It seemed interesting that the same idea is "to implement business logic in the database ".
came to mind not only to me alone.
I also wanted to keep for the future, for myself, first of all, the interesting developments that arose during the implementation. Especially considering the fact that relatively recently a strategic decision was made to change the architecture and transfer business logic to the backend level. So that everything that has been developed will soon be needed by no one and no one will be interested. know how , everything is classic and was implemented repeatedly (for example, I applied a similar approach 20 years ago on Oracle). I just decided to collect everything in one place. Suddenly someone will come in handy. Practice has shown that quite often the same idea comes independently to different people. And it’s useful to leave it for yourself.
The described methods are not some kind of discovery and exceptional
Of course, nothing in this world is perfect, mistakes and typos are unfortunately possible. Criticism and remarks are highly welcomed and expected. And one more small detail - specific implementation details are omitted. All the same, everything is still used in a really working project. So, the article is like an etude and a description of the general concept, nothing more. Hopefully there are enough details to understand the big picture.
The general idea is "divide and conquer, hide and own"
The idea is classic - a separate schema for tables, a separate schema for stored functions.
The client does not have direct access to the data. All the client can do is call the stored function and process the response.
Roles
CREATE ROLE store;
CREATE ROLE sys_functions;
CREATE ROLE loc_audit_functions;
CREATE ROLE service_functions;
CREATE ROLE business_functions;
Schemes
Table storage schema
Target tables that implement entities.
CREATE SCHEMA store AUTHORIZATION store ;
Scheme of system functions
System functions, in particular for logging table changes.
CREATE SCHEMA sys_functions AUTHORIZATION sys_functions ;
Local Audit Scheme
Functions and tables to implement local auditing of stored functions and target table changes.
CREATE SCHEMA loc_audit_functions AUTHORIZATION loc_audit_functions;
Service function diagram
Functions for service and DML functions.
CREATE SCHEMA service_functions AUTHORIZATION service_functions;
Business function diagram
Functions for final business functions called by the client.
CREATE SCHEMA business_functions AUTHORIZATION business_functions;
Access rights
Role - DBA has full access to all schemas (separate from the DB Owner role).
CREATE ROLE dba_role;
GRANT store TO dba_role;
GRANT sys_functions TO dba_role;
GRANT loc_audit_functions TO dba_role;
GRANT service_functions TO dba_role;
GRANT business_functions TO dba_role;
Role - USER has the EXECUTE privilege on the business_functions schema .
CREATE ROLE user_role;
Privileges between schemas
GRANT
SECURITY DEFINER REVOKE EXECUTE ON ALL FUNCTION… FROM public;
REVOKE EXECUTE ON ALL FUNCTION IN SCHEMA sys_functions FROM public ;
REVOKE EXECUTE ON ALL FUNCTION IN SCHEMA loc_audit_functions FROM public ;
REVOKE EXECUTE ON ALL FUNCTION IN SCHEMA service_functions FROM public ;
REVOKE EXECUTE ON ALL FUNCTION IN SCHEMA business_functions FROM public ;
GRANT USAGE ON SCHEMA sys_functions TO dba_role ;
GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA sys_functions TO dba_role ;
GRANT USAGE ON SCHEMA loc_audit_functions TO dba_role ;
GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA loc_audit_functions TO dba_role ;
GRANT USAGE ON SCHEMA service_functions TO dba_role ;
GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA service_functions TO dba_role ;
GRANT USAGE ON SCHEMA business_functions TO dba_role ;
GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA business_functions TO dba_role ;
GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA business_functions TO user_role ;
GRANT ALL PRIVILEGES ON SCHEMA store TO GROUP business_functions ;
GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA store TO business_functions ;
GRANT USAGE ON ALL SEQUENCES IN SCHEMA store TO business_functions ;
So the database schema is ready. You can start filling with data.
Target tables
Creating tables is trivial. Nothing special, except that it was decided not to use SERIAL and generate sequences explicitly. Plus, of course, the maximum use of instructions
COMMENT ON ...Comments for all objects, no exceptions.
Local audit
To log the execution of stored functions and change the target tables, a local audit table is used, which includes, among other things, the details of the client connection, the label of the called module, the actual values of the input and output parameters in the form of JSON.
System functions
Designed for logging changes in target tables. These are trigger functions.
