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Avoid O(N^2) overhead in repeated nocachegetattr calls when columns of

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a tuple are being accessed via ExecEvalVar and the attcacheoff shortcut
isn't usable (due to nulls and/or varlena columns).  To do this, cache
Datums extracted from a tuple in the associated TupleTableSlot.
Also some code cleanup in and around the TupleTable handling.
Atsushi Ogawa with some kibitzing by Tom Lane.
This commit is contained in:
Tom Lane
2005-03-14 04:41:13 +00:00
parent d1022ce3a1
commit a9b05bdc83
8 changed files with 378 additions and 300 deletions
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43
src/backend/executor/execQual.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.171 2004/12/31 21:59:45 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.172 2005/03/14 04:41:12 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -438,11 +438,8 @@ ExecEvalVar(ExprState *exprstate, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone)
{
Var *variable = (Var *) exprstate->expr;
Datum result;
TupleTableSlot *slot;
AttrNumber attnum;
HeapTuple heapTuple;
TupleDesc tuple_type;
if (isDone)
*isDone = ExprSingleResult;
@ -475,35 +472,19 @@ ExecEvalVar(ExprState *exprstate, ExprContext *econtext,
break;
}
/*
* extract tuple information from the slot
*/
heapTuple = slot->val;
tuple_type = slot->ttc_tupleDescriptor;
#ifdef USE_ASSERT_CHECKING
/*
* Some checks that are only applied for user attribute numbers (bogus
* system attnums will be caught inside heap_getattr).
* system attnums will be caught inside slot_getattr).
*/
if (attnum > 0)
{
TupleDesc tuple_type = slot->ttc_tupleDescriptor;
/*
* This assert checks that the attnum is valid.
*/
Assert(attnum <= tuple_type->natts &&
tuple_type->attrs[attnum - 1] != NULL);
/*
* If the attribute's column has been dropped, we force a NULL
* result. This case should not happen in normal use, but it could
* happen if we are executing a plan cached before the column was
* dropped.
*/
if (tuple_type->attrs[attnum - 1]->attisdropped)
{
*isNull = true;
return (Datum) 0;
}
Assert(attnum <= tuple_type->natts);
/*
* This assert checks that the datatype the plan expects to get
@ -515,16 +496,12 @@ ExecEvalVar(ExprState *exprstate, ExprContext *econtext,
* Note that we can't check dropped columns, since their atttypid has
* been zeroed.
*/
Assert(variable->vartype == tuple_type->attrs[attnum - 1]->atttypid);
Assert(variable->vartype == tuple_type->attrs[attnum - 1]->atttypid ||
tuple_type->attrs[attnum - 1]->attisdropped);
}
#endif /* USE_ASSERT_CHECKING */
result = heap_getattr(heapTuple, /* tuple containing attribute */
attnum, /* attribute number of desired
* attribute */
tuple_type, /* tuple descriptor of tuple */
isNull); /* return: is attribute null? */
return result;
return slot_getattr(slot, attnum, isNull);
}
/* ----------------------------------------------------------------