From a25665088d812d08bb888e961f208eaebf522050 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 13 Dec 2016 11:29:08 -0500
Subject: [PATCH] Fix bugs in RelationGetPartitionDispatchInfo.
The previous coding was not quite right for cases involving multiple
levels of partitioning.
Amit Langote
---
src/backend/catalog/partition.c | 39 ++++++++++++++++++++++++++++-----
1 file changed, 33 insertions(+), 6 deletions(-)
diff --git a/src/backend/catalog/partition.c b/src/backend/catalog/partition.c
index 63d9b13db4..9980582b77 100644
--- a/src/backend/catalog/partition.c
+++ b/src/backend/catalog/partition.c
@@ -950,7 +950,8 @@ RelationGetPartitionDispatchInfo(Relation rel, int lockmode,
*parted_rels;
ListCell *lc;
int i,
- k;
+ k,
+ offset;
/*
* Lock partitions and make a list of the partitioned ones to prepare
@@ -990,11 +991,19 @@ RelationGetPartitionDispatchInfo(Relation rel, int lockmode,
*/
}
- /* Generate PartitionDispatch objects for all partitioned tables */
+ /*
+ * We want to create two arrays - one for leaf partitions and another for
+ * partitioned tables (including the root table and internal partitions).
+ * While we only create the latter here, leaf partition array of suitable
+ * objects (such as, ResultRelInfo) is created by the caller using the
+ * list of OIDs we return. Indexes into these arrays get assigned in a
+ * breadth-first manner, whereby partitions of any given level are placed
+ * consecutively in the respective arrays.
+ */
pd = (PartitionDispatchData **) palloc(*num_parted *
sizeof(PartitionDispatchData *));
*leaf_part_oids = NIL;
- i = k = 0;
+ i = k = offset = 0;
foreach(lc, parted_rels)
{
Relation partrel = lfirst(lc);
@@ -1010,6 +1019,16 @@ RelationGetPartitionDispatchInfo(Relation rel, int lockmode,
pd[i]->partdesc = partdesc;
pd[i]->indexes = (int *) palloc(partdesc->nparts * sizeof(int));
+ /*
+ * Indexes corresponding to the internal partitions are multiplied by
+ * -1 to distinguish them from those of leaf partitions. Encountering
+ * an index >= 0 means we found a leaf partition, which is immediately
+ * returned as the partition we are looking for. A negative index
+ * means we found a partitioned table, whose PartitionDispatch object
+ * is located at the above index multiplied back by -1. Using the
+ * PartitionDispatch object, search is continued further down the
+ * partition tree.
+ */
m = 0;
for (j = 0; j < partdesc->nparts; j++)
{
@@ -1023,14 +1042,22 @@ RelationGetPartitionDispatchInfo(Relation rel, int lockmode,
else
{
/*
- * We can assign indexes this way because of the way
- * parted_rels has been generated.
+ * offset denotes the number of partitioned tables of upper
+ * levels including those of the current level. Any partition
+ * of this table must belong to the next level and hence will
+ * be placed after the last partitioned table of this level.
*/
- pd[i]->indexes[j] = -(i + 1 + m);
+ pd[i]->indexes[j] = -(1 + offset + m);
m++;
}
}
i++;
+
+ /*
+ * This counts the number of partitioned tables at upper levels
+ * including those of the current level.
+ */
+ offset += m;
}
return pd;
--
2.40.0