Template - system function
---------------------------------------------------------
-- INSERT
CREATE OR REPLACE FUNCTION sys_functions.table_insert_log ()
RETURNS TRIGGER AS $$
BEGIN
PERFORM loc_audit_functions.make_log( ' '||'table' , 'insert' , json_build_object('id', NEW.id) );
RETURN NULL ;
END
$$ LANGUAGE plpgsql SECURITY DEFINER;
CREATE TRIGGER table_after_insert AFTER INSERT ON storage.table FOR EACH ROW EXECUTE PROCEDURE sys_functions.table_insert_log();
---------------------------------------------------------
-- UPDATE
CREATE OR REPLACE FUNCTION sys_functions.table_update_log ()
RETURNS TRIGGER AS $$
BEGIN
IF OLD.column != NEW.column
THEN
PERFORM loc_audit_functions.make_log( ' '||'table' , 'update' , json_build_object('OLD.column', OLD.column , 'NEW.column' , NEW.column ) );
END IF ;
RETURN NULL ;
END
$$ LANGUAGE plpgsql SECURITY DEFINER;
CREATE TRIGGER table_after_update AFTER UPDATE ON storage.table FOR EACH ROW EXECUTE PROCEDURE sys_functions.table_update_log ();
---------------------------------------------------------
-- DELETE
CREATE OR REPLACE FUNCTION sys_functions.table_delete_log ()
RETURNS TRIGGER AS $$
BEGIN
PERFORM loc_audit_functions.make_log( ' '||'table' , 'delete' , json_build_object('id', OLD.id ) );
RETURN NULL ;
END
$$ LANGUAGE plpgsql SECURITY DEFINER;
CREATE TRIGGER table_after_delete AFTER DELETE ON storage.table FOR EACH ROW EXECUTE PROCEDURE sys_functions.table_delete_log ();Service functions
Designed to implement service and DML operations on target tables.
Template - service function
--INSERT
--RETURN id OF NEW ROW
CREATE OR REPLACE FUNCTION service_functions.table_insert ( new_column store.table.column%TYPE )
RETURNS integer AS $$
DECLARE
new_id integer ;
BEGIN
-- Generate new id
new_id = nextval('store.table.seq');
-- Insert into table
INSERT INTO store.table
(
id ,
column
)
VALUES
(
new_id ,
new_column
);
RETURN new_id ;
END
$$ LANGUAGE plpgsql SECURITY DEFINER;
--DELETE
--RETURN ROW NUMBERS DELETED
CREATE OR REPLACE FUNCTION service_functions.table_delete ( current_id integer )
RETURNS integer AS $$
DECLARE
rows_count integer ;
BEGIN
DELETE FROM store.table WHERE id = current_id;
GET DIAGNOSTICS rows_count = ROW_COUNT;
RETURN rows_count ;
END
$$ LANGUAGE plpgsql SECURITY DEFINER;
-- UPDATE DETAILS
-- RETURN ROW NUMBERS UPDATED
CREATE OR REPLACE FUNCTION service_functions.table_update_column
(
current_id integer
,new_column store.table.column%TYPE
)
RETURNS integer AS $$
DECLARE
rows_count integer ;
BEGIN
UPDATE store.table
SET
column = new_column
WHERE id = current_id;
GET DIAGNOSTICS rows_count = ROW_COUNT;
RETURN rows_count ;
END
$$ LANGUAGE plpgsql SECURITY DEFINER;Business functions
Designed for end business functions called by the client. They always return JSON . To intercept and log execution errors, the EXCEPTION block is used .
Template - business function
CREATE OR REPLACE FUNCTION business_functions.business_function_template(
--Input parameters
)
RETURNS JSON AS $$
DECLARE
------------------------
--for exception catching
error_message text ;
error_json json ;
result json ;
------------------------
BEGIN
--LOGGING
PERFORM loc_audit_functions.make_log
(
'business_function_template',
'STARTED',
json_build_object
(
--IN Parameters
)
);
PERFORM business_functions.notice('business_function_template');
--START BUSINESS PART
--END BUSINESS PART
-- SUCCESFULLY RESULT
PERFORM business_functions.notice('result');
PERFORM business_functions.notice(result);
PERFORM loc_audit_functions.make_log
(
'business_function_template',
'FINISHED',
json_build_object( 'result',result )
);
RETURN result ;
----------------------------------------------------------------------------------------------------------
-- EXCEPTION CATCHING
EXCEPTION
WHEN OTHERS THEN
PERFORM loc_audit_functions.make_log
(
'business_function_template',
'STARTED',
json_build_object
(
--IN Parameters
) , TRUE );
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR',
json_build_object('SQLSTATE',SQLSTATE ), TRUE
);
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR',
json_build_object('SQLERRM',SQLERRM ), TRUE
);
GET STACKED DIAGNOSTICS error_message = RETURNED_SQLSTATE ;
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR-RETURNED_SQLSTATE',json_build_object('RETURNED_SQLSTATE',error_message ), TRUE );
GET STACKED DIAGNOSTICS error_message = COLUMN_NAME ;
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR-COLUMN_NAME',
json_build_object('COLUMN_NAME',error_message ), TRUE );
