Drivers Overview

Implemented

Name	DB impact	Operations	Configurable primary key	Custom Conditions	Partial Fields	Graceful Shutdown/Restart
trigger	high ⚠️	All	not implemented	✅	✅	✅
wal_logical	low ⚡	All	not implemented	✅	✅	partial ⚠️ cannot restart if crash without client.Close()

NOT IMPLEMENTED

GLOBAL UPDATE/DELETE/INSERT TRIGGER + TRUNCATE TRIGGER FOR EACH ROW (Seems legit)

Bootstrapping

• Generation of a unique name:

  • If TRUNCATE: Unique reference + truncate -> e.g., flash_posts_truncate
  • Otherwise, Unique reference + other -> e.g., flash_posts_other

• Creation:

  • If TRUNCATE -> CREATE TRIGGER ON ... BEFORE TRUNCATE FOR EACH STATEMENT ...
  • Otherwise:
    • If a global trigger already exists -> ignore
    • If no global trigger is registered, create it -> CREATE TRIGGER ON ... BEFORE UPDATE, DELETE, INSERT FOR EACH STATEMENT ...
      • Iterate over old_table and new_table -> for each entry call pg_notify passing TG_OP

Event Reception

In this case, we will receive unlistened events.

We need to check if the received event is in the list of listened events.

• If yes, send it to the callback
• If not, ignore it

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GLOBAL UPDATE/DELETE/INSERT TRIGGER + TRUNCATE TRIGGER [FOR EACH STATEMENT] (Seems Legit)

Bootstrapping

• Like Approach 2 but instead of calling pg_notify for each row, generate a JSON array and send the complete payload only once

Event Reception

• Like Approach 2 but if we receive the payload, decode it and iterate over each entry to send an event for each entry

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PG EXTENSION - (FURTHER THOUGHT REQUIRED)

Bootstrapping

• CREATION:
  • Call custom function to listen
• DELETION:
  • Call custom function to stop listening

Event Reception

• Retrieve the emitted event
  • Forward it to the callback

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GATEWAY (Rejected)

Bootstrapping

• Open a TCP port
• Intercept SQL queries

Event Reception

• Parse the SQL query
• Detect the altered rows
  • If listening: forward it to the callback
  • Otherwise: ignore it

Rejection Reason

For UPDATE FROM (SELECT id from posts) queries, it is impossible to track the rows without making database queries.