0001-Set-pd_lower-correctly-in-the-GIN-metapage_v2.patch

From b05760739a36f3247019e75a9029ece7ab0bb09c Mon Sep 17 00:00:00 2001
From: amit <amitlangote09@gmail.com>
Date: Fri, 23 Jun 2017 11:20:41 +0900
Subject: [PATCH 1/3] Set pd_lower correctly in the GIN metapage.

---
 src/backend/access/gin/ginutil.c |  7 +++++++
 src/backend/access/gin/ginxlog.c | 23 ++++++++---------------
 2 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/src/backend/access/gin/ginutil.c b/src/backend/access/gin/ginutil.c
index 91e4a8cf70..52de599b29 100644
--- a/src/backend/access/gin/ginutil.c
+++ b/src/backend/access/gin/ginutil.c
@@ -372,6 +372,13 @@ GinInitMetabuffer(Buffer b)
 	metadata->nDataPages = 0;
 	metadata->nEntries = 0;
 	metadata->ginVersion = GIN_CURRENT_VERSION;
+
+	/*
+	 * Set pd_lower just past the end of the metadata.  This is not essential
+	 * but it makes the page look compressible to xlog.c.
+	 */
+	((PageHeader) page)->pd_lower =
+			((char *) metadata + sizeof(GinMetaPageData)) - (char *) page;
 }
 
 /*
diff --git a/src/backend/access/gin/ginxlog.c b/src/backend/access/gin/ginxlog.c
index 7ba04e324f..6d2e528852 100644
--- a/src/backend/access/gin/ginxlog.c
+++ b/src/backend/access/gin/ginxlog.c
@@ -514,7 +514,7 @@ ginRedoUpdateMetapage(XLogReaderState *record)
 	Assert(BufferGetBlockNumber(metabuffer) == GIN_METAPAGE_BLKNO);
 	metapage = BufferGetPage(metabuffer);
 
-	GinInitPage(metapage, GIN_META, BufferGetPageSize(metabuffer));
+	GinInitMetabuffer(metabuffer);
 	memcpy(GinPageGetMeta(metapage), &data->metadata, sizeof(GinMetaPageData));
 	PageSetLSN(metapage, lsn);
 	MarkBufferDirty(metabuffer);
@@ -656,7 +656,7 @@ ginRedoDeleteListPages(XLogReaderState *record)
 	Assert(BufferGetBlockNumber(metabuffer) == GIN_METAPAGE_BLKNO);
 	metapage = BufferGetPage(metabuffer);
 
-	GinInitPage(metapage, GIN_META, BufferGetPageSize(metabuffer));
+	GinInitMetabuffer(metabuffer);
 
 	memcpy(GinPageGetMeta(metapage), &data->metadata, sizeof(GinMetaPageData));
 	PageSetLSN(metapage, lsn);
@@ -776,18 +776,11 @@ gin_mask(char *pagedata, BlockNumber blkno)
 	mask_page_hint_bits(page);
 
 	/*
-	 * GIN metapage doesn't use pd_lower/pd_upper. Other page types do. Hence,
-	 * we need to apply masking for those pages.
+	 * For GIN_DELETED page, the page is initialized to empty. Hence, mask
+	 * the page content.
 	 */
-	if (opaque->flags != GIN_META)
-	{
-		/*
-		 * For GIN_DELETED page, the page is initialized to empty. Hence, mask
-		 * the page content.
-		 */
-		if (opaque->flags & GIN_DELETED)
-			mask_page_content(page);
-		else
-			mask_unused_space(page);
-	}
+	if (opaque->flags & GIN_DELETED)
+		mask_page_content(page);
+	else
+		mask_unused_space(page);
 }
-- 
2.11.0