01_audit.sql

BEGIN;

--
-- Audited data. Lots of information is available, it's just a matter of how much
-- you really want to record. See:
--
--   http://www.postgresql.org/docs/9.1/static/functions-info.html
--
-- Remember, every column you add takes up more audit table space and slows audit
-- inserts.
--
-- Every index you add has a big impact too, so avoid adding indexes to the
-- audit table unless you REALLY need them. The hstore GIST indexes are
-- particularly expensive.
--
-- It is sometimes worth copying the audit table, or a coarse subset of it that
-- you're interested in, into a temporary table where you CREATE any useful
-- indexes and do your analysis.
--
DROP TABLE IF EXISTS qgep_sys.logged_actions;

CREATE TABLE qgep_sys.logged_actions (
    event_id bigserial PRIMARY KEY,
    schema_name text NOT NULL,
    table_name text NOT NULL,
    relid oid NOT NULL,
    session_user_name text,
    action_tstamp_tx TIMESTAMP WITH TIME ZONE NOT NULL,
    action_tstamp_stm TIMESTAMP WITH TIME ZONE NOT NULL,
    action_tstamp_clk TIMESTAMP WITH TIME ZONE NOT NULL,
    transaction_id bigint,
    application_name text,
    client_addr inet,
    client_port integer,
    client_query text NOT NULL,
    action TEXT NOT NULL CHECK (action IN ('I','D','U', 'T')),
    row_data hstore,
    changed_fields hstore,
    statement_only BOOLEAN NOT NULL
);

REVOKE ALL ON qgep_sys.logged_actions FROM public;

COMMENT ON TABLE qgep_sys.logged_actions IS 'History of auditable actions on audited tables, from qgep_sys.if_modified_func()';
COMMENT ON COLUMN qgep_sys.logged_actions.event_id IS 'Unique identifier for each auditable event';
COMMENT ON COLUMN qgep_sys.logged_actions.schema_name IS 'Database schema audited table for this event is in';
COMMENT ON COLUMN qgep_sys.logged_actions.table_name IS 'Non-schema-qualified table name of table event occured in';
COMMENT ON COLUMN qgep_sys.logged_actions.relid IS 'Table OID. Changes with drop/create. Get with ''tablename''::regclass';
COMMENT ON COLUMN qgep_sys.logged_actions.session_user_name IS 'Login / session user whose statement caused the audited event';
COMMENT ON COLUMN qgep_sys.logged_actions.action_tstamp_tx IS 'Transaction start timestamp for tx in which audited event occurred';
COMMENT ON COLUMN qgep_sys.logged_actions.action_tstamp_stm IS 'Statement start timestamp for tx in which audited event occurred';
COMMENT ON COLUMN qgep_sys.logged_actions.action_tstamp_clk IS 'Wall clock time at which audited event''s trigger call occurred';
COMMENT ON COLUMN qgep_sys.logged_actions.transaction_id IS 'Identifier of transaction that made the change. May wrap, but unique paired with action_tstamp_tx.';
COMMENT ON COLUMN qgep_sys.logged_actions.client_addr IS 'IP address of client that issued query. Null for unix domain socket.';
COMMENT ON COLUMN qgep_sys.logged_actions.client_port IS 'Remote peer IP port address of client that issued query. Undefined for unix socket.';
COMMENT ON COLUMN qgep_sys.logged_actions.client_query IS 'Top-level query that caused this auditable event. May be more than one statement.';
COMMENT ON COLUMN qgep_sys.logged_actions.application_name IS 'Application name set when this audit event occurred. Can be changed in-session by client.';
COMMENT ON COLUMN qgep_sys.logged_actions.action IS 'Action type; I = insert, D = delete, U = update, T = truncate';
COMMENT ON COLUMN qgep_sys.logged_actions.row_data IS 'Record value. Null for statement-level trigger. For INSERT this is the new tuple. For DELETE and UPDATE it is the old tuple.';
COMMENT ON COLUMN qgep_sys.logged_actions.changed_fields IS 'New values of fields changed by UPDATE. Null except for row-level UPDATE events.';
COMMENT ON COLUMN qgep_sys.logged_actions.statement_only IS '''t'' if audit event is from an FOR EACH STATEMENT trigger, ''f'' for FOR EACH ROW';

CREATE INDEX logged_actions_relid_idx ON qgep_sys.logged_actions(relid);
CREATE INDEX logged_actions_action_tstamp_tx_stm_idx ON qgep_sys.logged_actions(action_tstamp_stm);
CREATE INDEX logged_actions_action_idx ON qgep_sys.logged_actions(action);

