On Tue, 20 Jan 2026 at 11:00, vignesh C <[email protected]> wrote: > > On Tue, 20 Jan 2026 at 09:47, Amit Kapila <[email protected]> wrote: > > > > On Mon, Jan 19, 2026 at 6:36 PM vignesh C <[email protected]> wrote: > > > > > > pg_get_sequence_data() internally uses try_relation_open() rather than > > > relation_open(). As a result, if the target sequence no longer exists > > > at the time of access, the function does not raise an error and > > > instead returns NULLs for the sequence state columns. The sequence > > > sync worker code previously assumed these columns to be non NULL and > > > asserted accordingly. This assumption does not hold in the presence of > > > concurrent DDL. The patch updates the sequence sync logic to > > > explicitly check for NULL values returned from pg_get_sequence_data(). > > > If any of the required sequence state fields are NULL, the sequence > > > sync worker skips processing that sequence to identify and report the > > > missing sequences. The attached patch has the changes for the same. > > > > > > > - seqinfo_local->last_value = DatumGetInt64(slot_getattr(slot, ++col, > > &isnull)); > > - Assert(!isnull); > > + /* > > + * If the sequence was dropped concurrently, pg_get_sequence_data() can > > + * return NULLs. > > + */ > > + datum = slot_getattr(slot, ++col, &isnull); > > + if (isnull) > > + return COPYSEQ_SKIPPED; > > + seqinfo_local->last_value = DatumGetInt64(datum); > > > > - seqinfo_local->is_called = DatumGetBool(slot_getattr(slot, ++col, > > &isnull)); > > - Assert(!isnull); > > + datum = slot_getattr(slot, ++col, &isnull); > > + if (isnull) > > + return COPYSEQ_SKIPPED; > > + seqinfo_local->is_called = DatumGetBool(datum); > > > > Is there a case where the first one (last_value) is non-null but later > > can be null? If not, then I think it is better to retain assert for > > other cases. > > That is not possible. Updated accordingly with slight change to > comment. The attached patch has the changes for the same.
During further testing, I identified an issue where the code could not reliably distinguish whether a sequence was dropped on the subscriber or on the publisher. A sequence dropped on the subscriber should be treated as a successful case, since the only viable action is to skip it, whereas a missing sequence on the publisher should be treated as an error. This distinction has now been handled correctly and fixed in the updated version. Regards, Vignesh
v3-0001-Fix-concurrent-sequence-drops-during-sequence-syn.patch
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