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One of the finals steps in my current Solr adventure was to make it possible to remove a large number of documents form the index at the same time. As we’re currently using Solr to store phone information, we may have to remove several thousand records in one large update. The examples on the Solr Wiki shows how to remove one single document by posting a simple XML-document, or remove something by query. I would rather avoid beating our solr server with 300k of single delete requests, so I tried the obvious tactics with submitting several id’s in one document, making several <delete>-elements in one document etc, but nothing worked as I wanted it to.

After a bit of searching and stumbling around with Google, I finally found this very useful tip from Erik Hatcher. The clue is to simply rewrite the delete request as a delete by query, and then submit all the id’s to be removed as a simple OR query. On our development machine, Solr removed 1000 documents in somewhere around 900ms. Needless to say, that’s more than fast enough and solved our problem.

To sum it up; write a delete-by-query-statement as:

id:(123123 OR 13371337 OR 42424242 .. ) 

Thanks intarwebs!

While working with a view of a collection of documents returned from Solr using Solrj earlier today, I was attempting to write out the number of documents found in the search. In pure Java code you’d just request this by just calling .getNumFound() on the SolrDocumentList containing your documents, which whould also mean that they should be available through EL in JSTL by calling ${solrDocumentList.numFound} (which in turn calls getNumFound() in the SolrDocumentList object). The code in question was as simple as:

Which resulted in this error message, which kind of came as a surprise:

java.lang.NumberFormatException: For input string: "numFound"
        at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
        at java.lang.Integer.parseInt(Integer.java:447)
        at java.lang.Integer.parseInt(Integer.java:497)

After digging around a bit and reading the error message yet again, it suddenly hit me: $solrDocumentList was being interpreted and casted to a List, and as such, EL expected an index into the List instead of my call to a function. I’ve not been working with JSTL for too long, so I thought a bit about how to solve this. One solution would be to do the calls in the Action and then just map them to separate variables in the template, but this wasn’t really as pretty as it could be. Instead I wrote a simple wrapper around the SolrDocumentList, which is not a list in itself, but exposes all the elements through it’s getDocumentList-method. That way we can access it in the template by calling ${solrDocumentList.documentList…}.

I’ve included the simple, simple wrapper here. It should be expanded with access to Facet fields etc, but this should be a simple indicator of my suggested solution.

public class SolrSearchResult
{
    SolrDocumentList resultDocuments = null;

    public SolrSearchResult(SolrDocumentList results)
    {
        this.resultDocuments = results;
    }

    public long getNumFound()
    {
        return this.resultDocuments.getNumFound();
    }

    public long getStart()
    {
        return this.resultDocuments.getStart();
    }

    public float getMaxScore()
    {
        return this.resultDocuments.getMaxScore();
    }

    public SolrDocumentList getDocumentList()
    {
        return this.resultDocuments;
    }

    public void setDocumentList(SolrDocumentList results)
    {
        this.resultDocuments = results;
    }
}

Any comments and updates are of course as always welcome.

Just found a post detailing the release of the preview version of the MYSQLND support for PDO! For those of us who have grown fond of PDO during the last years and still uses MySQL, this is great news! The MYSQLND library is a reimplementation of the MySQL library, intended for native PHP usage instead of bridging it with the regular interface to libmysql. This brings a neat speed increase and overall goodness.

All hail MYSQLND! I’ll try to give the preview version a try over the weekend. You can read even more over at The PDO/MYSQLND Annoucement at lists.mysql.com or you can have a look at the installation procedure.