Special Issue: Selection of Best Papers of the VLDB Data Management in Grids Workshop (VLDB DMG 2007)

Grid computing has greatly matured since the last decade. It exists now at a widely distributed scale. After 10 years of internationally combined efforts to develop from a vision to existing middlewares, we now face a large number of applications being deployed and taking benefit from the Grids. The need to handle data properly came with the applications, managing data at different semantic levels, from raw data coming from sensors in particle physics to rich data in Healthgrids. Most of the time, data management was ad hoc: The need to handle these data has been mainly seen as a constraint, and little effort has been put in their smart management in the early stages of the grid evolution. Data were present in raw files, or in databases, maybe distributed databases, but with little concerns from the application developer who focused on the core development of the process of the data. In the close past, the Grid community has been developing specialized services to handle data in a simpler and more smart way: Pieces of middlewares have been developed, for instance, to access several data sources with a common programming interface, giving the developer also the possibility of adding treatment on the data retrieved, anonymizing it, caching it, or replicating it. Works on data caching, replication, data integration, and security, to name but a few, have been seen. Efforts have been put to access and process the data, not in planning optimization or distributed balanced queries, which are core distributed database services. The database community has been investigating for a long time the issues related to the distribution of the data sources, data queries, query plan optimization in parallel systems, etc. Among the challenges rising in grid environments, we can cite, among others: dynamicity, reliability, security, data availability and transport, data indexing, search and access, autonomics, etc. These are existing distributed database challenges revisited with respect to the grid paradigm. This special issue of ‘Concurrency and Computation: Practice and Experience’ includes a selection of revised papers presented at the VLDB Data Management in Grids workshop, Vienna, Austria, held on 23rd September 2007. The 2007 edition of the workshop was the third in a raw, after the success of the 1st edition in Trondheim in 2005 and the second in Seoul in 2006. The idea of the workshop collocated with one of the most important conferences in databases (VLDB: Very Large Data Bases) is to bring together the experts from the database and grid communities, discuss, and argue the above-stated