Re: BUG #14279: Logical decoding misses a transaction completely

>>>>> "marko" == marko  <marko@joh.to> writes:

 marko> The problem seems to be that ReorderBufferCommitChild()
 marko> overwrites the main transaction's base_snapshot with a NULL
 marko> because it thinks the subtransaction's base_snapshot_lsn=0 is
 marko> older than the main transaction's actual snapshot

i.e. here in ReorderBufferCommitChild:

    /*
     * Pass the our base snapshot to the parent transaction if it doesn't have
     * one, or ours is older. That can happen if there are no changes in the
     * toplevel transaction but in one of the child transactions. This allows
     * the parent to simply use it's base snapshot initially.
     */
    if (txn->base_snapshot == NULL ||
        txn->base_snapshot_lsn > subtxn->base_snapshot_lsn)
    {

it's possible for subtxn to exist, but for subtxn->base_snapshot to be
NULL and base_snapshot_lsn to be 0, and obviously propagating this to
txn is wrong.

--
Andrew (irc:RhodiumToad)