On Sun, Dec 25, 2011 at 1:01 PM, Kevin Grittner
<[email protected]> wrote:
> This chicken-and-egg
> problem requires the checksum to be implemented first.
v2 of checksum patch, using a conditional copy if checksumming is
enabled, so locking is removed.
Thanks to Andres for thwacking me with the cluestick, though I have
used a simple copy rather than a copy & calc.
Tested using make installcheck with parameter on/off, then restart and
vacuumdb to validate all pages.
Reviews, objections, user interface tweaks all welcome.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
***************
*** 1701,1706 **** SET ENABLE_SEQSCAN TO OFF;
--- 1701,1748 ----
</listitem>
</varlistentry>
+ <varlistentry id="guc-page-checksums" xreflabel="page_checksums">
+ <indexterm>
+ <primary><varname>page_checksums</> configuration parameter</primary>
+ </indexterm>
+ <term><varname>page_checksums</varname> (<type>boolean</type>)</term>
+ <listitem>
+ <para>
+ When this parameter is on, the <productname>PostgreSQL</> server
+ calculates checksums when it writes main database pages to disk,
+ flagging the page as checksum protected. When this parameter is off,
+ no checksum is written, only a standard watermark in the page header.
+ The database may thus contain a mix of pages with checksums and pages
+ without checksums.
+ </para>
+
+ <para>
+ When pages are read into shared buffers any page flagged with a
+ checksum has the checksum re-calculated and compared against the
+ stored value to provide greatly improved validation of page contents.
+ </para>
+
+ <para>
+ Writes via temp_buffers are not checksummed.
+ </para>
+
+ <para>
+ Turning this parameter off speeds normal operation, but
+ might allow data corruption to go unnoticed. The checksum uses
+ 16-bit checksums, using the fast Fletcher 16 algorithm. With this
+ parameter enabled there is still a non-zero probability that an error
+ could go undetected, as well as a non-zero probability of false
+ positives.
+ </para>
+
+ <para>
+ This parameter can only be set in the <filename>postgresql.conf</>
+ file or on the server command line.
+ The default is <literal>off</>.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-wal-buffers" xreflabel="wal_buffers">
<term><varname>wal_buffers</varname> (<type>integer</type>)</term>
<indexterm>
*** a/src/backend/storage/buffer/bufmgr.c
--- b/src/backend/storage/buffer/bufmgr.c
***************
*** 440,446 **** ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
smgrread(smgr, forkNum, blockNum, (char *) bufBlock);
/* check for garbage data */
! if (!PageHeaderIsValid((PageHeader) bufBlock))
{
if (mode == RBM_ZERO_ON_ERROR || zero_damaged_pages)
{
--- 440,446 ----
smgrread(smgr, forkNum, blockNum, (char *) bufBlock);
/* check for garbage data */
! if (!PageIsVerified((Page) bufBlock))
{
if (mode == RBM_ZERO_ON_ERROR || zero_damaged_pages)
{
***************
*** 1860,1865 **** FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
--- 1860,1867 ----
{
XLogRecPtr recptr;
ErrorContextCallback errcontext;
+ Block bufBlock;
+ char *bufCopy;
/*
* Acquire the buffer's io_in_progress lock. If StartBufferIO returns
***************
*** 1907,1916 **** FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
buf->flags &= ~BM_JUST_DIRTIED;
UnlockBufHdr(buf);
smgrwrite(reln,
buf->tag.forkNum,
buf->tag.blockNum,
! (char *) BufHdrGetBlock(buf),
false);
pgBufferUsage.shared_blks_written++;
--- 1909,1932 ----
buf->flags &= ~BM_JUST_DIRTIED;
UnlockBufHdr(buf);
+ /*
+ * Set page verification info immediately before we write the buffer to disk.
+ * Once we have flushed the buffer is marked clean again, meaning it can
+ * be replaced quickly and silently with another data block, so we must
+ * write verification info now. For efficiency, the process of cleaning
+ * and page replacement is asynchronous, so we can't do this *only* when
+ * we are about to replace the buffer, we need to do this for every flush.
+ */
+ bufBlock = BufHdrGetBlock(buf);
+ bufCopy = PageSetVerificationInfo((Page) bufBlock);
+
+ /*
+ * bufToWrite is either the shared buffer or a copy, as appropriate.
