diff options
| author | Alexander Korotkov <akorotkov@postgresql.org> | 2018-07-19 21:04:17 +0300 |
|---|---|---|
| committer | Alexander Korotkov <akorotkov@postgresql.org> | 2018-07-19 21:22:07 +0300 |
| commit | 3c09b032afe548a4f0c3fd0658957650c3e22832 (patch) | |
| tree | a6041b0f8c7b5c2c7ddf7f5ce914857099dbea64 /src/backend/access/gin/gindatapage.c | |
| parent | 3ecd6c4ab9ddfe22e0c6df0fba412c900614aa23 (diff) | |
Fix handling of empty uncompressed posting list pages in GIN
PostgreSQL 9.4 introduces posting list compression in GIN. This feature
supports online upgrade, so that after pg_upgrade uncompressed posting
lists are compressed on-the-fly. Underlying code appears to always
expect at least one item on uncompressed posting list page. But there
could be completely empty pages, because VACUUM never deletes leftmost
and rightmost pages from posting trees. This commit fixes that.
Reported-by: Sivasubramanian Ramasubramanian
Discussion: https://postgr.es/m/1531867212836.63354%40amazon.com
Author: Sivasubramanian Ramasubramanian, Alexander Korotkov
Backpatch-through: 9.4
Diffstat (limited to 'src/backend/access/gin/gindatapage.c')
| -rw-r--r-- | src/backend/access/gin/gindatapage.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/src/backend/access/gin/gindatapage.c b/src/backend/access/gin/gindatapage.c index 93f2d8f350d..d25684949f5 100644 --- a/src/backend/access/gin/gindatapage.c +++ b/src/backend/access/gin/gindatapage.c @@ -1392,7 +1392,8 @@ disassembleLeaf(Page page) { /* * A pre-9.4 format uncompressed page is represented by a single - * segment, with an array of items. + * segment, with an array of items. The corner case is uncompressed + * page containing no items, which is represented as no segments. */ ItemPointer uncompressed; int nuncompressed; @@ -1400,15 +1401,18 @@ disassembleLeaf(Page page) uncompressed = dataLeafPageGetUncompressed(page, &nuncompressed); - seginfo = palloc(sizeof(leafSegmentInfo)); + if (nuncompressed > 0) + { + seginfo = palloc(sizeof(leafSegmentInfo)); - seginfo->action = GIN_SEGMENT_REPLACE; - seginfo->seg = NULL; - seginfo->items = palloc(nuncompressed * sizeof(ItemPointerData)); - memcpy(seginfo->items, uncompressed, nuncompressed * sizeof(ItemPointerData)); - seginfo->nitems = nuncompressed; + seginfo->action = GIN_SEGMENT_REPLACE; + seginfo->seg = NULL; + seginfo->items = palloc(nuncompressed * sizeof(ItemPointerData)); + memcpy(seginfo->items, uncompressed, nuncompressed * sizeof(ItemPointerData)); + seginfo->nitems = nuncompressed; - dlist_push_tail(&leaf->segments, &seginfo->node); + dlist_push_tail(&leaf->segments, &seginfo->node); + } leaf->oldformat = true; } |