]> granicus.if.org Git - postgresql/commitdiff
logical decoding: Fix handling of large old tuples with replica identity full.
authorAndres Freund <andres@anarazel.de>
Sun, 6 Mar 2016 02:02:20 +0000 (18:02 -0800)
committerAndres Freund <andres@anarazel.de>
Sun, 6 Mar 2016 02:02:20 +0000 (18:02 -0800)
When decoding the old version of an UPDATE or DELETE change, and if that
tuple was bigger than MaxHeapTupleSize, we either Assert'ed out, or
failed in more subtle ways in non-assert builds.  Normally individual
tuples aren't bigger than MaxHeapTupleSize, with big datums toasted.
But that's not the case for the old version of a tuple for logical
decoding; the replica identity is logged as one piece. With the default
replica identity btree limits that to small tuples, but that's not the
case for FULL.

Change the tuple buffer infrastructure to separate allocate over-large
tuples, instead of always going through the slab cache.

This unfortunately requires changing the ReorderBufferTupleBuf
definition, we need to store the allocated size someplace. To avoid
requiring output plugins to recompile, don't store HeapTupleHeaderData
directly after HeapTupleData, but point to it via t_data; that leaves
rooms for the allocated size.  As there's no reason for an output plugin
to look at ReorderBufferTupleBuf->t_data.header, remove the field. It
was just a minor convenience having it directly accessible.

Reported-By: Adam DratwiƄski
Discussion: CAKg6ypLd7773AOX4DiOGRwQk1TVOQKhNwjYiVjJnpq8Wo+i62Q@mail.gmail.com

contrib/test_decoding/expected/toast.out
contrib/test_decoding/sql/toast.sql
src/backend/replication/logical/decode.c
src/backend/replication/logical/reorderbuffer.c
src/include/replication/reorderbuffer.h

index 735b14c9786db5d211b985cafb2c240096c0983b..389748ff8c106a2bfd8468a2a834389fe414ec5d 100644 (file)
@@ -292,6 +292,64 @@ SELECT substr(data, 1, 200) FROM pg_logical_slot_get_changes('regression_slot',
  COMMIT
 (235 rows)
 
