From: | Aleksander Alekseev <aleksander(at)timescale(dot)com> |
---|---|
To: | pgsql-hackers(at)lists(dot)postgresql(dot)org |
Cc: | Ajay P S <ajayps547(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Subject: | Re: Difference between HeapTupleData and TupleTableSlot structures |
Date: | 2022-10-23 10:04:43 |
Message-ID: | CAJ7c6TMkQSziBeMR7=3iJNzeL6TpFkywt7E3Oj5qRbKirpQwKA@mail.gmail.com |
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Lists: | pgsql-hackers |
Hi hackers,
> TupleTableSlot is a more abstract concept, being a container
> for a tuple that can be present in several different forms.
> It can contain a concrete tuple (HeapTupleData), or a "virtual"
> tuple that is just an array of Datum+isnull values. The executor
> usually uses tuple slots to return tuples out of plan nodes;
> they're not very common elsewhere.
I came across another little piece of information about
TupleTableSlots [1] and recalled this thread:
"""
To implement an access method, an implementer will typically need to
implement an AM-specific type of tuple table slot (see
src/include/executor/tuptable.h), which allows code outside the access
method to hold references to tuples of the AM, and to access the
columns of the tuple.
"""
Hopefully this is helpful.
[1] https://www.postgresql.org/docs/current/tableam.html
--
Best regards,
Aleksander Alekseev
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