Re: [HACKERS] Adding support for Default partition in partitioning

Hello, I'd like to review this but it doesn't fit the master, as
Robert said. Especially the interface of predicate_implied_by is
changed by the suggested commit.

Anyway I have some comment on this patch with fresh eyes.  I
believe the basic design so my comment below are from a rather
micro viewpoint.

At Thu, 15 Jun 2017 16:01:53 +0900, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> wrote in <a1267081-6e9a-e570-f6cf-34ff801bf503@lab.ntt.co.jp>
> Oops, I meant to send one more comment.
>
> On 2017/06/15 15:48, Amit Langote wrote:
> > BTW, I noticed the following in 0002
> +                                      errmsg("there exists a default partition for table \"%s\", cannot
> add a new partition",
>
> This error message style seems novel to me.  I'm not sure about the best
> message text here, but maybe: "cannot add new partition to table \"%s\"
> with default partition"
>
> Note that the comment applies to both DefineRelation and
> ATExecAttachPartition.

- Considering on how canSkipPartConstraintValidation is called, I
  *think* that RelationProvenValid() would be better.  (But this
  would be disappear by rebasing..)

- 0002 changes the interface of get_qual_for_list, but left
  get_qual_for_range alone.  Anyway get_qual_for_range will have
  to do the similar thing soon.

- In check_new_partition_bound, "overlap" and "with" is
  completely correlated with each other. "with > -1" means
  "overlap = true". So overlap is not useless. ("with" would be
  better to be "overlap_with" or somehting if we remove
  "overlap")

- The error message of check_default_allows_bound is below.

  "updated partition constraint for default partition \"%s\"
   would be violated by some row"

  This looks an analog of validateCheckConstraint but as my
  understanding this function is called only when new partition
  is added. This would be difficult to recognize in the
  situation.

  "the default partition contains rows that should be in
   the new partition: \"%s\""

  or something?

- In check_default_allows_bound, the iteration over partitions is
  quite similar to what validateCheckConstraint does. Can we
  somehow share validateCheckConstraint with this function?

- In the same function, skipping RELKIND_PARTITIONED_TABLE is
  okay, but silently ignoring RELKIND_FOREIGN_TABLE doesn't seem
  good. I think at least some warning should be emitted.

  "Skipping foreign tables in the defalut partition. It might
   contain rows that should be in the new partition."  (Needs
   preventing multple warnings in single call, maybe)

- In the same function, the following condition seems somewhat
  strange in comparison to validateCheckConstraint.

> if (partqualstate && ExecCheck(partqualstate, econtext))

  partqualstate won't be null as long as partition_constraint is
  valid. Anyway (I'm believing that) an invalid constraint
  results in error by ExecPrepareExpr. Therefore 'if
  (partqualstate' is useless.

- In gram.y, the nonterminal for list spec clause is still
  "ForValues". It seems somewhat strange. partition_spec or
  something would be better.

- This is not a part of this patch, but in ruleutils.c, the error
  for unknown paritioning strategy is emitted as following.

>   elog(ERROR, "unrecognized partition strategy: %d",
>        (int) strategy);

  The cast is added because the strategy is a char. I suppose
  this is because strategy can be an unprintable. I'd like to see
  a comment if it is correct.


regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center