From 9d68ae6aea5dbca2fbfd961ef03a9f53b719c08f Mon Sep 17 00:00:00 2001 From: Zhijie Hou Date: Tue, 29 Jul 2025 12:18:24 +0800 Subject: [PATCH v55] Support the conflict detection for update_deleted This patch supports detecting update_deleted conflicts during update operations. If the target row cannot be found when applying update operations, we perform an additional scan of the table using snapshotAny. This scan aims to locate the most recently deleted row that matches the old column values from the remote update operation and has not yet been removed by VACUUM. If any such tuples are found, we report the update_deleted conflict along with the origin and transaction information that deleted the tuple. --- doc/src/sgml/catalogs.sgml | 3 +- doc/src/sgml/logical-replication.sgml | 16 ++ doc/src/sgml/ref/create_subscription.sgml | 5 +- src/backend/executor/execReplication.c | 252 ++++++++++++++++++++- src/backend/replication/logical/conflict.c | 22 ++ src/backend/replication/logical/worker.c | 176 ++++++++++++-- src/include/executor/executor.h | 14 +- src/include/replication/conflict.h | 3 + src/include/replication/worker_internal.h | 5 +- src/test/subscription/t/035_conflicts.pl | 66 +++++- 10 files changed, 529 insertions(+), 33 deletions(-) diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml index 97f547b3cc4..da8a7882580 100644 --- a/doc/src/sgml/catalogs.sgml +++ b/doc/src/sgml/catalogs.sgml @@ -8087,7 +8087,8 @@ SCRAM-SHA-256$<iteration count>:&l subretaindeadtuples bool - If true, the information (e.g., dead tuples, commit timestamps, and + If true, the detection of is + enabled and the information (e.g., dead tuples, commit timestamps, and origins) on the subscriber that is useful for conflict detection is retained. diff --git a/doc/src/sgml/logical-replication.sgml b/doc/src/sgml/logical-replication.sgml index fcac55aefe6..ab219e87f71 100644 --- a/doc/src/sgml/logical-replication.sgml +++ b/doc/src/sgml/logical-replication.sgml @@ -1804,6 +1804,22 @@ Publications: + + update_deleted + + + The tuple to be updated was recently deleted by another origin. The update + will simply be skipped in this scenario. Note that this conflict can only + be detected when + track_commit_timestamp + and retain_dead_tuples + are enabled. Note that if a tuple cannot be found due to the table being + truncated, only a update_missing conflict will + arise. Additionally, if the tuple was deleted by the same origin, an + update_missing conflict will arise. + + + update_missing diff --git a/doc/src/sgml/ref/create_subscription.sgml b/doc/src/sgml/ref/create_subscription.sgml index b8cd15f3280..e847e39fa84 100644 --- a/doc/src/sgml/ref/create_subscription.sgml +++ b/doc/src/sgml/ref/create_subscription.sgml @@ -445,8 +445,9 @@ CREATE SUBSCRIPTION subscription_namefalse. - If set to true, a physical replication slot named - pg_conflict_detection will be + If set to true, the detection of + is enabled, and a physical + replication slot named pg_conflict_detection created on the subscriber to prevent the conflict information from being removed. diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c index f262e7a66f7..9a0f7c31d4b 100644 --- a/src/backend/executor/execReplication.c +++ b/src/backend/executor/execReplication.c @@ -14,12 +14,14 @@ #include "postgres.h" +#include "access/commit_ts.h" #include "access/genam.h" #include "access/gist.h" #include "access/relscan.h" #include "access/tableam.h" #include "access/transam.h" #include "access/xact.h" +#include "access/heapam.h" #include "catalog/pg_am_d.h" #include "commands/trigger.h" #include "executor/executor.h" @@ -36,7 +38,7 @@ static bool tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2, - TypeCacheEntry **eq); + TypeCacheEntry **eq, Bitmapset *columns); /* * Setup a ScanKey for a search in the relation 'rel' for a tuple 'key' that @@ -221,7 +223,7 @@ retry: if (eq == NULL) eq = palloc0(sizeof(*eq) * outslot->tts_tupleDescriptor->natts); - if (!tuples_equal(outslot, searchslot, eq)) + if (!tuples_equal(outslot, searchslot, eq, NULL)) continue; } @@ -277,10 +279,13 @@ retry: /* * Compare the tuples in the slots by checking if they have equal values. + * + * If 'columns' is not null, only the columns specified within it will be + * considered for the equality check, ignoring all other columns. */ static bool tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2, - TypeCacheEntry **eq) + TypeCacheEntry **eq, Bitmapset *columns) { int attrnum; @@ -305,6 +310,14 @@ tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2, if (att->attisdropped || att->attgenerated) continue; + /* + * Ignore columns that are not listed for checking. + */ + if (columns && + !bms_is_member(att->attnum - FirstLowInvalidHeapAttributeNumber, + columns)) + continue; + /* * If one value is NULL and other is not, then they are certainly not * equal @@ -380,7 +393,7 @@ retry: /* Try to find the tuple */ while (table_scan_getnextslot(scan, ForwardScanDirection, scanslot)) { - if (!tuples_equal(scanslot, searchslot, eq)) + if (!tuples_equal(scanslot, searchslot, eq, NULL)) continue; found = true; @@ -455,6 +468,237 @@ BuildConflictIndexInfo(ResultRelInfo *resultRelInfo, Oid conflictindex) } } +/* + * If the tuple is recently dead and was deleted by a transaction with a newer + * commit timestamp than previously recorded, update the associated transaction + * ID, commit time, and origin. This helps ensure that conflict detection uses + * the most recent and relevant deletion metadata. + */ +static void +update_most_recent_deletion_info(TupleTableSlot *scanslot, + TransactionId oldestxmin, + TransactionId *delete_xid, + TimestampTz *delete_time, + RepOriginId *delete_origin) +{ + BufferHeapTupleTableSlot *hslot; + HeapTuple tuple; + Buffer buf; + bool recently_dead = false; + TransactionId xmax; + TimestampTz localts; + RepOriginId localorigin; + + hslot = (BufferHeapTupleTableSlot *) scanslot; + + tuple = ExecFetchSlotHeapTuple(scanslot, false, NULL); + buf = hslot->buffer; + + LockBuffer(buf, BUFFER_LOCK_SHARE); + + /* + * We do not consider HEAPTUPLE_DEAD status because it indicates either + * tuples whose inserting transaction was aborted (meaning there is no + * commit timestamp or origin), or tuples deleted by a transaction older + * than oldestxmin, making it safe to ignore them during conflict + * detection (See comments atop worker.c for details). + */ + if (HeapTupleSatisfiesVacuum(tuple, oldestxmin, buf) == HEAPTUPLE_RECENTLY_DEAD) + recently_dead = true; + + LockBuffer(buf, BUFFER_LOCK_UNLOCK); + + if (!recently_dead) + return; + + xmax = HeapTupleHeaderGetUpdateXid(tuple->t_data); + if (!TransactionIdIsValid(xmax)) + return; + + /* Select the dead tuple with the most recent commit timestamp */ + if (TransactionIdGetCommitTsData(xmax, &localts, &localorigin) && + (TimestampDifferenceExceeds(*delete_time, localts, 0) || + *delete_time == 0)) + { + *delete_xid = xmax; + *delete_time = localts; + *delete_origin = localorigin; + } +} + +/* + * Searches the relation 'rel' for the most recently deleted tuple that matches + * the values in 'searchslot' and is not yet removable by VACUUM. The function + * returns the transaction ID, origin, and commit timestamp of the transaction + * that deleted this tuple. + * + * 'oldestxmin' acts as a cutoff transaction ID. Tuples deleted by transactions + * with IDs >= 'oldestxmin' are considered recently dead and are eligible for + * conflict detection. + * + * Instead of stopping at the first match, we scan all matching dead tuples to + * identify most recent deletion. This is crucial because only the latest + * deletion is relevant for resolving conflicts. + * + * For example, consider a scenario on the subscriber where a row is deleted, + * re-inserted, and then deleted again only on the subscriber: + * + * - (pk, 1) - deleted at 9:00, + * - (pk, 1) - deleted at 9:02, + * + * Now, a remote update arrives: (pk, 1) -> (pk, 2), timestamped at 9:01. + * + * If we mistakenly return the older deletion (9:00), the