PostgreSQL logical decoder output plugin - unchanged toast data - Mailing list pgsql-hackers

From Georgy Buranov
Subject PostgreSQL logical decoder output plugin - unchanged toast data
Date
Msg-id CAGMDm37Dips9FhK0EARAQLdo8ov=0f4cfH-QSN1a64qSfXkn5A@mail.gmail.com
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Responses Re: PostgreSQL logical decoder output plugin - unchanged toast data
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Hi. I have a question about PostgreSQL logical decoder output plugin.

I am not specialist in Postgres at all, so maybe I miss some very
basic point. In the plugin, I want to always get all the values (even
those that are unchanged  toast data)


When I try to get the datum that is internal on disk (here is code)

```
        struct varlena *s = (struct varlena *)DatumGetPointer(origval);
        struct varlena * ret = heap_tuple_untoast_attr(s);
        Datum result = PointerGetDatum(PG_DETOAST_DATUM(ret));
```
it fails with no known snapshots error (from heap_tuple_untoast_attr).
My question is why is it that.

So, even theoretically it is not possible to the the varlena on disk
from logical replication plugin?



Mit freundlichen Grüßen,
Georgy Buranov


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