Fix the missing table sync due to improper invalidation handling.

We missed performing table sync if the invalidation happened while the
non-ready tables list was being prepared. This occurs because the sync
state was set to valid at the end of non-ready table list preparation
irrespective of the invalidations processed while the list is being
prepared.

Fix it by changing the boolean variable to a tri-state enum and by setting
table state to valid only if no invalidations have occurred while the list
is being prepared.

Reprted-by: Alexander Lakhin
Diagnosed-by: Alexander Lakhin
Author: Vignesh C
Reviewed-by: Hou Zhijie, Alexander Lakhin, Ajin Cherian, Amit Kapila
Backpatch-through: 15
Discussion: https://postgr.es/m/711a6afe-edb7-1211-cc27-1bef8239eec7@gmail.com

diff --git a/src/backend/replication/logical/tablesync.c b/src/backend/replication/logical/tablesync.c
index f1a3ad54595500e1308cd4d22632f1166b6d9925..b00267f0427086bfe32f4f5c6d9ba627e4cbeb90 100644 (file)
--- a/src/backend/replication/logical/tablesync.c
+++ b/src/backend/replication/logical/tablesync.c
@@ -123,7 +123,14 @@
 #include "utils/syscache.h"
 #include "utils/usercontext.h"
 
-static bool table_states_valid = false;
+typedef enum
+{
+   SYNC_TABLE_STATE_NEEDS_REBUILD,
+   SYNC_TABLE_STATE_REBUILD_STARTED,
+   SYNC_TABLE_STATE_VALID,
+} SyncingTablesState;
+
+static SyncingTablesState table_states_validity = SYNC_TABLE_STATE_NEEDS_REBUILD;
 static List *table_states_not_ready = NIL;
 static bool FetchTableStates(bool *started_tx);
 
@@ -273,7 +280,7 @@ wait_for_worker_state_change(char expected_state)
 void
 invalidate_syncing_table_states(Datum arg, int cacheid, uint32 hashvalue)
 {
-   table_states_valid = false;
+   table_states_validity = SYNC_TABLE_STATE_NEEDS_REBUILD;
 }
 
 /*
@@ -1568,13 +1575,15 @@ FetchTableStates(bool *started_tx)
 
    *started_tx = false;
 
-   if (!table_states_valid)
+   if (table_states_validity != SYNC_TABLE_STATE_VALID)
    {
        MemoryContext oldctx;
        List       *rstates;
        ListCell   *lc;
        SubscriptionRelState *rstate;
 
+       table_states_validity = SYNC_TABLE_STATE_REBUILD_STARTED;
+
        /* Clean the old lists. */
        list_free_deep(table_states_not_ready);
        table_states_not_ready = NIL;
@@ -1608,7 +1617,15 @@ FetchTableStates(bool *started_tx)
        has_subrels = (table_states_not_ready != NIL) ||
            HasSubscriptionRelations(MySubscription->oid);
 
-       table_states_valid = true;
+       /*
+        * If the subscription relation cache has been invalidated since we
+        * entered this routine, we still use and return the relations we just
+        * finished constructing, to avoid infinite loops, but we leave the
+        * table states marked as stale so that we'll rebuild it again on next
+        * access. Otherwise, we mark the table states as valid.
+        */
+       if (table_states_validity == SYNC_TABLE_STATE_REBUILD_STARTED)
+           table_states_validity = SYNC_TABLE_STATE_VALID;
    }
 
    return has_subrels;

diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index d551ada3255c76986443de9db9b83a2318137d5c..90a7c389b2186593e436ceab36fb907edabd610a 100644 (file)
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2764,6 +2764,7 @@ SupportRequestSelectivity
 SupportRequestSimplify
 SupportRequestWFuncMonotonic
 Syn
+SyncingTablesState
 SyncOps
 SyncRepConfigData
 SyncRepStandbyData