Export Mysql table into xml file same format as mysqldump using Perl

Question

Using Perl how to export Mysql table into xml file the same format as mysqldump do with command like this:

mysqldump --xml -u root -proot dbname tablename >tablename.xml

I know some Perl modules like XML::TreePP easy to use but their problem when they load xml file they have to load the entire file into memory before parsing and if the file size is larger than the allowed process memory will crash.

If you're running out of memory parsing a file generated by mysqldump, you'll still run out of memory if you dump the same data in the same format using a different method. I think what you're really asking is, "How can I parse a large XML file without running out of memory?" — ThisSuitIsBlackNot
– ThisSuitIsBlackNot, Commented Dec 22, 2014 at 21:48
See “Out of memory” while parsing large (100 Mb) XML file using perl for how to parse large XML files without loading their full contents into memory. — ThisSuitIsBlackNot
– ThisSuitIsBlackNot, Commented Dec 22, 2014 at 21:56
It is not the issue of out of memory, I need to implement the backup and restore manually not through mysqldump — daliaessam
– daliaessam, Commented Dec 22, 2014 at 22:12
Is there a particular reason you can't use mysqldump? As an alternative, you can use the SELECT ... INTO OUTFILE syntax to dump your data in CSV format, for example, and restore it with LOAD DATA INFILE — ThisSuitIsBlackNot
– ThisSuitIsBlackNot, Commented Dec 22, 2014 at 22:24
@ThisSuitIsBlackNot CSV exports are ok, but when the data has commas, then usually people switch to TSVs(tab-separated values) and when the data also contains tabs, then some other form of serialization is needed. From this point of view, XML is superior, but.. it also comes with the drawbacks XMLs usually have(verbosity, etc). — wsdookadr
– wsdookadr, Commented Jan 1, 2015 at 10:51

Community · Accepted Answer · 2017-05-23 10:26:09Z

1

If you need to parse very large XML documents, there's a particular category of XML parsers, SAX(Simple API for XML) that functions as a stream parser and emits events while parsing the XML document. On CPAN you can find XML::LibXML::SAX (part of the XML::LibXML module on CPAN) which implements SAX and can be used to parse large XML documents :

Such an interface is useful if very large XML documents have to be 
processed and no DOM functions are required. By using this interface
it is possible to read data stored within an XML document directly
into the application data structures without loading the document
into memory.

You can read another SO thread about a similar problem where XML::Twig was recommended.

edited May 23, 2017 at 10:26

CommunityBot

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answered Jan 1, 2015 at 10:31

wsdookadr

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