CREATE TABLE qgep_sys.logged_relations (
    relation_name text not null,
    uid_column text not null,
    PRIMARY KEY (relation_name, uid_column)
);

COMMENT ON TABLE qgep_sys.logged_relations IS 'Table used to store unique identifier columns for table or views, so that events can be replayed';
COMMENT ON COLUMN qgep_sys.logged_relations.relation_name IS 'Relation (table or view) name (with schema if needed)';
COMMENT ON COLUMN qgep_sys.logged_relations.uid_column IS 'Name of a column that is used to uniquely identify a row in the relation';

CREATE OR REPLACE FUNCTION qgep_sys.if_modified_func() RETURNS TRIGGER AS $body$
DECLARE
    audit_row qgep_sys.logged_actions;
    include_values BOOLEAN;
    log_diffs BOOLEAN;
    h_old hstore;
    h_new hstore;
    excluded_cols text[] = ARRAY[]::text[];
BEGIN

    IF NOT (TG_WHEN IN ('AFTER' , 'INSTEAD OF')) THEN
        RAISE EXCEPTION 'qgep_sys.if_modified_func() may only run as an AFTER trigger';
    END IF;

    audit_row = ROW(
        NEXTVAL('qgep_sys.logged_actions_event_id_seq'), -- event_id
        TG_TABLE_SCHEMA::text,                        -- schema_name
        TG_TABLE_NAME::text,                          -- table_name
        TG_RELID,                                     -- relation OID for much quicker searches
        session_user::text,                           -- session_user_name
        current_timestamp,                            -- action_tstamp_tx
        statement_timestamp(),                        -- action_tstamp_stm
        clock_timestamp(),                            -- action_tstamp_clk
        txid_current(),                               -- transaction ID
        (SELECT setting FROM pg_settings WHERE name = 'application_name'),
        inet_client_addr(),                           -- client_addr
        inet_client_port(),                           -- client_port
        current_query(),                              -- top-level query or queries (if multistatement) from client
        substring(TG_OP,1,1),                         -- action
        NULL, NULL,                                   -- row_data, changed_fields
        'f'                                           -- statement_only
        );

    IF NOT TG_ARGV[0]::BOOLEAN IS DISTINCT FROM 'f'::BOOLEAN THEN
        audit_row.client_query = NULL;

    END IF;

    IF TG_ARGV[1] IS NOT NULL THEN
        excluded_cols = TG_ARGV[1]::text[];
    END IF;

    IF (TG_OP = 'UPDATE' AND TG_LEVEL = 'ROW') THEN
        h_old = hstore(OLD.*) - excluded_cols;
        audit_row.row_data = h_old;
        h_new = hstore(NEW.*)- excluded_cols;
        audit_row.changed_fields =  h_new - h_old;

        IF audit_row.changed_fields = hstore('') THEN
            -- All changed fields are ignored. Skip this update.
            RAISE WARNING '[qgep_sys.if_modified_func] - Trigger detected NULL hstore. ending';
            RETURN NULL;
        END IF;
  INSERT INTO qgep_sys.logged_actions VALUES (audit_row.*);
  RETURN NEW;

    ELSIF (TG_OP = 'DELETE' AND TG_LEVEL = 'ROW') THEN
        audit_row.row_data = hstore(OLD.*) - excluded_cols;
  INSERT INTO qgep_sys.logged_actions VALUES (audit_row.*);
        RETURN OLD;

    ELSIF (TG_OP = 'INSERT' AND TG_LEVEL = 'ROW') THEN
        audit_row.row_data = hstore(NEW.*) - excluded_cols;
  INSERT INTO qgep_sys.logged_actions VALUES (audit_row.*);
        RETURN NEW;

    ELSIF (TG_LEVEL = 'STATEMENT' AND TG_OP IN ('INSERT','UPDATE','DELETE','TRUNCATE')) THEN
        audit_row.statement_only = 't';
        INSERT INTO qgep_sys.logged_actions VALUES (audit_row.*);
  RETURN NULL;

    ELSE
        RAISE EXCEPTION USING MESSAGE = '[qgep_sys.if_modified_func] - Trigger func added as trigger for unhandled case: '||TG_OP||', '||TG_LEVEL;
        RETURN NEW;
    END IF;


END;
$body$
LANGUAGE plpgsql
SECURITY DEFINER
SET search_path = pg_catalog, public;


COMMENT ON FUNCTION qgep_sys.if_modified_func() IS $body$
Track changes TO a TABLE at the statement AND/OR row level.

Optional parameters TO TRIGGER IN CREATE TRIGGER call:

param 0: BOOLEAN, whether TO log the query text. default 't'.

param 1: text[], COLUMNS TO IGNORE IN updates. default [].