system may wrongly + * apply the remote update using a last-update-wins strategy. Instead, we must + * recognize the more recent deletion at 9:02 and skip the update. See + * comments atop worker.c for details. Note, as of now, conflict resolution + * is not implemented. Consequently, the system may incorrectly report the + * older tuple as the conflicted one, leading to misleading results. + * + * The commit timestamp of the deleting transaction is used to determine which + * tuple was deleted most recently. + */ +bool +RelationFindDeletedTupleInfoSeq(Relation rel, TupleTableSlot *searchslot, + TransactionId oldestxmin, + TransactionId *delete_xid, + RepOriginId *delete_origin, + TimestampTz *delete_time) +{ + TupleTableSlot *scanslot; + TableScanDesc scan; + TypeCacheEntry **eq; + Bitmapset *indexbitmap; + TupleDesc desc PG_USED_FOR_ASSERTS_ONLY = RelationGetDescr(rel); + + Assert(equalTupleDescs(desc, searchslot->tts_tupleDescriptor)); + + *delete_xid = InvalidTransactionId; + *delete_origin = InvalidRepOriginId; + *delete_time = 0; + + /* + * If the relation has a replica identity key or a primary key that is + * unusable for locating deleted tuples (see + * IsIndexUsableForFindingDeletedTuple), a full table scan becomes + * necessary. In such cases, comparing the entire tuple is not required, + * since the remote tuple might not include all column values. Instead, + * the indexed columns alone are suffcient to identify the target tuple + * (see logicalrep_rel_mark_updatable). + */ + indexbitmap = RelationGetIndexAttrBitmap(rel, + INDEX_ATTR_BITMAP_IDENTITY_KEY); + + /* fallback to PK if no replica identity */ + if (!indexbitmap) + indexbitmap = RelationGetIndexAttrBitmap(rel, + INDEX_ATTR_BITMAP_PRIMARY_KEY); + + eq = palloc0(sizeof(*eq) * searchslot->tts_tupleDescriptor->natts); + + /* + * Start a heap scan using SnapshotAny to identify dead tuples that are + * not visible under a standard MVCC snapshot. Tuples from transactions + * not yet committed or those just committed prior to the scan are + * excluded in update_most_recent_deletion_info(). + */ + scan = table_beginscan(rel, SnapshotAny, 0, NULL); + scanslot = table_slot_create(rel, NULL); + + table_rescan(scan, NULL); + + /* Try to find the tuple */ + while (table_scan_getnextslot(scan, ForwardScanDirection, scanslot)) + { + if (!tuples_equal(scanslot, searchslot, eq, indexbitmap)) + continue; + + update_most_recent_deletion_info(scanslot, oldestxmin, delete_xid, + delete_time, delete_origin); + } + + table_endscan(scan); + ExecDropSingleTupleTableSlot(scanslot); + + return *delete_time != 0; +} + +/* + * Similar to RelationFindDeletedTupleInfoSeq() but using index scan to locate + * the deleted tuple. + */ +bool +RelationFindDeletedTupleInfoByIndex(Relation rel, Oid idxoid, + TupleTableSlot *searchslot, + TransactionId oldestxmin, + TransactionId *delete_xid, + RepOriginId *delete_origin, + TimestampTz *delete_time) +{ + Relation idxrel; + ScanKeyData skey[INDEX_MAX_KEYS]; + int skey_attoff; + IndexScanDesc scan; + TupleTableSlot *scanslot; + TypeCacheEntry **eq = NULL; + bool isIdxSafeToSkipDuplicates; + TupleDesc desc PG_USED_FOR_ASSERTS_ONLY = RelationGetDescr(rel); + + Assert(equalTupleDescs(desc, searchslot->tts_tupleDescriptor)); + Assert(OidIsValid(idxoid)); + + *delete_xid = InvalidTransactionId; + *delete_time = 0; + *delete_origin = InvalidRepOriginId; + + isIdxSafeToSkipDuplicates = (GetRelationIdentityOrPK(rel) == idxoid); + + scanslot = table_slot_create(rel, NULL); + + idxrel = index_open(idxoid, RowExclusiveLock); + + /* Build scan key. */ + skey_attoff = build_replindex_scan_key(skey, rel, idxrel, searchslot); + + /* + * Start an index scan using SnapshotAny to identify dead tuples that are + * not visible under a standard MVCC snapshot. Tuples from transactions + * not yet committed or those just committed prior to the scan are + * excluded in update_most_recent_deletion_info(). + */ + scan = index_beginscan(rel, idxrel, SnapshotAny, NULL, skey_attoff, 