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When a relation is truncated, shared_buffers needs to be scanned so that any buffers for the relation forks are invalidated in it. Previously, shared_buffers was scanned for each relation forks, i.e., MAIN, FSM and VM, when VACUUM truncated off any empty pages at the end of relation or TRUNCATE truncated the relation in place. Since shared_buffers needed to be scanned multiple times, it could take a long time to finish those commands especially when shared_buffers was large. This commit changes the logic so that shared_buffers is scanned only one time for those three relation forks. Author: Kirk Jamison Reviewed-by: Masahiko Sawada, Thomas Munro, Alvaro Herrera, Takayuki Tsunakawa and Fujii Masao Discussion: https://postgr.es/m/D09B13F772D2274BB348A310EE3027C64E2067@g01jpexmbkw24
51 lines
1.8 KiB
C
51 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) 2007-2019, 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 visibilitymap
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* 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 BlockNumber visibilitymap_prepare_truncate(Relation rel,
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BlockNumber nheapblocks);
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#endif /* VISIBILITYMAP_H */
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