Kluge slot_compile_deform() to ignore incorrect attnotnull markings.

Since we mustn't force an initdb in released branches, there is no
simple way to correct the markings of pg_subscription.subslotname
and pg_subscription_rel.srsublsn as attnotnull in existing pre-v13
installations.

Fortunately, released branches don't rely on attnotnull being correct
for much.  The planner looks at it in relation_excluded_by_constraints,
but it'd be difficult to get that to matter for a query on a system
catalog.  The only place where it's really problematic is in JIT's
slot_compile_deform(), which can produce incorrect code that crashes
if there are NULLs in an allegedly not-null column.

Hence, hack up slot_compile_deform() to be specifically aware of
these two incorrect markings and not trust them.

This applies to v11 and v12; the JIT code didn't exist before that,
and we've fixed the markings in v13.

Discussion: https://postgr.es/m/229396.1595191345@sss.pgh.pa.us

diff --git a/src/backend/jit/llvm/llvmjit_deform.c b/src/backend/jit/llvm/llvmjit_deform.c
index 835aea83e973de8666c788867f524527592cd6d7..409fc9e852577bb2769937af9fb1e5dfcb64ec44 100644 (file)
--- a/src/backend/jit/llvm/llvmjit_deform.c
+++ b/src/backend/jit/llvm/llvmjit_deform.c
@@ -22,11 +22,27 @@
 
 #include "access/htup_details.h"
 #include "access/tupdesc_details.h"
+#include "catalog/pg_subscription.h"
+#include "catalog/pg_subscription_rel.h"
 #include "executor/tuptable.h"
 #include "jit/llvmjit.h"
 #include "jit/llvmjit_emit.h"
 
 
+/*
+ * Through an embarrassing oversight, pre-v13 installations may have
+ * pg_subscription.subslotname and pg_subscription_rel.srsublsn marked as
+ * attnotnull, which they should not be.  To avoid possible crashes, use
+ * this macro instead of testing attnotnull directly.
+ */
+#define ATTNOTNULL(att) \
+   ((att)->attnotnull && \
+    !(((att)->attrelid == SubscriptionRelationId && \
+       (att)->attnum == Anum_pg_subscription_subslotname) || \
+      ((att)->attrelid == SubscriptionRelRelationId && \
+       (att)->attnum == Anum_pg_subscription_rel_srsublsn)))
+
+
 /*
  * Create a function that deforms a tuple of type desc up to natts columns.
  */
@@ -121,7 +137,7 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc,
         * combination of attisdropped && attnotnull combination shouldn't
         * exist.
         */
-       if (att->attnotnull &&
+       if (ATTNOTNULL(att) &&
            !att->atthasmissing &&
            !att->attisdropped)
            guaranteed_column_number = attnum;
@@ -419,7 +435,7 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc,
         * into account, because if they're present the heaptuple's natts
         * would have indicated that a slot_getmissingattrs() is needed.
         */
-       if (!att->attnotnull)
+       if (!ATTNOTNULL(att))
        {
            LLVMBasicBlockRef b_ifnotnull;
            LLVMBasicBlockRef b_ifnull;
@@ -600,7 +616,7 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc,
            known_alignment = -1;
            attguaranteedalign = false;
        }
-       else if (att->attnotnull && attguaranteedalign && known_alignment >= 0)
+       else if (ATTNOTNULL(att) && attguaranteedalign && known_alignment >= 0)
        {
            /*
             * If the offset to the column was previously known, a NOT NULL &
@@ -610,7 +626,7 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc,
            Assert(att->attlen > 0);
            known_alignment += att->attlen;
        }
-       else if (att->attnotnull && (att->attlen % alignto) == 0)
+       else if (ATTNOTNULL(att) && (att->attlen % alignto) == 0)
        {
            /*
             * After a NOT NULL fixed-width column with a length that is a

diff --git a/src/test/regress/expected/subscription.out b/src/test/regress/expected/subscription.out
index e7add9d2b81be9b9c1d2e7634fcec1596613c781..3ba1e5dcdd5a299115750f9be6fefbce544bf41c 100644 (file)
--- a/src/test/regress/expected/subscription.out
+++ b/src/test/regress/expected/subscription.out
@@ -147,6 +147,13 @@ DROP SUBSCRIPTION regress_testsub;
 ERROR:  DROP SUBSCRIPTION cannot run inside a transaction block
 COMMIT;
 ALTER SUBSCRIPTION regress_testsub SET (slot_name = NONE);
+\dRs+
+                                                      List of subscriptions
+      Name       |           Owner            | Enabled |     Publication     | Synchronous commit |           Conninfo           
+-----------------+----------------------------+---------+---------------------+--------------------+------------------------------
+ regress_testsub | regress_subscription_user2 | f       | {testpub2,testpub3} | local              | dbname=regress_doesnotexist2
+(1 row)
+
 -- now it works
 BEGIN;
 DROP SUBSCRIPTION regress_testsub;

diff --git a/src/test/regress/sql/subscription.sql b/src/test/regress/sql/subscription.sql
index 9e234ab8b3f7be6a20daa747a34742fd0977ec20..1bc58887f7ed50af809810754aab3f217ad75097 100644 (file)
--- a/src/test/regress/sql/subscription.sql
+++ b/src/test/regress/sql/subscription.sql
@@ -109,6 +109,8 @@ COMMIT;
 
 ALTER SUBSCRIPTION regress_testsub SET (slot_name = NONE);
 
+\dRs+
+
 -- now it works
 BEGIN;
 DROP SUBSCRIPTION regress_testsub;