0); + + index_rescan(scan, skey, skey_attoff, NULL, 0); + + /* Try to find the tuple */ + while (index_getnext_slot(scan, ForwardScanDirection, scanslot)) + { + /* + * Avoid expensive equality check if the index is primary key or + * replica identity index. + */ + if (!isIdxSafeToSkipDuplicates) + { + if (eq == NULL) + eq = palloc0(sizeof(*eq) * scanslot->tts_tupleDescriptor->natts); + + if (!tuples_equal(scanslot, searchslot, eq, NULL)) + continue; + } + + update_most_recent_deletion_info(scanslot, oldestxmin, delete_xid, + delete_time, delete_origin); + } + + index_endscan(scan); + + index_close(idxrel, NoLock); + + ExecDropSingleTupleTableSlot(scanslot); + + return *delete_time != 0; +} + /* * Find the tuple that violates the passed unique index (conflictindex). * diff --git a/src/backend/replication/logical/conflict.c b/src/backend/replication/logical/conflict.c index 97c4e26b586..2fd3e8bbda5 100644 --- a/src/backend/replication/logical/conflict.c +++ b/src/backend/replication/logical/conflict.c @@ -29,6 +29,7 @@ static const char *const ConflictTypeNames[] = { [CT_UPDATE_EXISTS] = "update_exists", [CT_UPDATE_MISSING] = "update_missing", [CT_DELETE_ORIGIN_DIFFERS] = "delete_origin_differs", + [CT_UPDATE_DELETED] = "update_deleted", [CT_DELETE_MISSING] = "delete_missing", [CT_MULTIPLE_UNIQUE_CONFLICTS] = "multiple_unique_conflicts" }; @@ -176,6 +177,7 @@ errcode_apply_conflict(ConflictType type) case CT_UPDATE_ORIGIN_DIFFERS: case CT_UPDATE_MISSING: case CT_DELETE_ORIGIN_DIFFERS: + case CT_UPDATE_DELETED: case CT_DELETE_MISSING: return errcode(ERRCODE_T_R_SERIALIZATION_FAILURE); } @@ -261,6 +263,26 @@ errdetail_apply_conflict(EState *estate, ResultRelInfo *relinfo, break; + case CT_UPDATE_DELETED: + if (localts) + { + if (localorigin == InvalidRepOriginId) + appendStringInfo(&err_detail, _("The row to be updated was deleted locally in transaction %u at %s."), + localxmin, timestamptz_to_str(localts)); + else if (replorigin_by_oid(localorigin, true, &origin_name)) + appendStringInfo(&err_detail, _("The row to be updated was deleted by a different origin \"%s\" in transaction %u at %s."), + origin_name, localxmin, timestamptz_to_str(localts)); + + /* The origin that modified this row has been removed. */ + else + appendStringInfo(&err_detail, _("The row to be updated was deleted by a non-existent origin in transaction %u at %s."), + localxmin, timestamptz_to_str(localts)); + } + else + appendStringInfo(&err_detail, _("The row to be updated was deleted.")); + + break; + case CT_UPDATE_MISSING: appendStringInfoString(&err_detail, _("Could not find the row to be updated.")); break; diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c index b59221c4d06..2071c1b28af 100644 --- a/src/backend/replication/logical/worker.c +++ b/src/backend/replication/logical/worker.c @@ -138,9 +138,9 @@ * Each apply worker that enabled retain_dead_tuples option maintains a * non-removable transaction ID (oldest_nonremovable_xid) in shared memory to * prevent dead rows from being removed prematurely when the apply worker still - * needs them to detect conflicts reliably. This helps to retain the required - * commit_ts module information, which further helps to detect - * update_origin_differs and delete_origin_differs conflicts reliably, as + * needs them to detect update_deleted conflicts. Additionally, this helps to + * retain the required commit_ts module information, which further helps to + * detect update_origin_differs and delete_origin_differs conflicts reliably, as * otherwise, vacuum freeze could remove the required information. * * The logical replication launcher manages an internal replication slot named @@ -185,10 +185,10 @@ * transactions that occurred concurrently with the tuple DELETE, any * subsequent UPDATE from a remote node should have a later timestamp. In such * cases, it is acceptable to detect an update_missing scenario and convert the - * UPDATE to an INSERT when applying it. But, detecting concurrent remote - * transactions with earlier