+-- test we can decode "old" tuples bigger than the max heap tuple size correctly
+DROP TABLE IF EXISTS toasted_several;
+NOTICE:  table "toasted_several" does not exist, skipping
+CREATE TABLE toasted_several (
+    id serial unique not null,
+    toasted_key text primary key,
+    toasted_col1 text,
+    toasted_col2 text
+);
+ALTER TABLE toasted_several REPLICA IDENTITY FULL;
+ALTER TABLE toasted_several ALTER COLUMN toasted_key SET STORAGE EXTERNAL;
+ALTER TABLE toasted_several ALTER COLUMN toasted_col1 SET STORAGE EXTERNAL;
+ALTER TABLE toasted_several ALTER COLUMN toasted_col2 SET STORAGE EXTERNAL;
+INSERT INTO toasted_several(toasted_key) VALUES(repeat('9876543210', 2000));
+SELECT regexp_replace(data, '^(.{100}).*(.{100})$', '\1..\2') FROM pg_logical_slot_peek_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+                                                                                               regexp_replace                                                                                               
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ BEGIN
+ table public.toasted_several: INSERT: id[integer]:1 toasted_key[text]:'98765432109876543210987654321..098765432109876543210987654321098765432109876543210' toasted_col1[text]:null toasted_col2[text]:null
+ COMMIT
+(3 rows)
+
+-- test update of a toasted key without changing it
+UPDATE toasted_several SET toasted_col1 = toasted_key;
+UPDATE toasted_several SET toasted_col2 = toasted_col1;
+SELECT regexp_replace(data, '^(.{100}).*(.{100})$', '\1..\2') FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+                                                                                               regexp_replace                                                                                               
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ BEGIN
+ table public.toasted_several: INSERT: id[integer]:1 toasted_key[text]:'98765432109876543210987654321..098765432109876543210987654321098765432109876543210' toasted_col1[text]:null toasted_col2[text]:null
+ COMMIT
+ BEGIN
+ table public.toasted_several: UPDATE: old-key: id[integer]:1 toasted_key[text]:'98765432109876543210..432109876543210987654321098765432109876543210987654321098765432109876543210' toasted_col2[text]:null
+ COMMIT
+ BEGIN
+ table public.toasted_several: UPDATE: old-key: id[integer]:1 toasted_key[text]:'98765432109876543210..876543210987654321098765432109876543210987654321098765432109876543210987654321098765432109876543210'
+ COMMIT
+(9 rows)
+
+/*
+ * update with large tuplebuf, in a transaction large enough to force to spool to disk
+ */
+BEGIN;
+INSERT INTO toasted_several(toasted_key) SELECT * FROM generate_series(1, 10234);
+UPDATE toasted_several SET toasted_col1 = toasted_col2 WHERE id = 1;
+DELETE FROM toasted_several WHERE id = 1;
+COMMIT;
+DROP TABLE toasted_several;
+SELECT regexp_replace(data, '^(.{100}).*(.{100})$', '\1..\2') FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1')
+WHERE data NOT LIKE '%INSERT: %';
+                                                                                               regexp_replace                                                                                               
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ BEGIN
+ table public.toasted_several: UPDATE: old-key: id[integer]:1 toasted_key[text]:'98765432109876543210..7654321098765432109876543210987654321098765432109876543210' toasted_col2[text]:unchanged-toast-datum
+ table public.toasted_several: DELETE: id[integer]:1 toasted_key[text]:'98765432109876543210987654321..876543210987654321098765432109876543210987654321098765432109876543210987654321098765432109876543210'
+ COMMIT
+(4 rows)
+
 SELECT pg_drop_replication_slot('regression_slot');
  pg_drop_replication_slot 
 --------------------------
index 26d6b4fbdd6f330ec14f482093ada8d44c1637ce..dcb74e38c77dbf7c55e6e9c0abc73b7c5c37385e 100644 (file)
@@ -265,4 +265,41 @@ ALTER TABLE toasted_copy ALTER COLUMN data SET STORAGE EXTERNAL;
 203    untoasted200
 \.
 SELECT substr(data, 1, 200) FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+
+-- test we can decode "old" tuples bigger than the max heap tuple size correctly
+DROP TABLE IF EXISTS toasted_several;
+CREATE TABLE toasted_several (
+    id serial unique not null,
+    toasted_key text primary key,
+    toasted_col1 text,
+    toasted_col2 text
+);
+ALTER TABLE toasted_several REPLICA IDENTITY FULL;
+ALTER TABLE toasted_several ALTER COLUMN toasted_key SET STORAGE EXTERNAL;
+ALTER TABLE toasted_several ALTER COLUMN toasted_col1 SET STORAGE EXTERNAL;
+ALTER TABLE toasted_several ALTER COLUMN toasted_col2 SET STORAGE EXTERNAL;
+
+INSERT INTO toasted_several(toasted_key) VALUES(repeat('9876543210', 2000));
+
+SELECT regexp_replace(data, '^(.{100}).*(.{100})$', '\1..\2') FROM pg_logical_slot_peek_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+
+-- test update of a toasted key without changing it
+UPDATE toasted_several SET toasted_col1 = toasted_key;
+UPDATE toasted_several SET toasted_col2 = toasted_col1;
+
+SELECT regexp_replace(data, '^(.{100}).*(.{100})$', '\1..\2') FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+
+/*
+ * update with large tuplebuf, in a transaction large enough to force to spool to disk
+ */
+BEGIN;
+INSERT INTO toasted_several(toasted_key) SELECT * FROM generate_series(1, 10234);
+UPDATE toasted_several SET toasted_col1 = toasted_col2 WHERE id = 1;
+DELETE FROM toasted_several WHERE id = 1;
+COMMIT;
+
+DROP TABLE toasted_several;
+
+SELECT regexp_replace(data, '^(.{100}).*(.{100})$', '\1..\2') FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1')
+WHERE data NOT LIKE '%INSERT: %';
 SELECT pg_drop_replication_slot('regression_slot');
index 33e4343cc224528fe82d44222555c782295ca5d2..36e6d9a5c90f41c5e45a23de603d99367e47a4c6 100644 (file)
@@ -610,7 +610,8 @@ DecodeInsert(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
                Size            tuplelen;
                char       *tupledata = XLogRecGetBlockData(r, 0, &tuplelen);
 
