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.
(Butthis 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
haveto 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
partitionis 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.
Canwe somehow share validateCheckConstraint with this function?
 

- In the same function, skipping RELKIND_PARTITIONED_TABLE is okay, but silently ignoring RELKIND_FOREIGN_TABLE doesn't
seemgood. 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
constraintresults 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
somethingwould 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
tosee a comment if it is correct.
 


regards,

-- 
Kyotaro Horiguchi
NTT Open Source Software Center