Re: path toward faster partition pruning

Hello,

On Wed, Oct 25, 2017 at 1:07 PM, Amit Langote
<Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> On 2017/10/25 15:47, Amit Langote wrote:
>> On 2017/10/24 1:38, Beena Emerson wrote:
>>> I had noticed this and also that this crash:
>>>
>>> tprt PARTITION BY RANGE(Col1)
>>> tprt_1 FOR VALUES FROM (1) TO (50001) PARTITION BY RANGE(Col1)
>>> tprt_11 FOR VALUES FROM (1) TO (10000),
>>> tprt_1d DEFAULT
>>> tprt_2 FOR VALUES FROM (50001) TO (100001)
>>>
>>> EXPLAIN (COSTS OFF) SELECT * FROM tprt WHERE col1 BETWEEN 20000 AND 70000;
>>> server closed the connection unexpectedly
>>> This probably means the server terminated abnormally
>>> before or while processing the request.
>>> The connection to the server was lost. Attempting reset: Failed.
>>> !>
>>
>> ...and this (crash) were due to bugs in the 0005 patch.
>
> [ .... ]
>
>> Should be fixed in the attached updated version.
>
> Oops, not quite. The crash that Beena reported wasn't fixed (or rather
> reintroduced by some unrelated change after once confirming it was fixed).
>
> Really fixed this time.

Some minor comments:

1. wrong function name (0003)

The comment on function get_partitions_from_clauses_guts uses wrong name:
instead of "_from_", "_using_" is written.

/*
+ * get_partitions_using_clauses_guts
+ * Determine relation's partitions that satisfy *all* of the clauses
+ * in the list (return value describes the set of such partitions)
+ *

2. typo information (0003)

+/*
+ * classify_partition_bounding_keys
+ * Classify partition clauses into equal, min, max keys, along with any
+ * Nullness constraints and return that informatin in the output argument

3. misspell admissible (0003)
+ * columns, whereas a prefix of all partition key columns is addmissible
+ * as min and max keys.

4. double and? (0002)
+ * as part of the operator family, check if its negator
+ * exists and and that the latter is compatible with

5. typo inequality (0002)
+ * (key < val OR key > val), if the partitioning method
+ * supports such notion of inequlity.

6. typo output (0005)
+ * return it as the only scannable partition, that means the query
+ * doesn't want null values in its outout.

7. typo provide (0005)
+ /* Valid keys->eqkeys must provoide all partition keys. */
+ Assert(keys->n_eqkeys == 0 || keys->n_eqkeys == partkey->partnatts);

8. comment of struct PartClause (0003)
+/*
+ * Information about a clause matched with a partition key column kept to
+ * avoid repeated recomputation in remove_redundant_clauses().
+ */

Instead of repeated recomputation, we can use just " repeated
computation" or just " recomputation"

--

Beena Emerson

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