On 2017/09/26 12:17, Michael Paquier wrote:
> On Mon, Sep 25, 2017 at 3:48 PM, Amit Langote wrote:
>> So, ISTM, comments that the patches add should all say that setting the
>> meta pages' pd_lower to the correct value helps to pass those pages to
>> xlog.c as compressible standard layout pages, regardless of whether they
>> are actually passed that way. Even if the patches do take care of the
>> latter as well.
>>
>> Did I miss something?
>
> Not that I think of.
Thanks.
> Buffer metabuffer;
> + Page metapage;
> SpGistMetaPageData *metadata;
>
> metabuffer = ReadBuffer(index, SPGIST_METAPAGE_BLKNO);
> + metapage = BufferGetPage(metabuffer);
> No need to define metapage here and to call BufferGetPage() as long as
> the lock on the buffer is not taken.
Ah, okay.
Moved those additions inside the if (ConditionalLockBuffer(metabuffer)) block.
> Except that small thing, the patches do their duty.
Thanks, revised patches attached.
Regards,
Amit
From e82e787bc9533977e73456b0782ed78354637bda Mon Sep 17 00:00:00 2001
From: amit <amitlangot...@gmail.com>
Date: Fri, 23 Jun 2017 11:20:41 +0900
Subject: [PATCH 1/5] Set pd_lower correctly in the GIN metapage.
Also tell xlog.c to treat the metapage like a standard page, so any
hole in it is compressed.
---
src/backend/access/gin/ginfast.c | 20 ++++++++++++++++++--
src/backend/access/gin/gininsert.c | 4 ++--
src/backend/access/gin/ginutil.c | 17 ++++++++++++++++-
src/backend/access/gin/ginxlog.c | 25 ++++++++++---------------
4 files changed, 46 insertions(+), 20 deletions(-)
diff --git a/src/backend/access/gin/ginfast.c b/src/backend/access/gin/ginfast.c
index 59e435465a..359de85dfc 100644
--- a/src/backend/access/gin/ginfast.c
+++ b/src/backend/access/gin/ginfast.c
@@ -399,6 +399,14 @@ ginHeapTupleFastInsert(GinState *ginstate,
GinTupleCollector *collector)
/*
* Write metabuffer, make xlog entry
*/
+
+ /*
+ * Set pd_lower just past the end of the metadata. This is essential,
+ * because without doing so, metadata will be lost if xlog.c compresses
+ * the page.
+ */
+ ((PageHeader) metapage)->pd_lower =
+ ((char *) metadata + sizeof(GinMetaPageData)) - (char
*) metapage;
MarkBufferDirty(metabuffer);
if (needWal)
@@ -407,7 +415,7 @@ ginHeapTupleFastInsert(GinState *ginstate,
GinTupleCollector *collector)
memcpy(&data.metadata, metadata, sizeof(GinMetaPageData));
- XLogRegisterBuffer(0, metabuffer, REGBUF_WILL_INIT);
+ XLogRegisterBuffer(0, metabuffer, REGBUF_WILL_INIT |
REGBUF_STANDARD);
XLogRegisterData((char *) &data, sizeof(ginxlogUpdateMeta));
recptr = XLogInsert(RM_GIN_ID, XLOG_GIN_UPDATE_META_PAGE);
@@ -572,6 +580,13 @@ shiftList(Relation index, Buffer metabuffer, BlockNumber
newHead,
metadata->nPendingHeapTuples = 0;
}
+ /*
+ * Set pd_lower just past the end of the metadata. This is
essential,
+ * because without doing so, metadata will be lost if xlog.c
compresses
+ * the page.
