On Fri, 23 Jun 2017 15:57:54 +0900
Yugo Nagata <nag...@sraoss.co.jp> wrote:
> Hi,
>
> When we create a range partitioned table, we cannot use
> a column more than once in the partition key.
>
> postgres=# create table t (i int) partition by range(i,i);
> ERROR: column "i" appears more than once in partition key
>
> However, I can use same expression more than once in partition key.
>
> postgres=# create table t (i int) partition by range((i),(i));
> CREATE TABLE
>
> Although this can be blocked by the attached parch, for example,
> the following is still possible.
I forgot to attach it.
>
> postgres=# create table t (i int) partition by range((i),i);
> CREATE TABLE
>
> Can these definition be a problem in the internal of partitioning?
> If not, we might not need to check column that apears more than once
> in the partition key.
>
> Regards,
>
>
>
> --
> Yugo Nagata <nag...@sraoss.co.jp>
--
Yugo Nagata <nag...@sraoss.co.jp>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 7d9c769..dc4540b 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -13171,6 +13171,19 @@ transformPartitionSpec(Relation rel, PartitionSpec *partspec, char *strategy)
PartitionElem *pelem = castNode(PartitionElem, lfirst(l));
ListCell *lc;
+ if (pelem->expr)
+ {
+ /* Copy, to avoid scribbling on the input */
+ pelem = copyObject(pelem);
+
+ /* Now do parse transformation of the expression */
+ pelem->expr = transformExpr(pstate, pelem->expr,
+ EXPR_KIND_PARTITION_EXPRESSION);
+
+ /* we have to fix its collations too */
+ assign_expr_collations(pstate, pelem->expr);
+ }
+
/* Check for PARTITION BY ... (foo, foo) */
foreach(lc, newspec->partParams)
{
@@ -13183,19 +13196,11 @@ transformPartitionSpec(Relation rel, PartitionSpec *partspec, char *strategy)
errmsg("column \"%s\" appears more than once in partition key",
pelem->name),
parser_errposition(pstate, pelem->location)));
- }
-
- if (pelem->expr)
- {
- /* Copy, to avoid scribbling on the input */
- pelem = copyObject(pelem);
-
- /* Now do parse transformation of the expression */
- pelem->expr = transformExpr(pstate, pelem->expr,
- EXPR_KIND_PARTITION_EXPRESSION);
-
- /* we have to fix its collations too */
- assign_expr_collations(pstate, pelem->expr);
+ else if (pelem->expr && pparam->expr && equal(pelem->expr, pparam->expr))
+ ereport(ERROR,
+ (errcode(ERRCODE_DUPLICATE_COLUMN),
+ errmsg("same expression appears more than once in partition key"),
+ parser_errposition(pstate, pelem->location)));
}
newspec->partParams = lappend(newspec->partParams, pelem);
--
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