Re: TRAP: FailedAssertion("HaveRegisteredOrActiveSnapshot()", File: "toast_internals.c", Line: 670, PID: 19403)

At Mon, 28 Mar 2022 18:36:46 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in 
> Inserting EnsurePortalSnapshotExists() to RunFromStore fixes this but
> I'm not sure where is the right place to do this..

Then, I found that portal->holdSnapshot is that.  I came up with the
attached.  It does the follows:

1. Teach PlannedStmtRequiresSnapshot() to return true for FetchStmt.

2. Use holdSnapshot in RunFromStore if any.


The rerpducer is reduced to as small as the following.

CREATE TABLE t (a text);
INSERT INTO t VALUES('some random text');
BEGIN;
DECLARE c CURSOR FOR SELECT * FROM t;
FETCH ALL IN c;

But I haven't come up with a reasonable way to generate the 'some
random text' yet.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center