Postgres trigger

[ea-rus]

Description

Added subscribe method to postgres handler.
How it works:

• Creates trigger for table in postgres database
• Postgres trigger creates event
  • if columns are defined - it checks they are not null (for insert) or changed (for update)
• Mindsdb listen to event and executes query for every event.

Limitations:

• Because it creates real trigger, write access to database is required

Example

create trigger tr_pg 
on my_pg.home_rentals    -- < table to track
columns rental_price, location -- < columns to track, optional
(      
  insert into my_pg.rentals_predicted (
    SELECT   t.rental_price as real_price,   m.rental_price as predicted_price
    FROM TABLE_DELTA as t
    JOIN home_rentals_model as m
  )
)

Demo
https://www.loom.com/share/8b27d9c467e6471e89ab22121daa7b85

Fixes #issue_number

Type of change

• ⚡ New feature (non-breaking change which adds functionality)

Verification Process

To ensure the changes are working as expected:

• Test Location: Specify the URL or path for testing.
• Verification Steps: Outline the steps or queries needed to validate the change. Include any data, configurations, or actions required to reproduce or see the new functionality.

Additional Media:

• I have attached a brief loom video or screenshots showcasing the new functionality or change.

Checklist:

• My code follows the style guidelines(PEP 8) of MindsDB.
• I have appropriately commented on my code, especially in complex areas.
• Necessary documentation updates are either made or tracked in issues.
• Relevant unit and integration tests are updated or added.

[StpMax]

Why not to use psycopg?

[ea-rus]

changed to psycopg

[StpMax]

is it required? will it clear current notifies list?

[ea-rus]

this was updated after switching to psycopg

[StpMax]

in this case processing order if LIFO. Do we need FIFO? If so, then need to add 0 to .pop(0)

[ea-rus]

this was updated after switching to psycopg

[StpMax]

Is it required to add handler in each iteration?

[StpMax]

spam db with query each 0.5s looks badly. Let put here comment with reminder to rewrite it to generator when psycopg 3.2.2 will be released (they added timeout arg there)