* memory and writing them directly to smgr. If you're using buffers, call
* log_newpage_buffer instead.
*
- * Note: the NEWPAGE log record is used for both heaps and indexes, so do
- * not do anything that assumes we are touching a heap.
+ * If the page follows the standard page layout, with a PageHeader and unused
+ * space between pd_lower and pd_upper, set 'page_std' to TRUE. That allows
+ * the unused space to be left out from the WAL record, making it smaller.
*/
XLogRecPtr
log_newpage(RelFileNode *rnode, ForkNumber forkNum, BlockNumber blkno,
- Page page)
+ Page page, bool page_std)
{
xl_heap_newpage xlrec;
XLogRecPtr recptr;
- XLogRecData rdata[2];
+ XLogRecData rdata[3];
+
+ /*
+ * Note: the NEWPAGE log record is used for both heaps and indexes, so do
+ * not do anything that assumes we are touching a heap.
+ */
/* NO ELOG(ERROR) from here till newpage op is logged */
START_CRIT_SECTION();
xlrec.forknum = forkNum;
xlrec.blkno = blkno;
+ if (page_std)
+ {
+ /* Assume we can omit data between pd_lower and pd_upper */
+ uint16 lower = ((PageHeader) page)->pd_lower;
+ uint16 upper = ((PageHeader) page)->pd_upper;
+
+ if (lower >= SizeOfPageHeaderData &&
+ upper > lower &&
+ upper <= BLCKSZ)
+ {
+ xlrec.hole_offset = lower;
+ xlrec.hole_length = upper - lower;
+ }
+ else
+ {
+ /* No "hole" to compress out */
+ xlrec.hole_offset = 0;
+ xlrec.hole_length = 0;
+ }
+ }
+ else
+ {
+ /* Not a standard page header, don't try to eliminate "hole" */
+ xlrec.hole_offset = 0;
+ xlrec.hole_length = 0;
+ }
+
rdata[0].data = (char *) &xlrec;
rdata[0].len = SizeOfHeapNewpage;
rdata[0].buffer = InvalidBuffer;
rdata[0].next = &(rdata[1]);
- rdata[1].data = (char *) page;
- rdata[1].len = BLCKSZ;
- rdata[1].buffer = InvalidBuffer;
- rdata[1].next = NULL;
+ if (xlrec.hole_length == 0)
+ {
+ rdata[1].data = (char *) page;
+ rdata[1].len = BLCKSZ;
+ rdata[1].buffer = InvalidBuffer;
+ rdata[1].next = NULL;
+ }
+ else
+ {
+ /* must skip the hole */
+ rdata[1].data = (char *) page;
+ rdata[1].len = xlrec.hole_offset;
+ rdata[1].buffer = InvalidBuffer;
+ rdata[1].next = &rdata[2];
+
+ rdata[2].data = (char *) page + (xlrec.hole_offset + xlrec.hole_length);
+ rdata[2].len = BLCKSZ - (xlrec.hole_offset + xlrec.hole_length);
+ rdata[2].buffer = InvalidBuffer;
+ rdata[2].next = NULL;
+ }
recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_NEWPAGE, rdata);
* Caller should initialize the buffer and mark it dirty before calling this
* function. This function will set the page LSN and TLI.
*
- * Note: the NEWPAGE log record is used for both heaps and indexes, so do
- * not do anything that assumes we are touching a heap.
+ * If the page follows the standard page layout, with a PageHeader and unused
+ * space between pd_lower and pd_upper, set 'page_std' to TRUE. That allows
+ * the unused space to be left out from the WAL record, making it smaller.
*/
XLogRecPtr
-log_newpage_buffer(Buffer buffer)
+log_newpage_buffer(Buffer buffer, bool page_std)
{
- xl_heap_newpage xlrec;
- XLogRecPtr recptr;
- XLogRecData rdata[2];
Page page = BufferGetPage(buffer);
+ RelFileNode rnode;
+ ForkNumber forkNum;
+ BlockNumber blkno;
- /* We should be in a critical section. */
+ /* Shared buffers should be modified in a critical section. */
Assert(CritSectionCount > 0);
- BufferGetTag(buffer, &xlrec.node, &xlrec.forknum, &xlrec.blkno);
-
- rdata[0].data = (char *) &xlrec;
- rdata[0].len = SizeOfHeapNewpage;
- rdata[0].buffer = InvalidBuffer;
- rdata[0].next = &(rdata[1]);
-
- rdata[1].data = page;
- rdata[1].len = BLCKSZ;
- rdata[1].buffer = InvalidBuffer;
- rdata[1].next = NULL;
-
- recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_NEWPAGE, rdata);
-
- /*
- * The page may be uninitialized. If so, we can't set the LSN and TLI
- * because that would corrupt the page.