+ */
smgrwrite(reln,
buf->tag.forkNum,
buf->tag.blockNum,
! (char *) bufCopy,
false);
pgBufferUsage.shared_blks_written++;
***************
*** 1921,1926 **** FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
--- 1937,1944 ----
*/
TerminateBufferIO(buf, true, 0);
+ /* XXX Assert(buf is not BM_JUST_DIRTIED) */
+
TRACE_POSTGRESQL_BUFFER_FLUSH_DONE(buf->tag.forkNum,
buf->tag.blockNum,
reln->smgr_rnode.node.spcNode,
*** a/src/backend/storage/buffer/localbuf.c
--- b/src/backend/storage/buffer/localbuf.c
***************
*** 200,205 **** LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
--- 200,207 ----
/* Find smgr relation for buffer */
oreln = smgropen(bufHdr->tag.rnode, MyBackendId);
+ /* XXX do we want to write checksums for local buffers? An option? */
+
/* And write... */
smgrwrite(oreln,
bufHdr->tag.forkNum,
*** a/src/backend/storage/page/bufpage.c
--- b/src/backend/storage/page/bufpage.c
***************
*** 16,21 ****
--- 16,27 ----
#include "access/htup.h"
+ bool page_checksums = false;
+
+ static char pageCopy[BLCKSZ]; /* temporary buffer to allow checksum calculation */
+
+ static bool PageVerificationInfoOK(Page page);
+ static uint16 PageCalcChecksum16(Page page);
/* ----------------------------------------------------------------
* Page support functions
***************
*** 25,30 ****
--- 31,40 ----
/*
* PageInit
* Initializes the contents of a page.
+ * Note that we don't automatically add a checksum, or flag that the
+ * page has a checksum field. We start with a normal page layout and defer
+ * the decision on what page verification will be written just before
+ * we write the block to disk.
*/
void
PageInit(Page page, Size pageSize, Size specialSize)
***************
*** 67,86 **** PageInit(Page page, Size pageSize, Size specialSize)
* will clean up such a page and make it usable.
*/
bool
! PageHeaderIsValid(PageHeader page)
{
char *pagebytes;
int i;
/* Check normal case */
! if (PageGetPageSize(page) == BLCKSZ &&
! PageGetPageLayoutVersion(page) == PG_PAGE_LAYOUT_VERSION &&
! (page->pd_flags & ~PD_VALID_FLAG_BITS) == 0 &&
! page->pd_lower >= SizeOfPageHeaderData &&
! page->pd_lower <= page->pd_upper &&
! page->pd_upper <= page->pd_special &&
! page->pd_special <= BLCKSZ &&
! page->pd_special == MAXALIGN(page->pd_special))
return true;
/* Check all-zeroes case */
--- 77,96 ----
* will clean up such a page and make it usable.
*/
bool
! PageIsVerified(Page page)
{
+ PageHeader p = (PageHeader) page;
char *pagebytes;
int i;
/* Check normal case */
! if (PageVerificationInfoOK(page) &&
! (p->pd_flags & ~PD_VALID_FLAG_BITS) == 0 &&
! p->pd_lower >= SizeOfPageHeaderData &&
! p->pd_lower <= p->pd_upper &&
! p->pd_upper <= p->pd_special &&
! p->pd_special <= BLCKSZ &&
! p->pd_special == MAXALIGN(p->pd_special))
return true;
/* Check all-zeroes case */
***************
*** 827,829 **** PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
--- 837,1050 ----
pfree(itemidbase);
}
+
+ /*
+ * Test whether the page verification information is correct or not.
+ *
+ * IMPORTANT NOTE -
+ * Verification info is not valid at all times on a data page. We set
+ * verification info before we flush page/buffer, and implicitly invalidate
+ * verification info when we write to the page. A heavily accessed buffer
+ * might then spend most of its life with invalid page verification info,
+ * so testing verification info on random pages in the buffer pool will tell
+ * you nothing. The reason for this is that page verification info protects
+ * Postgres data from errors on the filesystems on which we rely. We do not
+ * protect buffers against uncorrectable memory errors, since these have a
+ * very low measured incidence according to research on large server farms,
+ * http://www.google.com/research/pubs/archive/35162.pdf, discussed 2010/12/22.
+ *
+ * To confirm your understanding that means that WAL-logged changes to a page
+ * do NOT update the page verification info, so full page images may not have
+ * correct verification information on them. But those page images have the
+ * WAL CRC covering them and so are verified separately from this mechanism.
+ * WAL replay ignores page verification info unless it writes out or reads in
+ * blocks from disk; restoring full page writes does not check verification
+ * info via this function.
