Hello,
I just realized that 7e534adcdc7 broke support for hypothetical
indexes using BRIN am. Attached patch fix the issue.
There's no interface to provide the hypothetical pagesPerRange value,
so I used the default one, and used simple estimates.
I'll add this patch to the next commitfest.
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index d7e3f09f1a..64f27369c0 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -102,6 +102,7 @@
#include <math.h>
#include "access/brin.h"
+#include "access/brin_page.h"
#include "access/gin.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
@@ -6802,12 +6803,26 @@ brincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
&spc_seq_page_cost);
/*
- * Obtain some data from the index itself. A lock should have already
- * been obtained on the index in plancat.c.
+ * Obtain some data from the index itself, if possible. Otherwise invent
+ * some plausible internal statistics based on the relation page count.
*/
- indexRel = index_open(index->indexoid, NoLock);
- brinGetStats(indexRel, &statsData);
- index_close(indexRel, NoLock);
+ if (!index->hypothetical)
+ {
+ /*
+ * A lock should have already been obtained on the index in plancat.c.
+ */
+ indexRel = index_open(index->indexoid, NoLock);
+ brinGetStats(indexRel, &statsData);
+ index_close(indexRel, NoLock);
+ }
+ else
+ {
+ indexRanges = Max(ceil((double) baserel->pages /
+ BRIN_DEFAULT_PAGES_PER_RANGE), 1.0);
+
+ statsData.pagesPerRange = BRIN_DEFAULT_PAGES_PER_RANGE;
+ statsData.revmapNumPages = (indexRanges / REVMAP_PAGE_MAXITEMS) + 1;
+ }
/*
* Compute index correlation