- */
- if (!PageIsNew(page))
- {
- PageSetLSN(page, recptr);
- }
+ BufferGetTag(buffer, &rnode, &forkNum, &blkno);
- return recptr;
+ return log_newpage(&rnode, forkNum, blkno, page, page_std);
}
/*
heap_xlog_newpage(XLogRecPtr lsn, XLogRecord *record)
{
xl_heap_newpage *xlrec = (xl_heap_newpage *) XLogRecGetData(record);
+ char *blk = ((char *) xlrec) + sizeof(xl_heap_newpage);
Buffer buffer;
Page page;
/* Backup blocks are not used in newpage records */
Assert(!(record->xl_info & XLR_BKP_BLOCK_MASK));
+ Assert(record->xl_len == SizeOfHeapNewpage + BLCKSZ - xlrec->hole_length);
+
/*
* Note: the NEWPAGE log record is used for both heaps and indexes, so do
* not do anything that assumes we are touching a heap.
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
page = (Page) BufferGetPage(buffer);
- Assert(record->xl_len == SizeOfHeapNewpage + BLCKSZ);
- memcpy(page, (char *) xlrec + SizeOfHeapNewpage, BLCKSZ);
+ if (xlrec->hole_length == 0)
+ {
+ memcpy((char *) page, blk, BLCKSZ);
+ }
+ else
+ {
+ memcpy((char *) page, blk, xlrec->hole_offset);
+ /* must zero-fill the hole */
+ MemSet((char *) page + xlrec->hole_offset, 0, xlrec->hole_length);
+ memcpy((char *) page + (xlrec->hole_offset + xlrec->hole_length),
+ blk + xlrec->hole_offset,
+ BLCKSZ - (xlrec->hole_offset + xlrec->hole_length));
+ }
/*
* The page may be uninitialized. If so, we can't set the LSN because that
(char *) page, true);
if (XLogIsNeeded())
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
- SPGIST_METAPAGE_BLKNO, page);
+ SPGIST_METAPAGE_BLKNO, page, false);
/* Likewise for the root page. */
SpGistInitPage(page, SPGIST_LEAF);
(char *) page, true);
if (XLogIsNeeded())
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
- SPGIST_ROOT_BLKNO, page);
+ SPGIST_ROOT_BLKNO, page, true);
/* Likewise for the null-tuples root page. */
SpGistInitPage(page, SPGIST_LEAF | SPGIST_NULLS);
(char *) page, true);
if (XLogIsNeeded())
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
- SPGIST_NULL_BLKNO, page);
+ SPGIST_NULL_BLKNO, page, true);
/*
* An immediate sync is required even if we xlog'd the pages, because the
RelFileNode node;
ForkNumber forknum;
BlockNumber blkno; /* location of new page */
- /* entire page contents follow at end of record */
+ uint16 hole_offset; /* number of bytes before "hole" */
+ uint16 hole_length; /* number of bytes in "hole" */
+ /* entire page contents (minus the hole) follow at end of record */
} xl_heap_newpage;
-#define SizeOfHeapNewpage (offsetof(xl_heap_newpage, blkno) + sizeof(BlockNumber))
+#define SizeOfHeapNewpage (offsetof(xl_heap_newpage, hole_length) + sizeof(uint16))
/* flags for infobits_set */
#define XLHL_XMAX_IS_MULTI 0x01
extern XLogRecPtr log_heap_visible(RelFileNode rnode, Buffer heap_buffer,
Buffer vm_buffer, TransactionId cutoff_xid);
extern XLogRecPtr log_newpage(RelFileNode *rnode, ForkNumber forkNum,
- BlockNumber blk, Page page);
-extern XLogRecPtr log_newpage_buffer(Buffer buffer);
+ BlockNumber blk, Page page, bool page_std);
+extern XLogRecPtr log_newpage_buffer(Buffer buffer, bool page_std);
#endif /* HEAPAM_XLOG_H */
projects / postgresql / commitdiff