An example of code qhich allows you to reindex:
$indexer = Mage::getSingleton('index/indexer');
$process = $indexer->getProcessByCode('catalog_product_price');
$process->reindexEverything();
The following are indexer codes which you can use instead of the catalog_product_price
index above:
catalog_product_attribute Product Attributes
catalog_product_price Product Prices
catalog_url Catalog URL Rewrites
catalog_product_flat Product Flat Data
catalog_category_flat Category Flat Data
catalog_category_product Category Products
catalogsearch_fulltext Catalog Search Index
cataloginventory_stock Stock Status
tag_summary Tag Aggregation Data
Posted by Mike Whitby to Magento (2012-08-16 14:34)