diff options
Diffstat (limited to 'src/include/column.i')
| -rw-r--r-- | src/include/column.i | 36 |
1 files changed, 28 insertions, 8 deletions
diff --git a/src/include/column.i b/src/include/column.i index fc1f372b2a9..9f3e2101f6f 100644 --- a/src/include/column.i +++ b/src/include/column.i @@ -1,5 +1,5 @@ /*- - * Copyright (c) 2014-2015 MongoDB, Inc. + * Copyright (c) 2014-2016 MongoDB, Inc. * Copyright (c) 2008-2014 WiredTiger, Inc. * All rights reserved. * @@ -176,6 +176,16 @@ __col_insert_search(WT_INSERT_HEAD *inshead, continue; } + /* + * When no exact match is found, the search returns the smallest + * key larger than the searched-for key, or the largest key + * smaller than the searched-for key, if there is no larger key. + * Our callers depend on that: specifically, the fixed-length + * column store cursor code interprets returning a key smaller + * than the searched-for key to mean the searched-for key is + * larger than any key on the page. Don't change that behavior, + * things will break. + */ ins_recno = WT_INSERT_RECNO(ret_ins); cmp = (recno == ins_recno) ? 0 : (recno < ins_recno) ? -1 : 1; @@ -204,9 +214,9 @@ __col_var_last_recno(WT_PAGE *page) WT_COL_RLE *repeat; /* - * If there's an append list (the last page), then there may be more - * records on the page. This function ignores those records, so our - * callers have to handle that explicitly, if they care. + * If there's an append list, there may be more records on the page. + * This function ignores those records, our callers must handle that + * explicitly, if they care. */ if (page->pg_var_nrepeats == 0) return (page->pg_var_entries == 0 ? 0 : @@ -225,9 +235,9 @@ static inline uint64_t __col_fix_last_recno(WT_PAGE *page) { /* - * If there's an append list (the last page), then there may be more - * records on the page. This function ignores those records, so our - * callers have to handle that explicitly, if they care. + * If there's an append list, there may be more records on the page. + * This function ignores those records, our callers must handle that + * explicitly, if they care. */ return (page->pg_fix_entries == 0 ? 0 : page->pg_fix_recno + (page->pg_fix_entries - 1)); @@ -282,7 +292,17 @@ __col_var_search(WT_PAGE *page, uint64_t recno, uint64_t *start_recnop) start_recno = repeat->recno + repeat->rle; } - if (recno >= start_recno + (page->pg_var_entries - start_indx)) + /* + * !!! + * The test could be written more simply as: + * + * (recno >= start_recno + (page->pg_var_entries - start_indx)) + * + * It's split into two parts because the simpler test will overflow if + * searching for large record numbers. + */ + if (recno >= start_recno && + recno - start_recno >= page->pg_var_entries - start_indx) return (NULL); return (page->pg_var_d + start_indx + (uint32_t)(recno - start_recno)); |