-               change->data.tp.newtuple = ReorderBufferGetTupleBuf(ctx->reorder);
+               change->data.tp.newtuple =
+                       ReorderBufferGetTupleBuf(ctx->reorder, tuplelen);
 
                DecodeXLogTuple(tupledata, tuplelen, change->data.tp.newtuple);
        }
@@ -656,7 +657,8 @@ DecodeUpdate(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
        {
                data = XLogRecGetBlockData(r, 0, &datalen);
 
-               change->data.tp.newtuple = ReorderBufferGetTupleBuf(ctx->reorder);
+               change->data.tp.newtuple =
+                       ReorderBufferGetTupleBuf(ctx->reorder, datalen);
 
                DecodeXLogTuple(data, datalen, change->data.tp.newtuple);
        }
@@ -667,7 +669,8 @@ DecodeUpdate(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
                data = XLogRecGetData(r) + SizeOfHeapUpdate;
                datalen = XLogRecGetDataLen(r) - SizeOfHeapUpdate;
 
-               change->data.tp.oldtuple = ReorderBufferGetTupleBuf(ctx->reorder);
+               change->data.tp.oldtuple =
+                       ReorderBufferGetTupleBuf(ctx->reorder, datalen);
 
                DecodeXLogTuple(data, datalen, change->data.tp.oldtuple);
        }
@@ -717,13 +720,15 @@ DecodeDelete(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
        /* old primary key stored */
        if (xlrec->flags & XLH_DELETE_CONTAINS_OLD)
        {
+               Size            len = XLogRecGetDataLen(r) - SizeOfHeapDelete;
+
                Assert(XLogRecGetDataLen(r) > (SizeOfHeapDelete + SizeOfHeapHeader));
 
-               change->data.tp.oldtuple = ReorderBufferGetTupleBuf(ctx->reorder);
+               change->data.tp.oldtuple =
+                       ReorderBufferGetTupleBuf(ctx->reorder, len);
 
                DecodeXLogTuple((char *) xlrec + SizeOfHeapDelete,
-                                               XLogRecGetDataLen(r) - SizeOfHeapDelete,
-                                               change->data.tp.oldtuple);
+                                               len, change->data.tp.oldtuple);
        }
 
        change->data.tp.clear_toast_afterwards = true;
@@ -783,35 +788,39 @@ DecodeMultiInsert(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
                 */
                if (xlrec->flags & XLH_INSERT_CONTAINS_NEW_TUPLE)
                {
-                       change->data.tp.newtuple = ReorderBufferGetTupleBuf(ctx->reorder);
+                       HeapTupleHeader header;
+
+                       xlhdr = (xl_multi_insert_tuple *) SHORTALIGN(data);
+                       data = ((char *) xlhdr) + SizeOfMultiInsertTuple;
+                       datalen = xlhdr->datalen;
+
+                       change->data.tp.newtuple =
+                               ReorderBufferGetTupleBuf(ctx->reorder, datalen);
 
                        tuple = change->data.tp.newtuple;
+                       header = tuple->tuple.t_data;
 
                        /* not a disk based tuple */
                        ItemPointerSetInvalid(&tuple->tuple.t_self);
 
-                       xlhdr = (xl_multi_insert_tuple *) SHORTALIGN(data);
-                       data = ((char *) xlhdr) + SizeOfMultiInsertTuple;
-                       datalen = xlhdr->datalen;
-
                        /*
                         * We can only figure this out after reassembling the
                         * transactions.
                         */
                        tuple->tuple.t_tableOid = InvalidOid;
-                       tuple->tuple.t_data = &tuple->t_data.header;
+
                        tuple->tuple.t_len = datalen + SizeofHeapTupleHeader;
 
-                       memset(&tuple->t_data.header, 0, SizeofHeapTupleHeader);
+                       memset(header, 0, SizeofHeapTupleHeader);
 
-                       memcpy((char *) &tuple->t_data.header + SizeofHeapTupleHeader,
+                       memcpy((char *) tuple->tuple.t_data + SizeofHeapTupleHeader,
                                   (char *) data,
                                   datalen);
                        data += datalen;
 
-                       tuple->t_data.header.t_infomask = xlhdr->t_infomask;
-                       tuple->t_data.header.t_infomask2 = xlhdr->t_infomask2;
-                       tuple->t_data.header.t_hoff = xlhdr->t_hoff;
+                       header->t_infomask = xlhdr->t_infomask;
+                       header->t_infomask2 = xlhdr->t_infomask2;
+                       header->t_hoff = xlhdr->t_hoff;
                }
 