timestamps than the DELETE is necessary, as the - * UPDATEs in remote transactions should be ignored if their timestamp is - * earlier than that of the dead tuples. + * UPDATE to an INSERT when applying it. But, for concurrent remote + * transactions with earlier timestamps than the DELETE, detecting + * update_deleted is necessary, as the UPDATEs in remote transactions should be + * ignored if their timestamp is earlier than that of the dead tuples. * * Note that advancing the non-removable transaction ID is not supported if the * publisher is also a physical standby. This is because the logical walsender @@ -576,6 +576,12 @@ static bool FindReplTupleInLocalRel(ApplyExecutionData *edata, Relation localrel Oid localidxoid, TupleTableSlot *remoteslot, TupleTableSlot **localslot); +static bool FindDeletedTupleInLocalRel(Relation localrel, + Oid localidxoid, + TupleTableSlot *remoteslot, + TransactionId *delete_xid, + RepOriginId *delete_origin, + TimestampTz *delete_time); static void apply_handle_tuple_routing(ApplyExecutionData *edata, TupleTableSlot *remoteslot, LogicalRepTupleData *newtup, @@ -2912,17 +2918,32 @@ apply_handle_update_internal(ApplyExecutionData *edata, } else { + ConflictType type; TupleTableSlot *newslot = localslot; + /* + * Detecting whether the tuple was recently deleted or never existed + * is crucial to avoid misleading the user during confict handling. + */ + if (MySubscription->retaindeadtuples && + FindDeletedTupleInLocalRel(localrel, localindexoid, remoteslot, + &conflicttuple.xmin, + &conflicttuple.origin, + &conflicttuple.ts) && + conflicttuple.origin != replorigin_session_origin) + type = CT_UPDATE_DELETED; + else + type = CT_UPDATE_MISSING; + /* Store the new tuple for conflict reporting */ slot_store_data(newslot, relmapentry, newtup); /* - * The tuple to be updated could not be found. Do nothing except for - * emitting a log message. + * The tuple to be updated could not be found or was deleted. Do + * nothing except for emitting a log message. */ - ReportApplyConflict(estate, relinfo, LOG, CT_UPDATE_MISSING, - remoteslot, newslot, list_make1(&conflicttuple)); + ReportApplyConflict(estate, relinfo, LOG, type, remoteslot, newslot, + list_make1(&conflicttuple)); } /* Cleanup. */ @@ -3142,6 +3163,100 @@ FindReplTupleInLocalRel(ApplyExecutionData *edata, Relation localrel, return found; } +/* + * Determine whether the index can reliably locate the deleted tuple in the + * local relation. + * + * An index may exclude deleted tuples if it was re-indexed or re-created during + * change application. Therefore, an index is considered usable only if the + * conflict detection slot.xmin (conflict_detection_xmin) is greater than the + * index tuple's xmin. This ensures that any tuples deleted prior to the index + * creation or re-indexing are not relevant for conflict detection in the + * current apply worker. + * + * Note that indexes may also be excluded if they were modified by other DDL + * operations, such as ALTER INDEX. However, this is acceptable, as the + * likelihood of such DDL changes coinciding with the need to scan dead + * tuples for the update_deleted is low. + */ +static bool +IsIndexUsableForFindingDeletedTuple(Oid localindexoid, + TransactionId conflict_detection_xmin) +{ + HeapTuple index_tuple; + TransactionId index_xmin; + + index_tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(localindexoid)); + + if (!HeapTupleIsValid(index_tuple)) /* should not happen */ + elog(ERROR, "cache lookup failed for index %u", localindexoid); + + /* + * No need to check for a frozen transaction ID, as + * TransactionIdPrecedes() manages it internally, treating it as falling + * behind the oldest_nonremovable_xid. + */ + index_xmin = HeapTupleHeaderGetXmin(index_tuple->t_data); + + ReleaseSysCache(index_tuple); + + return TransactionIdPrecedes(index_xmin, conflict_detection_xmin); +} + +/* + * Attempts to locate a deleted tuple in the local relation that matches the + * values of the tuple received from