Auto-pick up latest checkpoint in disagg follower mode for wt tool

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    • Type: Sub-task
    • Resolution: Unresolved
    • Priority: Major - P3
    • None
    • Affects Version/s: None
    • Component/s: Tools
    • Security Level: Public (Available to anyone on the web)
    • Storage Engines - Persistence
    • 518.782
    • SE Persistence backlog
    • None

      Context

      In src/conn/conn_layered.c (~lines 1527-1553), at connection startup WiredTiger calls __wti_layered_get_disagg_checkpoint (which invokes page_log->pl_get_complete_checkpoint_ext)
      only when role="leader" and no disaggregated.checkpoint_meta is supplied. Followers without an explicit checkpoint_meta register system table handles but never load a checkpoint,
      so plh_get is never driven and wt list / wt dump see nothing from the page server.

      Motivation

      • We want to open the wt tool as a follower so that it behaves as a read-only conneciton. Opening as a leader leaves the possibility of unwanted writes.
      • Finding the checkpoint metadata through the CMS or otherwise can be fiddly.

      Examples

      Follower repro (no checkpoint pickup, no page reads):

        SLS_PALI_CONFIG='log_id=1,page=(single=http://localhost:20047),kek=(static_base64=xxx=)' \
        wt -h /tmp/wt_pali_follower \                                                                                                                                                                   
           -C 'create,extensions=[.../libwiredtiger_snappy.so,.../libext_pali.so],disaggregated=(page_log="pali",role="follower"),precise_checkpoint=true' \
           list                                                                                                                                                                                         
        

      Switching only role to "leader" on the same config successfully picked up the checkpoint and listed the shared tables.

            Assignee:
            Dylan Liang
            Reporter:
            Sean Watt
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              Created:
              Updated: