Re: Adding REPACK [concurrently]

On 2026-Apr-06, Mihail Nikalayeu wrote:

> repack.c:2725
>
> if (!VARATT_IS_EXTERNAL(varlen))
> continue;
>
> I think it should be VARATT_IS_EXTERNAL_INDIRECT - the same as in pgrepack:244.

Right.

> Also, after
>
> natt_ext--;
>
> I think it worth to add
>
> Assert(natt_ext >= 0);
>
> or Assert(natt_ext == 0); but in another place.
>
> Or exit early with
> for (int i = 0; i < desc->natts && natt_ext > 0; i++)

Hmm, how about something like this?

natt_ext--;
if (natt_ext < 0)
ereport(ERROR,
errcode(ERRCODE_DATA_CORRUPTED),
errmsg("insufficient number of attributes stored separately"));

I'd like to give more details, such as the tuple's identity, but that
seems hard ...

> ----------------------------
> repack.c:2587
>
> table_tuple_insert(rel, slot, GetCurrentCommandId(true),
> HEAP_INSERT_NO_LOGICAL, NULL);
>
> More idiomatic to use TABLE_INSERT_NO_LOGICAL instead.

Ah right.

> ----------------------------
> repack.c:2696
>
> ExecForceStoreHeapTuple(tup, slot, false);
>
> AFAIU there is a memory leak here. Memory allocated above (for tuple)
> is not freed in any way, because shouldFree == false.
> Also, ExecClearTuple (tts_virtual_clear for virtual tuples) requires
> TTS_SHOULDFREE to be set to free anything.

Yeah but I don't want the virtual tuple to be materialized (which would
happen in tts_virtual_materialize if I set shouldFree=true). The memory
should be freed in
ResetPerTupleExprContext(chgcxt->cc_estate);
anyway, right? Maybe deserves a comment.

> -------------------------
> grab ShareUpdateExclusiveLock (jsut like VACUUM
>
> typo in "just"

Right.

> --------------------------
>
> "If the identity index is not set due to replica identity being, PK"
>
> Missing "FULL" after "being"?

Ah yeah, I rewrote this.

> -------------------------
>
> Commit message:
>
> "intial copy" -> "initial copy"
> "backed performing REPACK" -> "backend performing REPACK"

Thanks!

--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
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