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Sincea892234&fd31cd265the visibilitymap's freeze bit is used to avoid vacuuming the whole relation in anti-wraparound vacuums. Doing so correctly relies on not adding xids to the heap without also unsetting the visibilitymap flag. Tuple locking related code has not done so. To allow selectively resetting all-frozen - to avoid pessimizing heap_lock_tuple - allow to selectively reset the all-frozen with visibilitymap_clear(). To avoid having to use visibilitymap_get_status (e.g. via VM_ALL_FROZEN) inside a critical section, have visibilitymap_clear() return whether any bits have been reset. There's a remaining issue (denoted by XXX): After the PageIsAllVisible() check in heap_lock_tuple() and heap_lock_updated_tuple_rec() the page status could theoretically change. Practically that currently seems impossible, because updaters will hold a page level pin already. Due to the next beta coming up, it seems better to get the required WAL magic bump done before resolving this issue. The added flags field fields to xl_heap_lock and xl_heap_lock_updated require bumping the WAL magic. Since there's already been a catversion bump since the last beta, that's not an issue. Reviewed-By: Robert Haas, Amit Kapila and Andres Freund Author: Masahiko Sawada, heavily revised by Andres Freund Discussion: CAEepm=3fWAbWryVW9swHyLTY4sXVf0xbLvXqOwUoDiNCx9mBjQ@mail.gmail.com Backpatch: -
49 lines
1.8 KiB
C
49 lines
1.8 KiB
C
/*-------------------------------------------------------------------------
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*
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* visibilitymap.h
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* visibility map interface
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*
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*
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* Portions Copyright (c) 2007-2016, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/access/visibilitymap.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef VISIBILITYMAP_H
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#define VISIBILITYMAP_H
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#include "access/xlogdefs.h"
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#include "storage/block.h"
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#include "storage/buf.h"
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#include "utils/relcache.h"
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/* Number of bits for one heap page */
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#define BITS_PER_HEAPBLOCK 2
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/* Flags for bit map */
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#define VISIBILITYMAP_ALL_VISIBLE 0x01
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#define VISIBILITYMAP_ALL_FROZEN 0x02
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#define VISIBILITYMAP_VALID_BITS 0x03 /* OR of all valid
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* visiblitymap flags bits */
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/* Macros for visibilitymap test */
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#define VM_ALL_VISIBLE(r, b, v) \
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((visibilitymap_get_status((r), (b), (v)) & VISIBILITYMAP_ALL_VISIBLE) != 0)
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#define VM_ALL_FROZEN(r, b, v) \
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((visibilitymap_get_status((r), (b), (v)) & VISIBILITYMAP_ALL_FROZEN) != 0)
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extern bool visibilitymap_clear(Relation rel, BlockNumber heapBlk,
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Buffer vmbuf, uint8 flags);
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extern void visibilitymap_pin(Relation rel, BlockNumber heapBlk,
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Buffer *vmbuf);
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extern bool visibilitymap_pin_ok(BlockNumber heapBlk, Buffer vmbuf);
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extern void visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf,
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XLogRecPtr recptr, Buffer vmBuf, TransactionId cutoff_xid,
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uint8 flags);
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extern uint8 visibilitymap_get_status(Relation rel, BlockNumber heapBlk, Buffer *vmbuf);
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extern void visibilitymap_count(Relation rel, BlockNumber *all_visible, BlockNumber *all_frozen);
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extern void visibilitymap_truncate(Relation rel, BlockNumber nheapblocks);
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#endif /* VISIBILITYMAP_H */
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