mirror of
https://github.com/postgres/postgres.git
synced 2025-04-22 23:02:54 +03:00
Move VM update code from lazy_scan_heap() to lazy_scan_prune().
Most of the output parameters of lazy_scan_prune() were being used to update the VM in lazy_scan_heap(). Moving that code into lazy_scan_prune() simplifies lazy_scan_heap() and requires less communication between the two. This change permits some further code simplification, but that is left for a separate commit. Melanie Plageman, reviewed by me. Discussion: http://postgr.es/m/CAAKRu_aM=OL85AOr-80wBsCr=vLVzhnaavqkVPRkFBtD0zsuLQ@mail.gmail.com
This commit is contained in:
Robert Haas
parent
0a157a4d44
commit
cb970240f1
@ -249,6 +249,7 @@ static bool lazy_scan_new_or_empty(LVRelState *vacrel, Buffer buf,
|
|||||||
bool sharelock, Buffer vmbuffer);
|
bool sharelock, Buffer vmbuffer);
|
||||||
static void lazy_scan_prune(LVRelState *vacrel, Buffer buf,
|
static void lazy_scan_prune(LVRelState *vacrel, Buffer buf,
|
||||||
BlockNumber blkno, Page page,
|
BlockNumber blkno, Page page,
|
||||||
|
Buffer vmbuffer, bool all_visible_according_to_vm,
|
||||||
LVPagePruneState *prunestate);
|
LVPagePruneState *prunestate);
|
||||||
static bool lazy_scan_noprune(LVRelState *vacrel, Buffer buf,
|
static bool lazy_scan_noprune(LVRelState *vacrel, Buffer buf,
|
||||||
BlockNumber blkno, Page page,
|
BlockNumber blkno, Page page,
|
||||||
@ -1032,117 +1033,9 @@ lazy_scan_heap(LVRelState *vacrel)
|
|||||||
* tuple headers of remaining items with storage. It also determines
|
* tuple headers of remaining items with storage. It also determines
|
||||||
* if truncating this block is safe.
|
* if truncating this block is safe.
|
||||||
*/
|
*/
|
||||||
lazy_scan_prune(vacrel, buf, blkno, page, &prunestate);
|
lazy_scan_prune(vacrel, buf, blkno, page,
|
||||||
|
vmbuffer, all_visible_according_to_vm,
|
||||||
Assert(!prunestate.all_visible || !prunestate.has_lpdead_items);
|
&prunestate);
|
||||||
|
|
||||||
/*
|
|
||||||
* Handle setting visibility map bit based on information from the VM
|
|
||||||
* (as of last lazy_scan_skip() call), and from prunestate
|
|
||||||
*/
|
|
||||||
if (!all_visible_according_to_vm && prunestate.all_visible)
|
|
||||||
{
|
|
||||||
uint8 flags = VISIBILITYMAP_ALL_VISIBLE;
|
|
||||||
|
|
||||||
if (prunestate.all_frozen)
|
|
||||||
{
|
|
||||||
Assert(!TransactionIdIsValid(prunestate.visibility_cutoff_xid));
|
|
||||||
flags |= VISIBILITYMAP_ALL_FROZEN;
|
|
||||||
}
|
|
||||||
|
|
||||||
/*
|
|
||||||
* It should never be the case that the visibility map page is set
|
|
||||||
* while the page-level bit is clear, but the reverse is allowed
|
|
||||||
* (if checksums are not enabled). Regardless, set both bits so
|
|
||||||
* that we get back in sync.
|
|
||||||
*
|
|
||||||
* NB: If the heap page is all-visible but the VM bit is not set,
|
|
||||||
* we don't need to dirty the heap page. However, if checksums
|
|
||||||
* are enabled, we do need to make sure that the heap page is
|
|
||||||
* dirtied before passing it to visibilitymap_set(), because it
|
|
||||||
* may be logged. Given that this situation should only happen in
|
|
||||||
* rare cases after a crash, it is not worth optimizing.
