From b4645780074cdb0a3abdb7c84435d6abad4e3bec Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Fri, 10 May 2024 03:07:22 +0300 Subject: [PATCH v3 4/4] amcheck: Report an error when the next page to a leaf is not a leaf This is a very unlikely condition during checking a B-tree unique constraint, meaning that the index structure is violated badly, and we shouldn't continue checking to avoid endless loops, etc. So it's worth immediately throwing an error. Reported-by: Peter Geoghegan Discussion: https://postgr.es/m/CAH2-Wzk%2B2116uOXdOViA27SHcr31WKPgmjsxXLBs_aTxAeThzg%40mail.gmail.com Author: Pavel Borisov --- contrib/amcheck/verify_nbtree.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c index 977f8b6799d..e9bbc18c4a5 100644 --- a/contrib/amcheck/verify_nbtree.c +++ b/contrib/amcheck/verify_nbtree.c @@ -1849,7 +1849,6 @@ bt_target_page_check(BtreeCheckState *state) if (offset == max) { BTScanInsert rightkey; - BlockNumber rightblock_number; /* first offset on a right index page (log only) */ OffsetNumber rightfirstoffset = InvalidOffsetNumber; @@ -1894,10 +1893,11 @@ bt_target_page_check(BtreeCheckState *state) * If index has unique constraint make sure that no more than one * found equal items is visible. */ - rightblock_number = topaque->btpo_next; if (state->checkunique && state->indexinfo->ii_Unique && - rightkey && P_ISLEAF(topaque) && rightblock_number != P_NONE) + rightkey && P_ISLEAF(topaque) && !P_RIGHTMOST(topaque)) { + BlockNumber rightblock_number = topaque->btpo_next; + elog(DEBUG2, "check cross page unique condition"); /* @@ -1924,9 +1924,19 @@ bt_target_page_check(BtreeCheckState *state) rightblock_number); topaque = BTPageGetOpaque(rightpage); - if (P_IGNORE(topaque) || !P_ISLEAF(topaque)) - break; - + if (P_IGNORE(topaque)) + { + if (unlikely(!P_ISLEAF(topaque))) + ereport(ERROR, + (errcode(ERRCODE_INDEX_CORRUPTED), + errmsg("right block of leaf block is non-leaf for index \"%s\"", + RelationGetRelationName(state->rel)), + errdetail_internal("Block=%u page lsn=%X/%X.", + state->targetblock, + LSN_FORMAT_ARGS(state->targetlsn)))); + else + break; + } itemid = PageGetItemIdCareful(state, rightblock_number, rightpage, rightfirstoffset); -- 2.39.3 (Apple Git-145)