                /*
@@ -877,31 +886,31 @@ DecodeXLogTuple(char *data, Size len, ReorderBufferTupleBuf *tuple)
 {
        xl_heap_header xlhdr;
        int                     datalen = len - SizeOfHeapHeader;
+       HeapTupleHeader header;
 
        Assert(datalen >= 0);
-       Assert(datalen <= MaxHeapTupleSize);
 
        tuple->tuple.t_len = datalen + SizeofHeapTupleHeader;
+       header = tuple->tuple.t_data;
 
        /* not a disk based tuple */
        ItemPointerSetInvalid(&tuple->tuple.t_self);
 
        /* we can only figure this out after reassembling the transactions */
        tuple->tuple.t_tableOid = InvalidOid;
-       tuple->tuple.t_data = &tuple->t_data.header;
 
        /* data is not stored aligned, copy to aligned storage */
        memcpy((char *) &xlhdr,
                   data,
                   SizeOfHeapHeader);
 
-       memset(&tuple->t_data.header, 0, SizeofHeapTupleHeader);
+       memset(header, 0, SizeofHeapTupleHeader);
 
-       memcpy((char *) &tuple->t_data.header + SizeofHeapTupleHeader,
+       memcpy(((char *) tuple->tuple.t_data) + SizeofHeapTupleHeader,
                   data + SizeOfHeapHeader,
                   datalen);
 
-       tuple->t_data.header.t_infomask = xlhdr.t_infomask;
-       tuple->t_data.header.t_infomask2 = xlhdr.t_infomask2;
-       tuple->t_data.header.t_hoff = xlhdr.t_hoff;
+       header->t_infomask = xlhdr.t_infomask;
+       header->t_infomask2 = xlhdr.t_infomask2;
+       header->t_hoff = xlhdr.t_hoff;
 }
index e20c5114e2a85f96444e4b7f0b9152187d446085..570400ffb736aae75927f8286e9e965391539a31 100644 (file)
@@ -444,27 +444,48 @@ ReorderBufferReturnChange(ReorderBuffer *rb, ReorderBufferChange *change)
 
 
 /*
- * Get an unused, possibly preallocated, ReorderBufferTupleBuf
+ * Get an unused, possibly preallocated, ReorderBufferTupleBuf fitting at
+ * least a tuple of size tuple_len (excluding header overhead).
  */
 ReorderBufferTupleBuf *
-ReorderBufferGetTupleBuf(ReorderBuffer *rb)
+ReorderBufferGetTupleBuf(ReorderBuffer *rb, Size tuple_len)
 {
        ReorderBufferTupleBuf *tuple;
+       Size            alloc_len;
 
-       /* check the slab cache */
-       if (rb->nr_cached_tuplebufs)
+       alloc_len = tuple_len + SizeofHeapTupleHeader;
+
+       /*
+        * Most tuples are below MaxHeapTupleSize, so we use a slab allocator for
+        * those. Thus always allocate at least MaxHeapTupleSize. Note that tuples
+        * tuples generated for oldtuples can be bigger, as they don't have
+        * out-of-line toast columns.
+        */
+       if (alloc_len < MaxHeapTupleSize)
+               alloc_len = MaxHeapTupleSize;
+
+
+       /* if small enough, check the slab cache */
+       if (alloc_len <= MaxHeapTupleSize && rb->nr_cached_tuplebufs)
        {
                rb->nr_cached_tuplebufs--;
                tuple = slist_container(ReorderBufferTupleBuf, node,
                                                                slist_pop_head_node(&rb->cached_tuplebufs));
 #ifdef USE_ASSERT_CHECKING
-               memset(tuple, 0xa9, sizeof(ReorderBufferTupleBuf));
+               memset(&tuple->tuple, 0xa9, sizeof(HeapTupleData));
+#endif
+               tuple->tuple.t_data = ReorderBufferTupleBufData(tuple);
+#ifdef USE_ASSERT_CHECKING
+               memset(tuple->tuple.t_data, 0xa8, tuple->alloc_tuple_size);
 #endif
        }
        else
        {
                tuple = (ReorderBufferTupleBuf *)
-                       MemoryContextAlloc(rb->context, sizeof(ReorderBufferTupleBuf));
+                       MemoryContextAlloc(rb->context,
+                                                          sizeof(ReorderBufferTupleBuf) + alloc_len);
+               tuple->alloc_tuple_size = alloc_len;
+               tuple->tuple.t_data = ReorderBufferTupleBufData(tuple);
        }
 
