Avoid repeating loads of frozen ID values.

Repeating loads of inplace-updated fields tends to cause bugs like the
one from the previous commit.  While there's no bug to fix in these code
sites, adopt the load-once style.  This improves the chance of future
copy/paste finding the safe style.

Discussion: https://postgr.es/m/20240423003956[email protected]

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 32e7d3c146436b36f1b5d4a736a529ac57143c7a..4be0dee4de0b544ed6f85ac6c135dd719d06013e 100644 (file)
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -5907,7 +5907,6 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
    Page        page;
    BlockNumber block;
    Buffer      buffer;
-   TransactionId prune_xid;
 
    Assert(ItemPointerIsValid(tid));
 
@@ -5960,11 +5959,16 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
     * TransactionXmin, so there's no race here).
     */
    Assert(TransactionIdIsValid(TransactionXmin));
-   if (TransactionIdPrecedes(TransactionXmin, relation->rd_rel->relfrozenxid))
-       prune_xid = relation->rd_rel->relfrozenxid;
-   else
-       prune_xid = TransactionXmin;
-   PageSetPrunable(page, prune_xid);
+   {
+       TransactionId relfrozenxid = relation->rd_rel->relfrozenxid;
+       TransactionId prune_xid;
+
+       if (TransactionIdPrecedes(TransactionXmin, relfrozenxid))
+           prune_xid = relfrozenxid;
+       else
+           prune_xid = TransactionXmin;
+       PageSetPrunable(page, prune_xid);
+   }
 
    /* store transaction information of xact deleting the tuple */
    tp.t_data->t_infomask &= ~(HEAP_XMAX_BITS | HEAP_MOVED);

diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index c04886c4090ababde2f19584c2c79e8a8aafd4db..78f96789b0e84dc0a246c9e0334455e0201c997b 100644 (file)
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -919,18 +919,24 @@ copy_table_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex, bool verbose,
     * FreezeXid will become the table's new relfrozenxid, and that mustn't go
     * backwards, so take the max.
     */
-   if (TransactionIdIsValid(OldHeap->rd_rel->relfrozenxid) &&
-       TransactionIdPrecedes(cutoffs.FreezeLimit,
-                             OldHeap->rd_rel->relfrozenxid))
-       cutoffs.FreezeLimit = OldHeap->rd_rel->relfrozenxid;
+   {
+       TransactionId relfrozenxid = OldHeap->rd_rel->relfrozenxid;
+
+       if (TransactionIdIsValid(relfrozenxid) &&
+           TransactionIdPrecedes(cutoffs.FreezeLimit, relfrozenxid))
+           cutoffs.FreezeLimit = relfrozenxid;
+   }
 
    /*
     * MultiXactCutoff, similarly, shouldn't go backwards either.
     */
-   if (MultiXactIdIsValid(OldHeap->rd_rel->relminmxid) &&
-       MultiXactIdPrecedes(cutoffs.MultiXactCutoff,
-                           OldHeap->rd_rel->relminmxid))
-       cutoffs.MultiXactCutoff = OldHeap->rd_rel->relminmxid;
+   {
+       MultiXactId relminmxid = OldHeap->rd_rel->relminmxid;
+
+       if (MultiXactIdIsValid(relminmxid) &&
+           MultiXactIdPrecedes(cutoffs.MultiXactCutoff, relminmxid))
+           cutoffs.MultiXactCutoff = relminmxid;
+   }
 
    /*
     * Decide whether to use an indexscan or seqscan-and-optional-sort to scan

diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index a63a71c984de017d7f0b5bbb2022f92701fc4a59..521ee74586a6e4e39dc1779c9d27df7cfdd4f6b4 100644 (file)
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -1200,7 +1200,7 @@ vacuum_get_cutoffs(Relation rel, const VacuumParams *params,
    aggressiveXIDCutoff = nextXID - freeze_table_age;
    if (!TransactionIdIsNormal(aggressiveXIDCutoff))
        aggressiveXIDCutoff = FirstNormalTransactionId;
-   if (TransactionIdPrecedesOrEquals(rel->rd_rel->relfrozenxid,
+   if (TransactionIdPrecedesOrEquals(cutoffs->relfrozenxid,
                                      aggressiveXIDCutoff))
        return true;
 
@@ -1221,7 +1221,7 @@ vacuum_get_cutoffs(Relation rel, const VacuumParams *params,
    aggressiveMXIDCutoff = nextMXID - multixact_freeze_table_age;
    if (aggressiveMXIDCutoff < FirstMultiXactId)
        aggressiveMXIDCutoff = FirstMultiXactId;
-   if (MultiXactIdPrecedesOrEquals(rel->rd_rel->relminmxid,
+   if (MultiXactIdPrecedesOrEquals(cutoffs->relminmxid,
                                    aggressiveMXIDCutoff))
        return true;
 

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index c367ede6f88530eb725fcb18b42f566b87443afa..9a925a10cdc7df3b77949b6197e83c0c46de28b8 100644 (file)
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -2938,6 +2938,7 @@ relation_needs_vacanalyze(Oid relid,
    int         freeze_max_age;
    int         multixact_freeze_max_age;
    TransactionId xidForceLimit;
+   TransactionId relfrozenxid;
    MultiXactId multiForceLimit;
 
    Assert(classForm != NULL);
@@ -2989,16 +2990,18 @@ relation_needs_vacanalyze(Oid relid,
    xidForceLimit = recentXid - freeze_max_age;
    if (xidForceLimit < FirstNormalTransactionId)
        xidForceLimit -= FirstNormalTransactionId;
-   force_vacuum = (TransactionIdIsNormal(classForm->relfrozenxid) &&
-                   TransactionIdPrecedes(classForm->relfrozenxid,
-                                         xidForceLimit));
+   relfrozenxid = classForm->relfrozenxid;
+   force_vacuum = (TransactionIdIsNormal(relfrozenxid) &&
+                   TransactionIdPrecedes(relfrozenxid, xidForceLimit));
    if (!force_vacuum)
    {
+       MultiXactId relminmxid = classForm->relminmxid;
+
        multiForceLimit = recentMulti - multixact_freeze_max_age;
        if (multiForceLimit < FirstMultiXactId)
            multiForceLimit -= FirstMultiXactId;
-       force_vacuum = MultiXactIdIsValid(classForm->relminmxid) &&
-           MultiXactIdPrecedes(classForm->relminmxid, multiForceLimit);
+       force_vacuum = MultiXactIdIsValid(relminmxid) &&
+           MultiXactIdPrecedes(relminmxid, multiForceLimit);
    }
    *wraparound = force_vacuum;