Re: Difference between HeapTupleData and TupleTableSlot structures - Mailing list pgsql-hackers

From Aleksander Alekseev
Subject Re: Difference between HeapTupleData and TupleTableSlot structures
Date
Msg-id CAJ7c6TMkQSziBeMR7=3iJNzeL6TpFkywt7E3Oj5qRbKirpQwKA@mail.gmail.com
Whole thread Raw
In response to Re: Difference between HeapTupleData and TupleTableSlot structures  (Tom Lane <tgl@sss.pgh.pa.us>)
List 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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