         Updates TO ignored cols are omitted FROM changed_fields.

         Updates WITH only ignored cols changed are NOT inserted
         INTO the audit log.

         Almost ALL the processing work IS still done for updates
         that ignored. If you need to save the load, you need to use
         WHEN clause on the trigger instead.

         No warning or error is issued if ignored_cols contains columns
         that do not exist in the target table. This lets you specify
         a standard set of ignored columns.

There is no parameter to disable logging of values. Add this trigger as
a 'FOR EACH STATEMENT' rather than 'FOR EACH ROW' trigger if you do not
want to log row values.

Note that the user name logged is the login role for the session. The audit trigger
cannot obtain the active role because it is reset by the SECURITY DEFINER invocation
of the audit trigger its self.
$body$;



CREATE OR REPLACE FUNCTION qgep_sys.audit_table(target_table regclass, audit_rows BOOLEAN, audit_query_text BOOLEAN, ignored_cols text[]) RETURNS void AS $body$
DECLARE
  stm_targets text = 'INSERT OR UPDATE OR DELETE OR TRUNCATE';
  _q_txt text;
  _ignored_cols_snip text = '';
BEGIN
    EXECUTE 'DROP TRIGGER IF EXISTS audit_trigger_row ON ' || target_table::text;
    EXECUTE 'DROP TRIGGER IF EXISTS audit_trigger_stm ON ' || target_table::text;

    IF audit_rows THEN
        IF array_length(ignored_cols,1) > 0 THEN
            _ignored_cols_snip = ', ' || quote_literal(ignored_cols);
        END IF;
        _q_txt = 'CREATE TRIGGER audit_trigger_row AFTER INSERT OR UPDATE OR DELETE ON ' ||
                 target_table::text ||
                 ' FOR EACH ROW EXECUTE PROCEDURE qgep_sys.if_modified_func(' ||
                 quote_literal(audit_query_text) || _ignored_cols_snip || ');';
        RAISE NOTICE '%',_q_txt;
        EXECUTE _q_txt;
        stm_targets = 'TRUNCATE';
    ELSE
    END IF;

    _q_txt = 'CREATE TRIGGER audit_trigger_stm AFTER ' || stm_targets || ' ON ' ||
             target_table ||
             ' FOR EACH STATEMENT EXECUTE PROCEDURE qgep_sys.if_modified_func('||
             quote_literal(audit_query_text) || ');';
    RAISE NOTICE '%',_q_txt;
    EXECUTE _q_txt;

    -- store primary key names
    insert into qgep_sys.logged_relations (relation_name, uid_column)
         select target_table, a.attname
           from pg_index i
           join pg_attribute a on a.attrelid = i.indrelid
                              and a.attnum = any(i.indkey)
          where i.indrelid = target_table::regclass
            and i.indisprimary
          on conflict do nothing;
END;
$body$
LANGUAGE plpgsql;

COMMENT ON FUNCTION qgep_sys.audit_table(regclass, BOOLEAN, BOOLEAN, text[]) IS $body$
ADD auditing support TO a TABLE.

Arguments:
   target_table:     TABLE name, schema qualified IF NOT ON search_path
   audit_rows:       Record each row CHANGE, OR only audit at a statement level
   audit_query_text: Record the text of the client query that triggered the audit event?
   ignored_cols:     COLUMNS TO exclude FROM UPDATE diffs, IGNORE updates that CHANGE only ignored cols.
$body$;

-- Pg doesn't allow variadic calls with 0 params, so provide a wrapper
CREATE OR REPLACE FUNCTION qgep_sys.audit_table(target_table regclass, audit_rows BOOLEAN, audit_query_text BOOLEAN) RETURNS void AS $body$
SELECT qgep_sys.audit_table($1, $2, $3, ARRAY[]::text[]);
$body$ LANGUAGE SQL;

-- And provide a convenience call wrapper for the simplest case
-- of row-level logging with no excluded cols and query logging enabled.
--
CREATE OR REPLACE FUNCTION qgep_sys.audit_table(target_table regclass) RETURNS void AS $body$
SELECT qgep_sys.audit_table($1, BOOLEAN 't', BOOLEAN 't');
$body$ LANGUAGE 'sql';

COMMENT ON FUNCTION qgep_sys.audit_table(regclass) IS $body$
Add auditing support to the given table. Row-level changes will be logged with full client query text. No cols are ignored.
$body$;

