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Teach SP-GiST to do index-only scans.
Operator classes can specify whether or not they support this; this preserves the flexibility to use lossy representations within an index. In passing, move constant data about a given index into the rd_amcache cache area, instead of doing fresh lookups each time we start an index operation. This is mainly to try to make sure that spgcanreturn() has insignificant cost; I still don't have any proof that it matters for actual index accesses. Also, get rid of useless copying of FmgrInfo pointers; we can perfectly well use the relcache's versions in-place.
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10 files changed

+286
-172
lines changed

10 files changed

+286
-172
lines changed

‎doc/src/sgml/spgist.sgml

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -145,6 +145,7 @@ typedef struct spgConfigOut
145145
{
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Oid prefixType; /* Data type of inner-tuple prefixes */
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Oid labelType; /* Data type of inner-tuple node labels */
148+
bool canReturnData; /* Opclass can reconstruct original data */
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bool longValuesOK; /* Opclass can cope with values > 1 page */
149150
} spgConfigOut;
150151
</programlisting>
@@ -159,6 +160,8 @@ typedef struct spgConfigOut
159160
<structfield>prefixType</> can be set to <literal>VOIDOID</>.
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Likewise, for operator classes that do not use node labels,
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<structfield>labelType</> can be set to <literal>VOIDOID</>.
163+
<structfield>canReturnData</> should be set true if the operator class
164+
is capable of reconstructing the originally-supplied index value.
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<structfield>longValuesOK</> should be set true only when the
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<structfield>attType</> is of variable length and the operator
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class is capable of segmenting long values by repeated suffixing
@@ -441,6 +444,7 @@ typedef struct spgInnerConsistentIn
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442445
Datum reconstructedValue; /* value reconstructed at parent */
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int level; /* current level (counting from zero) */
447+
bool returnData; /* original data must be returned? */
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/* Data from current inner tuple */
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bool allTheSame; /* tuple is marked all-the-same? */
@@ -467,6 +471,9 @@ typedef struct spgInnerConsistentOut
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parent level.
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<structfield>level</> is the current inner tuple's level, starting at
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zero for the root level.
474+
<structfield>returnData</> is <literal>true</> if reconstructed data is
475+
required for this query; this will only be so if the
476+
<function>config</> function asserted <structfield>canReturnData</>.
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<structfield>allTheSame</> is true if the current inner tuple is
471478
marked <quote>all-the-same</>; in this case all the nodes have the
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same label (if any) and so either all or none of them match the query
@@ -525,12 +532,14 @@ typedef struct spgLeafConsistentIn
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526533
Datum reconstructedValue; /* value reconstructed at parent */
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int level; /* current level (counting from zero) */
535+
bool returnData; /* original data must be returned? */
528536

529537
Datum leafDatum; /* datum in leaf tuple */
530538
} spgLeafConsistentIn;
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typedef struct spgLeafConsistentOut
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{
542+
Datum leafValue; /* reconstructed original data, if any */
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bool recheck; /* set true if operator must be rechecked */
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} spgLeafConsistentOut;
536545
</programlisting>
@@ -543,13 +552,19 @@ typedef struct spgLeafConsistentOut
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parent level.
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<structfield>level</> is the current leaf tuple's level, starting at
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zero for the root level.
555+
<structfield>returnData</> is <literal>true</> if reconstructed data is
556+
required for this query; this will only be so if the
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<function>config</> function asserted <structfield>canReturnData</>.
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<structfield>leafDatum</> is the key value stored in the current
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leaf tuple.
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</para>
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<para>
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The function must return <literal>true</> if the leaf tuple matches the
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query, or <literal>false</> if not. In the <literal>true</> case,
565+
if <structfield>returnData</> is <literal>true</> then
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<structfield>leafValue</> must be set to the value originally supplied
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to be indexed for this leaf tuple. Also,
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<structfield>recheck</> may be set to <literal>true</> if the match
554569
is uncertain and so the operator must be re-applied to the actual heap
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tuple to verify the match.

‎src/backend/access/spgist/spgdoinsert.c

Lines changed: 7 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,7 @@
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#include "postgres.h"
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18+
#include "access/genam.h"
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#include "access/spgist_private.h"
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#include "miscadmin.h"
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#include "storage/bufmgr.h"
@@ -678,6 +679,7 @@ doPickSplit(Relation index, SpGistState *state,
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bool insertedNew = false;
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spgPickSplitIn in;
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spgPickSplitOut out;
682+
FmgrInfo *procinfo;
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bool includeNew;
682684
int i,
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max,
@@ -816,7 +818,8 @@ doPickSplit(Relation index, SpGistState *state,
816818
*/
817819
memset(&out, 0, sizeof(out));
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819-
FunctionCall2Coll(&state->picksplitFn,
821+
procinfo = index_getprocinfo(index, 1, SPGIST_PICKSPLIT_PROC);
822+
FunctionCall2Coll(procinfo,
820823
index->rd_indcollation[0],
821824
PointerGetDatum(&in),
822825
PointerGetDatum(&out));
@@ -1944,6 +1947,7 @@ spgdoinsert(Relation index, SpGistState *state,
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SpGistInnerTuple innerTuple;
19451948
spgChooseIn in;
19461949
spgChooseOut out;
1950+
FmgrInfo *procinfo;
19471951

19481952
/*
19491953
* spgAddNode and spgSplitTuple cases will loop back to here to
@@ -1968,7 +1972,8 @@ spgdoinsert(Relation index, SpGistState *state,
19681972

19691973
memset(&out, 0, sizeof(out));
19701974

1971-
FunctionCall2Coll(&state->chooseFn,
1975+
procinfo = index_getprocinfo(index, 1, SPGIST_CHOOSE_PROC);
1976+
FunctionCall2Coll(procinfo,
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index->rd_indcollation[0],
19731978
PointerGetDatum(&in),
19741979
PointerGetDatum(&out));

‎src/backend/access/spgist/spgkdtreeproc.c

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,7 @@ spg_kd_config(PG_FUNCTION_ARGS)
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cfg->prefixType = FLOAT8OID;
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cfg->labelType = VOIDOID; /* we don't need node labels */
33+
cfg->canReturnData = true;
3334
cfg->longValuesOK = false;
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PG_RETURN_VOID();
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}

‎src/backend/access/spgist/spgquadtreeproc.c

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,7 @@ spg_quad_config(PG_FUNCTION_ARGS)
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cfg->prefixType = POINTOID;
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cfg->labelType = VOIDOID; /* we don't need node labels */
33+
cfg->canReturnData = true;
3334
cfg->longValuesOK = false;
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PG_RETURN_VOID();
3536
}
@@ -324,6 +325,9 @@ spg_quad_leaf_consistent(PG_FUNCTION_ARGS)
324325
/* all tests are exact */
325326
out->recheck = false;
326327

328+
/* leafDatum is what it is... */
329+
out->leafValue = in->leafDatum;
330+
327331
switch (in->strategy)
328332
{
329333
case RTLeftStrategyNumber:

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