adsharma

Phase-0 Design Doc — Full MVCC Version Retention for #1184

Field	Value
Issue	LadybugDB/ladybug #1184 — read-only txn loses snapshot on CHECKPOINT
Phase	0 (design only, no code)
Direction	Full MVCC version retention: never delete data that open read transactions need (Postgres oldestXmin / snapshot-horizon approach)
Rejects	PR #1202 wait/fail checkpoint semantics (branch issue-1184, head 7eca5b6b5) — checkpoint liveness is non-negotiable
Worktree	/home/ubuntu/src/ladybug/tmp/worktrees/dev-loops/issue-1184 (read-only this phase)

adsharma

attach 'props.db' as props;
select type, count(type) as cnt, l.value 
from relations r
join props.labels l on r.type=l.property
group by type, l.value
order by cnt desc 
limit 200;

adsharma

┌───────┬───────────┬──────────────────────────────────────────────────┐
│ type  │    cnt    │                      value                       │
├───────┼───────────┼──────────────────────────────────────────────────┤
│ 2860  │ 296522832 │ cites work                                       │
│ 31    │ 117443387 │ instance of                                      │
│ 1433  │ 45655528  │ published in                                     │
│ 50    │ 33099215  │ author                                           │
│ 921   │ 31212176  │ main subject                                     │
│ 407   │ 23502631  │ language of work or name                         │
│ 17    │ 18087948  │ country                                          │

adsharma

BEGIN { LETTERS = "abcdefghijklmnopqrstuvwxyz" }

{
    len = length($0);
    if (len == 5) {
        for (i = 1; i <= len; i++) {
            c = substr($0, i, 1);
            ltr = index(LETTERS, c);

            if (ltr > 0) {