30.07.2015 16:33, Alexander Korotkov пишет:
Hi!
On Thu, Jul 30, 2015 at 2:51 PM, Anastasia Lubennikova
<lubennikov...@gmail.com <mailto:lubennikov...@gmail.com>> wrote:
I have written microvacuum support for gist access method.
Briefly microvacuum includes two steps:
1. When search tells us that the tuple is invisible to all
transactions it is marked LP_DEAD and page is marked as "has dead
tuples",
2. Then, when insert touches full page which has dead tuples it
calls microvacuum instead of splitting page.
You can find a kind of review here [1].
[1]
http://www.google-melange.com/gsoc/proposal/public/google/gsoc2015/ivanitskiy_ilya/5629499534213120
Patch is in attachements. Please review it.
Nice!
Some notes about this patch.
1) Could you give same test case demonstrating that microvacuum really
work with patch? Finally, we should get index less growing with
microvacuum.
2) Generating notices for every dead tuple would be too noisy. I
suggest to replace notice with one of debug levels.
+ elog(NOTICE, "gistkillitems. Mark Item Dead offnum %hd, blkno %d",
offnum, BufferGetBlockNumber(buffer));
3) Please, recheck coding style. For instance, this line needs more
spaces and open brace should be on the next line.
+ if ((scan->kill_prior_tuple)&&(so->curPageData >
0)&&(so->curPageData == so->nPageData)) {
------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
<http://www.postgrespro.com/>
The Russian Postgres Company
1) Test and results are in attachments. Everything seems to work as
expected.
2) I dropped these notices. It was done only for debug purposes. Updated
patch is attached.
3) fixed
//
--
Anastasia Lubennikova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
*** a/src/backend/access/gist/gist.c
--- b/src/backend/access/gist/gist.c
***************
*** 36,42 **** static bool gistinserttuples(GISTInsertState *state,
GISTInsertStack *stack,
bool unlockbuf, bool unlockleftchild);
static void gistfinishsplit(GISTInsertState *state, GISTInsertStack *stack,
GISTSTATE *giststate, List *splitinfo, bool
releasebuf);
!
#define ROTATEDIST(d) do { \
SplitedPageLayout
*tmp=(SplitedPageLayout*)palloc(sizeof(SplitedPageLayout)); \
--- 36,42 ----
bool unlockbuf, bool unlockleftchild);
static void gistfinishsplit(GISTInsertState *state, GISTInsertStack *stack,
GISTSTATE *giststate, List *splitinfo, bool
releasebuf);
! static void gistvacuumpage(Relation rel, Page page, Buffer buffer);
#define ROTATEDIST(d) do { \
SplitedPageLayout
*tmp=(SplitedPageLayout*)palloc(sizeof(SplitedPageLayout)); \
***************
*** 209,214 **** gistplacetopage(Relation rel, Size freespace, GISTSTATE
*giststate,
--- 209,225 ----
* because the tuple vector passed to gistSplit won't include this
tuple.
*/
is_split = gistnospace(page, itup, ntup, oldoffnum, freespace);
+
+ /*
+ * If leaf page is full, try at first to delete dead tuples. And then
+ * check again.
+ */
+ if ((is_split) && GistPageIsLeaf(page) && GistPageHasGarbage(page))
+ {
+ gistvacuumpage(rel, page, buffer);
+ is_split = gistnospace(page, itup, ntup, oldoffnum, freespace);
+ }
+
if (is_split)
{
/* no space for insertion */
***************
*** 1440,1442 **** freeGISTstate(GISTSTATE *giststate)
--- 1451,1519 ----
/* It's sufficient to delete the scanCxt */
MemoryContextDelete(giststate->scanCxt);
}
+
+ static void
+ gistvacuumpage(Relation rel, Page page, Buffer buffer)
+ {
+ OffsetNumber deletable[MaxOffsetNumber];
+ int ndeletable = 0;
+ OffsetNumber offnum,
+ minoff,
+ maxoff;
+
+ /*
+ * Scan over all items to see which ones need to be deleted according to
+ * LP_DEAD flags.
+ */
+ maxoff = PageGetMaxOffsetNumber(page);
+ for (offnum = FirstOffsetNumber;
+ offnum <= maxoff;
+ offnum = OffsetNumberNext(offnum))
+ {
+ ItemId itemId = PageGetItemId(page, offnum);
+
+ if (ItemIdIsDead(itemId))
+ deletable[ndeletable++] = offnum;
+ }
+
+ if (ndeletable > 0)
+ {
+ START_CRIT_SECTION();
+
+ PageIndexMultiDelete(page, deletable, ndeletable);
+
+ /*
+ * Mark the page as not containing any LP_DEAD items. This is
not
+ * certainly true (there might be some that have recently been
marked,
+ * but weren't included in our target-item list), but it will
almost
+ * always be true and it doesn't seem worth an additional page
scan to
+ * check it. Remember that F_HAS_GARBAGE is only a hint anyway.