+ */
+ ((PageHeader) metapage)->pd_lower =
+ ((char *) metadata + sizeof(GinMetaPageData)) - (char
*) metapage;
MarkBufferDirty(metabuffer);
for (i = 0; i < data.ndeleted; i++)
@@ -586,7 +601,8 @@ shiftList(Relation index, Buffer metabuffer, BlockNumber
newHead,
XLogRecPtr recptr;
XLogBeginInsert();
- XLogRegisterBuffer(0, metabuffer, REGBUF_WILL_INIT);
+ XLogRegisterBuffer(0, metabuffer,
+ REGBUF_WILL_INIT |
REGBUF_STANDARD);
for (i = 0; i < data.ndeleted; i++)
XLogRegisterBuffer(i + 1, buffers[i],
REGBUF_WILL_INIT);
diff --git a/src/backend/access/gin/gininsert.c
b/src/backend/access/gin/gininsert.c
index 5378011f50..c9aa4ee147 100644
--- a/src/backend/access/gin/gininsert.c
+++ b/src/backend/access/gin/gininsert.c
@@ -348,7 +348,7 @@ ginbuild(Relation heap, Relation index, IndexInfo
*indexInfo)
Page page;
XLogBeginInsert();
- XLogRegisterBuffer(0, MetaBuffer, REGBUF_WILL_INIT);
+ XLogRegisterBuffer(0, MetaBuffer, REGBUF_WILL_INIT |
REGBUF_STANDARD);
XLogRegisterBuffer(1, RootBuffer, REGBUF_WILL_INIT);
recptr = XLogInsert(RM_GIN_ID, XLOG_GIN_CREATE_INDEX);
@@ -447,7 +447,7 @@ ginbuildempty(Relation index)
START_CRIT_SECTION();
GinInitMetabuffer(MetaBuffer);
MarkBufferDirty(MetaBuffer);
- log_newpage_buffer(MetaBuffer, false);
+ log_newpage_buffer(MetaBuffer, true);
GinInitBuffer(RootBuffer, GIN_LEAF);
MarkBufferDirty(RootBuffer);
log_newpage_buffer(RootBuffer, false);
diff --git a/src/backend/access/gin/ginutil.c b/src/backend/access/gin/ginutil.c
index 136ea27718..f6e776dbe9 100644
--- a/src/backend/access/gin/ginutil.c
+++ b/src/backend/access/gin/ginutil.c
@@ -374,6 +374,14 @@ 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 essential,
+ * because without doing so, metadata will be lost if xlog.c compresses
+ * the page.
+ */
+ ((PageHeader) page)->pd_lower =
+ ((char *) metadata + sizeof(GinMetaPageData)) - (char
*) page;
}
/*
@@ -676,6 +684,13 @@ ginUpdateStats(Relation index, const GinStatsData *stats)
metadata->nDataPages = stats->nDataPages;
metadata->nEntries = stats->nEntries;
+ /*
+ * Set pd_lower just past the end of the metadata. This is essential,
+ * because without doing so, metadata will be lost if xlog.c compresses
+ * the page.
+ */
+ ((PageHeader) metapage)->pd_lower =
+ ((char *) metadata + sizeof(GinMetaPageData)) - (char *)
metapage;
MarkBufferDirty(metabuffer);
if (RelationNeedsWAL(index))
@@ -690,7 +705,7 @@ ginUpdateStats(Relation index, const GinStatsData *stats)
XLogBeginInsert();
XLogRegisterData((char *) &data, sizeof(ginxlogUpdateMeta));
- XLogRegisterBuffer(0, metabuffer, REGBUF_WILL_INIT);
+ XLogRegisterBuffer(0, metabuffer, REGBUF_WILL_INIT |
REGBUF_STANDARD);
recptr = XLogInsert(RM_GIN_ID, XLOG_GIN_UPDATE_META_PAGE);
PageSetLSN(metapage, recptr);
diff --git a/src/backend/access/gin/ginxlog.c b/src/backend/access/gin/ginxlog.c
index 92cafe950b..2261447926 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);
@@ -768,6 +768,7 @@ void
gin_mask(char *pagedata, BlockNumber blkno)
{
Page page = (Page) pagedata;
+ PageHeader pagehdr = (PageHeader) page;
GinPageOpaque opaque;
mask_page_lsn_and_checksum(page);
@@ -776,18 +777,12 @@ 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. For other pages, mask the hole if the pd_lower
+ * appears to have been set correctly.
*/
- 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 if (pagehdr->pd_lower > SizeOfPageHeaderData)
+ mask_unused_space(page);
}
--
2.11.0
From 34c43597b35921c6b3e5cd6fb96b47bc19c99c16 Mon Sep 17 00:00:00 2001
From: amit <amitlangot...@gmail.com>
Date: Mon, 26 Jun 2017 15:13:32 +0900
Subject: [PATCH 2/5] Set pd_lower correctly in the BRIN index metapage
Also tell xlog.c to treat the metapage like a standard page, so any
hole in it is compressed.