        return tuple;
@@ -479,13 +500,16 @@ ReorderBufferGetTupleBuf(ReorderBuffer *rb)
 void
 ReorderBufferReturnTupleBuf(ReorderBuffer *rb, ReorderBufferTupleBuf *tuple)
 {
-       /* check whether to put into the slab cache */
-       if (rb->nr_cached_tuplebufs < max_cached_tuplebufs)
+       /* check whether to put into the slab cache, oversized tuples never are */
+       if (tuple->alloc_tuple_size == MaxHeapTupleSize &&
+               rb->nr_cached_tuplebufs < max_cached_tuplebufs)
        {
                rb->nr_cached_tuplebufs++;
                slist_push_head(&rb->cached_tuplebufs, &tuple->node);
+               VALGRIND_MAKE_MEM_UNDEFINED(tuple->tuple.t_data, tuple->alloc_tuple_size);
                VALGRIND_MAKE_MEM_UNDEFINED(tuple, sizeof(ReorderBufferTupleBuf));
                VALGRIND_MAKE_MEM_DEFINED(&tuple->node, sizeof(tuple->node));
+               VALGRIND_MAKE_MEM_DEFINED(&tuple->alloc_tuple_size, sizeof(tuple->alloc_tuple_size));
        }
        else
        {
@@ -2092,15 +2116,18 @@ ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
                                newtup = change->data.tp.newtuple;
 
                                if (oldtup)
-                                       oldlen = offsetof(ReorderBufferTupleBuf, t_data) +
-                                               oldtup->tuple.t_len;
+                               {
+                                       sz += sizeof(HeapTupleData);
+                                       oldlen = oldtup->tuple.t_len;
+                                       sz += oldlen;
+                               }
 
                                if (newtup)
-                                       newlen = offsetof(ReorderBufferTupleBuf, t_data) +
-                                               newtup->tuple.t_len;
-
-                               sz += oldlen;
-                               sz += newlen;
+                               {
+                                       sz += sizeof(HeapTupleData);
+                                       newlen = newtup->tuple.t_len;
+                                       sz += newlen;
+                               }
 
                                /* make sure we have enough space */
                                ReorderBufferSerializeReserve(rb, sz);
@@ -2111,14 +2138,20 @@ ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
 
                                if (oldlen)
                                {
-                                       memcpy(data, oldtup, oldlen);
+                                       memcpy(data, &oldtup->tuple, sizeof(HeapTupleData));
+                                       data += sizeof(HeapTupleData);
+
+                                       memcpy(data, oldtup->tuple.t_data, oldlen);
                                        data += oldlen;
                                }
 
                                if (newlen)
                                {
-                                       memcpy(data, newtup, newlen);
-                                       data += newlen;
+                                       memcpy(data, &newtup->tuple, sizeof(HeapTupleData));
+                                       data += sizeof(HeapTupleData);
+
+                                       memcpy(data, newtup->tuple.t_data, newlen);
+                                       data += oldlen;
                                }
                                break;
                        }
@@ -2337,27 +2370,46 @@ ReorderBufferRestoreChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
                case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
                        if (change->data.tp.oldtuple)
                        {
-                               Size            len = offsetof(ReorderBufferTupleBuf, t_data) +
-                               ((ReorderBufferTupleBuf *) data)->tuple.t_len;
+                               Size            tuplelen = ((HeapTuple) data)->t_len;
+
+                               change->data.tp.oldtuple =
+                                       ReorderBufferGetTupleBuf(rb, tuplelen - SizeofHeapTupleHeader);
 
