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Commitb648b70

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Speed up CREATE INDEX CONCURRENTLY's TID sort.
Encode TIDs as 64-bit integers to speed up comparisons. This seems tospeed things up on all platforms, but is even more beneficial when8-byte integers are passed by value.Peter Geoghegan. Design suggestions and review by Tom Lane. Reviewalso by Simon Riggs and by me.
1 parentf27a6b1 commitb648b70

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1 file changed

+67
-4
lines changed

1 file changed

+67
-4
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‎src/backend/catalog/index.c

Lines changed: 67 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -109,6 +109,8 @@ static void index_update_stats(Relation rel,
109109
staticvoidIndexCheckExclusion(RelationheapRelation,
110110
RelationindexRelation,
111111
IndexInfo*indexInfo);
112+
staticinlineint64itemptr_encode(ItemPointeritemptr);
113+
staticinlinevoiditemptr_decode(ItemPointeritemptr,int64encoded);
112114
staticboolvalidate_index_callback(ItemPointeritemptr,void*opaque);
113115
staticvoidvalidate_index_heapscan(RelationheapRelation,
114116
RelationindexRelation,
@@ -2832,7 +2834,13 @@ validate_index(Oid heapId, Oid indexId, Snapshot snapshot)
28322834
ivinfo.num_heap_tuples=heapRelation->rd_rel->reltuples;
28332835
ivinfo.strategy=NULL;
28342836

2835-
state.tuplesort=tuplesort_begin_datum(TIDOID,TIDLessOperator,
2837+
/*
2838+
* Encode TIDs as int8 values for the sort, rather than directly sorting
2839+
* item pointers. This can be significantly faster, primarily because TID
2840+
* is a pass-by-reference type on all platforms, whereas int8 is
2841+
* pass-by-value on most platforms.
2842+
*/
2843+
state.tuplesort=tuplesort_begin_datum(INT8OID,Int8LessOperator,
28362844
InvalidOid, false,
28372845
maintenance_work_mem,
28382846
false);
@@ -2871,15 +2879,56 @@ validate_index(Oid heapId, Oid indexId, Snapshot snapshot)
28712879
heap_close(heapRelation,NoLock);
28722880
}
28732881

2882+
/*
2883+
* itemptr_encode - Encode ItemPointer as int64/int8
2884+
*
2885+
* This representation must produce values encoded as int64 that sort in the
2886+
* same order as their corresponding original TID values would (using the
2887+
* default int8 opclass to produce a result equivalent to the default TID
2888+
* opclass).
2889+
*
2890+
* As noted in validate_index(), this can be significantly faster.
2891+
*/
2892+
staticinlineint64
2893+
itemptr_encode(ItemPointeritemptr)
2894+
{
2895+
BlockNumberblock=ItemPointerGetBlockNumber(itemptr);
2896+
OffsetNumberoffset=ItemPointerGetOffsetNumber(itemptr);
2897+
int64encoded;
2898+
2899+
/*
2900+
* Use the 16 least significant bits for the offset. 32 adjacent bits are
2901+
* used for the block number. Since remaining bits are unused, there
2902+
* cannot be negative encoded values (We assume a two's complement
2903+
* representation).
2904+
*/
2905+
encoded= ((uint64)block <<16) | (uint16)offset;
2906+
2907+
returnencoded;
2908+
}
2909+
2910+
/*
2911+
* itemptr_decode - Decode int64/int8 representation back to ItemPointer
2912+
*/
2913+
staticinlinevoid
2914+
itemptr_decode(ItemPointeritemptr,int64encoded)
2915+
{
2916+
BlockNumberblock= (BlockNumber) (encoded >>16);
2917+
OffsetNumberoffset= (OffsetNumber) (encoded&0xFFFF);
2918+
2919+
ItemPointerSet(itemptr,block,offset);
2920+
}
2921+
28742922
/*
28752923
* validate_index_callback - bulkdelete callback to collect the index TIDs
28762924
*/
28772925
staticbool
28782926
validate_index_callback(ItemPointeritemptr,void*opaque)
28792927
{
28802928
v_i_state*state= (v_i_state*)opaque;
2929+
int64encoded=itemptr_encode(itemptr);
28812930

2882-
tuplesort_putdatum(state->tuplesort,PointerGetDatum(itemptr), false);
2931+
tuplesort_putdatum(state->tuplesort,Int64GetDatum(encoded), false);
28832932
state->itups+=1;
28842933
return false;/* never actually delete anything */
28852934
}
@@ -2911,6 +2960,7 @@ validate_index_heapscan(Relation heapRelation,
29112960

29122961
/* state variables for the merge */
29132962
ItemPointerindexcursor=NULL;
2963+
ItemPointerDatadecoded;
29142964
booltuplesort_empty= false;
29152965

29162966
/*
@@ -3020,13 +3070,26 @@ validate_index_heapscan(Relation heapRelation,
30203070
*/
30213071
if (ItemPointerGetBlockNumber(indexcursor)==root_blkno)
30223072
in_index[ItemPointerGetOffsetNumber(indexcursor)-1]= true;
3023-
pfree(indexcursor);
30243073
}
30253074

30263075
tuplesort_empty= !tuplesort_getdatum(state->tuplesort, true,
30273076
&ts_val,&ts_isnull);
30283077
Assert(tuplesort_empty|| !ts_isnull);
3029-
indexcursor= (ItemPointer)DatumGetPointer(ts_val);
3078+
if (!tuplesort_empty)
3079+
{
3080+
itemptr_decode(&decoded,DatumGetInt64(ts_val));
3081+
indexcursor=&decoded;
3082+
3083+
/* If int8 is pass-by-ref, free (encoded) TID Datum memory */
3084+
#ifndefUSE_FLOAT8_BYVAL
3085+
pfree(DatumGetPointer(ts_val));
3086+
#endif
3087+
}
3088+
else
3089+
{
3090+
/* Be tidy */
3091+
indexcursor=NULL;
3092+
}
30303093
}
30313094

30323095
/*

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