FAQ: PostgreSQL Database Maintenance - Vacuum Full

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This community-built FAQ covers the “Vacuum Full” exercise from the lesson “PostgreSQL Database Maintenance”.

Paths and Courses
This exercise can be found in the following Codecademy content:

(Beta) CS103: Databases

FAQs on the exercise Vacuum Full

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SELECT pg_size_pretty(
    pg_total_relation_size('mock.orders')
) as total_size;
-- 1024kb size

select relname, n_live_tup, n_dead_tup , last_vacuum
from pg_catalog.pg_stat_all_tables
where relname = 'orders';
-- 7500 live, 7500 dead

VACUUM FULL mock.orders;

SELECT pg_size_pretty(
    pg_total_relation_size('mock.orders')
) as total_size;
-- 504kb total size

select relname, n_live_tup, n_dead_tup , last_vacuum
from pg_catalog.pg_stat_all_tables
where relname = 'orders';
-- still returns 7500, 7500..?

So I’m confused at what actually went on in this lesson, since the info clearly states that “VACUUM FULL which rewrites all the data from a table into a “new” location on disk and only copies the required data (excluding dead tuples)”

Yet my copied codeblock demonstrates that the dead tuples are all still present in the example workspace when I rechecked after the VACCUM FULL (and also doesn’t seem to recognise the fact that a vacuum took place)

…what?

If the new VACUUM’ed data is in a new table, how do we get to said new table?

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