Fetch minmxid from remote nodes and compute local value

This was a TODO for quite sometime now. Just like we fetch relfrozenxid from
the remote nodes and compute a value at the coordinator, we now do the same for
multi-xid too.

diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index e0f2300e8c0ea5215d81d3751122b8bf8b566a4e..e0d8901d60739d371b32473159d05a6e45bbedb6 100644 (file)
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -1693,7 +1693,9 @@ make_relation_tle(Oid reloid, const char *relname, const char *column)
 static int
 get_remote_relstat(char *nspname, char *relname, bool istemp, bool replicated,
                                   int32 *pages, int32 *allvisiblepages,
-                                  float4 *tuples, TransactionId *frozenXid)
+                                  float4 *tuples,
+                                  TransactionId *frozenXid,
+                                  MultiXactId *multiXid)
 {
        StringInfoData query;
        EState     *estate;
@@ -1704,7 +1706,8 @@ get_remote_relstat(char *nspname, char *relname, bool istemp, bool replicated,
        int                     validpages,
                                validtuples,
                                validfrozenxids,
-                               validallvisiblepages;
+                               validallvisiblepages,
+                               validminmxids;
 
        /* Make up query string */
        initStringInfo(&query);
@@ -1719,7 +1722,8 @@ get_remote_relstat(char *nspname, char *relname, bool istemp, bool replicated,
                appendStringInfo(&query, "SELECT c.relpages, "
                                "c.reltuples, "
                                "c.relallvisible, "
-                               "c.relfrozenxid "
+                               "c.relfrozenxid, "
+                               "c.relminmxid "
                                "FROM pg_class c "
                                "WHERE c.relnamespace = pg_my_temp_schema() "
                                "AND c.relname = '%s'",
@@ -1728,7 +1732,8 @@ get_remote_relstat(char *nspname, char *relname, bool istemp, bool replicated,
                appendStringInfo(&query, "SELECT c.relpages, "
                                "c.reltuples, "
                                "c.relallvisible, "
-                               "c.relfrozenxid "
+                               "c.relfrozenxid, "
+                               "c.relminmxid "
                                "FROM pg_class c JOIN pg_namespace n "
                                "ON c.relnamespace = n.oid "
                                "WHERE n.nspname = '%s' "
@@ -1760,6 +1765,10 @@ get_remote_relstat(char *nspname, char *relname, bool istemp, bool replicated,
                                                                                 make_relation_tle(RelationRelationId,
                                                                                                                   "pg_class",
                                                                                                                   "relfrozenxid"));
+       step->scan.plan.targetlist = lappend(step->scan.plan.targetlist,
+                                                                                make_relation_tle(RelationRelationId,
+                                                                                                                  "pg_class",
+                                                                                                                  "relminmxid"));
 
        /* Execute query on the data nodes */
        estate = CreateExecutorState();
@@ -1775,10 +1784,12 @@ get_remote_relstat(char *nspname, char *relname, bool istemp, bool replicated,
        *allvisiblepages = 0;
        *tuples = 0.0;
        *frozenXid = InvalidTransactionId;
+       *multiXid = InvalidMultiXactId;
        validpages = 0;
        validallvisiblepages = 0;
        validtuples = 0;
        validfrozenxids = 0;
+       validminmxids = 0;
        result = ExecRemoteQuery((PlanState *) node);
        while (result != NULL && !TupIsNull(result))
        {
@@ -1814,13 +1825,26 @@ get_remote_relstat(char *nspname, char *relname, bool istemp, bool replicated,
                        if (TransactionIdIsValid(xid))
                        {
                                validfrozenxids++;
-                               if (!TransactionIdIsValid(*frozenXid) ||
-                                               TransactionIdPrecedes(xid, *frozenXid))
-                               {
+                               if (!TransactionIdIsValid(*frozenXid) || TransactionIdPrecedes(xid, *frozenXid))
                                        *frozenXid = xid;
-                               }
                        }
                }
+               value = slot_getattr(result, 5, &isnull); /* relminmxid */
+               if (!isnull)
+               {
+                       /*
+                        * relminmxid on coordinator should be the lowest one from the
+                        * datanodes.
+                        */
+                       MultiXactId mxid = DatumGetTransactionId(value);
+                       if (MultiXactIdIsValid(mxid))
+                       {
+                               validminmxids++;
+                               if (!MultiXactIdIsValid(*multiXid) || MultiXactIdPrecedes(mxid, *multiXid))
+                                       *multiXid = mxid;
+                       }
+               }
+
                /* fetch next */
                result = ExecRemoteQuery((PlanState *) node);
        }
@@ -1843,22 +1867,20 @@ get_remote_relstat(char *nspname, char *relname, bool istemp, bool replicated,
                        *allvisiblepages /= validallvisiblepages;
        }
 
