Fix memory leak in Memoize code

Ensure we switch to the per-tuple memory context to prevent any memory
leaks of detoasted Datums in MemoizeHash_hash() and MemoizeHash_equal().

Reported-by: Orlov Aleksej
Author: Orlov Aleksej, David Rowley
Discussion: https://postgr.es/m/83281eed63c74e4f940317186372abfd%40cft.ru
Backpatch-through: 14, where Memoize was added

diff --git a/src/backend/executor/nodeMemoize.c b/src/backend/executor/nodeMemoize.c
index 94bf4792873a8ce18dd5919df784c2f00eae83df..1085b3c79dd3cce053bd24d20147e0234d9d1b59 100644 (file)
--- a/src/backend/executor/nodeMemoize.c
+++ b/src/backend/executor/nodeMemoize.c
@@ -158,10 +158,14 @@ static uint32
 MemoizeHash_hash(struct memoize_hash *tb, const MemoizeKey *key)
 {
    MemoizeState *mstate = (MemoizeState *) tb->private_data;
+   ExprContext *econtext = mstate->ss.ps.ps_ExprContext;
+   MemoryContext oldcontext;
    TupleTableSlot *pslot = mstate->probeslot;
    uint32      hashkey = 0;
    int         numkeys = mstate->nkeys;
 
+   oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
+
    if (mstate->binary_mode)
    {
        for (int i = 0; i < numkeys; i++)
@@ -203,6 +207,8 @@ MemoizeHash_hash(struct memoize_hash *tb, const MemoizeKey *key)
        }
    }
 
+   ResetExprContext(econtext);
+   MemoryContextSwitchTo(oldcontext);
    return murmurhash32(hashkey);
 }
 
@@ -226,7 +232,11 @@ MemoizeHash_equal(struct memoize_hash *tb, const MemoizeKey *key1,
 
    if (mstate->binary_mode)
    {
+       MemoryContext oldcontext;
        int         numkeys = mstate->nkeys;
+       bool        match = true;
+
+       oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
 
        slot_getallattrs(tslot);
        slot_getallattrs(pslot);
@@ -236,7 +246,10 @@ MemoizeHash_equal(struct memoize_hash *tb, const MemoizeKey *key1,
            FormData_pg_attribute *attr;
 
            if (tslot->tts_isnull[i] != pslot->tts_isnull[i])
-               return false;
+           {
+               match = false;
+               break;
+           }
 
            /* both NULL? they're equal */
            if (tslot->tts_isnull[i])
@@ -246,9 +259,15 @@ MemoizeHash_equal(struct memoize_hash *tb, const MemoizeKey *key1,
            attr = &tslot->tts_tupleDescriptor->attrs[i];
            if (!datum_image_eq(tslot->tts_values[i], pslot->tts_values[i],
                                attr->attbyval, attr->attlen))
-               return false;
+           {
+               match = false;
+               break;
+           }
        }
-       return true;
+
+       ResetExprContext(econtext);
+       MemoryContextSwitchTo(oldcontext);
+       return match;
    }
    else
    {