GET STACKED DIAGNOSTICS error_message = CONSTRAINT_NAME ;
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR-CONSTRAINT_NAME',
json_build_object('CONSTRAINT_NAME',error_message ), TRUE );
GET STACKED DIAGNOSTICS error_message = PG_DATATYPE_NAME ;
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR-PG_DATATYPE_NAME',
json_build_object('PG_DATATYPE_NAME',error_message ), TRUE );
GET STACKED DIAGNOSTICS error_message = MESSAGE_TEXT ;
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR-MESSAGE_TEXT',json_build_object('MESSAGE_TEXT',error_message ), TRUE );
GET STACKED DIAGNOSTICS error_message = SCHEMA_NAME ;
PERFORM loc_audit_functions.make_log
(s
'business_function_template',
' ERROR-SCHEMA_NAME',json_build_object('SCHEMA_NAME',error_message ), TRUE );
GET STACKED DIAGNOSTICS error_message = PG_EXCEPTION_DETAIL ;
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR-PG_EXCEPTION_DETAIL',
json_build_object('PG_EXCEPTION_DETAIL',error_message ), TRUE );
GET STACKED DIAGNOSTICS error_message = PG_EXCEPTION_HINT ;
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR-PG_EXCEPTION_HINT',json_build_object('PG_EXCEPTION_HINT',error_message ), TRUE );
GET STACKED DIAGNOSTICS error_message = PG_EXCEPTION_CONTEXT ;
PERFORM loc_audit_functions.make_log
(
'business_function_template',
' ERROR-PG_EXCEPTION_CONTEXT',json_build_object('PG_EXCEPTION_CONTEXT',error_message ), TRUE );
RAISE WARNING 'ALARM: %' , SQLERRM ;
SELECT json_build_object
(
'isError' , TRUE ,
'errorMsg' , SQLERRM
) INTO error_json ;
RETURN error_json ;
END
$$ LANGUAGE plpgsql SECURITY DEFINER;Outcome
To describe the overall picture, I think it is enough. If anyone is interested in the details and results, write comments, I will gladly add additional touches to the picture.
PS
Simple error logging - input parameter type
-[ RECORD 1 ]-
date_trunc | 2020-08-19 13:15:46
id | 1072
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | STARTED
jsonb_pretty | {
| "dko": {
| "id": 4,
| "type": "Type1",
| "title": "CREATED BY addKD",
| "Weight": 10,
| "Tr": "300",
| "reduction": 10,
| "isTrud": "TRUE",
| "description": "decription",
| "lowerTr": "100",
| "measurement": "measurement1",
| "methodology": "m1",
| "passportUrl": "files",
| "upperTr": "200",
| "weightingFactor": 100.123,
| "actualTrValue": null,
| "upperTrCalcNumber": "120"
| },
| "CardId": 3
| }
-[ RECORD 2 ]-
date_trunc | 2020-08-19 13:15:46
id | 1073
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR
jsonb_pretty | {
| "SQLSTATE": "22P02"
| }
-[ RECORD 3 ]-
date_trunc | 2020-08-19 13:15:46
id | 1074
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR
jsonb_pretty | {
| "SQLERRM": "invalid input syntax for type numeric: \"null\""
| }
-[ RECORD 4 ]-
date_trunc | 2020-08-19 13:15:46
id | 1075
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-RETURNED_SQLSTATE
jsonb_pretty | {
| "RETURNED_SQLSTATE": "22P02"
| }
-[ RECORD 5 ]-
date_trunc | 2020-08-19 13:15:46
id | 1076
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-COLUMN_NAME
jsonb_pretty | {
| "COLUMN_NAME": ""
| }
-[ RECORD 6 ]-
date_trunc | 2020-08-19 13:15:46
id | 1077
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-CONSTRAINT_NAME
jsonb_pretty | {
| "CONSTRAINT_NAME": ""
| }
-[ RECORD 7 ]-
date_trunc | 2020-08-19 13:15:46
id | 1078
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-PG_DATATYPE_NAME
jsonb_pretty | {
| "PG_DATATYPE_NAME": ""
| }
-[ RECORD 8 ]-
date_trunc | 2020-08-19 13:15:46
id | 1079
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-MESSAGE_TEXT
jsonb_pretty | {
| "MESSAGE_TEXT": "invalid input syntax for type numeric: \"null\""
| }
-[ RECORD 9 ]-
date_trunc | 2020-08-19 13:15:46
id | 1080
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-SCHEMA_NAME
jsonb_pretty | {
| "SCHEMA_NAME": ""
| }
-[ RECORD 10 ]-
date_trunc | 2020-08-19 13:15:46
id | 1081
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-PG_EXCEPTION_DETAIL
jsonb_pretty | {
| "PG_EXCEPTION_DETAIL": ""
| }
-[ RECORD 11 ]-
date_trunc | 2020-08-19 13:15:46
id | 1082
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-PG_EXCEPTION_HINT
jsonb_pretty | {
| "PG_EXCEPTION_HINT": ""
| }
-[ RECORD 12 ]-
date_trunc | 2020-08-19 13:15:46
id | 1083
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-PG_EXCEPTION_CONTEXT
jsonb_pretty | {
usename | emp1
log_module | addKD
log_module_hash | 0b4c1529a89af3ddf6af3821dc790e8a
status | ERROR-MESSAGE_TEXT
jsonb_pretty | {
| "MESSAGE_TEXT": "invalid input syntax for type numeric: \"null\""
| }