+ */
+ GistClearPageHasGarbage(page);
+
+ MarkBufferDirty(buffer);
+
+ /* XLOG stuff */
+ if (RelationNeedsWAL(rel))
+ {
+ XLogRecPtr recptr;
+
+ recptr = gistXLogUpdate(rel->rd_node, buffer,
+
deletable, ndeletable,
+ NULL,
0, InvalidBuffer);
+
+ PageSetLSN(page, recptr);
+ }
+ else
+ PageSetLSN(page, gistGetFakeLSN(rel));
+
+ END_CRIT_SECTION();
+ }
+
+ /*
+ * Note: if we didn't find any LP_DEAD items, then the page's
+ * F_HAS_GARBAGE hint bit is falsely set. We do not bother expending a
+ * separate write to clear it, however. We will clear it when we split
+ * the page.
+ */
+ }
*** a/src/backend/access/gist/gistget.c
--- b/src/backend/access/gist/gistget.c
***************
*** 25,30 ****
--- 25,93 ----
#include "utils/rel.h"
+ static void
+ gistkillitems(IndexScanDesc scan)
+ {
+ GISTScanOpaque so = (GISTScanOpaque) scan->opaque;
+ Buffer buffer;
+ Page page;
+ OffsetNumber minoff;
+ OffsetNumber maxoff;
+ int i;
+ bool killedsomething = false;
+
+ Assert(so->curBlkno != InvalidBlockNumber);
+
+ buffer = ReadBuffer(scan->indexRelation, so->curBlkno);
+ if (!BufferIsValid(buffer))
+ return;
+
+ LockBuffer(buffer, GIST_SHARE);
+ gistcheckpage(scan->indexRelation, buffer);
+ page = BufferGetPage(buffer);
+
+ minoff = FirstOffsetNumber;
+ maxoff = PageGetMaxOffsetNumber(page);
+
+ maxoff = PageGetMaxOffsetNumber(page);
+ for (i = 0; i < so->numKilled; i++)
+ {
+ if (so->killedItems != NULL)
+ {
+ OffsetNumber offnum = FirstOffsetNumber;
+
+ while (offnum <= maxoff)
+ {
+ ItemId iid = PageGetItemId(page,
offnum);
+ IndexTuple ituple = (IndexTuple)
PageGetItem(page, iid);
+
+ if (ItemPointerEquals(&ituple->t_tid,
&(so->killedItems[i])))
+ {
+ /* found the item */
+ ItemIdMarkDead(iid);
+ killedsomething = true;
+ break; /* out of inner search
loop */
+ }
+ offnum = OffsetNumberNext(offnum);
+ }
+ }
+ }
+
+ if (killedsomething)
+ {
+ GistMarkPageHasGarbage(page);
+ MarkBufferDirtyHint(buffer, true);
+ }
+
+ UnlockReleaseBuffer(buffer);
+
+ /*
+ * Always reset the scan state, so we don't look for same items on other
+ * pages.
+ */
+ so->numKilled = 0;
+ }
+
/*
* gistindex_keytest() -- does this index tuple satisfy the scan key(s)?
*
***************
*** 331,337 **** gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem,
double *myDistances,
/* Ignore tuple if it doesn't match */
if (!match)
continue;
-
if (tbm && GistPageIsLeaf(page))
{
/*
--- 394,399 ----
***************
*** 451,456 **** getNextNearest(IndexScanDesc scan)
--- 513,535 ----
if (scan->xs_itup)
{
+ /*
+ * If previously returned index tuple is not visible save it
into
+ * so->killedItems. And at the end of the page scan mark all
saved
+ * tuples as dead.
