sql: retry errors report the wrong key if the table was created in the same txn

[knz]

Found while investigating #14264
The txn there does begin; create database; create table; insert; commit and fails with:

pq: restart transaction: retry txn "sql txn" id=67fdee7f key=/Table/0/0 ...

(note the bogus /Table/0/0 key in the msg)

Whereas if the create database; create table; are performed before begin (prior to the start of the txn) the same retry error is reported as:

pq: restart transaction: retry txn "sql txn" id=0181dd9a key=/Table/51/1/229294915573186561/0 ...

(i.e. with a valid key)

The question is 1) where is the bogus key name coming from 2) is that a problem?

cc @vivekmenezes @dt @danhhz

[dianasaur323]

@knz, assigning to you now for reassignment. We should figure out if this will be a problem, and if not, punt the investigation for 1.1. Currently setting as 1.0 for now though so that it doesn't fall through the cracks.

[knz]

@andreimatei do you know who is best placed to look at this?

[andreimatei]

I think any of us are as good as any other... I've removed the milestone; it doesn't worry me too much :).

[vivekmenezes]

assigning to myself because I'm making major changes in this area.

[bdarnell]

1. where is the bogus key name coming from

Here, which is called from various points in the sql layer related to schema changes. Since #16701, this key is printed as /Table/SystemConfigSpan/Start instead of /Table/0/0.

2. is that a problem?

I don't think so. @andreimatei and @vivekmenezes is there anything you want to do here or can we close this issue?

[andreimatei]

Yeah, txns that perform schema changes are anchored in the "system config span" so that they trigger gossip.
No problems here AFAICS.