(aka "Historical records")
Temporal tables maintain historical versions of data. Modifying operations (UPDATE, DELETE) on these tables don't cause permanent changes to entries, but create new versions of them. Hence this might be used to:
- log changes (security/auditing)
- undo functionalities
- track interactions (customer support)
Under the hood a history table with the same structure, but without constraints is created.
The normal singular/plural naming scheme in Sequelize is used:
- model name:
modelName + History - table name:
modelName + Histories
npm install sequelize-temporal
var Sequelize = require('sequelize');
var Temporal = require('sequelize-temporal');
Create a sequelize instance and your models, e.g.
var sequelize = new Sequelize('', '', '', {
dialect: 'sqlite',
storage: __dirname + '/.test.sqlite'
});
var User = Temporal(sequelize.define('User'), sequelize);
The output of temporal is its input model, so assigning it's output to your
Model is not necessary, hence it's just the lazy version of:
var User = sequelize.define('User', {.types.}, {.options.}); // Sequelize Docu
Temporal(User, sequelize);
The default syntax for Temporal is:
Temporal(model, sequelizeInstance, options)
whereas the options are listed here (with default value).
{
/**
* Runs the insert within the sequelize hook chain, disable for increased performance without warranties
*/
blocking: true,
/**
* By default sequelize-temporal persist only changes, and saves the previous state in the history table.
* The "full" option saves all transactions into the temporal database (i.e. this includes the latest state.)
* This allows to only query the hostory table to get the full history of an entity.
*/
full: false,
/**
* Whether to skip inserting an History line if the update() call is silent.
*/
skipIfSilent: false,
/**
* This library will sometimes reload() an updated entity because it misses a few attributes. In order to minimize
* the number of extra SQL queries, an heuristic is applied to perform the reload() only if necessary. This mainly
* boils down to "is this attribute <x> missing ?".
* The `reloadIgnoredAttributes` can be used to ignore certain attributes from this check.
*/
reloadIgnoredAttributes: ['deletedAt']
}@See: https://wiki.postgresql.org/wiki/SQL2011Temporal
History table stores historical versions of rows, which are inserted by triggers on every modifying operation executed on current table. It has the same structure and indexes as current table, but it doesn’t have any constraints. History tables are insert only and creator should prevent other users from executing updates or deletes by correct user rights settings. Otherwise the history can be violated.
Triggers for storing old versions of rows to history table are inspired by referential integrity triggers. They are fired for each row before UPDATE and DELETE (within the same transaction)
If you only use Postgres, you might want to have a look at the Temporal Table extension.
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Copyright (c) 2015 BonaVal
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