the publication side (in 'remoteslot'). + * The search is performed using either the replica identity index, primary + * key, other available index, or a sequential scan if necessary. + * + * Returns true if the deleted tuple is found. If found, the transaction ID, + * origin, and commit timestamp of the deletion are stored in '*delete_xid', + * '*delete_origin', and '*delete_time' respectively. + */ +static bool +FindDeletedTupleInLocalRel(Relation localrel, + Oid localidxoid, TupleTableSlot *remoteslot, + TransactionId *delete_xid, RepOriginId *delete_origin, + TimestampTz *delete_time) +{ + TransactionId oldestxmin; + ReplicationSlot *slot; + + /* Return if the commit timestamp data is not available */ + if (!track_commit_timestamp) + return false; + + /* + * Instead of invoking GetOldestNonRemovableTransactionId() for conflict + * detection, we use the conflict detection slot.xmin. This value will be + * greater than or equal to the other threshold and provides a more direct + * and efficient way to identify recently deleted dead tuples relevant to + * the conflict detection. The oldest_nonremovable_xid is not used here, + * as it is maintained only by the leader apply worker and unavailable to + * table sync and parallel apply workers. + */ + slot = SearchNamedReplicationSlot(CONFLICT_DETECTION_SLOT, true); + + Assert(slot); + + SpinLockAcquire(&slot->mutex); + oldestxmin = slot->data.xmin; + SpinLockRelease(&slot->mutex); + + Assert(TransactionIdIsValid(oldestxmin)); + + if (OidIsValid(localidxoid) && + IsIndexUsableForFindingDeletedTuple(localidxoid, oldestxmin)) + return RelationFindDeletedTupleInfoByIndex(localrel, localidxoid, + remoteslot, oldestxmin, + delete_xid, delete_origin, + delete_time); + else + return RelationFindDeletedTupleInfoSeq(localrel, remoteslot, + oldestxmin, delete_xid, + delete_origin, delete_time); +} + /* * This handles insert, update, delete on a partitioned table. */ @@ -3260,18 +3375,36 @@ apply_handle_tuple_routing(ApplyExecutionData *edata, remoteslot_part, &localslot); if (!found) { + ConflictType type; TupleTableSlot *newslot = localslot; + /* + * Detecting whether the tuple was recently deleted or + * never existed is crucial to avoid misleading the user + * during confict handling. + */ + if (MySubscription->retaindeadtuples && + FindDeletedTupleInLocalRel(partrel, + part_entry->localindexoid, + remoteslot_part, + &conflicttuple.xmin, + &conflicttuple.origin, + &conflicttuple.ts) && + conflicttuple.origin != replorigin_session_origin) + type = CT_UPDATE_DELETED; + else + type = CT_UPDATE_MISSING; + /* Store the new tuple for conflict reporting */ slot_store_data(newslot, part_entry, newtup); /* - * The tuple to be updated could not be found. Do nothing - * except for emitting a log message. + * The tuple to be updated could not be found or was + * deleted. Do nothing except for emitting a log message. */ ReportApplyConflict(estate, partrelinfo, LOG, - CT_UPDATE_MISSING, remoteslot_part, - newslot, list_make1(&conflicttuple)); + type, remoteslot_part, newslot, + list_make1(&conflicttuple)); return; } @@ -4172,8 +4305,8 @@ can_advance_nonremovable_xid(RetainDeadTuplesData *rdt_data) { /* * It is sufficient to manage non-removable transaction ID for a - * subscription by the main apply worker to detect conflicts reliably even - * for table sync or parallel apply workers. + * subscription by the main apply worker to detect update_deleted reliably + * even for table sync or parallel apply workers. */ if (!am_leader_apply_worker()) return false; @@ -4374,10 +4507,11 @@ wait_for_local_flush(RetainDeadTuplesData *rdt_data) * We expect the publisher and subscriber clocks to be in sync using time * sync service like NTP. Otherwise, we will advance this worker's * oldest_nonremovable_xid prematurely, leading to the removal of rows - * required to detect conflicts reliably. This check primarily addresses - * scenarios where the publisher's clock falls behind; if the publisher's - * clock is ahead, subsequent