Horton

Re: unsupportable composite type partition keys

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Amit Langote <amitlangote09@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-12-23T21:33:55Z
Lists: pgsql-hackers

Attachments

I wrote:
> One thing I see is that you chose to relocate RelationGetPartitionDesc's
> declaration to partdesc.h, whereupon RelationBuildPartitionDesc doesn't
> have to be exported at all anymore.  Perhaps that's a better factorization
> than what I did.  It supposes that any caller of RelationGetPartitionDesc
> is going to need partdesc.h, but that seems reasonable.  We could likewise
> move RelationGetPartitionKey to partcache.h.

I concluded that that is indeed a better solution; it does allow removing
some rel.h inclusions (though possibly those were just duplicative?), and
it also means that relcache.c itself doesn't need any partitioning
inclusions at all.

Here's a cleaned-up patch that does it like that and also fixes the
memory leakage issue.

I noticed along the way that with partkeys only being loaded on demand,
we no longer need the incredibly-unsafe hack in RelationBuildPartitionKey
whereby it just silently ignores failure to read the pg_partitioned_table
entry.  I also rearranged RelationBuildPartitionDesc so that it uses the
same context-reparenting trick as RelationBuildPartitionKey.  That doesn't
save us anything, but it makes the code considerably more robust, I think;
we don't need to assume as much about what partition_bounds_copy does.

One other thing worth noting is that I used unlikely() to try to
discourage the compiler from inlining RelationBuildPartitionDesc
into RelationGetPartitionDesc (and likewise for the Key functions).
Not sure how effective that is, but it can't hurt.

I haven't removed equalPartitionDescs here; that seems like material
for a separate patch (to make it easier to put it back if we need it).

			regards, tom lane

Commits

  1. Fix CheckAttributeType's handling of collations for ranges.

  2. Improve comments in utils/rel.h.

  3. Allow whole-row Vars to be used in partitioning expressions.

  4. Remove equalPartitionDescs().

  5. Load relcache entries' partitioning data on-demand, not immediately.

  6. Disallow partition key expressions that return pseudo-types.

  7. Prevent a rowtype from being included in itself via a range.