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Perform slot validity checks in a separate pass over expression.

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This reduces code duplication a bit, but the primary benefit that it
makes JITing expression evaluation easier. When doing so we can't, as
previously done in the interpreted case, really change opcode without
recompiling. Nor dow we just carry around unnecessary branches to
avoid re-checking over and over.

As a minor side-effect this makes ExecEvalStepOp() O(log(N)) rather
than O(N).

Author: Andres Freund
Discussion: https://postgr.es/m/20170901064131.tazjxwus3k2w3ybh@alap3.anarazel.de
This commit is contained in:
Andres Freund
2017-12-29 12:38:15 -08:00
parent 4717fdb14c
commit b40933101c
4 changed files with 167 additions and 138 deletions
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7
src/backend/executor/execExpr.c
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@ -680,20 +680,19 @@ ExecInitExprRec(Expr *node, ExprState *state,
/* regular user column */
scratch.d.var.attnum = variable->varattno - 1;
scratch.d.var.vartype = variable->vartype;
/* select EEOP_*_FIRST opcode to force one-time checks */
switch (variable->varno)
{
case INNER_VAR:
scratch.opcode = EEOP_INNER_VAR_FIRST;
scratch.opcode = EEOP_INNER_VAR;
break;
case OUTER_VAR:
scratch.opcode = EEOP_OUTER_VAR_FIRST;
scratch.opcode = EEOP_OUTER_VAR;
break;
/* INDEX_VAR is handled by default case */
default:
scratch.opcode = EEOP_SCAN_VAR_FIRST;
scratch.opcode = EEOP_SCAN_VAR;
break;
}
}