CREATE OR REPLACE FUNCTION qgep_sys.unaudit_table(target_table regclass) RETURNS void AS $body$
BEGIN
    EXECUTE 'DROP TRIGGER IF EXISTS audit_trigger_row ON ' || target_table::text;
    EXECUTE 'DROP TRIGGER IF EXISTS audit_trigger_stm ON ' || target_table::text;
END;
$body$
LANGUAGE plpgsql;


CREATE OR REPLACE FUNCTION qgep_sys.replay_event(pevent_id int) RETURNS void AS $body$
DECLARE
  query text;
BEGIN
    with
    event as (
        select * from qgep_sys.logged_actions where event_id = pevent_id
    )
    -- get primary key names
    , where_pks as (
        select array_to_string(array_agg(uid_column || '=' || quote_literal(row_data->uid_column)), ' AND ') as where_clause
          from qgep_sys.logged_relations r
          join event on relation_name = (schema_name || '.' || table_name)
    )
    select into query
        case
            when action = 'I' then
                'INSERT INTO ' || schema_name || '.' || table_name ||
                ' ('||(select string_agg(key, ',') from each(row_data))||') VALUES ' ||
                '('||(select string_agg(case when value is null then 'null' else quote_literal(value) end, ',') from each(row_data))||')'
            when action = 'D' then
                'DELETE FROM ' || schema_name || '.' || table_name ||
                ' WHERE ' || where_clause
            when action = 'U' then
                'UPDATE ' || schema_name || '.' || table_name ||
                ' SET ' || (select string_agg(key || '=' || case when value is null then 'null' else quote_literal(value) end, ',') from each(changed_fields)) ||
                ' WHERE ' || where_clause
        end
    from
        event, where_pks
    ;

    execute query;
END;
$body$
LANGUAGE plpgsql;

COMMENT ON FUNCTION qgep_sys.replay_event(int) IS $body$
Replay a logged event.

Arguments:
   pevent_id:  The event_id of the event in qgep_sys.logged_actions to replay
$body$;

CREATE OR REPLACE FUNCTION qgep_sys.audit_view(target_view regclass, audit_query_text BOOLEAN, ignored_cols text[], uid_cols text[]) RETURNS void AS $body$
DECLARE
  stm_targets text = 'INSERT OR UPDATE OR DELETE';
  _q_txt text;
  _ignored_cols_snip text = '';

BEGIN
    EXECUTE 'DROP TRIGGER IF EXISTS audit_trigger_row ON ' || target_view::text;
    EXECUTE 'DROP TRIGGER IF EXISTS audit_trigger_stm ON ' || target_view::text;

	IF array_length(ignored_cols,1) > 0 THEN
	    _ignored_cols_snip = ', ' || quote_literal(ignored_cols);
	END IF;
	_q_txt = 'CREATE TRIGGER audit_trigger_row INSTEAD OF INSERT OR UPDATE OR DELETE ON ' ||
		 target_view::TEXT ||
		 ' FOR EACH ROW EXECUTE PROCEDURE qgep_sys.if_modified_func(' ||
		 quote_literal(audit_query_text) || _ignored_cols_snip || ');';
	RAISE NOTICE '%',_q_txt;
	EXECUTE _q_txt;

    -- store uid columns if not already present
  IF (select count(*) from qgep_sys.logged_relations where relation_name = (select target_view)::text AND  uid_column= (select unnest(uid_cols))::text) = 0 THEN
      insert into qgep_sys.logged_relations (relation_name, uid_column)
       select target_view, unnest(uid_cols);
  END IF;

END;
$body$
LANGUAGE plpgsql;

COMMENT ON FUNCTION qgep_sys.audit_view(regclass, BOOLEAN, text[], text[]) IS $body$
ADD auditing support TO a VIEW.

Arguments:
   target_view:      TABLE name, schema qualified IF NOT ON search_path
   audit_query_text: Record the text of the client query that triggered the audit event?
   ignored_cols:     COLUMNS TO exclude FROM UPDATE diffs, IGNORE updates that CHANGE only ignored cols.
   uid_cols:         MANDATORY COLUMNS to use to uniquely identify a row from the view (in order to replay UPDATE and DELETE)

Example:
  SELECT qgep_sys.audit_view('qgep_od.vw_element_installation', 'true'::BOOLEAN, '{field_to_ignore}'::text[], '{key_field1, keyfield2}'::text[])
$body$;

CREATE OR REPLACE FUNCTION qgep_sys.unaudit_view(target_view regclass) RETURNS void AS $body$
BEGIN
    EXECUTE 'DROP TRIGGER IF EXISTS audit_trigger_row ON ' || target_view::text;
    EXECUTE 'DROP TRIGGER IF EXISTS audit_trigger_stm ON ' || target_view::text;
END;
$body$
LANGUAGE plpgsql;


COMMIT;