+       /*
+        * If some node returned invalid value for frozenxid we can not set
+        * it on coordinator. There are other cases when returned value of
+        * frozenXid should be ignored, these cases are checked by caller.
+        * Basically, to be sure, there should be one value from each node,
+        * where the table is partitioned.
+        */
        if (validfrozenxids < validpages || validfrozenxids < validtuples)
-       {
-               /*
-                * If some node returned invalid value for frozenxid we can not set
-                * it on coordinator. There are other cases when returned value of
-                * frozenXid should be ignored, these cases are checked by caller.
-                * Basically, to be sure, there should be one value from each node,
-                * where the table is partitioned.
-                */
                *frozenXid = InvalidTransactionId;
-               return Max(validpages, validtuples);
-       }
-       else
-       {
-               return validfrozenxids;
-       }
+
+       if (validminmxids < validpages || validminmxids < validtuples)
+               *multiXid = InvalidMultiXactId;
+
+       return Max(validpages, validtuples);
 }
 
 
@@ -1877,6 +1899,7 @@ vacuum_rel_coordinator(Relation onerel, bool is_outer)
        int32           num_allvisible_pages;
        float4          num_tuples;
        TransactionId min_frozenxid;
+       MultiXactId     min_mxid;
        bool            hasindex;
        bool            replicated;
        int             rel_nodes;
@@ -1894,7 +1917,9 @@ vacuum_rel_coordinator(Relation onerel, bool is_outer)
         */
        rel_nodes = get_remote_relstat(nspname, relname, istemp, replicated,
                                                                   &num_pages, &num_allvisible_pages,
-                                                                  &num_tuples, &min_frozenxid);
+                                                                  &num_tuples,
+                                                                  &min_frozenxid,
+                                                                  &min_mxid);
        if (rel_nodes > 0)
        {
                int                     nindexes;
@@ -1913,7 +1938,8 @@ vacuum_rel_coordinator(Relation onerel, bool is_outer)
                        {
                                int32   idx_pages, idx_allvisible_pages;
                                float4  idx_tuples;
-                               TransactionId idx_frozenxid;
+                               TransactionId   idx_frozenxid;
+                               MultiXactId             idx_mxid;
                                int idx_nodes;
 
                                /* Get the index identifier */
@@ -1923,7 +1949,8 @@ vacuum_rel_coordinator(Relation onerel, bool is_outer)
                                idx_nodes = get_remote_relstat(nspname, relname, istemp,
                                                                                replicated,
                                                                                &idx_pages, &idx_allvisible_pages,
-                                                                               &idx_tuples, &idx_frozenxid);
+                                                                               &idx_tuples, &idx_frozenxid,
+                                                                               &idx_mxid);
                                if (idx_nodes > 0)
                                {
                                        /*
@@ -1942,7 +1969,7 @@ vacuum_rel_coordinator(Relation onerel, bool is_outer)
                                                                                0,
                                                                                false,
                                                                                idx_frozenxid,
-                                                                               InvalidMultiXactId,
+                                                                               idx_mxid,
                                                                                is_outer);
                                }
                        }
@@ -1958,6 +1985,7 @@ vacuum_rel_coordinator(Relation onerel, bool is_outer)
                if (rel_nodes < nodes)
                {
                        min_frozenxid = InvalidTransactionId;
+                       min_mxid = InvalidMultiXactId;
                }
 
                /* save changes */
@@ -1967,7 +1995,7 @@ vacuum_rel_coordinator(Relation onerel, bool is_outer)
                                                        num_allvisible_pages,
                                                        hasindex,
                                                        min_frozenxid,
-                                                       InvalidMultiXactId,
+                                                       min_mxid,
                                                        is_outer);
        }
 }