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Diffstat (limited to 'lib/relation.ml')
| -rw-r--r-- | lib/relation.ml | 189 |
1 files changed, 0 insertions, 189 deletions
diff --git a/lib/relation.ml b/lib/relation.ml deleted file mode 100644 index 863316b..0000000 --- a/lib/relation.ml +++ /dev/null @@ -1,189 +0,0 @@ -(** Relation: a lightweight versioned root describing a named collection of - tuples. Physical storage owns the tuple B+ tree; this object holds only - metadata and a tree pointer. - - Class hierarchy: - - [relation] — base, storable, has membership_criteria/provenance/lineage - - [ephemeral_relation] — adds a generator (query-time computed, not stored) - - [pseudo_relation] — adds a producer (system-defined, not stored) - - [domain] — adds a generator (system or user defined, not necessarily - stored) *) - -module RelationConstraint = struct - type name = string - type t = (name * Constraint.t) list -end - -module Lineage = struct - (** Tracks which relational algebra operations produced the tuples. Lives in - the relation, but refers to the tuple. *) - type t = - | Base of Conventions.Name.t - | Select of t - | Project of Conventions.Name.t list * t - | Join of t * t - | ThetaJoin of t * t - | Sort of t - | Take of t -end - -module Provenance = struct - (** Tracks which base relation each attribute originates from. Lives on the - relation and refers to the `entity group`. *) - type source = {relation: Conventions.Name.t; attribute: string} - - type t = - | Undefined - | Base of Conventions.Name.t - | Sources of source list BatMap.String.t - (** Maps attribute name -> list of sources (multiple after joins) *) - - let base ~relation ~attributes : t = - Sources - (List.fold_left - (fun acc attr -> BatMap.String.add attr [{relation; attribute= attr}] acc) - BatMap.String.empty attributes ) - - let empty : t = Sources BatMap.String.empty - let undefined : t = Undefined -end - -type producer = (string * Conventions.AbstractValue.t) list -> Generator.t -type kind = [`Stored | `Ephemeral | `Pseudo | `Domain] - -class virtual relation = - object (_self) - method virtual kind : kind - method virtual name : Conventions.Name.t - method virtual schema : Schema.t - method virtual hash : Conventions.Hash.t - method virtual constraints : RelationConstraint.t option - method virtual cardinality : Conventions.Cardinality.t - method virtual lineage : Lineage.t - method virtual provenance : Provenance.t - method virtual membership_criteria : Tuple.t -> bool - method virtual timestamp : float - method virtual serialize : unit -> Storable.Relation.t - end - -class stored ~name:(init_name : Conventions.Name.t) ~schema:(init_schema : Schema.t) - ~constraints:(init_constraints : RelationConstraint.t option) - ~cardinality:(init_cardinality : Conventions.Cardinality.t) - ~membership_criteria:(init_membership : Tuple.t -> bool) - ~lineage:(init_lineage : Lineage.t option) ~provenance:(init_provenance : Provenance.t option) = - object - inherit relation - val name = init_name - val schema = init_schema - val tree_pointer : Conventions.Hash.t option = None - val constraints = init_constraints - val cardinality = init_cardinality - val membership_criteria = init_membership - val timestamp = Unix.gettimeofday () - val lineage = Option.value init_lineage ~default:(Lineage.Base init_name) - - val provenance = - Option.value init_provenance - ~default:(Provenance.base ~relation:init_name ~attributes:(Schema.attributes init_schema)) - - method name = name - method kind = `Stored - method hash = Option.value tree_pointer ~default:"" - method schema = schema - method tree_pointer = tree_pointer - method constraints = constraints - method cardinality = cardinality - method membership_criteria = membership_criteria - method timestamp = timestamp - method lineage = lineage - method provenance = provenance - method set_tree_pointer tp = {<tree_pointer = tp; timestamp = Unix.gettimeofday ()>} - method set_cardinality c = {<cardinality = c>} - method set_constraints c = {<constraints = c>} - - method serialize () = - {Storable.Relation.name; schema; tree_pointer= Option.value tree_pointer ~default:""} - end - -class ephemeral ~name:(init_name : Conventions.Name.t) ~schema ~constraints ~cardinality - ~membership_criteria ~lineage ~provenance ~generator:(init_generator : Generator.t) = - object - inherit relation - val name : Conventions.Name.t = init_name - val schema : Schema.t = schema - val generator : Generator.t = init_generator - val constraints = constraints - val cardinality = cardinality - val membership_criteria = membership_criteria - val lineage = Option.value lineage ~default:(Lineage.Base init_name) - val provenance = Option.value provenance ~default:(Provenance.Base init_name) - val timestamp = Unix.gettimeofday () - method name = name - method kind = `Ephemeral - method schema = schema - method generator = generator - method hash = Conventions.Hash.hash_text (name ^ "ephemeral") - method constraints = constraints - method cardinality = cardinality - method membership_criteria = membership_criteria - method lineage = lineage - method provenance = provenance - method timestamp = timestamp - method serialize () = failwith "Ephemeral relations cannot be serialized directly" - end - -class pseudo ~name:(init_name : Conventions.Name.t) ~schema ~constraints ~cardinality - ~membership_criteria ~lineage ~provenance ~producer:(init_producer : producer) = - object - inherit relation - val name = init_name - val schema = schema - val producer = init_producer - val constraints = constraints - val cardinality = cardinality - val membership_criteria = membership_criteria - val lineage = Option.value lineage ~default:(Lineage.Base init_name) - val provenance = provenance - val timestamp = Unix.gettimeofday () - method name = name - method kind = `Pseudo - method schema = schema - method producer = producer - - method as_generator (bindings : (string * Conventions.AbstractValue.t) list) : Generator.t = - producer bindings - - method hash = Conventions.Hash.hash_text (name ^ "pseudo") - method constraints = constraints - method cardinality = cardinality - method membership_criteria = membership_criteria - method lineage = lineage - method provenance = provenance - method timestamp = timestamp - - (* TODO: Remove this from the virtual definition *) - method serialize () = failwith "Pseudo relations are procedural" - end - -let deserialize_stored (_bytes : bytes) : (stored, string) result = - try - let stored = Storable.Relation.of_bytes _bytes in - let membership_criteria = - Constraint.build_membership_criteria ~_name:stored.name ~schema:stored.schema - in - Ok - (new stored - ~name:stored.name ~schema:stored.schema ~constraints:None - ~cardinality:Conventions.Cardinality.ConstrainedFinite ~membership_criteria ~lineage:None - ~provenance:None ) - with Invalid_argument message -> Error message - -class domain ~name ~schema ~constraints ~cardinality ~membership_criteria ~lineage ~provenance - ~generator = - object - inherit - ephemeral - ~name ~schema ~constraints ~cardinality ~membership_criteria ~lineage ~provenance ~generator - - method! kind = `Domain - end |