SGJP / Kuznia

CREATE TABLE history
(
 id serial PRIMARY KEY, -- The primary key for this table, though no primary key constraint was created (for the sake of performance and conservation). This column and timestamp_ column are the only two columns about this table itself. All other columns are about the inserted/modified/deleted record in some other table.
 table_name_ character varying(120) NOT NULL, -- Name of table whose row is being affected (inserted, deleted, or modified).
 column_name_ character varying(120) NOT NULL, -- Name of the column in some other table whose row value is being modified. This column's value is empty string if the operation was DELETE.
 timestamp_ timestamp with time zone NOT NULL DEFAULT clock_timestamp(), -- The moment this record was created. Using the clock_timestamp() function as a default, to capture the actual moment in time rather than moment when transaction began.
 --db_user_name_ character varying(120) NOT NULL DEFAULT "current_user"(), -- The name of the Postgres user logged in to this database connection/session.
 --app_name_ character varying(120) NOT NULL DEFAULT current_setting('application_name'::text), -- The name of the application connected to the database. May also include the version number of app, and the name of the human user authenticated within the app.
 user_id_ integer NOT NULL DEFAULT current_setting('var.user_id'::text)::integer,
 old_value_ text NOT NULL DEFAULT ''::text,
 new_value_ text NOT NULL DEFAULT ''::text,
 lexeme_id_ integer NULL,
 pattern_id_ integer NULL,
 id_ integer NOT NULL, -- The UUID of the row being affected, the row being inserted, updated, or deleted. Assumes every table whose history is being recorded uses the 'uuid' data type as its primary key.
 operation_ character varying(120) NOT NULL, -- What database operation resulted in this trigger running: INSERT, UPDATE, DELETE, or TRUNCATE.
 table_oid_ oid NOT NULL, -- The oid of the table whose record is being modified. May be helpful if a table name changes over time.
 ordinal_position_of_column_ integer NOT NULL, -- The position of the affected column in its table. Every new column gets a number, incremented by one for each. This may be helpful when analyzing changes across a stretch of time during which a column's name was changed. Apparently columns have no oid, so we are recording this number instead.
 transaction_began_ timestamp with time zone NOT NULL DEFAULT transaction_timestamp() -- The time when the current transaction began. Can act like a transaction identifier, to group multiple "history_" rows of the same transaction together. This is not foolproof, as multiple transaction could possibly start in the same split second moment. Assuming the computer's clock has a fine resolution, this chance of a coincidence should be quite miniscule.
);

CREATE INDEX "history_user_id__idx"
 ON "history" ("user_id_");
CREATE INDEX "history_lexeme_id__idx"
 ON "history" ("lexeme_id_");
CREATE INDEX "history_pattern_id__idx"
 ON "history" ("pattern_id_");