|
|
||||||
*/
|
|
||||||
PageSetAllVisible(page);
|
|
||||||
MarkBufferDirty(buf);
|
|
||||||
visibilitymap_set(vacrel->rel, blkno, buf, InvalidXLogRecPtr,
|
|
||||||
vmbuffer, prunestate.visibility_cutoff_xid,
|
|
||||||
flags);
|
|
||||||
}
|
|
||||||
|
|
||||||
/*
|
|
||||||
* As of PostgreSQL 9.2, the visibility map bit should never be set if
|
|
||||||
* the page-level bit is clear. However, it's possible that the bit
|
|
||||||
* got cleared after lazy_scan_skip() was called, so we must recheck
|
|
||||||
* with buffer lock before concluding that the VM is corrupt.
|
|
||||||
*/
|
|
||||||
else if (all_visible_according_to_vm && !PageIsAllVisible(page) &&
|
|
||||||
visibilitymap_get_status(vacrel->rel, blkno, &vmbuffer) != 0)
|
|
||||||
{
|
|
||||||
elog(WARNING, "page is not marked all-visible but visibility map bit is set in relation \"%s\" page %u",
|
|
||||||
vacrel->relname, blkno);
|
|
||||||
visibilitymap_clear(vacrel->rel, blkno, vmbuffer,
|
|
||||||
VISIBILITYMAP_VALID_BITS);
|
|
||||||
}
|
|
||||||
|
|
||||||
/*
|
|
||||||
* It's possible for the value returned by
|
|
||||||
* GetOldestNonRemovableTransactionId() to move backwards, so it's not
|
|
||||||
* wrong for us to see tuples that appear to not be visible to
|
|
||||||
* everyone yet, while PD_ALL_VISIBLE is already set. The real safe
|
|
||||||
* xmin value never moves backwards, but
|
|
||||||
* GetOldestNonRemovableTransactionId() is conservative and sometimes
|
|
||||||
* returns a value that's unnecessarily small, so if we see that
|
|
||||||
* contradiction it just means that the tuples that we think are not
|
|
||||||
* visible to everyone yet actually are, and the PD_ALL_VISIBLE flag
|
|
||||||
* is correct.
|
|
||||||
*
|
|
||||||
* There should never be LP_DEAD items on a page with PD_ALL_VISIBLE
|
|
||||||
* set, however.
|
|
||||||
*/
|
|
||||||
else if (prunestate.has_lpdead_items && PageIsAllVisible(page))
|
|
||||||
{
|
|
||||||
elog(WARNING, "page containing LP_DEAD items is marked as all-visible in relation \"%s\" page %u",
|
|
||||||
vacrel->relname, blkno);
|
|
||||||
PageClearAllVisible(page);
|
|
||||||
MarkBufferDirty(buf);
|
|
||||||
visibilitymap_clear(vacrel->rel, blkno, vmbuffer,
|
|
||||||
VISIBILITYMAP_VALID_BITS);
|
|
||||||
}
|
|
||||||
|
|
||||||
/*
|
|
||||||
* If the all-visible page is all-frozen but not marked as such yet,
|
|
||||||
* mark it as all-frozen. Note that all_frozen is only valid if
|
|
||||||
* all_visible is true, so we must check both prunestate fields.
|
|
||||||
*/
|
|
||||||
else if (all_visible_according_to_vm && prunestate.all_visible &&
|
|
||||||
prunestate.all_frozen &&
|
|
||||||
!VM_ALL_FROZEN(vacrel->rel, blkno, &vmbuffer))
|
|
||||||
{
|
|
||||||
/*
|
|
||||||
* Avoid relying on all_visible_according_to_vm as a proxy for the
|
|
||||||
* page-level PD_ALL_VISIBLE bit being set, since it might have
|
|
||||||
* become stale -- even when all_visible is set in prunestate
|
|
||||||
*/
|
|
||||||
if (!PageIsAllVisible(page))
|
|
||||||
{
|
|
||||||
PageSetAllVisible(page);
|
|
||||||
MarkBufferDirty(buf);
|
|
||||||
}
|
|
||||||
|
|
||||||
/*
|
|
||||||
* Set the page all-frozen (and all-visible) in the VM.
