Fix broken logic in logical_heap_rewrite_flush_mappings().

It's blatantly obvious that commit 4d0d607a454ee832574afd52a3c515099cc85eb3
wasn't tested.  The leak's real enough, though.

diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 4cf07eaa2e4cfae2e2928a75599fd3e90d40caca..ef8c12194c7773f3918946196aee8fc82ffb5a0b 100644 (file)
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -897,8 +897,7 @@ logical_heap_rewrite_flush_mappings(RewriteState state)
 
                /* write all mappings consecutively */
                len = src->num_mappings * sizeof(LogicalRewriteMappingData);
-               waldata = palloc(len);
-               waldata_start = waldata;
+               waldata_start = waldata = palloc(len);
 
                /*
                 * collect data we need to write out, but don't modify ondisk data yet
@@ -921,6 +920,9 @@ logical_heap_rewrite_flush_mappings(RewriteState state)
                        src->num_mappings--;
                }
 
+               Assert(src->num_mappings == 0);
+               Assert(waldata == waldata_start + len);
+
                /*
                 * Note that we deviate from the usual WAL coding practices here,
                 * check the above "Logical rewrite support" comment for reasoning.
@@ -933,8 +935,6 @@ logical_heap_rewrite_flush_mappings(RewriteState state)
                                                        written, len)));
                src->off += len;
 
-               Assert(src->num_mappings == 0);
-
                rdata[1].data = waldata_start;
                rdata[1].len = len;
                rdata[1].buffer = InvalidBuffer;
@@ -943,6 +943,7 @@ logical_heap_rewrite_flush_mappings(RewriteState state)
                /* write xlog record */
                XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_REWRITE, rdata);
 
+               pfree(waldata_start);
        }
        Assert(state->rs_num_rewrite_mappings == 0);
 }