Horton

Re: Pluggable Storage - Andres's take

Andres Freund <andres@anarazel.de>

View thread View on postgr.es
From: Andres Freund <andres@anarazel.de>
To: Haribabu Kommi <kommi.haribabu@gmail.com>
Cc: Asim R P <apraveen@pivotal.io>, Pg Hackers <pgsql-hackers@postgresql.org>, aagrawal@pivotal.io, Dmitry Dolgov <9erthalion6@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Alexander Korotkov <a.korotkov@postgrespro.ru>
Date: 2018-12-11T02:13:40Z
Lists: pgsql-hackers 
Hi,

On 2018-11-26 17:55:57 -0800, Andres Freund wrote:
> FWIW, now that oids are removed, and the tuple table slot abstraction
> got in, I'm working on rebasing the pluggable storage patchset ontop of
> that.

I've pushed a version to that to the git tree, including a rebased
version of zheap:
https://github.com/anarazel/postgres-pluggable-storage
https://github.com/anarazel/postgres-pluggable-zheap

I'm still working on moving some of the out-of-access/zheap
modifications into pluggable storage (see e.g. the first commit of the
pluggable-zheap series). But this should allow others to start on a more
recent codebasis.

My next steps are:
- make relation creation properly pluggable
- remove the typedefs from tableam.h, instead move them into the
  TableAmRoutine struct.
- Move rs_{nblocks, startblock, numblocks} out of TableScanDescData
- Move HeapScanDesc and IndexFetchHeapData out of relscan.h
- See if the slot in SysScanDescData can be avoided, it's not exactly
  free of overhead.
- remove ExecSlotCompare(), it's entirely unrelated to these changes imo
  (and in the wrong place)
- rename HeapUpdateFailureData et al to not reference Heap
- split pluggable storage patchset, to commit earlier:
  - EvalPlanQual slotification
  - trigger slotification
  - split of IndexBuildHeapScan out of index.c

I'm wondering whether we should add
table_beginscan/table_getnextslot/index_getnext_slot using the old API
in an earlier commit that then could be committed separately, allowing
the tablecmd.c changes to be committed soon.

I'm wondering whether we should change the table_beginscan* API so it
provides a slot - pretty much every caller has to do so, and it seems
just as easy to create/dispose via table_beginscan/endscan.

Further tasks I'm not yet planning to tackle, that I'd welcome help on:
- pg_dump support
- pg_upgrade testing
- I think we should consider removing HeapTuple->t_tableOid, it should
  imo live entirely in the slot

Greetings,

Andres Freund

Commits

  1. Add default_table_access_method to postgresql.conf.sample.

  2. tableam: Avoid relying on relation size to determine validity of tids.

  3. tableam: Don't assume that every AM uses md.c style storage.

  4. Allow pg_class xid & multixid horizons to not be set.

  5. Fix slot type issue for fuzzy distance index scan over out-of-core table AM.

  6. tableam: comment and formatting fixes.

  7. table: docs: fix typos and grammar.

  8. tableam: basic documentation.

  9. Only allow heap in a number of contrib modules.

  10. tableam: Add table_finish_bulk_insert().

  11. tableam: sample scan.

  12. tableam: bitmap table scan.

  13. tableam: Move heap specific logic from estimate_rel_size below tableam.

  14. tableam: VACUUM and ANALYZE support.

  15. tableam: relation creation, VACUUM FULL/CLUSTER, SET TABLESPACE.

  16. tableam: Support for an index build's initial table scan(s).

  17. tableam: Add table_get_latest_tid, to wrap heap_get_latest_tid.

  18. tableam: Add helper for indexes to check if a corresponding table tuples exist.

  19. tableam: Add and use table_fetch_row_version().

  20. tableam: Use in CREATE TABLE AS and CREATE MATERIALIZED VIEW.

  21. Ensure sufficient alignment for ParallelTableScanDescData in BTShared.

  22. Don't reuse slots between root and partition in ON CONFLICT ... UPDATE.

  23. Use a virtual rather than a heap slot in two places where that suffices.

  24. Store tuples for EvalPlanQual in slots, rather than as HeapTuples.

  25. Use slots in trigger infrastructure, except for the actual invocation.

  26. Store table oid and tuple's tid in tuple slots directly.

  27. Allow to use HeapTupleData embedded in [Buffer]HeapTupleTableSlot.

  28. Add ExecStorePinnedBufferHeapTuple.

  29. Add ArchiveOpts to pass options to ArchiveEntry

  30. Rename RelationData.rd_amroutine to rd_indam.

  31. Rephrase references to "time qualification".

  32. Move remaining code from tqual.[ch] to heapam.h / heapam_visibility.c.

  33. Move generic snapshot related code from tqual.h to snapmgr.h.

  34. Remove superfluous tqual.h includes.

  35. Don't duplicate parallel seqscan shmem sizing logic in nbtree.

  36. Move vacuumlazy.c into access/heap.

  37. Support parallel bitmap heap scans.