|
|
||||||
*
|
|
||||||
* We can pass InvalidTransactionId as our visibility_cutoff_xid,
|
|
||||||
* since a snapshotConflictHorizon sufficient to make everything
|
|
||||||
* safe for REDO was logged when the page's tuples were frozen.
|
|
||||||
*/
|
|
||||||
Assert(!TransactionIdIsValid(prunestate.visibility_cutoff_xid));
|
|
||||||
visibilitymap_set(vacrel->rel, blkno, buf, InvalidXLogRecPtr,
|
|
||||||
vmbuffer, InvalidTransactionId,
|
|
||||||
VISIBILITYMAP_ALL_VISIBLE |
|
|
||||||
VISIBILITYMAP_ALL_FROZEN);
|
|
||||||
}
|
|
||||||
|
|
||||||
/*
|
/*
|
||||||
* Final steps for block: drop cleanup lock, record free space in the
|
* Final steps for block: drop cleanup lock, record free space in the
|
||||||
@ -1496,6 +1389,8 @@ lazy_scan_prune(LVRelState *vacrel,
|
|||||||
Buffer buf,
|
Buffer buf,
|
||||||
BlockNumber blkno,
|
BlockNumber blkno,
|
||||||
Page page,
|
Page page,
|
||||||
|
Buffer vmbuffer,
|
||||||
|
bool all_visible_according_to_vm,
|
||||||
LVPagePruneState *prunestate)
|
LVPagePruneState *prunestate)
|
||||||
{
|
{
|
||||||
Relation rel = vacrel->rel;
|
Relation rel = vacrel->rel;
|
||||||
@ -1880,6 +1775,115 @@ lazy_scan_prune(LVRelState *vacrel,
|
|||||||
/* Can't truncate this page */
|
/* Can't truncate this page */
|
||||||
if (hastup)
|
if (hastup)
|
||||||
vacrel->nonempty_pages = blkno + 1;
|
vacrel->nonempty_pages = blkno + 1;
|
||||||
|
|
||||||
|
Assert(!prunestate->all_visible || !prunestate->has_lpdead_items);
|
||||||
|
|
||||||
|
/*
|
||||||
|
* Handle setting visibility map bit based on information from the VM (as
|
||||||
|
* of last lazy_scan_skip() call), and from prunestate
|
||||||
|
*/
|
||||||
|
if (!all_visible_according_to_vm && prunestate->all_visible)
|
||||||
|
{
|
||||||
|
uint8 flags = VISIBILITYMAP_ALL_VISIBLE;
|
||||||
|
|
||||||
|
if (prunestate->all_frozen)
|
||||||
|
{
|
||||||
|
Assert(!TransactionIdIsValid(prunestate->visibility_cutoff_xid));
|
||||||
|
flags |= VISIBILITYMAP_ALL_FROZEN;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* It should never be the case that the visibility map page is set
|
||||||
|
* while the page-level bit is clear, but the reverse is allowed (if
|
||||||
|
* checksums are not enabled). Regardless, set both bits so that we
|
||||||
|
* get back in sync.
|
||||||
|
*
|
||||||
|
* NB: If the heap page is all-visible but the VM bit is not set, we
|
||||||
|
* don't need to dirty the heap page. However, if checksums are
|
||||||
|
* enabled, we do need to make sure that the heap page is dirtied
|
||||||
|
* before passing it to visibilitymap_set(), because it may be logged.
|
||||||
|
* Given that this situation should only happen in rare cases after a
|
||||||
|
* crash, it is not worth optimizing.
|
||||||
|
*/
|
||||||
|
PageSetAllVisible(page);
|
||||||
|
MarkBufferDirty(buf);
|
||||||
|
visibilitymap_set(vacrel->rel, blkno, buf, InvalidXLogRecPtr,
|
||||||
|
vmbuffer, prunestate->visibility_cutoff_xid,
|
||||||
|
flags);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* As of PostgreSQL 9.2, the visibility map bit should never be set if the
|
||||||
|
* page-level bit is clear. However, it's possible that the bit got
|
||||||
|
* cleared after lazy_scan_skip() was called, so we must recheck with
|
||||||
|
* buffer lock before concluding that the VM is corrupt.