+ *
+ * The best way to understand this is that WAL CRCs protect records entering
+ * the WAL stream, and page verification protects blocks entering and leaving
+ * the buffer pool. They are similar in purpose, yet completely separate.
+ * Together they ensure we are able to detect errors in data leaving and
+ * re-entering PostgreSQL controlled memory.
+ *
+ * Note also that the verification mechanism can vary from page to page.
+ * All we do here is look at what the page itself says is the verification
+ * mechanism and then apply that test. This allows us to run without the CPU
+ * cost of verification if we choose, as well as to provide an upgrade path
+ * for anyone doing direct upgrades using pg_upgrade.
+ *
+ * There is some concern that trusting page data to say how to check page
+ * data is dangerously self-referential. To ensure no mistakes we set two
+ * non-adjacent bits to signify that the page has a checksum and
+ * should be verified when that block is read back into a buffer.
+ * We use two bits in case a multiple bit error removes one of the checksum
+ * flags *and* destroys data, which would lead to skipping the checksum check
+ * and silently accepting bad data.
+ *
+ * Note also that this returns a boolean, not a full damage assessment.
+ */
+ static bool
+ PageVerificationInfoOK(Page page)
+ {
+ PageHeader p = (PageHeader) page;
+
+ /*
+ * We set two non-adjacent bits to signify that the page has a checksum and
+ * should be verified against that block is read back into a buffer.
+ * We use two bits in case a multiple bit error removes one of the checksum
+ * flags and destroys data, which would lead to skipping the checksum check
+ * and silently accepting bad data.
+ */
+ if (PageHasChecksumFlag1(p) && PageHasChecksumFlag2(p))
+ {
+ uint16 checksum = PageCalcChecksum16(page);
+
+ if (checksum == p->pd_verify.pd_checksum16)
+ return true;
+
+ elog(LOG, "page verification failed - checksum was %u page checksum field is %u",
+ checksum, p->pd_verify.pd_checksum16);
+ }
+ else if (!PageHasChecksumFlag1(p) && !PageHasChecksumFlag2(p))
+ {
+ if (PageGetPageLayoutVersion(p) == PG_PAGE_LAYOUT_VERSION &&
+ PageGetPageSize(p) == BLCKSZ)
+ return true;
+ }
+
+ elog(LOG, "page verification failed - page has one checksum flag set");
+ return false;
+ }
+
+ /*
+ * Set verification info for page.
+ *
+ * Either we set a new checksum, or we set the standard watermark. We must
+ * not leave an invalid checksum in place. Note that the verification info is
+ * not WAL logged, whereas the data changes to pages are, so data is safe
+ * whether or not we have page_checksums enabled. The purpose of checksums
+ * is to detect page corruption to allow replacement from backup.
+ *
+ * Returns a pointer to the block-sized data that needs to be written. That
+ * allows us to either copy, or not, depending upon whether we checksum.
+ */
+ char *
+ PageSetVerificationInfo(Page page)
+ {
+ PageHeader p;
+
+ if (PageIsNew(page))
+ return (char *) page;
+
+ if (page_checksums)
+ {
+ /*
+ * We make a copy iff we need to calculate a checksum because other
+ * backends may set hint bits on this page while we write, which
+ * would mean the checksum differs from the page contents. It doesn't
+ * matter if we include or exclude hints during the copy, as long
+ * as we write a valid page and associated checksum.
+ */
+ memcpy(&pageCopy, page, BLCKSZ);
+
+ p = (PageHeader) &pageCopy;
+ p->pd_flags |= PD_CHECKSUM;
+ p->pd_verify.pd_checksum16 = PageCalcChecksum16((Page) &pageCopy);
+
+ return (char *) &pageCopy;
+ }
+
+ p = (PageHeader) page;
+
+ if (PageHasChecksumFlag1(p) || PageHasChecksumFlag2(p))
+ {
+ /* ensure any older checksum info is overwritten with watermark */
+ p->pd_flags &= ~PD_CHECKSUM;
+ PageSetPageSizeAndVersion(p, BLCKSZ, PG_PAGE_LAYOUT_VERSION);
+ }
+
+ return (char *) page;
+ }
+
+ /*
+ * Calculate checksum for a PostgreSQL Page. We do this in 3 steps, first
+ * we calculate the checksum for the header, avoiding the verification
+ * info, which will be added afterwards. Next, we add the line pointers up to
+ * the hole in the middle of the block at pd_lower. Last, we add the tail
+ * of the page from pd_upper to the end of page.
