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Revise TupleTableSlot code to avoid unnecessary construction and disassembly

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of tuples when passing data up through multiple plan nodes.  A slot can now
hold either a normal "physical" HeapTuple, or a "virtual" tuple consisting
of Datum/isnull arrays.  Upper plan levels can usually just copy the Datum
arrays, avoiding heap_formtuple() and possible subsequent nocachegetattr()
calls to extract the data again.  This work extends Atsushi Ogawa's earlier
patch, which provided the key idea of adding Datum arrays to TupleTableSlots.
(I believe however that something like this was foreseen way back in Berkeley
days --- see the old comment on ExecProject.)  A test case involving many
levels of join of fairly wide tables (about 80 columns altogether) showed
about 3x overall speedup, though simple queries will probably not be
helped very much.

I have also duplicated some code in heaptuple.c in order to provide versions
of heap_formtuple and friends that use "bool" arrays to indicate null
attributes, instead of the old convention of "char" arrays containing either
'n' or ' '.  This provides a better match to the convention used by
ExecEvalExpr.  While I have not made a concerted effort to get rid of uses
of the old routines, I think they should be deprecated and eventually removed.
This commit is contained in:
Tom Lane
2005-03-16 21:38:10 +00:00
parent 712f053587
commit f97aebd162
44 changed files with 1766 additions and 934 deletions
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45
src/include/nodes/execnodes.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.123 2005/03/06 22:15:05 tgl Exp $
* $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.124 2005/03/16 21:38:10 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -175,20 +175,28 @@ typedef struct ReturnSetInfo
* This is all the information needed to perform projections ---
* that is, form new tuples by evaluation of targetlist expressions.
* Nodes which need to do projections create one of these.
* In theory, when a node wants to perform a projection
* it should just update this information as necessary and then
* call ExecProject(). -cim 6/3/91
*
* ExecProject() evaluates the tlist, forms a tuple, and stores it
* in the given slot. As a side-effect, the actual datum values and
* null indicators are placed in the work arrays tupValues/tupNulls.
* in the given slot. Note that the result will be a "virtual" tuple
* unless ExecMaterializeSlot() is then called to force it to be
* converted to a physical tuple. The slot must have a tupledesc
* that matches the output of the tlist!
*
* The planner very often produces tlists that consist entirely of
* simple Var references (lower levels of a plan tree almost always
* look like that). So we have an optimization to handle that case
* with minimum overhead.
*
* targetlist target list for projection
* exprContext expression context in which to evaluate targetlist
* slot slot to place projection result in
* tupValues array of computed values
* tupNull array of null indicators
* itemIsDone workspace for ExecProject
* isVarList TRUE if simple-Var-list optimization applies
* varSlotOffsets array indicating which slot each simple Var is from
* varNumbers array indicating attr numbers of simple Vars
* lastInnerVar highest attnum from inner tuple slot (0 if none)
* lastOuterVar highest attnum from outer tuple slot (0 if none)
* lastScanVar highest attnum from scan tuple slot (0 if none)
* ----------------
*/
typedef struct ProjectionInfo
@ -197,9 +205,13 @@ typedef struct ProjectionInfo
List *pi_targetlist;
ExprContext *pi_exprContext;
TupleTableSlot *pi_slot;
Datum *pi_tupValues;
char *pi_tupNulls;
ExprDoneCond *pi_itemIsDone;
bool pi_isVarList;
int *pi_varSlotOffsets;
int *pi_varNumbers;
int pi_lastInnerVar;
int pi_lastOuterVar;
int pi_lastScanVar;
} ProjectionInfo;
/* ----------------
@ -222,7 +234,7 @@ typedef struct ProjectionInfo
* cleanMap: A map with the correspondence between the non-junk
* attribute numbers of the "original" tuple and the
* attribute numbers of the "clean" tuple.
* resultSlot: tuple slot that can be used to hold cleaned tuple.
* resultSlot: tuple slot used to hold cleaned tuple.
* ----------------
*/
typedef struct JunkFilter
@ -354,7 +366,8 @@ typedef struct TupleHashTableData
MemoryContext tablecxt; /* memory context containing table */
MemoryContext tempcxt; /* context for function evaluations */
Size entrysize; /* actual size to make each hash entry */
TupleDesc tupdesc; /* tuple descriptor */
TupleTableSlot *tableslot; /* slot for referencing table entries */
TupleTableSlot *inputslot; /* current input tuple's slot */
} TupleHashTableData;
typedef HASH_SEQ_STATUS TupleHashIterator;
@ -589,9 +602,9 @@ typedef struct ConvertRowtypeExprState
TupleDesc outdesc; /* tupdesc for result rowtype */
AttrNumber *attrMap; /* indexes of input fields, or 0 for null */
Datum *invalues; /* workspace for deconstructing source */
char *innulls;
bool *inisnull;
Datum *outvalues; /* workspace for constructing result */
char *outnulls;
bool *outisnull;
} ConvertRowtypeExprState;
/* ----------------
@ -1065,7 +1078,6 @@ typedef struct GroupState
{
ScanState ss; /* its first field is NodeTag */
FmgrInfo *eqfunctions; /* per-field lookup data for equality fns */
HeapTuple grp_firstTuple; /* copy of first tuple of current group */
bool grp_done; /* indicates completion of Group scan */
} GroupState;
@ -1111,7 +1123,7 @@ typedef struct AggState
* Unique nodes are used "on top of" sort nodes to discard
* duplicate tuples returned from the sort phase. Basically
* all it does is compare the current tuple from the subplan
* with the previously fetched tuple stored in priorTuple.
* with the previously fetched tuple (stored in its result slot).
* If the two are identical in all interesting fields, then
* we just fetch another tuple from the sort and try again.
* ----------------
@ -1120,7 +1132,6 @@ typedef struct UniqueState
{
PlanState ps; /* its first field is NodeTag */
FmgrInfo *eqfunctions; /* per-field lookup data for equality fns */
HeapTuple priorTuple; /* most recently returned tuple, or NULL */
MemoryContext tempContext; /* short-term context for comparisons */
} UniqueState;