Re: Add SPLIT PARTITION/MERGE PARTITIONS commands

hi.

+/*
+ * check_two_partitions_bounds_range
+ *
+ * (function for BY RANGE partitioning)
+ *
+ * This is a helper function for check_partitions_for_split() and
+ * calculate_partition_bound_for_merge().
check_partitions_for_split does not exist in v43-0001.

+ /*
+ * Rename the existing partition with a temporary name, leaving it
+ * free for the new partition. We don't need to care about this
+ * in the future because we're going to eventually drop the
+ * existing partition anyway.
+ */
+ RenameRelationInternal(RelationGetRelid(sameNamePartition),
+ tmpRelName, false, false);
the third argument, is_internal should set to true?

+ /* Cycle for CHECK constraints. */
+ for (ccnum = 0; ccnum < constr->num_check; ccnum++)
+ {
+ char *ccname = constr->check[ccnum].ccname;
+ char *ccbin = constr->check[ccnum].ccbin;
+ bool ccenforced = constr->check[ccnum].ccenforced;
+ bool ccnoinherit = constr->check[ccnum].ccnoinherit;

a partitioned table can not have NO INHERIT check constraint,
you may see StoreRelCheck.
we can add an Assert: Assert(!ccnoinherit);

+ /* Reproduce not-null constraints. */
+ if (constr->has_not_null)
+ {
+ List *nnconstraints;
+
+ nnconstraints = RelationGetNotNullConstraints(RelationGetRelid(modelRel),
+ false, true);
as mentioned in above, partitioned table cannot have NO INHERIT constraint,
maybe we should set RelationGetNotNullConstraints last argument to false

/*
* calculate_partition_bound_for_merge
*
* Calculates the bound of merged partition "spec" by using the bounds of
* partitions to be merged.
*
* parent: partitioned table
* partNames: names of partitions to be merged
* partOids: Oids of partitions to be merged
* spec (out): bounds specification of the merged partition
* pstate: pointer to ParseState struct for determine error position
*/
void
calculate_partition_bound_for_merge(Relation parent,
List *partNames,
List *partOids,
PartitionBoundSpec *spec,
ParseState *pstate)

if we are within calculate_partition_bound_for_merge,
then we at least hold AccessShareLock for all the partOids
(see transformPartitionCmdForMerge)
partNames is a list of RangeVar one to one corresponding to partOids,
then we really do not need partNames at all for error messages handling, we can
just use get_rel_name.
so we don't need to pass partNames to calculate_partition_bound_for_merge
The attached patch is a rewrite for
calculate_partition_bound_for_merge and callees.
please let me know whether this improves code readability

in RelationBuildPartitionDesc
we have the following code pattern:
foreach(cell, inhoids)
{
Oid inhrelid = lfirst_oid(cell);
HeapTuple tuple;
PartitionBoundSpec *boundspec = NULL;
/* Try fetching the tuple from the catcache, for speed. */
tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(inhrelid));
if (HeapTupleIsValid(tuple))
{
datum = SysCacheGetAttr(RELOID, tuple,
Anum_pg_class_relpartbound,
&isnull);
if (!isnull)
boundspec = stringToNode(TextDatumGetCString(datum));
ReleaseSysCache(tuple);
}
if (boundspec == NULL)
{
pg_class = table_open(RelationRelationId, AccessShareLock);
ScanKeyInit(&key[0],
Anum_pg_class_oid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(inhrelid));
scan = systable_beginscan(pg_class, ClassOidIndexId, true,
NULL, 1, key);
....
}
I wonder if we should do the same in get_partition_bound_spec?
you may also see comments in RelationBuildPartitionDesc, partdesc.c line 203.