Fix incorrect output from gin_desc().

Previously gin_desc() displayed incorrect output "unknown action 0"
for XLOG_GIN_INSERT and XLOG_GIN_VACUUM_DATA_LEAF_PAGE records with
valid actions. The cause of this problem was that gin_desc() wrongly
used XLogRecGetData() to extract data from those records.
Since they were registered by XLogRegisterBufData(), gin_desc() should
have used XLogRecGetBlockData(), instead, like gin_redo().
Also there were other differences about how to treat XLOG_GIN_INSERT
record between gin_desc() and gin_redo().

This commit fixes gin_desc() routine so that it treats those records
in the same way as gin_redo().

Batch-patch to 9.5 where WAL record format was revamped and
XLogRegisterBufData() was added.

Reported-By: Andres Freund
Reviewed-By: Tom Lane
Discussion: <20160509194645.7lewnpw647zegx2m@alap3.anarazel.de>

diff --git a/src/backend/access/rmgrdesc/gindesc.c b/src/backend/access/rmgrdesc/gindesc.c
index db832a5f789cf01eb3d0d41aeb0ca5a37cb33df2..b058d493f7721642575338374f11241eb5465ca6 100644 (file)
--- a/src/backend/access/rmgrdesc/gindesc.c
+++ b/src/backend/access/rmgrdesc/gindesc.c
@@ -87,13 +87,13 @@ gin_desc(StringInfo buf, XLogReaderState *record)
                case XLOG_GIN_INSERT:
                        {
                                ginxlogInsert *xlrec = (ginxlogInsert *) rec;
-                               char       *payload = rec + sizeof(ginxlogInsert);
 
                                appendStringInfo(buf, "isdata: %c isleaf: %c",
                                                          (xlrec->flags & GIN_INSERT_ISDATA) ? 'T' : 'F',
                                                         (xlrec->flags & GIN_INSERT_ISLEAF) ? 'T' : 'F');
                                if (!(xlrec->flags & GIN_INSERT_ISLEAF))
                                {
+                                       char       *payload = rec + sizeof(ginxlogInsert);
                                        BlockNumber leftChildBlkno;
                                        BlockNumber rightChildBlkno;
 
@@ -104,27 +104,27 @@ gin_desc(StringInfo buf, XLogReaderState *record)
                                        appendStringInfo(buf, " children: %u/%u",
                                                                         leftChildBlkno, rightChildBlkno);
                                }
-                               if (!(xlrec->flags & GIN_INSERT_ISDATA))
-                                       appendStringInfo(buf, " isdelete: %c",
-                                       (((ginxlogInsertEntry *) payload)->isDelete) ? 'T' : 'F');
-                               else if (xlrec->flags & GIN_INSERT_ISLEAF)
-                               {
-                                       ginxlogRecompressDataLeaf *insertData =
-                                       (ginxlogRecompressDataLeaf *) payload;
-
-                                       if (XLogRecHasBlockImage(record, 0))
-                                               appendStringInfoString(buf, " (full page image)");
-                                       else
-                                               desc_recompress_leaf(buf, insertData);
-                               }
+                               if (XLogRecHasBlockImage(record, 0))
+                                       appendStringInfoString(buf, " (full page image)");
                                else
                                {
-                                       ginxlogInsertDataInternal *insertData = (ginxlogInsertDataInternal *) payload;
+                                       char       *payload = XLogRecGetBlockData(record, 0, NULL);
 
-                                       appendStringInfo(buf, " pitem: %u-%u/%u",
-                                                        PostingItemGetBlockNumber(&insertData->newitem),
-                                                ItemPointerGetBlockNumber(&insertData->newitem.key),
-                                          ItemPointerGetOffsetNumber(&insertData->newitem.key));
+                                       if (!(xlrec->flags & GIN_INSERT_ISDATA))
+                                               appendStringInfo(buf, " isdelete: %c",
+                                                (((ginxlogInsertEntry *) payload)->isDelete) ? 'T' : 'F');
+                                       else if (xlrec->flags & GIN_INSERT_ISLEAF)
+                                               desc_recompress_leaf(buf, (ginxlogRecompressDataLeaf *) payload);
+                                       else
+                                       {
+                                               ginxlogInsertDataInternal *insertData =
+                                                       (ginxlogInsertDataInternal *) payload;
+
+                                               appendStringInfo(buf, " pitem: %u-%u/%u",
+                                                                                PostingItemGetBlockNumber(&insertData->newitem),
+                                                                                ItemPointerGetBlockNumber(&insertData->newitem.key),
+                                                                                ItemPointerGetOffsetNumber(&insertData->newitem.key));
+                                       }
                                }
                        }
                        break;
@@ -144,12 +144,15 @@ gin_desc(StringInfo buf, XLogReaderState *record)
                        break;
                case XLOG_GIN_VACUUM_DATA_LEAF_PAGE:
                        {
-                               ginxlogVacuumDataLeafPage *xlrec = (ginxlogVacuumDataLeafPage *) rec;
-
                                if (XLogRecHasBlockImage(record, 0))
                                        appendStringInfoString(buf, " (full page image)");
                                else
+                               {
+                                       ginxlogVacuumDataLeafPage *xlrec =
+                                               (ginxlogVacuumDataLeafPage *) XLogRecGetBlockData(record, 0, NULL);
+
                                        desc_recompress_leaf(buf, &xlrec->data);
+                               }
                        }
                        break;
                case XLOG_GIN_DELETE_PAGE: