TAILIEUCHUNG - Graceful Database Schema Evolution: the PRISM Workbench

The seed and full alignments, accompanied by annotation and cross-references to other family and structure databases and to the literature and the HMMs, are what make up Pfam-A. Each family has a permanent accession number and can thus be referenced from other databases. For release , we strived to include every family with more than 50 members in Pfam-A. All sequence domains not in Pfam-A were then clustered and aligned automati- cally by the Domainer program into Pfam-B. To- gether, Pfam-A and Pfam-B provide a complete clus- tering of all protein sequences. The quality of the Pfam-B alignments is generally not sufficient to construct useful HMMs. The main purposes of Pfam-B are instead to. | Graceful Database Schema Evolution the PRISM Workbench Carlo A. Curino Hyun J. Moon Carlo Zaniolo Politecnico di Milano UCLA UCLA hjmoon@ zaniolo@ ABSTRACT Supporting graceful schema evolution represents an unsolved problem for traditional information systems that is further exacerbated in web information systems such as Wikipedia and public scientific databases in these projects based on multiparty cooperation the frequency of database schema changes has increased while tolerance for downtimes has nearly disappeared. As of today schema evolution remains an error-prone and time-consuming undertaking because the DB Administrator DBA lacks the methods and tools needed to manage and automate this endeavor by i predicting and evaluating the effects of the proposed schema changes ii rewriting queries and applications to operate on the new schema and iii migrating the database. Our PRISM system takes a big first step toward addressing this pressing need by providing i a language of Schema Modification Operators to express concisely complex schema changes ii tools that allow the DBA to evaluate the effects of such changes iii optimized translation of old queries to work on the new schema version iv automatic data migration and v full documentation of intervened changes as needed to support data provenance database flash back and historical queries. PRISM solves these problems by integrating recent theoretical advances on mapping composition and invertibility into a design that also achieves usability and scalability. Wikipedia and its 170 schema versions provided an invaluable testbed for validating PRISM tools and their ability to support legacy queries. 1. INTRODUCTION The incessant pressure of schema evolution is impacting every database from the world s largest1 World Data Centre for Climate featuring over 6 petabytes of data to the smallest single-website DB. DBMSs have long addressed 1Source http .

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