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Commit5279e9d

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heapam: Pass number of required pages to RelationGetBufferForTuple()
A future commit will use this information to determine how aggressively toextend the relation by. In heap_multi_insert() we know accurately how manypages we need once we need to extend the relation, providing an accurate lowerbound for how much to extend.Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>Discussion:https://postgr.es/m/20221029025420.eplyow6k7tgu6he3@awork3.anarazel.de
1 parent7d71d3d commit5279e9d

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3 files changed

+63
-6
lines changed

3 files changed

+63
-6
lines changed

‎src/backend/access/heap/heapam.c

Lines changed: 54 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1847,7 +1847,8 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
18471847
*/
18481848
buffer=RelationGetBufferForTuple(relation,heaptup->t_len,
18491849
InvalidBuffer,options,bistate,
1850-
&vmbuffer,NULL);
1850+
&vmbuffer,NULL,
1851+
0);
18511852

18521853
/*
18531854
* We're about to do the actual insert -- but check for conflict first, to
@@ -2050,6 +2051,32 @@ heap_prepare_insert(Relation relation, HeapTuple tup, TransactionId xid,
20502051
returntup;
20512052
}
20522053

2054+
/*
2055+
* Helper for heap_multi_insert() that computes the number of entire pages
2056+
* that inserting the remaining heaptuples requires. Used to determine how
2057+
* much the relation needs to be extended by.
2058+
*/
2059+
staticint
2060+
heap_multi_insert_pages(HeapTuple*heaptuples,intdone,intntuples,SizesaveFreeSpace)
2061+
{
2062+
size_tpage_avail=BLCKSZ-SizeOfPageHeaderData-saveFreeSpace;
2063+
intnpages=1;
2064+
2065+
for (inti=done;i<ntuples;i++)
2066+
{
2067+
size_ttup_sz=sizeof(ItemIdData)+MAXALIGN(heaptuples[i]->t_len);
2068+
2069+
if (page_avail<tup_sz)
2070+
{
2071+
npages++;
2072+
page_avail=BLCKSZ-SizeOfPageHeaderData-saveFreeSpace;
2073+
}
2074+
page_avail-=tup_sz;
2075+
}
2076+
2077+
returnnpages;
2078+
}
2079+
20532080
/*
20542081
*heap_multi_insert- insert multiple tuples into a heap
20552082
*
@@ -2076,6 +2103,9 @@ heap_multi_insert(Relation relation, TupleTableSlot **slots, int ntuples,
20762103
SizesaveFreeSpace;
20772104
boolneed_tuple_data=RelationIsLogicallyLogged(relation);
20782105
boolneed_cids=RelationIsAccessibleInLogicalDecoding(relation);
2106+
boolstarting_with_empty_page= false;
2107+
intnpages=0;
2108+
intnpages_used=0;
20792109

20802110
/* currently not needed (thus unsupported) for heap_multi_insert() */
20812111
Assert(!(options&HEAP_INSERT_NO_LOGICAL));
@@ -2126,13 +2156,31 @@ heap_multi_insert(Relation relation, TupleTableSlot **slots, int ntuples,
21262156
while (ndone<ntuples)
21272157
{
21282158
Bufferbuffer;
2129-
boolstarting_with_empty_page;
21302159
boolall_visible_cleared= false;
21312160
boolall_frozen_set= false;
21322161
intnthispage;
21332162

21342163
CHECK_FOR_INTERRUPTS();
21352164

2165+
/*
2166+
* Compute number of pages needed to fit the to-be-inserted tuples in
2167+
* the worst case. This will be used to determine how much to extend
2168+
* the relation by in RelationGetBufferForTuple(), if needed. If we
2169+
* filled a prior page from scratch, we can just update our last
2170+
* computation, but if we started with a partially filled page,
2171+
* recompute from scratch, the number of potentially required pages
2172+
* can vary due to tuples needing to fit onto the page, page headers
2173+
* etc.
2174+
*/
2175+
if (ndone==0|| !starting_with_empty_page)
2176+
{
2177+
npages=heap_multi_insert_pages(heaptuples,ndone,ntuples,
2178+
saveFreeSpace);
2179+
npages_used=0;
2180+
}
2181+
else
2182+
npages_used++;
2183+
21362184
/*
21372185
* Find buffer where at least the next tuple will fit. If the page is
21382186
* all-visible, this will also pin the requisite visibility map page.
@@ -2142,7 +2190,8 @@ heap_multi_insert(Relation relation, TupleTableSlot **slots, int ntuples,
21422190
*/
21432191
buffer=RelationGetBufferForTuple(relation,heaptuples[ndone]->t_len,
21442192
InvalidBuffer,options,bistate,
2145-
&vmbuffer,NULL);
2193+
&vmbuffer,NULL,
2194+
npages-npages_used);
21462195
page=BufferGetPage(buffer);
21472196

21482197
starting_with_empty_page=PageGetMaxOffsetNumber(page)==0;
@@ -3576,7 +3625,8 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
35763625
/* It doesn't fit, must use RelationGetBufferForTuple. */
35773626
newbuf=RelationGetBufferForTuple(relation,heaptup->t_len,
35783627
buffer,0,NULL,
3579-
&vmbuffer_new,&vmbuffer);
3628+
&vmbuffer_new,&vmbuffer,
3629+
0);
35803630
/* We're all done. */
35813631
break;
35823632
}

‎src/backend/access/heap/hio.c

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -301,6 +301,11 @@ RelationAddExtraBlocks(Relation relation, BulkInsertState bistate)
301301
*Returns pinned and exclusive-locked buffer of a page in given relation
302302
*with free space >= given len.
303303
*
304+
*If num_pages is > 1, we will try to extend the relation by at least that
305+
*many pages when we decide to extend the relation. This is more efficient
306+
*for callers that know they will need multiple pages
307+
*(e.g. heap_multi_insert()).
308+
*
304309
*If otherBuffer is not InvalidBuffer, then it references a previously
305310
*pinned buffer of another page in the same relation; on return, this
306311
*buffer will also be exclusive-locked. (This case is used by heap_update;
@@ -359,7 +364,8 @@ Buffer
359364
RelationGetBufferForTuple(Relationrelation,Sizelen,
360365
BufferotherBuffer,intoptions,
361366
BulkInsertStatebistate,
362-
Buffer*vmbuffer,Buffer*vmbuffer_other)
367+
Buffer*vmbuffer,Buffer*vmbuffer_other,
368+
intnum_pages)
363369
{
364370
booluse_fsm= !(options&HEAP_INSERT_SKIP_FSM);
365371
Bufferbuffer=InvalidBuffer;

‎src/include/access/hio.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -38,6 +38,7 @@ extern void RelationPutHeapTuple(Relation relation, Buffer buffer,
3838
externBufferRelationGetBufferForTuple(Relationrelation,Sizelen,
3939
BufferotherBuffer,intoptions,
4040
BulkInsertStateData*bistate,
41-
Buffer*vmbuffer,Buffer*vmbuffer_other);
41+
Buffer*vmbuffer,Buffer*vmbuffer_other,
42+
intnum_pages);
4243

4344
#endif/* HIO_H */

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