cdb is a fast, reliable, lightweight package for creating and reading constant databases. Its database structure provides several features: * Fast lookups: A successful lookup in a large database normally takes just two disk accesses. An unsuccessful lookup takes only one. * Low overhead: A database uses 2048 bytes (or 4096 bytes for cdb64), plus 24 bytes per record (or 48 bytes per record for cdb64), plus the space for keys and data. * No random limits: cdb can handle any database up to 4 gigabytes (or up to an exabyte for cdb64). There are no other restrictions. Records are streamed and don't have to fit into memory. Databases are stored in a machine-independent format (one format for cdb, one format for cdb64). * Fast atomic database replacement: `cdbmake` rewrites an entire database much more quickly than other hashing packages. Database replacement is safe against system crashes. Readers don't pause during a rewrite: they continue transparently using the old database until the new database is in place. * Fast database dumps: `cdbdump` prints the contents of a database in cdbmake-compatible format.