|
||||||
|
*/
|
||||||
|
else if (all_visible_according_to_vm && !PageIsAllVisible(page) &&
|
||||||
|
visibilitymap_get_status(vacrel->rel, blkno, &vmbuffer) != 0)
|
||||||
|
{
|
||||||
|
elog(WARNING, "page is not marked all-visible but visibility map bit is set in relation \"%s\" page %u",
|
||||||
|
vacrel->relname, blkno);
|
||||||
|
visibilitymap_clear(vacrel->rel, blkno, vmbuffer,
|
||||||
|
VISIBILITYMAP_VALID_BITS);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* It's possible for the value returned by
|
||||||
|
* GetOldestNonRemovableTransactionId() to move backwards, so it's not
|
||||||
|
* wrong for us to see tuples that appear to not be visible to everyone
|
||||||
|
* yet, while PD_ALL_VISIBLE is already set. The real safe xmin value
|
||||||
|
* never moves backwards, but GetOldestNonRemovableTransactionId() is
|
||||||
|
* conservative and sometimes returns a value that's unnecessarily small,
|
||||||
|
* so if we see that contradiction it just means that the tuples that we
|
||||||
|
* think are not visible to everyone yet actually are, and the
|
||||||
|
* PD_ALL_VISIBLE flag is correct.
|
||||||
|
*
|
||||||
|
* There should never be LP_DEAD items on a page with PD_ALL_VISIBLE set,
|
||||||
|
* however.
|
||||||
|
*/
|
||||||
|
else if (prunestate->has_lpdead_items && PageIsAllVisible(page))
|
||||||
|
{
|
||||||
|
elog(WARNING, "page containing LP_DEAD items is marked as all-visible in relation \"%s\" page %u",
|
||||||
|
vacrel->relname, blkno);
|
||||||
|
PageClearAllVisible(page);
|
||||||
|
MarkBufferDirty(buf);
|
||||||
|
visibilitymap_clear(vacrel->rel, blkno, vmbuffer,
|
||||||
|
VISIBILITYMAP_VALID_BITS);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* If the all-visible page is all-frozen but not marked as such yet, mark
|
||||||
|
* it as all-frozen. Note that all_frozen is only valid if all_visible is
|
||||||
|
* true, so we must check both prunestate fields.
|
||||||
|
*/
|
||||||
|
else if (all_visible_according_to_vm && prunestate->all_visible &&
|
||||||
|
prunestate->all_frozen &&
|
||||||
|
!VM_ALL_FROZEN(vacrel->rel, blkno, &vmbuffer))
|
||||||
|
{
|
||||||
|
/*
|
||||||
|
* Avoid relying on all_visible_according_to_vm as a proxy for the
|
||||||
|
* page-level PD_ALL_VISIBLE bit being set, since it might have become
|
||||||
|
* stale -- even when all_visible is set in prunestate
|
||||||
|
*/
|
||||||
|
if (!PageIsAllVisible(page))
|
||||||
|
{
|
||||||
|
PageSetAllVisible(page);
|
||||||
|
MarkBufferDirty(buf);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* Set the page all-frozen (and all-visible) in the VM.
|
||||||
|
*
|
||||||
|
* We can pass InvalidTransactionId as our visibility_cutoff_xid,
|
||||||
|
* since a snapshotConflictHorizon sufficient to make everything safe
|
||||||
|
* for REDO was logged when the page's tuples were frozen.
|
||||||
|
*/
|
||||||
|
Assert(!TransactionIdIsValid(prunestate->visibility_cutoff_xid));
|
||||||
|
visibilitymap_set(vacrel->rel, blkno, buf, InvalidXLogRecPtr,
|
||||||
|
vmbuffer, InvalidTransactionId,
|
||||||
|
VISIBILITYMAP_ALL_VISIBLE |
|
||||||
|
VISIBILITYMAP_ALL_FROZEN);
|
||||||
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
/*
|
/*
|
||||||
|
|||||||
Loading…
x
Reference in New Issue
Block a user