Peak MB: 1.75
real    2m55.619s
user    0m4.998s
sys 0m4.588s

What that says is you processed a 15MB mysqldump with a peak RAM usage of 1.75 MB in just under 3 minutes.

Alternate Export

If you have a high enough memory_limit and this is too slow, you can try this using the following export:

~: mysqldump test --opt | grep -v '^--' | grep . > test.sql

This will allow extended inserts, which insert multiple rows in a single query. Here are the statistics for the same datbase:

daves-macbookpro:~ hobodave$ du -hs test.sql 
 11M    test.sql
daves-macbookpro:~ hobodave$ time php import.php 
Peak MB: 3.75
real    0m23.878s
user    0m0.110s
sys 0m0.101s

Notice that it uses over 2x the RAM at 3.75 MB, but takes about 1/6th as long. I suggest trying both methods and seeing which suits your needs.

Edit:

I was unable to get a newline to appear literally in any mysqldump output using any of CHAR, VARCHAR, BINARY, VARBINARY, and BLOB field types. If you do have BLOB/BINARY fields though then please use the following just in case:

~: mysqldump5 test --hex-blob --opt | grep -v '^--' | grep . > test.sql

Answer 6

Splitting a query cannot be reliably done without parsing. Here is valid SQL that would be impossible to split correctly with a regular expression.

SELECT ";"; SELECT ";\"; a;";
SELECT ";
    abc";

I wrote a small SqlFormatter class in PHP that includes a query tokenizer. I added a splitQuery method to it that splits all queries (including the above example) reliably.

https://github.com/jdorn/sql-formatter/blob/master/SqlFormatter.php

You can remove the format and highlight methods if you don't need them.

One downside is that it requires the whole sql string to be in memory, which could be a problem if you're working with huge sql files. I'm sure with a little bit of tinkering, you could make the getNextToken method work on a file pointer instead.

Answer 7

First at all thanks for this topic. This saved a lot of time for me :) And let me to make little fix for your code. Sometimes if TRIGGERS or PROCEDURES is in dump file, it is not enough to examine the ; delimiters. In this case may be DELIMITER [something] in sql code, to say that the statement will not end with ; but [something]. For example a section in xxx.sql:

    DELIMITER //
    CREATE TRIGGER `mytrigger` BEFORE INSERT ON `mytable`
    FOR EACH ROW BEGIN
         SET NEW.`create_time` = NOW();
    END
    //
    DELIMITER ;

So first need to have a falg, to detect, that query does not ends with ; And delete the unqanted query chunks, because the mysql_query does not need delimiter (the delimiter is the end of string) so mysql_query need someting like this:

    CREATE TRIGGER `mytrigger` BEFORE INSERT ON `mytable`
    FOR EACH ROW BEGIN
         SET NEW.`create_time` = NOW();
    END;

So a little work and here is the fixed code:

    function SplitSQL($file, $delimiter = ';')
    {
        set_time_limit(0);            
        $matches = array();
        $otherDelimiter = false;
        if (is_file($file) === true) {
            $file = fopen($file, 'r');
            if (is_resource($file) === true) {
                $query = array();
                while (feof($file) === false) {
                    $query[] = fgets($file);
                    if (preg_match('~' . preg_quote('delimiter', '~') . '\s*([^\s]+)$~iS', end($query), $matches) === 1){     
                        //DELIMITER DIRECTIVE DETECTED
                        array_pop($query); //WE DON'T NEED THIS LINE IN SQL QUERY
                        if( $otherDelimiter = ( $matches[1] != $delimiter )){
                        }else{
                            //THIS IS THE DEFAULT DELIMITER, DELETE THE LINE BEFORE THE LAST (THAT SHOULD BE THE NOT DEFAULT DELIMITER) AND WE SHOULD CLOSE THE STATEMENT                                
                            array_pop($query);
                            $query[]=$delimiter;
                        }                                                                                    
                    }                        
                    if ( !$otherDelimiter && preg_match('~' . preg_quote($delimiter, '~') . '\s*$~iS', end($query)) === 1) {                            
                        $query = trim(implode('', $query));
                        if (mysql_query($query) === false){
                            echo '<h3>ERROR: ' . $query . '</h3>' . "\n";
                        }else{
                            echo '<h3>SUCCESS: ' . $query . '</h3>' . "\n";
                        }
                        while (ob_get_level() > 0){
                            ob_end_flush();
                        }
                        flush();                        
                    }
                    if (is_string($query) === true) {
                        $query = array();
                    }
                }                    
                return fclose($file);
            }
        }
        return false;
}

I hope i could help somebody too. Have a nice day!

Answer 8

http://www.ozerov.de/bigdump/ was very useful for me in importing 200+ MB sql file.

Note: SQL file should be already present in the server so that the process can be completed without any issue

Answer 9

Can you use LOAD DATA INFILE?

If you format your db dump file using SELECT INTO OUTFILE, this should be exactly what you need. No reason to have PHP parse anything.

Answer 10

Already answered: Loading .sql files from within PHP Also:

• http://webxadmin.free.fr/article/import-huge-mysql-dumps-using-php-only-342.php
• http://www.phpbuilder.com/board/showthread.php?t=10323180
• http://forums.tizag.com/archive/index.php?t-3581.html

Answer 11

I ran into the same problem. I solved it using a regular expression:

function splitQueryText($query) {
    // the regex needs a trailing semicolon
    $query = trim($query);

    if (substr($query, -1) != ";")
        $query .= ";";

    // i spent 3 days figuring out this line
    preg_match_all("/(?>[^;']|(''|(?>'([^']|\\')*[^\\\]')))+;/ixU", $query, $matches, PREG_SET_ORDER);

    $querySplit = "";

    foreach ($matches as $match) {
        // get rid of the trailing semicolon
        $querySplit[] = substr($match[0], 0, -1);
    }

    return $querySplit;
}

$queryList = splitQueryText($inputText);

foreach ($queryList as $query) {
    $result = mysql_query($query);
}

Answer 12

You can use phpMyAdmin for importing the file. Even if it is huge, just use UploadDir configuration directory, upload it there and choose it from phpMyAdmin import page. Once file processing will be close to the PHP limits, phpMyAdmin interrupts importing, shows you again import page with predefined values indicating where to continue in the import.

Answer 13

what do you think about:

system("cat xxx.sql | mysql -l username database");