Re: Fix logical decoding not track transaction during SNAPBUILD_BUILDING_SNAPSHOT

> Looks like the assert in ReorderBufferForget failed because
> ninvalidations is not 0.

I think it can be fixed by this:

```
@@ -282,18 +286,24 @@ xact_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
{
TransactionId xid;
xl_xact_invals *invals;
+ bool has_snapshot;

xid = XLogRecGetXid(r);
invals = (xl_xact_invals *) XLogRecGetData(r);
+ has_snapshot =
+ SnapBuildCurrentState(builder) >= SNAPBUILD_FULL_SNAPSHOT;

/*
* Execute the invalidations for xid-less transactions,
* otherwise, accumulate them so that they can be processed at
* the commit time.
+ *
+ * Note that we only need to do this when we are not fast-forwarding
+ * and there is a snapshot.
*/
if (TransactionIdIsValid(xid))
{
- if (!ctx->fast_forward)
+ if (!ctx->fast_forward && has_snapshot)
ReorderBufferAddInvalidations(reorder, xid,
buf->origptr,
invals->nmsgs,
@@ -301,7 +311,7 @@ xact_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
ReorderBufferXidSetCatalogChanges(ctx->reorder, xid,
buf->origptr);
}
- else if (!ctx->fast_forward)
+ else if (!ctx->fast_forward && has_snapshot)
ReorderBufferImmediateInvalidation(ctx->reorder,
invals->nmsgs,
invals->msgs);
```

--
Regards,
ChangAo Chen