Introduction to Temporal Database

Here, we want to introduce some basic idea about Temporal Database, For Example, History, Idea, problem......

  1. Why we need Temporal Database:
    In the last two decades, the relational data model has gained popularity because of its simplity and solid mathematical foundation. However, the relational data model as proposed by Codd [Cod70] does not address the temporal dimension of data. Variation of data over time is treated in the same way as ordinary data. This is not satisfactory for applications that require past persent, and/or future data values--to be dealt with by the database, In real life such applications abound. In fact, most application require temporal data to a certain extent.
  2. The Main Goal of Temporal Database:
  3. What we can do by Temporal Database:
  4. Historical Relational in HRDM
    The HRDM model, presented in [CC87] and building on the work reportde in [Cli82b] (the HDBM model) and [CT85], was one of the early historical database models presented in the literature.HRDM is In order to address these temporal issues, we use the lifespan notion introduced in [CT85] . The lifespan is valid time of a data object, we could use [t1, t2] to repersent it and use mathematic "SET ALGEBRA" to operate them.
    When we want to handle temporal data. we define

    D = {D1,D2,......Dn}
    T = universal time lifespan
    TD = {TD1, TD2, TD3,...TDn}, where for each i , TDi = {fi|fi:T->Di} is the set of all partial function from T into the value domain Di.
    TT = {g|g:T->T} is the set of all partial functions from T into itself.
    U={A1, A2,......,An} be a (universal) set of attributes.

    All attributes in the historical relational data model are defined iver sets of parial temporal function.
    HD = (TD or {TT}) = { TT, TD1, TD2....TDn }
    is the set of all historical domains.

    Therefore, all temporal data could represent a tuple t on scheme R like, t = [v,l], and calculate by some operator.
  5. Different solution about temporal database