+ */
+ if (scan->kill_prior_tuple)
+ {
+ if (so->killedItems == NULL)
+ {
+ MemoryContext oldCxt2 =
MemoryContextSwitchTo(so->giststate->scanCxt);
+
+ so->killedItems = (ItemPointerData *)
palloc(MaxIndexTuplesPerPage * sizeof(ItemPointerData));
+ MemoryContextSwitchTo(oldCxt2);
+ }
+ if ((so->numKilled < MaxIndexTuplesPerPage))
+ so->killedItems[so->numKilled++] =
scan->xs_ctup.t_self;
+ }
/* free previously returned tuple */
pfree(scan->xs_itup);
scan->xs_itup = NULL;
***************
*** 515,520 **** getNextNearest(IndexScanDesc scan)
--- 594,605 ----
}
else
{
+ if ((so->curBlkno != InvalidBlockNumber) &&
(so->numKilled > 0))
+ gistkillitems(scan);
+
+ /* save current item BlockNumber for next
gistkillitems() call */
+ so->curBlkno = item->blkno;
+
/* visit an index page, extract its items into queue */
CHECK_FOR_INTERRUPTS();
***************
*** 572,578 **** gistgettuple(PG_FUNCTION_ARGS)
--- 657,675 ----
{
if (so->curPageData < so->nPageData)
{
+ if ((scan->kill_prior_tuple) &&
(so->curPageData > 0))
+ {
+ if (so->killedItems == NULL)
+ {
+ MemoryContext oldCxt =
MemoryContextSwitchTo(so->giststate->scanCxt);
+
+ so->killedItems =
(ItemPointerData *) palloc(MaxIndexTuplesPerPage * sizeof(ItemPointerData));
+ MemoryContextSwitchTo(oldCxt);
+ }
+ if (so->numKilled <
MaxIndexTuplesPerPage)
+
so->killedItems[so->numKilled++] = so->pageData[so->curPageData - 1].heapPtr;
+ }
/* continuing to return tuples from a leaf page
*/
scan->xs_ctup.t_self =
so->pageData[so->curPageData].heapPtr;
scan->xs_recheck =
so->pageData[so->curPageData].recheck;
***************
*** 586,594 **** gistgettuple(PG_FUNCTION_ARGS)
--- 683,711 ----
PG_RETURN_BOOL(true);
}
+ /*
+ * Check the last returned tuple and add it to
killitems if
+ * necessary
+ */
+ if ((scan->kill_prior_tuple) && (so->curPageData > 0)
&& (so->curPageData == so->nPageData))
+ {
+
+ if (so->killedItems == NULL)
+ {
+ MemoryContext oldCxt =
MemoryContextSwitchTo(so->giststate->scanCxt);
+
+ so->killedItems = (ItemPointerData *)
palloc(MaxIndexTuplesPerPage * sizeof(ItemPointerData));
+ MemoryContextSwitchTo(oldCxt);
+ }
+ if ((so->numKilled < MaxIndexTuplesPerPage))
+ so->killedItems[so->numKilled++] =
so->pageData[so->curPageData - 1].heapPtr;
+ }
/* find and process the next index page */
do
{
+ if ((so->curBlkno != InvalidBlockNumber) &&
(so->numKilled > 0))
+ gistkillitems(scan);
+
GISTSearchItem *item =
getNextGISTSearchItem(so);
if (!item)
***************
*** 596,601 **** gistgettuple(PG_FUNCTION_ARGS)
--- 713,721 ----
CHECK_FOR_INTERRUPTS();
+ /* save current item BlockNumber for next
gistkillitems() call */
+ so->curBlkno = item->blkno;
+
/*
* While scanning a leaf page, ItemPointers of
matching heap
* tuples are stored in so->pageData. If there
are any on
*** a/src/backend/access/gist/gistscan.c
--- b/src/backend/access/gist/gistscan.c
***************
*** 93,98 **** gistbeginscan(PG_FUNCTION_ARGS)
--- 93,102 ----
memset(scan->xs_orderbynulls, true, sizeof(bool) *
scan->numberOfOrderBys);
}
+ so->killedItems = NULL; /* until needed */
+ so->numKilled = 0;
+ so->curBlkno = InvalidBlockNumber;
+
scan->opaque = so;
/*
*** a/src/include/access/gist.h
--- b/src/include/access/gist.h
***************
*** 41,48 ****
*/
#define F_LEAF (1 << 0) /* leaf page */
#define F_DELETED (1 << 1) /* the page has been
deleted */
! #define F_TUPLES_DELETED (1 << 2) /* some tuples on the page are
dead */
#define F_FOLLOW_RIGHT (1 << 3) /* page to the right
has no downlink */
typedef XLogRecPtr GistNSN;
--- 41,51 ----
*/
#define F_LEAF (1 << 0) /* leaf page */
#define F_DELETED (1 << 1) /* the page has been
deleted */
! #define F_TUPLES_DELETED (1 << 2) /* some tuples on the page were
!
