From 4f393793f7d637e4ab8e6460e7bb4cd747f01f85 Mon Sep 17 00:00:00 2001 From: Peter Geoghegan Date: Mon, 12 Aug 2019 15:21:28 -0700 Subject: [PATCH] amcheck: Skip unlogged relations during recovery. contrib/amcheck failed to consider the possibility that unlogged relations will not have any main relation fork files when running in hot standby mode. This led to low-level "can't happen" errors that complain about the absence of a relfilenode file. To fix, simply skip verification of unlogged index relations during recovery. In passing, add a direct check for the presence of a main fork just before verification proper begins, so that we cleanly verify the presence of the main relation fork file. Author: Andrey Borodin, Peter Geoghegan Reported-By: Andrey Borodin Diagnosed-By: Andrey Borodin Discussion: https://postgr.es/m/DA9B33AC-53CB-4643-96D4-7A0BBC037FA1@yandex-team.ru Backpatch: 10-, where amcheck was introduced. --- contrib/amcheck/verify_nbtree.c | 38 +++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c index afbcd8ce76..f88d06997f 100644 --- a/contrib/amcheck/verify_nbtree.c +++ b/contrib/amcheck/verify_nbtree.c @@ -33,6 +33,7 @@ #include "lib/bloomfilter.h" #include "miscadmin.h" #include "storage/lmgr.h" +#include "storage/smgr.h" #include "utils/memutils.h" #include "utils/snapmgr.h" @@ -120,6 +121,7 @@ PG_FUNCTION_INFO_V1(bt_index_parent_check); static void bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed); static inline void btree_index_checkable(Relation rel); +static inline bool btree_index_mainfork_expected(Relation rel); static void bt_check_every_level(Relation rel, Relation heaprel, bool readonly, bool heapallindexed); static BtreeLevel bt_check_level_from_leftmost(BtreeCheckState *state, @@ -252,8 +254,18 @@ bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed) /* Relation suitable for checking as B-Tree? */ btree_index_checkable(indrel); - /* Check index, possibly against table it is an index on */ - bt_check_every_level(indrel, heaprel, parentcheck, heapallindexed); + if (btree_index_mainfork_expected(indrel)) + { + RelationOpenSmgr(indrel); + if (!smgrexists(indrel->rd_smgr, MAIN_FORKNUM)) + ereport(ERROR, + (errcode(ERRCODE_INDEX_CORRUPTED), + errmsg("index \"%s\" lacks a main relation fork", + RelationGetRelationName(indrel)))); + + /* Check index, possibly against table it is an index on */ + bt_check_every_level(indrel, heaprel, parentcheck, heapallindexed); + } /* * Release locks early. That's ok here because nothing in the called @@ -299,6 +311,28 @@ btree_index_checkable(Relation rel) errdetail("Index is not valid"))); } +/* + * Check if B-Tree index relation should have a file for its main relation + * fork. Verification uses this to skip unlogged indexes when in hot standby + * mode, where there is simply nothing to verify. + * + * NB: Caller should call btree_index_checkable() before calling here. + */ +static inline bool +btree_index_mainfork_expected(Relation rel) +{ + if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED || + !RecoveryInProgress()) + return true; + + ereport(NOTICE, + (errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION), + errmsg("cannot verify unlogged index \"%s\" during recovery, skipping", + RelationGetRelationName(rel)))); + + return false; +} + /* * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in * logical order, verifying invariants as it goes. Optionally, verification