How to extract bytes from a bit/bit(n) Datum pointer?

On Thu, Jan 19, 2017 at 5:53 PM, valeriof <valerio_farruggio@hotmail.com> wrote:

Hi,

This may come from my lack of experience with Postgres, but I'm trying to
extract the byte portion of a Datum that is of type VarBit - bit/bit(n). I
see that the Datum pointer contains the value content of the bytes (after a
few bytes for the header) but I would need to point to the actual value
(plus also the number of bytes to be picked up).

I currently have a similar issue with BYTEAOID columns. I have a Datum
pointer but can't get the actual content.

If you have not looked at DatumGetVarBitP() and DatumGetByteaP(), that
will get you corresponding structure pointers from a Datum. Then check
src/backend/utils/adt/varbit.c and bytea_* functions from
src/backend/utils/adt/varlena.c to understand how those structures are
used.

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

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Thank you Ashutosh! I've been looking everywhere for this info

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