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Change CRCs in WAL records from 64bit to 32bit for performance reasons.
Instead of a separate CRC on each backup block, include backup blocks in their parent WAL record's CRC; this is important to ensure that the backup block really goes with the WAL record, ie there was not a page tear right at the start of the backup block. Implement a simple form of compression of backup blocks: drop any run of zeroes starting at pd_lower, so as not to store the unused 'hole' that commonly exists in PG heap and index pages. Tweak PageRepairFragmentation and related routines to ensure they keep the unused space zeroed, so that the above compression method remains effective. All per recent discussions.
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11 files changed

+511
-207
lines changed

11 files changed

+511
-207
lines changed

‎src/backend/access/nbtree/nbtpage.c‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.84 2005/05/07 21:32:23 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.85 2005/06/02 05:55:28 tgl Exp $
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*
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* NOTES
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* Postgres btree pages look like ordinary relation pages. The opaque
@@ -113,6 +113,13 @@ _bt_initmetapage(Page page, BlockNumber rootbknum, uint32 level)
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metaopaque = (BTPageOpaque) PageGetSpecialPointer(page);
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metaopaque->btpo_flags = BTP_META;
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/*
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* Set pd_lower just past the end of the metadata. This is not
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* essential but it makes the page look compressible to xlog.c.
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*/
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((PageHeader) page)->pd_lower =
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((char *) metad + sizeof(BTMetaPageData)) - (char *) page;
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}
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/*

‎src/backend/access/nbtree/nbtxlog.c‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.20 2005/03/22 06:17:03 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.21 2005/06/02 05:55:28 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -135,6 +135,13 @@ _bt_restore_meta(Relation reln, XLogRecPtr lsn,
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pageop = (BTPageOpaque) PageGetSpecialPointer(metapg);
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pageop->btpo_flags = BTP_META;
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/*
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* Set pd_lower just past the end of the metadata. This is not
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* essential but it makes the page look compressible to xlog.c.
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*/
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((PageHeader) metapg)->pd_lower =
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((char *) md + sizeof(BTMetaPageData)) - (char *) metapg;
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PageSetLSN(metapg, lsn);
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PageSetTLI(metapg, ThisTimeLineID);
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LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);

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