-                               change->data.tp.oldtuple = ReorderBufferGetTupleBuf(rb);
-                               memcpy(change->data.tp.oldtuple, data, len);
+                               /* restore ->tuple */
+                               memcpy(&change->data.tp.oldtuple->tuple, data,
+                                          sizeof(HeapTupleData));
+                               data += sizeof(HeapTupleData);
+
+                               /* reset t_data pointer into the new tuplebuf */
                                change->data.tp.oldtuple->tuple.t_data =
-                                       &change->data.tp.oldtuple->t_data.header;
-                               data += len;
+                                       ReorderBufferTupleBufData(change->data.tp.oldtuple);
+
+                               /* restore tuple data itself */
+                               memcpy(change->data.tp.oldtuple->tuple.t_data, data, tuplelen);
+                               data += tuplelen;
                        }
 
                        if (change->data.tp.newtuple)
                        {
-                               Size            len = offsetof(ReorderBufferTupleBuf, t_data) +
-                               ((ReorderBufferTupleBuf *) data)->tuple.t_len;
+                               Size            tuplelen = ((HeapTuple) data)->t_len;
+
+                               change->data.tp.newtuple =
+                                       ReorderBufferGetTupleBuf(rb, tuplelen - SizeofHeapTupleHeader);
 
-                               change->data.tp.newtuple = ReorderBufferGetTupleBuf(rb);
-                               memcpy(change->data.tp.newtuple, data, len);
+                               /* restore ->tuple */
+                               memcpy(&change->data.tp.newtuple->tuple, data,
+                                          sizeof(HeapTupleData));
+                               data += sizeof(HeapTupleData);
+
+                               /* reset t_data pointer into the new tuplebuf */
                                change->data.tp.newtuple->tuple.t_data =
-                                       &change->data.tp.newtuple->t_data.header;
-                               data += len;
+                                       ReorderBufferTupleBufData(change->data.tp.newtuple);
+
+                               /* restore tuple data itself */
+                               memcpy(change->data.tp.newtuple->tuple.t_data, data, tuplelen);
+                               data += tuplelen;
                        }
+
                        break;
                case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
                        {
@@ -2734,7 +2786,7 @@ ReorderBufferToastReplace(ReorderBuffer *rb, ReorderBufferTXN *txn,
         */
        tmphtup = heap_form_tuple(desc, attrs, isnull);
        Assert(newtup->tuple.t_len <= MaxHeapTupleSize);
-       Assert(&newtup->t_data.header == newtup->tuple.t_data);
+       Assert(ReorderBufferTupleBufData(newtup) == newtup->tuple.t_data);
 
        memcpy(newtup->tuple.t_data, tmphtup->t_data, tmphtup->t_len);
        newtup->tuple.t_len = tmphtup->t_len;
index b25eae832ae7a4658c98ca37c84abe275901a10f..b52d06af92806ef376959fb4dd8687dde2650f6e 100644 (file)
@@ -23,16 +23,19 @@ typedef struct ReorderBufferTupleBuf
        /* position in preallocated list */
        slist_node      node;
 
-       /* tuple, stored sequentially */
+       /* tuple header, the interesting bit for users of logical decoding */
        HeapTupleData tuple;
-       union
-       {
-               HeapTupleHeaderData header;
-               char            data[MaxHeapTupleSize];
-               double          align_it;       /* ensure t_data is MAXALIGN'd */
-       }                       t_data;
+
+       /* pre-allocated size of tuple buffer, different from tuple size */
+       Size    alloc_tuple_size;
+
+       /* actual tuple data follows */
 } ReorderBufferTupleBuf;
 
+/* pointer to the data stored in a TupleBuf */
+#define ReorderBufferTupleBufData(p) \
+       ((HeapTupleHeader) MAXALIGN(((char *) p) + sizeof(ReorderBufferTupleBuf)))
+
 /*
  * Types of the change passed to a 'change' callback.
  *
@@ -341,7 +344,7 @@ struct ReorderBuffer
 ReorderBuffer *ReorderBufferAllocate(void);
 void           ReorderBufferFree(ReorderBuffer *);
 
-ReorderBufferTupleBuf *ReorderBufferGetTupleBuf(ReorderBuffer *);
+ReorderBufferTupleBuf *ReorderBufferGetTupleBuf(ReorderBuffer *, Size tuple_len);
 void           ReorderBufferReturnTupleBuf(ReorderBuffer *, ReorderBufferTupleBuf *tuple);
 ReorderBufferChange *ReorderBufferGetChange(ReorderBuffer *);
 void           ReorderBufferReturnChange(ReorderBuffer *, ReorderBufferChange *);