* deleted */
#define F_FOLLOW_RIGHT (1 << 3) /* page to the right
has no downlink */
+ #define F_HAS_GARBAGE (1 << 4) /* some tuples on the page are
dead,
+
* but not deleted yet */
typedef XLogRecPtr GistNSN;
***************
*** 137,142 **** typedef struct GISTENTRY
--- 140,149 ----
#define GistMarkTuplesDeleted(page) ( GistPageGetOpaque(page)->flags |=
F_TUPLES_DELETED)
#define GistClearTuplesDeleted(page) ( GistPageGetOpaque(page)->flags &=
~F_TUPLES_DELETED)
+ #define GistPageHasGarbage(page) ( GistPageGetOpaque(page)->flags &
F_HAS_GARBAGE)
+ #define GistMarkPageHasGarbage(page) ( GistPageGetOpaque(page)->flags |=
F_HAS_GARBAGE)
+ #define GistClearPageHasGarbage(page) ( GistPageGetOpaque(page)->flags &=
~F_HAS_GARBAGE)
+
#define GistFollowRight(page) ( GistPageGetOpaque(page)->flags &
F_FOLLOW_RIGHT)
#define GistMarkFollowRight(page) ( GistPageGetOpaque(page)->flags |=
F_FOLLOW_RIGHT)
#define GistClearFollowRight(page) ( GistPageGetOpaque(page)->flags &=
~F_FOLLOW_RIGHT)
*** a/src/include/access/gist_private.h
--- b/src/include/access/gist_private.h
***************
*** 22,27 ****
--- 22,28 ----
#include "storage/bufmgr.h"
#include "storage/buffile.h"
#include "utils/hsearch.h"
+ #include "access/genam.h"
/*
* Maximum number of "halves" a page can be split into in one operation.
***************
*** 161,166 **** typedef struct GISTScanOpaqueData
--- 162,172 ----
/* pre-allocated workspace arrays */
double *distances; /* output area for gistindex_keytest */
+ /* info about killed items if any (killedItems is NULL if never used) */
+ ItemPointerData *killedItems; /* heap pointers of killed
items */
+ int numKilled; /* number of currently
stored items */
+ BlockNumber curBlkno; /* current number of block */
+
/* In a non-ordered search, returnable heap items are stored here: */
GISTSearchHeapItem pageData[BLCKSZ / sizeof(IndexTupleData)];
OffsetNumber nPageData; /* number of valid items in array */
drop table test;
CREATE TABLE test as (select box(point(x, x),point(x, x))
from generate_series(1,500000) as x);
CREATE INDEX test_idx ON test USING gist (box);
SET enable_seqscan TO false;
SET enable_bitmapscan TO false;
SET enable_indexscan TO true;
SET enable_indexonlyscan TO true;
select pg_size_pretty(pg_relation_size('test_idx'));
delete from test where box && box(point(0,0), point(500000,500000));
select pg_size_pretty(pg_relation_size('test_idx'));
-- This query invokes gistkillitems()
select box from test where box && box(point(0,0), point(500000,500000));
insert into test (select box(point(x, x),point(x, x))
from generate_series(1,500000) as x);
select pg_size_pretty(pg_relation_size('test_idx'));
insert into test (select box(point(x, x),point(x, x))
from generate_series(1,500000) as x);
select pg_size_pretty(pg_relation_size('test_idx'));
insert into test (select box(point(x, x),point(x, x))
from generate_series(1,500000) as x);
select pg_size_pretty(pg_relation_size('test_idx'));
DROP TABLE
SELECT 500000
CREATE INDEX
SET
SET
SET
SET
pg_size_pretty
----------------
48 MB
(1 row)
DELETE 500000
pg_size_pretty
----------------
48 MB
(1 row)
box
-----
(0 rows)
INSERT 0 500000
pg_size_pretty
----------------
48 MB
(1 row)
INSERT 0 500000
pg_size_pretty
----------------
95 MB
(1 row)
INSERT 0 500000
pg_size_pretty
----------------
142 MB
(1 row)
DROP TABLE
SELECT 500000
CREATE INDEX
SET
SET
SET
SET
pg_size_pretty
----------------
48 MB
(1 row)
DELETE 500000
pg_size_pretty
----------------
48 MB
(1 row)
box
-----
(0 rows)
INSERT 0 500000
pg_size_pretty
----------------
48 MB
(1 row)
INSERT 0 500000
pg_size_pretty
----------------
48 MB
(1 row)
INSERT 0 500000
pg_size_pretty
----------------
95 MB
(1 row)
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