+ */
+ static uint16
+ PageCalcChecksum16(Page page)
+ {
+ #define PAGE_VERIFICATION_USES_FLETCHER16 (true)
+ #ifdef PAGE_VERIFICATION_USES_FLETCHER16
+ /*
+ * Following calculation is a Flecther's 16 checksum. The calc is isolated
+ * here and tuning and/or replacement algorithms are possible.
+ *
+ * XXX present implementation is raw, untuned calculation, please tweak
+ */
+ PageHeader p = (PageHeader) page;
+ uint page_header_stop = (uint)(offsetof(PageHeaderData, pd_special) + sizeof(LocationIndex));
+ uint page_lower_start = (uint)(offsetof(PageHeaderData, pd_prune_xid));
+ uint page_lower_stop;
+ uint16 sum1 = 0;
+ uint16 sum2 = 0;
+ int i;
+
+ /*
+ * Avoid calculating checksum if page is new, just return a value that
+ * will cause the check to fail. We may still pass the all-zeroes check.
+ */
+ if (PageIsNew(page))
+ return 1;
+
+ /*
+ * Just add in the pd_prune_xid if there are no line pointers yet.
+ */
+ page_lower_stop = p->pd_lower;
+ if (page_lower_stop == 0)
+ page_lower_stop = page_lower_start + sizeof(TransactionId);
+
+ Assert(p->pd_upper != 0);
+
+ #ifdef DEBUG_CHECKSUM
+ elog(LOG, "calculating checksum for %u-%u %u-%u %u-%u",
+ 0, /* page_header_start */
+ page_header_stop,
+ page_lower_start,
+ page_lower_stop,
+ p->pd_upper,
+ BLCKSZ
+ );
+ #endif
+
+ #define COMP_F16(from, to) \
+ do { \
+ for (i = from; i < to; i++) \
+ { \
+ sum1 = (sum1 + page[i]) % 255; \
+ sum2 = (sum1 + sum2) % 255; \
+ } \
+ } while (0); \
+
+ COMP_F16(0,
+ page_header_stop);
+
+ /* ignore the checksum field since not done yet... */
+
+ COMP_F16(page_lower_start,
+ page_lower_stop);
+
+ /* ignore the hole in the middle of the block */
+
+ COMP_F16(p->pd_upper,
+ BLCKSZ - 1);
+
+ #ifdef DEBUG_CHECKSUM
+ elog(LOG, "checksum %u", ((sum2 << 8) | sum1));
+ #endif
+
+ return ((sum2 << 8) | sum1);
+ #endif
+ }
*** a/src/backend/utils/misc/guc.c
--- b/src/backend/utils/misc/guc.c
***************
*** 830,835 **** static struct config_bool ConfigureNamesBool[] =
--- 830,849 ----
NULL, NULL, NULL
},
{
+ {"page_checksums", PGC_SIGHUP, WAL_SETTINGS,
+ gettext_noop("Marks database blocks with a checksum before writing them to disk. "),
+ gettext_noop("When enabled all database blocks will be marked with a checksums before writing to disk. "
+ "When we read a database block from disk the checksum is checked, if it exists. "
+ "If there is no checksum marked yet then no check is performed, though a "
+ "checksum will be added later when we re-write the database block. "
+ "When disabled checksums will be ignored, even if the block was marked "
+ "with checksum. When disabled checksums will not be added to database blocks.")
+ },
+ &page_checksums,
+ false,
+ NULL, NULL, NULL
+ },
+ {
{"full_page_writes", PGC_SIGHUP, WAL_SETTINGS,
gettext_noop("Writes full pages to WAL when first modified after a checkpoint."),
gettext_noop("A page write in process during an operating system crash might be "
*** a/src/backend/utils/misc/postgresql.conf.sample
--- b/src/backend/utils/misc/postgresql.conf.sample
***************
*** 150,164 ****
#------------------------------------------------------------------------------
! # WRITE AHEAD LOG
#------------------------------------------------------------------------------
! # - Settings -
! #wal_level = minimal # minimal, archive, or hot_standby
! # (change requires restart)
#fsync = on # turns forced synchronization on or off
#synchronous_commit = on # synchronization level; on, off, or local
#wal_sync_method = fsync # the default is the first option
# supported by the operating system:
# open_datasync
--- 150,170 ----
#------------------------------------------------------------------------------
! # WRITE AHEAD LOG & RELIABILITY
#------------------------------------------------------------------------------
! # - Reliability -
! #page_checksums = off # calculate checksum before database I/O
! #full_page_writes = on # recover from partial page writes
#fsync = on # turns forced synchronization on or off
+
#synchronous_commit = on # synchronization level; on, off, or local
+
+ # - Write Ahead Log -
+
+ #wal_level = minimal # minimal, archive, or hot_standby
+ # (change requires restart)
#wal_sync_method = fsync # the default is the first option
# supported by the operating system:
# open_datasync
***************
*** 166,172 ****
# fsync
# fsync_writethrough
# open_sync
- #full_page_writes = on # recover from partial page writes
#wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers
# (change requires restart)
#wal_writer_delay = 200ms # 1-10000 milliseconds
--- 172,177 ----
*** a/src/include/storage/bufpage.h
--- b/src/include/storage/bufpage.h
***************
*** 18,23 ****
--- 18,25 ----
#include "storage/item.h"
#include "storage/off.h"
+ extern bool page_checksums;
+
/*
* A postgres disk page is an abstraction layered on top of a postgres
* disk block (which is simply a unit of i/o, see block.h).
