Methods and systems for serving documents are provided. Documents may be served to users, for example, in response to search query inputs. Documents may be individually received for serving to users. In order to serve documents, documents are typically indexed. To serve documents in a real-time environment, a data structure is configured to index documents that are received while simultaneously being queried for documents to serve to a user. Documents that have not yet completed the indexing process are not available for serving and, thus, are not queried. Additionally, the data structure includes a memory optimizer such that indexing does not waste memory of the data structure.