transactions will naturally bear later - * commit timestamps, conforming to the design outlined atop worker.c. + * required to detect update_deleted reliably. This check primarily + * addresses scenarios where the publisher's clock falls behind; if the + * publisher's clock is ahead, subsequent transactions will naturally bear + * later commit timestamps, conforming to the design outlined atop + * worker.c. * * XXX Consider waiting for the publisher's clock to catch up with the * subscriber's before proceeding to the next phase. diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 104b059544d..a71502efeed 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -14,6 +14,7 @@ #ifndef EXECUTOR_H #define EXECUTOR_H +#include "datatype/timestamp.h" #include "executor/execdesc.h" #include "fmgr.h" #include "nodes/lockoptions.h" @@ -759,7 +760,18 @@ extern bool RelationFindReplTupleByIndex(Relation rel, Oid idxoid, TupleTableSlot *outslot); extern bool RelationFindReplTupleSeq(Relation rel, LockTupleMode lockmode, TupleTableSlot *searchslot, TupleTableSlot *outslot); - +extern bool RelationFindDeletedTupleInfoSeq(Relation rel, + TupleTableSlot *searchslot, + TransactionId oldestxmin, + TransactionId *delete_xid, + RepOriginId *delete_origin, + TimestampTz *delete_time); +extern bool RelationFindDeletedTupleInfoByIndex(Relation rel, Oid idxoid, + TupleTableSlot *searchslot, + TransactionId oldestxmin, + TransactionId *delete_xid, + RepOriginId *delete_origin, + TimestampTz *delete_time); extern void ExecSimpleRelationInsert(ResultRelInfo *resultRelInfo, EState *estate, TupleTableSlot *slot); extern void ExecSimpleRelationUpdate(ResultRelInfo *resultRelInfo, diff --git a/src/include/replication/conflict.h b/src/include/replication/conflict.h index 6c59125f256..21340641224 100644 --- a/src/include/replication/conflict.h +++ b/src/include/replication/conflict.h @@ -32,6 +32,9 @@ typedef enum /* The updated row value violates unique constraint */ CT_UPDATE_EXISTS, + /* The row to be updated was deleted by a different origin */ + CT_UPDATE_DELETED, + /* The row to be updated is missing */ CT_UPDATE_MISSING, diff --git a/src/include/replication/worker_internal.h b/src/include/replication/worker_internal.h index 0c7b8440a61..7c0204dd6f4 100644 --- a/src/include/replication/worker_internal.h +++ b/src/include/replication/worker_internal.h @@ -87,8 +87,9 @@ typedef struct LogicalRepWorker bool parallel_apply; /* - * The changes made by this and later transactions must be retained to - * ensure reliable conflict detection during the apply phase. + * Changes made by this transaction and subsequent ones must be preserved. + * This ensures that update_deleted conflicts can be accurately detected + * during the apply phase of logical replication by this worker. * * The logical replication launcher manages an internal replication slot * named "pg_conflict_detection". It asynchronously collects this ID to diff --git a/src/test/subscription/t/035_conflicts.pl b/src/test/subscription/t/035_conflicts.pl index 976d53a870e..36aeb14c563 100644 --- a/src/test/subscription/t/035_conflicts.pl +++ b/src/test/subscription/t/035_conflicts.pl @@ -150,7 +150,9 @@ pass('multiple_unique_conflicts detected on a leaf partition during insert'); # Setup a bidirectional logical replication between node_A & node_B ############################################################################### -# Initialize nodes. +# Initialize nodes. Enable the track_commit_timestamp on both nodes to detect +# the conflict when attempting to update a row that was previously modified by +# a different origin. # node_A. Increase the log_min_messages setting to DEBUG2 to debug test # failures. Disable autovacuum to avoid generating xid that could affect the @@ -158,7 +160,8 @@ pass('multiple_unique_conflicts detected on a leaf partition during insert'); my $node_A = $node_publisher; $node_A->append_conf( 'postgresql.conf', - qq{autovacuum = off + qq{track_commit_timestamp = on + autovacuum = off