1. A system comprising: one or more processors; memory; a parser module stored in the memory and executable by the one or more processors to process a document into a document tree that includes at least two nodes corresponding to user-generated content; and a record extraction module stored in the memory and executable by the one or more processors to: apply a domain-constraint-guided similarity measure to locate, using at least one domain constraint and an upward path matching procedure, two or more anchor trees in the document tree, the two or more anchor trees being a first set of sibling sub-trees, wherein each sibling sub-tree in the first set of sibling sub-trees includes a similar tag path, the domain-constraint-guided similarity measure based in part on a tag path hash map of a format structure of the document; determine a record boundary of a second set of sibling sub-trees in the document tree around each of the two or more anchor trees; and extract at least one data record around each of the two or more anchor trees based at least in part on the record boundary.