---
src/backend/access/brin/brin.c | 4 ++--
src/backend/access/brin/brin_pageops.c | 8 ++++++++
src/backend/access/brin/brin_revmap.c | 10 +++++++++-
src/backend/access/brin/brin_xlog.c | 18 ++++++++++++++++--
4 files changed, 35 insertions(+), 5 deletions(-)
diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index b3aa6d1ced..e6909d7aea 100644
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -685,7 +685,7 @@ brinbuild(Relation heap, Relation index, IndexInfo
*indexInfo)
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfBrinCreateIdx);
- XLogRegisterBuffer(0, meta, REGBUF_WILL_INIT);
+ XLogRegisterBuffer(0, meta, REGBUF_WILL_INIT | REGBUF_STANDARD);
recptr = XLogInsert(RM_BRIN_ID, XLOG_BRIN_CREATE_INDEX);
@@ -742,7 +742,7 @@ brinbuildempty(Relation index)
brin_metapage_init(BufferGetPage(metabuf), BrinGetPagesPerRange(index),
BRIN_CURRENT_VERSION);
MarkBufferDirty(metabuf);
- log_newpage_buffer(metabuf, false);
+ log_newpage_buffer(metabuf, true);
END_CRIT_SECTION();
UnlockReleaseBuffer(metabuf);
diff --git a/src/backend/access/brin/brin_pageops.c
b/src/backend/access/brin/brin_pageops.c
index 80f803e438..30bc5051ff 100644
--- a/src/backend/access/brin/brin_pageops.c
+++ b/src/backend/access/brin/brin_pageops.c
@@ -491,6 +491,14 @@ brin_metapage_init(Page page, BlockNumber pagesPerRange,
uint16 version)
* revmap page to be created when the index is.
*/
metadata->lastRevmapPage = 0;
+
+ /*
+ * Set pd_lower just past the end of the metadata. This is essential,
+ * because without doing so, metadata will be lost if xlog.c compresses
+ * the page.
+ */
+ ((PageHeader) page)->pd_lower =
+ ((char *) metadata + sizeof(BrinMetaPageData)) - (char *) page;
}
/*
diff --git a/src/backend/access/brin/brin_revmap.c
b/src/backend/access/brin/brin_revmap.c
index 22f2076887..a276dc79ad 100644
--- a/src/backend/access/brin/brin_revmap.c
+++ b/src/backend/access/brin/brin_revmap.c
@@ -624,6 +624,14 @@ revmap_physical_extend(BrinRevmap *revmap)
MarkBufferDirty(buf);
metadata->lastRevmapPage = mapBlk;
+
+ /*
+ * Set pd_lower just past the end of the metadata. This is essential,
+ * because without doing so, metadata will be lost if xlog.c compresses
+ * the page.
+ */
+ ((PageHeader) metapage)->pd_lower =
+ ((char *) metadata + sizeof(BrinMetaPageData)) - (char *)
metapage;
MarkBufferDirty(revmap->rm_metaBuf);
if (RelationNeedsWAL(revmap->rm_irel))
@@ -635,7 +643,7 @@ revmap_physical_extend(BrinRevmap *revmap)
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfBrinRevmapExtend);
- XLogRegisterBuffer(0, revmap->rm_metaBuf, 0);
+ XLogRegisterBuffer(0, revmap->rm_metaBuf, REGBUF_STANDARD);
XLogRegisterBuffer(1, buf, REGBUF_WILL_INIT);
diff --git a/src/backend/access/brin/brin_xlog.c
b/src/backend/access/brin/brin_xlog.c
index 60daa54a95..55d4dea891 100644
--- a/src/backend/access/brin/brin_xlog.c
+++ b/src/backend/access/brin/brin_xlog.c
@@ -234,6 +234,14 @@ brin_xlog_revmap_extend(XLogReaderState *record)
metadata->lastRevmapPage = xlrec->targetBlk;
PageSetLSN(metapg, lsn);
+
+ /*
+ * Set pd_lower just past the end of the metadata. This is
essential,
+ * because without doing so, metadata will be lost if xlog.c
+ * compresses the page.
+ */
+ ((PageHeader) metapg)->pd_lower =
+ ((char *) metadata + sizeof(BrinMetaPageData)) - (char
*) metapg;
MarkBufferDirty(metabuf);
}
@@ -331,14 +339,20 @@ void
brin_mask(char *pagedata, BlockNumber blkno)
{
Page page = (Page) pagedata;
+ PageHeader pagehdr = (PageHeader) page;
mask_page_lsn_and_checksum(page);
mask_page_hint_bits(page);
- if (BRIN_IS_REGULAR_PAGE(page))
+ /*
+ * Regular brin pages contain unused space which needs to be masked.
+ * Similarly for meta pages, but mask it only if pd_lower appears to
have
+ * been set correctly.
+ */
+ if (BRIN_IS_REGULAR_PAGE(page) ||
+ (BRIN_IS_META_PAGE(page) && pagehdr->pd_lower >
SizeOfPageHeaderData))
{
- /* Regular brin pages contain unused space which needs to be
masked. */
mask_unused_space(page);
}
}
--
2.11.0
From 645384e0d0bcd0fb57d4b3a9b611364cdf1c2109 Mon Sep 17 00:00:00 2001
From: amit <amitlangot...@gmail.com>
Date: Mon, 26 Jun 2017 15:23:34 +0900
Subject: [PATCH 3/5] Set pd_lower correctly in the SP-GiST index metapage
Also tell xlog.c to treat the metapage like a standard page, so any
hole in it is compressed.