log_min_messages = 'debug2'}); $node_A->restart; @@ -270,6 +273,8 @@ $node_A->psql('postgres', ############################################################################### # Check that dead tuples on node A cannot be cleaned by VACUUM until the # concurrent transactions on Node B have been applied and flushed on Node A. +# Also, check that an update_deleted conflict is detected when updating a row +# that was deleted by a different origin. ############################################################################### # Insert a record @@ -288,6 +293,8 @@ $node_A->poll_query_until('postgres', "SELECT count(*) = 0 FROM pg_stat_activity WHERE backend_type = 'logical replication apply worker'" ); +my $log_location = -s $node_B->logfile; + $node_B->safe_psql('postgres', "UPDATE tab SET b = 3 WHERE a = 1;"); $node_A->safe_psql('postgres', "DELETE FROM tab WHERE a = 1;"); @@ -299,10 +306,30 @@ ok( $stderr =~ qr/1 are dead but not yet removable/, 'the deleted column is non-removable'); +# Ensure the DELETE is replayed on Node B +$node_A->wait_for_catchup($subname_BA); + +# Check the conflict detected on Node B +my $logfile = slurp_file($node_B->logfile(), $log_location); +ok( $logfile =~ + qr/conflict detected on relation "public.tab": conflict=delete_origin_differs.* +.*DETAIL:.* Deleting the row that was modified locally in transaction [0-9]+ at .* +.*Existing local tuple \(1, 3\); replica identity \(a\)=\(1\)/, + 'delete target row was modified in tab'); + +$log_location = -s $node_A->logfile; + $node_A->safe_psql( 'postgres', "ALTER SUBSCRIPTION $subname_AB ENABLE;"); $node_B->wait_for_catchup($subname_AB); +$logfile = slurp_file($node_A->logfile(), $log_location); +ok( $logfile =~ + qr/conflict detected on relation "public.tab": conflict=update_deleted.* +.*DETAIL:.* The row to be updated was deleted locally in transaction [0-9]+ at .* +.*Remote tuple \(1, 3\); replica identity \(a\)=\(1\)/, + 'update target row was deleted in tab'); + # Remember the next transaction ID to be assigned my $next_xid = $node_A->safe_psql('postgres', "SELECT txid_current() + 1;"); @@ -324,6 +351,41 @@ ok( $stderr =~ qr/1 removed, 1 remain, 0 are dead but not yet removable/, 'the deleted column is removed'); +############################################################################### +# Ensure that the deleted tuple needed to detect an update_deleted conflict is +# accessible via a sequential table scan. +############################################################################### + +# Drop the primary key from tab on node A and set REPLICA IDENTITY to FULL to +# enforce sequential scanning of the table. +$node_A->safe_psql('postgres', "ALTER TABLE tab REPLICA IDENTITY FULL"); +$node_B->safe_psql('postgres', "ALTER TABLE tab REPLICA IDENTITY FULL"); +$node_A->safe_psql('postgres', "ALTER TABLE tab DROP CONSTRAINT tab_pkey;"); + +# Disable the logical replication from node B to node A +$node_A->safe_psql('postgres', "ALTER SUBSCRIPTION $subname_AB DISABLE"); + +# Wait for the apply worker to stop +$node_A->poll_query_until('postgres', + "SELECT count(*) = 0 FROM pg_stat_activity WHERE backend_type = 'logical replication apply worker'" +); + +$node_B->safe_psql('postgres', "UPDATE tab SET b = 4 WHERE a = 2;"); +$node_A->safe_psql('postgres', "DELETE FROM tab WHERE a = 2;"); + +$log_location = -s $node_A->logfile; + +$node_A->safe_psql( + 'postgres', "ALTER SUBSCRIPTION $subname_AB ENABLE;"); +$node_B->wait_for_catchup($subname_AB); + +$logfile = slurp_file($node_A->logfile(), $log_location); +ok( $logfile =~ + qr/conflict detected on relation "public.tab": conflict=update_deleted.* +.*DETAIL:.* The row to be updated was deleted locally in transaction [0-9]+ at .* +.*Remote tuple \(2, 4\); replica identity full \(2, 2\)/, + 'update target row was deleted in tab'); + ############################################################################### # Check that the replication slot pg_conflict_detection is dropped after # removing all the subscriptions. -- 2.31.1