***************
*** 93,99 **** typedef uint16 LocationIndex;
* pd_lower - offset to start of free space.
* pd_upper - offset to end of free space.
* pd_special - offset to start of special space.
! * pd_pagesize_version - size in bytes and page layout version number.
* pd_prune_xid - oldest XID among potentially prunable tuples on page.
*
* The LSN is used by the buffer manager to enforce the basic rule of WAL:
--- 95,101 ----
* pd_lower - offset to start of free space.
* pd_upper - offset to end of free space.
* pd_special - offset to start of special space.
! * pd_verify - page verification information of different kinds
* pd_prune_xid - oldest XID among potentially prunable tuples on page.
*
* The LSN is used by the buffer manager to enforce the basic rule of WAL:
***************
*** 106,112 **** typedef uint16 LocationIndex;
* pd_prune_xid is a hint field that helps determine whether pruning will be
* useful. It is currently unused in index pages.
*
! * The page version number and page size are packed together into a single
* uint16 field. This is for historical reasons: before PostgreSQL 7.3,
* there was no concept of a page version number, and doing it this way
* lets us pretend that pre-7.3 databases have page version number zero.
--- 108,115 ----
* pd_prune_xid is a hint field that helps determine whether pruning will be
* useful. It is currently unused in index pages.
*
! * For verification we store either a 16 bit checksum or a watermark of
! * the page version number and page size packed together into a single
* uint16 field. This is for historical reasons: before PostgreSQL 7.3,
* there was no concept of a page version number, and doing it this way
* lets us pretend that pre-7.3 databases have page version number zero.
***************
*** 130,136 **** typedef struct PageHeaderData
LocationIndex pd_lower; /* offset to start of free space */
LocationIndex pd_upper; /* offset to end of free space */
LocationIndex pd_special; /* offset to start of special space */
! uint16 pd_pagesize_version;
TransactionId pd_prune_xid; /* oldest prunable XID, or zero if none */
ItemIdData pd_linp[1]; /* beginning of line pointer array */
} PageHeaderData;
--- 133,145 ----
LocationIndex pd_lower; /* offset to start of free space */
LocationIndex pd_upper; /* offset to end of free space */
LocationIndex pd_special; /* offset to start of special space */
!
! union
! {
! uint16 pd_pagesize_version;
! uint16 pd_checksum16;
! } pd_verify; /* page verification data */
!
TransactionId pd_prune_xid; /* oldest prunable XID, or zero if none */
ItemIdData pd_linp[1]; /* beginning of line pointer array */
} PageHeaderData;
***************
*** 155,161 **** typedef PageHeaderData *PageHeader;
#define PD_ALL_VISIBLE 0x0004 /* all tuples on page are visible to
* everyone */
! #define PD_VALID_FLAG_BITS 0x0007 /* OR of all valid pd_flags bits */
/*
* Page layout version number 0 is for pre-7.3 Postgres releases.
--- 164,179 ----
#define PD_ALL_VISIBLE 0x0004 /* all tuples on page are visible to
* everyone */
! #define PD_VALID_FLAG_BITS 0x800F /* OR of all non-checksum pd_flags bits */
!
! #define PD_CHECKSUM1 0x0008 /* First checksum bit */
! #define PD_CHECKSUM2 0x8000 /* Second checksum bit */
! #define PD_CHECKSUM 0x8008 /* OR of both checksum flags */
!
! #define PageHasChecksumFlag1(page) \
! ((((PageHeader) (page))->pd_flags & PD_CHECKSUM1) == PD_CHECKSUM1)
! #define PageHasChecksumFlag2(page) \
! ((((PageHeader) (page))->pd_flags & PD_CHECKSUM2) == PD_CHECKSUM2)
/*
* Page layout version number 0 is for pre-7.3 Postgres releases.
***************
*** 165,170 **** typedef PageHeaderData *PageHeader;
--- 183,190 ----
* Release 8.3 uses 4; it changed the HeapTupleHeader layout again, and
* added the pd_flags field (by stealing some bits from pd_tli),
* as well as adding the pd_prune_xid field (which enlarges the header).
+ * Release 9.2 uses 4 as well, though with changed meaning of verification bits.
+ * We deliberately don't bump the page version for that, to allow upgrades.
*/
#define PG_PAGE_LAYOUT_VERSION 4
***************
*** 231,249 **** typedef PageHeaderData *PageHeader;
* PageGetPageSize
* Returns the page size of a page.
*
! * this can only be called on a formatted page (unlike
! * BufferGetPageSize, which can be called on an unformatted page).
! * however, it can be called on a page that is not stored in a buffer.
*/
! #define PageGetPageSize(page) \
! ((Size) (((PageHeader) (page))->pd_pagesize_version & (uint16) 0xFF00))
/*
* PageGetPageLayoutVersion
* Returns the page layout version of a page.
*/
#define PageGetPageLayoutVersion(page) \
! (((PageHeader) (page))->pd_pagesize_version & 0x00FF)
/*
* PageSetPageSizeAndVersion
--- 251,272 ----
* PageGetPageSize
* Returns the page size of a page.
*
! * Since PageSizeIsValid() when pagesize == BLCKSZ, just written BLCKSZ.
! * This can be called on any page, initialised or not, in or out of buffers.
! * You might think this can vary at runtime but you'd be wrong, since pages
! * frequently need to occupy buffers and pages are copied from one to another
! * so there are many hidden assumptions that this simple definition is true.
*/
! #define PageGetPageSize(page) (BLCKSZ)
/*
* PageGetPageLayoutVersion
* Returns the page layout version of a page.
+ *
+ * Must not be used on a page that is flagged for checksums.
*/
#define PageGetPageLayoutVersion(page) \
! (((PageHeader) (page))->pd_verify.pd_pagesize_version & 0x00FF)
/*
* PageSetPageSizeAndVersion
***************
*** 251,262 **** typedef PageHeaderData *PageHeader;
*
* We could support setting these two values separately, but there's
* no real need for it at the moment.
*/
#define PageSetPageSizeAndVersion(page, size, version) \
( \
AssertMacro(((size) & 0xFF00) == (size)), \
AssertMacro(((version) & 0x00FF) == (version)), \
! ((PageHeader) (page))->pd_pagesize_version = (size) | (version) \
)
/* ----------------
--- 274,287 ----
*
* We could support setting these two values separately, but there's
* no real need for it at the moment.
+ *
+ * Must not be used on a page that is flagged for checksums.
*/
#define PageSetPageSizeAndVersion(page, size, version) \
( \
AssertMacro(((size) & 0xFF00) == (size)), \
AssertMacro(((version) & 0x00FF) == (version)), \
! ((PageHeader) (page))->pd_verify.pd_pagesize_version = (size) | (version) \
)
/* ----------------
***************
*** 368,374 **** do { \
*/
extern void PageInit(Page page, Size pageSize, Size specialSize);
! extern bool PageHeaderIsValid(PageHeader page);
extern OffsetNumber PageAddItem(Page page, Item item, Size size,
OffsetNumber offsetNumber, bool overwrite, bool is_heap);
extern Page PageGetTempPage(Page page);
--- 393,399 ----
*/
extern void PageInit(Page page, Size pageSize, Size specialSize);
! extern bool PageIsVerified(Page page);
extern OffsetNumber PageAddItem(Page page, Item item, Size size,
OffsetNumber offsetNumber, bool overwrite, bool is_heap);
extern Page PageGetTempPage(Page page);
***************
*** 381,385 **** extern Size PageGetExactFreeSpace(Page page);
--- 406,411 ----
extern Size PageGetHeapFreeSpace(Page page);
extern void PageIndexTupleDelete(Page page, OffsetNumber offset);
extern void PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems);
+ extern char *PageSetVerificationInfo(Page page);
#endif /* BUFPAGE_H */
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