---
src/backend/access/spgist/spginsert.c | 4 ++--
src/backend/access/spgist/spgutils.c | 18 ++++++++++++++++++
src/backend/access/spgist/spgxlog.c | 7 ++++---
3 files changed, 24 insertions(+), 5 deletions(-)
diff --git a/src/backend/access/spgist/spginsert.c
b/src/backend/access/spgist/spginsert.c
index e4b2c29b0e..80b82e1602 100644
--- a/src/backend/access/spgist/spginsert.c
+++ b/src/backend/access/spgist/spginsert.c
@@ -110,7 +110,7 @@ spgbuild(Relation heap, Relation index, IndexInfo
*indexInfo)
* Replay will re-initialize the pages, so don't take full pages
* images. No other data to log.
*/
- XLogRegisterBuffer(0, metabuffer, REGBUF_WILL_INIT);
+ XLogRegisterBuffer(0, metabuffer, REGBUF_WILL_INIT |
REGBUF_STANDARD);
XLogRegisterBuffer(1, rootbuffer, REGBUF_WILL_INIT |
REGBUF_STANDARD);
XLogRegisterBuffer(2, nullbuffer, REGBUF_WILL_INIT |
REGBUF_STANDARD);
@@ -173,7 +173,7 @@ spgbuildempty(Relation index)
smgrwrite(index->rd_smgr, INIT_FORKNUM, SPGIST_METAPAGE_BLKNO,
(char *) page, true);
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
- SPGIST_METAPAGE_BLKNO, page, false);
+ SPGIST_METAPAGE_BLKNO, page, true);
/* Likewise for the root page. */
SpGistInitPage(page, SPGIST_LEAF);
diff --git a/src/backend/access/spgist/spgutils.c
b/src/backend/access/spgist/spgutils.c
index 22f64b0103..5cccb4bc9f 100644
--- a/src/backend/access/spgist/spgutils.c
+++ b/src/backend/access/spgist/spgutils.c
@@ -262,9 +262,19 @@ SpGistUpdateMetaPage(Relation index)
if (ConditionalLockBuffer(metabuffer))
{
+ Page metapage;
+
metadata = SpGistPageGetMeta(BufferGetPage(metabuffer));
metadata->lastUsedPages = cache->lastUsedPages;
+ /*
+ * Set pd_lower just past the end of the metadata.
This is
+ * essential, because without doing so, metadata will
be lost if
+ * xlog.c compresses the page.
+ */
+ metapage = BufferGetPage(metabuffer);
+ ((PageHeader) metapage)->pd_lower = ((char *) metadata +
+
sizeof(SpGistMetaPageData)) - (char *) metapage;
MarkBufferDirty(metabuffer);
UnlockReleaseBuffer(metabuffer);
}
@@ -534,6 +544,14 @@ SpGistInitMetapage(Page page)
/* initialize last-used-page cache to empty */
for (i = 0; i < SPGIST_CACHED_PAGES; i++)
metadata->lastUsedPages.cachedPage[i].blkno =
InvalidBlockNumber;
+
+ /*
+ * Set pd_lower just past the end of the metadata. This is essential,
+ * because without doing so, metadata will be lost if xlog.c compresses
+ * the page.
+ */
+ ((PageHeader) page)->pd_lower =
+ ((char *) metadata + sizeof(SpGistMetaPageData)) - (char *)
page;
}
/*
diff --git a/src/backend/access/spgist/spgxlog.c
b/src/backend/access/spgist/spgxlog.c
index 87def79ee5..539ce8eb8c 100644
--- a/src/backend/access/spgist/spgxlog.c
+++ b/src/backend/access/spgist/spgxlog.c
@@ -1033,15 +1033,16 @@ void
spg_mask(char *pagedata, BlockNumber blkno)
{
Page page = (Page) pagedata;
+ PageHeader pagehdr = (PageHeader) page;
mask_page_lsn_and_checksum(page);
mask_page_hint_bits(page);
/*
- * Any SpGist page other than meta contains unused space which needs to
be
- * masked.
+ * Mask the unused space, only if the page's pd_lower appears to have
been
+ * set correctly.
*/
- if (!SpGistPageIsMeta(page))
+ if (pagehdr->pd_lower > SizeOfPageHeaderData)
mask_unused_space(page);
}
--
2.11.0
--
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