From 95f3471c8d97bbfb17314035b9583eba6bbb2b9e Mon Sep 17 00:00:00 2001 From: Jim Jones Date: Fri, 6 Nov 2026 13:59:56 +0100 Subject: [PATCH v5 1/2] pageinspect: Reject unlogged relations during recovery Unlogged tables and indexes have no data on a standby, so reading one there must fail. get_raw_page(), bt_metap(), bt_page_stats(), bt_multi_page_stats(), bt_page_items() and hash_bitmap_info() read the relation directly instead of going through the planner, so on a standby they failed with a confusing low-level message instead of the error that SELECT reports: ERROR: could not open file "base/5/16384": No such file or directory Check for this case and report the same error as SELECT: ERROR: cannot access temporary or unlogged relations during recovery The init fork of an unlogged relation does exist on a standby, so get_raw_page() can still read it. This check and the existing check against temporary relations of other sessions are now grouped in the helper check_relation_accessible(), shared by all these functions. heap_page_item_attrs() and tuple_data_split() can also reach unlogged storage when detoasting values from a saved page image, so check the persistence of the TOAST relation referenced by each external on-disk value before detoasting as well. Author: Jim Jones Co-authored-by: Kirill Reshke Co-authored-by: Surya Poondla Reported-by: Zsolt Parragi Reviewed-by: Michael Paquier Discussion: https://www.postgresql.org/message-id/flat/82ba0876-6127-4770-b900-aa1bd52abfed@uni-muenster.de --- contrib/pageinspect/btreefuncs.c | 20 ++-------------- contrib/pageinspect/hashfuncs.c | 5 +--- contrib/pageinspect/heapfuncs.c | 25 +++++++++++++++++++ contrib/pageinspect/pageinspect.h | 3 +++ contrib/pageinspect/rawpage.c | 40 ++++++++++++++++++++++++------- 5 files changed, 62 insertions(+), 31 deletions(-) diff --git a/contrib/pageinspect/btreefuncs.c b/contrib/pageinspect/btreefuncs.c index 9917663593b..c9a6c2cf3fa 100644 --- a/contrib/pageinspect/btreefuncs.c +++ b/contrib/pageinspect/btreefuncs.c @@ -231,15 +231,7 @@ bt_index_block_validate(Relation rel, int64 blkno) errmsg("\"%s\" is not a %s index", RelationGetRelationName(rel), "btree"))); - /* - * Reject attempts to read non-local temporary relations; we would be - * likely to get wrong data since we have no visibility into the owning - * session's local buffers. - */ - if (RELATION_IS_OTHER_TEMP(rel)) - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("cannot access temporary tables of other sessions"))); + check_relation_accessible(rel, MAIN_FORKNUM); if (blkno == 0) ereport(ERROR, @@ -864,15 +856,7 @@ bt_metap(PG_FUNCTION_ARGS) errmsg("\"%s\" is not a %s index", RelationGetRelationName(rel), "btree"))); - /* - * Reject attempts to read non-local temporary relations; we would be - * likely to get wrong data since we have no visibility into the owning - * session's local buffers. - */ - if (RELATION_IS_OTHER_TEMP(rel)) - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("cannot access temporary tables of other sessions"))); + check_relation_accessible(rel, MAIN_FORKNUM); buffer = ReadBuffer(rel, 0); LockBuffer(buffer, BUFFER_LOCK_SHARE); diff --git a/contrib/pageinspect/hashfuncs.c b/contrib/pageinspect/hashfuncs.c index 30870329cc9..340bfa21c15 100644 --- a/contrib/pageinspect/hashfuncs.c +++ b/contrib/pageinspect/hashfuncs.c @@ -426,10 +426,7 @@ hash_bitmap_info(PG_FUNCTION_ARGS) errmsg("\"%s\" is not a %s index", RelationGetRelationName(indexRel), "hash"))); - if (RELATION_IS_OTHER_TEMP(indexRel)) - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("cannot access temporary tables of other sessions"))); + check_relation_accessible(indexRel, MAIN_FORKNUM); if (ovflblkno < 0 || ovflblkno > MaxBlockNumber) ereport(ERROR, diff --git a/contrib/pageinspect/heapfuncs.c b/contrib/pageinspect/heapfuncs.c index 7be4770dc84..b2a14444dcc 100644 --- a/contrib/pageinspect/heapfuncs.c +++ b/contrib/pageinspect/heapfuncs.c @@ -25,8 +25,10 @@ #include "postgres.h" +#include "access/detoast.h" #include "access/htup_details.h" #include "access/relation.h" +#include "access/xlog.h" #include "catalog/pg_am_d.h" #include "catalog/pg_type.h" #include "funcapi.h" @@ -36,7 +38,9 @@ #include "port/pg_bitutils.h" #include "utils/array.h" #include "utils/builtins.h" +#include "utils/lsyscache.h" #include "utils/rel.h" +#include "utils/syscache.h" /* * It's not supported to create tuples with oids anymore, but when pg_upgrade @@ -389,7 +393,28 @@ tuple_data_split_internal(Oid relid, char *tupdata, errmsg("unexpected end of tuple data"))); if (attr->attlen == -1 && do_detoast) + { + /* A saved page can still refer to unlogged TOAST storage. */ + if (VARATT_IS_EXTERNAL_ONDISK(tupdata + off) && + RecoveryInProgress()) + { + toast_external_data toast_ext_data; + + toast_external_info_get((varlena *) (tupdata + off), + &toast_ext_data); + + /* If the relation is gone, let detoasting complain. */ + if (SearchSysCacheExists1(RELOID, + ObjectIdGetDatum(toast_ext_data.toastrelid)) && + get_rel_persistence(toast_ext_data.toastrelid) != + RELPERSISTENCE_PERMANENT) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot access temporary or unlogged relations during recovery"))); + } + attr_data = pg_detoast_datum_copy((varlena *) (tupdata + off)); + } else { attr_data = (bytea *) palloc(len + VARHDRSZ); diff --git a/contrib/pageinspect/pageinspect.h b/contrib/pageinspect/pageinspect.h index b241fdc97b2..37d52b8d29d 100644 --- a/contrib/pageinspect/pageinspect.h +++ b/contrib/pageinspect/pageinspect.h @@ -13,7 +13,9 @@ #ifndef _PAGEINSPECT_H_ #define _PAGEINSPECT_H_ +#include "common/relpath.h" #include "storage/bufpage.h" +#include "utils/relcache.h" /* * Extension version number, for supporting older extension versions' objects @@ -26,5 +28,6 @@ enum pageinspect_version /* in rawpage.c */ extern Page get_page_from_raw(bytea *raw_page); +extern void check_relation_accessible(Relation rel, ForkNumber forknum); #endif /* _PAGEINSPECT_H_ */ diff --git a/contrib/pageinspect/rawpage.c b/contrib/pageinspect/rawpage.c index d136593edb2..3b65c070d07 100644 --- a/contrib/pageinspect/rawpage.c +++ b/contrib/pageinspect/rawpage.c @@ -17,6 +17,7 @@ #include "access/htup_details.h" #include "access/relation.h" +#include "access/xlog.h" #include "catalog/namespace.h" #include "catalog/pg_type.h" #include "funcapi.h" @@ -165,15 +166,7 @@ get_raw_page_internal(text *relname, ForkNumber forknum, BlockNumber blkno) RelationGetRelationName(rel)), errdetail_relkind_not_supported(rel->rd_rel->relkind))); - /* - * Reject attempts to read non-local temporary relations; we would be - * likely to get wrong data since we have no visibility into the owning - * session's local buffers. - */ - if (RELATION_IS_OTHER_TEMP(rel)) - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("cannot access temporary tables of other sessions"))); + check_relation_accessible(rel, forknum); if (blkno >= RelationGetNumberOfBlocksInFork(rel, forknum)) ereport(ERROR, @@ -200,6 +193,35 @@ get_raw_page_internal(text *relname, ForkNumber forknum, BlockNumber blkno) return raw_page; } +/* + * check_relation_accessible + * + * Check that the given fork of a relation can be read by this session. + */ +void +check_relation_accessible(Relation rel, ForkNumber forknum) +{ + /* + * Reject attempts to read non-local temporary relations; we would be + * likely to get wrong data since we have no visibility into the owning + * session's local buffers. + */ + if (RELATION_IS_OTHER_TEMP(rel)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot access temporary tables of other sessions"))); + + /* + * Temporary and unlogged relations are inaccessible during recovery, + * except for the init fork of an unlogged relation, which does exist. + */ + if (!RelationIsPermanent(rel) && RecoveryInProgress() && + forknum != INIT_FORKNUM) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot access temporary or unlogged relations during recovery"))); +} + /* * get_page_from_raw -- 2.56.0