Proposed Server API

Data Model

API (objId below refers to (table, key)):

• get(objId) -> (val, version) | error
• put(objId, val, version, [[ idxname, key ] ... ]) -> version | error
  • version either specifies the previous version read, to ensure update consistency, or INF to force
  • [ idxname, key ] pairs specify indexes to insert into in the associated table with associated keys
• delete(objId, version) -> version | error
  • Remove the object, but only if version matches the current instance or is INF
• lookup(tblpath, idxname, min, max) -> (val, version, primary_key?)
  • What types for indexes (i.e. are min & max one of string, int, float)?

Note that using versions we can create higher-level synchronization primitives, but do we want cmpxchg or something similar for performance reasons?

Do we want reads/writes to be full-update only? What about appending writes or writes to subranges?

What do we want keys to be?

1. Fixed n-bit length, set by system?
2. hash(crud), user-defined?
3. Variable-length blobs (generalization of above)?

Indexing

API (objId below refers to (table, key)):

• createIndex(table, idxname)
• destroyIndex(table, idxname)
• addIndexEntry(objId, idxname)
• delIndexEntry(objId, idxname)
• findEntries(table, idxname, min, max)

We probably want multiple flavours of indexes (hash tables, trees, etc).

• Hash tables often add a performance advantage at cost of range queries (http://www.sanger.ac.uk/Users/lh3/udb.shtml).
• Is there a reasonable compromise?