01.02.2018 05:12, Tom Lane:
Yugo Nagata <nag...@sraoss.co.jp> writes:
I'm sorry the patch attached in the previous mail is broken and
not raises a compile error. I attached the fixed patch.
This patch is almost certainly wrong: you can't assume that the scan-level
state matches the tuple we are currently processing at top level. Any
sort of delaying action, for instance a sort or materialize node in
between, would break it.
We need to either fix this aspect:
IndexOnlyScan returns a virtual tuple that doesn't have system
column, so we can not get ctid in the same way of other plans.
I'd like to propose the patch that fixes the issue.
We already have a way to return heaptuple from IndexOnlyScan,
but it was not applied to b-tree for some reason.
Attached patch solves the reported bug.
Moreover, it will come in handy for "index with included attributes"
feature [1],
where we can store long (and even TOASTed) attributes in indextuple.
[1] https://commitfest.postgresql.org/17/1350/
--
Anastasia Lubennikova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index 8158508..db8a55c 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -374,6 +374,8 @@ btbeginscan(Relation rel, int nkeys, int norderbys)
so->currTuples = so->markTuples = NULL;
scan->xs_itupdesc = RelationGetDescr(rel);
+ scan->xs_hitupdesc = NULL;
+ scan->xs_hitup = NULL;
scan->opaque = so;
diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c
index 51dca64..dd3e8b2 100644
--- a/src/backend/access/nbtree/nbtsearch.c
+++ b/src/backend/access/nbtree/nbtsearch.c
@@ -25,6 +25,7 @@
#include "utils/tqual.h"
+static HeapTuple _bt_fetch_tuple(IndexScanDesc scandesc);
static bool _bt_readpage(IndexScanDesc scan, ScanDirection dir,
OffsetNumber offnum);
static void _bt_saveitem(BTScanOpaque so, int itemIndex,
@@ -38,6 +39,31 @@ static bool _bt_endpoint(IndexScanDesc scan, ScanDirection dir);
static void _bt_drop_lock_and_maybe_pin(IndexScanDesc scan, BTScanPos sp);
static inline void _bt_initialize_more_data(BTScanOpaque so, ScanDirection dir);
+/*
+ * Fetch all keys in tuple.
+ * Returns a new HeapTuple containing the originally-indexed data.
+ */
+static HeapTuple
+_bt_fetch_tuple(IndexScanDesc scandesc)
+{
+ Relation index = scandesc->indexRelation;
+ Datum fetchatt[INDEX_MAX_KEYS];
+ bool isnull[INDEX_MAX_KEYS];
+ int i;
+ HeapTuple htuple;
+
+ for (i = 0; i < index->rd_att->natts; i++)
+ {
+ fetchatt[i] = index_getattr(scandesc->xs_itup, i + 1,
+ scandesc->xs_itupdesc, &isnull[i]);
+ }
+
+ htuple = heap_form_tuple(scandesc->xs_hitupdesc, fetchatt, isnull);
+ htuple->t_tableOid = scandesc->heapRelation->rd_id;
+
+
+ return htuple;
+}
/*
* _bt_drop_lock_and_maybe_pin()
@@ -1105,8 +1131,32 @@ readcomplete:
/* OK, itemIndex says what to return */
currItem = &so->currPos.items[so->currPos.itemIndex];
scan->xs_ctup.t_self = currItem->heapTid;
+
if (scan->xs_want_itup)
+ {
+ if (!scan->xs_hitupdesc)
+ {
+ int natts = RelationGetNumberOfAttributes(scan->indexRelation);
+ int attno;
+ /*
+ * The storage type of the index can be different from the original
+ * datatype being indexed, so we cannot just grab the index's tuple
+ * descriptor. Instead, construct a descriptor with the original data
+ * types.
+ */
+ scan->xs_hitupdesc = CreateTemplateTupleDesc(natts, false);
+ for (attno = 1; attno <= natts; attno++)
+ {
+ TupleDescInitEntry(scan->xs_hitupdesc, attno, NULL,
+ scan->indexRelation->rd_opcintype[attno - 1],
+ -1, 0);
+ }
+ }
+
scan->xs_itup = (IndexTuple) (so->currTuples + currItem->tupleOffset);
+ scan->xs_hitup = _bt_fetch_tuple(scan);
+ scan->xs_hitup->t_self = currItem->heapTid;
+ }
return true;
}
@@ -1155,8 +1205,34 @@ _bt_next(IndexScanDesc scan, ScanDirection dir)
/* OK, itemIndex says what to return */
currItem = &so->currPos.items[so->currPos.itemIndex];
scan->xs_ctup.t_self = currItem->heapTid;
+
if (scan->xs_want_itup)
+ {
+ if (!scan->xs_hitupdesc)
+ {
+ int natts = RelationGetNumberOfAttributes(scan->indexRelation);
+ int attno;
+ /*
+ * The storage type of the index can be different from the original
+ * datatype being indexed, so we cannot just grab the index's tuple
+ * descriptor. Instead, construct a descriptor with the original data
+ * types.
+ */
+ scan->xs_hitupdesc = CreateTemplateTupleDesc(natts, false);
+ for (attno = 1; attno <= natts; attno++)
+ {
+ TupleDescInitEntry(scan->xs_hitupdesc, attno, NULL,
+ scan->indexRelation->rd_opcintype[attno - 1],
+ -1, 0);
+ }
+ }
+
scan->xs_itup = (IndexTuple) (so->currTuples + currItem->tupleOffset);
+ if (scan->xs_hitup)
+ pfree(scan->xs_hitup);
+ scan->xs_hitup = _bt_fetch_tuple(scan);
+ scan->xs_hitup->t_self = currItem->heapTid;
+ }
return true;
}
@@ -1932,8 +2008,34 @@ _bt_endpoint(IndexScanDesc scan, ScanDirection dir)
/* OK, itemIndex says what to return */
currItem = &so->currPos.items[so->currPos.itemIndex];
scan->xs_ctup.t_self = currItem->heapTid;
+
if (scan->xs_want_itup)
+ {
+ if (!scan->xs_hitupdesc)
+ {
+ int natts = RelationGetNumberOfAttributes(scan->indexRelation);
+ int attno;
+ /*
+ * The storage type of the index can be different from the original
+ * datatype being indexed, so we cannot just grab the index's tuple
+ * descriptor. Instead, construct a descriptor with the original data
+ * types.
+ */
+ scan->xs_hitupdesc = CreateTemplateTupleDesc(natts, false);
+ for (attno = 1; attno <= natts; attno++)
+ {
+ TupleDescInitEntry(scan->xs_hitupdesc, attno, NULL,
+ scan->indexRelation->rd_opcintype[attno - 1],
+ -1, 0);
+ }
+ }
+
scan->xs_itup = (IndexTuple) (so->currTuples + currItem->tupleOffset);
+ if (scan->xs_hitup)
+ pfree(scan->xs_hitup);
+ scan->xs_hitup = _bt_fetch_tuple(scan);
+ scan->xs_hitup->t_self = currItem->heapTid;
+ }
return true;
}
