Horton

Re: Pluggable Storage - Andres's take

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Haribabu Kommi <kommi.haribabu@gmail.com>, 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: 2019-03-11T21:29:34Z
Lists: pgsql-hackers 
On 2019-03-11 13:31:26 -0700, Andres Freund wrote:
> On 2019-03-11 12:37:46 -0700, Andres Freund wrote:
> > Hi,
> > 
> > On 2019-03-08 19:13:10 -0800, Andres Freund wrote:
> > > Changes:
> > > - I've added comments to all the callbacks in the first commit / the
> > >   scan commit
> > > - I've renamed table_gimmegimmeslot to table_slot_create
> > > - I've made the callbacks and their wrappers more consistently named
> > > - I've added asserts for necessary callbacks in scan commit
> > > - Lots of smaller cleanup
> > > - Added a commit message
> > > 
> > > While 0001 is pretty bulky, the interesting bits concentrate on a
> > > comparatively small area. I'd appreciate if somebody could give the
> > > comments added in tableam.h a read (both on callbacks, and their
> > > wrappers, as they have different audiences). It'd make sense to first
> > > read the commit message, to understand the goal (and I'd obviously also
> > > appreciate suggestions for improvements there as well).
> > > 
> > > I'm pretty happy with the current state of the scan patch. I plan to do
> > > two more passes through it (formatting, comment polishing, etc. I don't
> > > know of any functional changes needed), and then commit it, lest
> > > somebody objects.
> > 
> > Here's a further polished version. Pretty boring changes:
> > - newlines
> > - put tableam.h into the correct place
> > - a few comment improvements, including typos
> > - changed reorderqueue_push() to accept the slot. That avoids an
> >   unnecessary heap_copytuple() in some cases
> > 
> > No meaningful changes in later patches.
> 
> I pushed this.  There's a failure on 32bit machines, unfortunately. The
> problem comes from the ParallelTableScanDescData embedded in BTShared -
> after the change the compiler can't see that that actually needs more
> alignment, because ParallelTableScanDescData doesn't have any 8byte
> members. That's a problem for just about all such "struct inheritance"
> type tricks postgres, but we normally just allocate them separately,
> guaranteeing maxalign. Given that we here already allocate enough space
> after the BTShared struct, it's probably easiest to just not embed the
> struct anymore.

I've pushed an attempt to fix this, which locally fixes 32bit
builds. It's copying the alignment logic for shm_toc_allocate, namely
using BUFFERALIGN for alignment.  We should probably invent a more
appropriate define for this at some point...

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.