Re: Centralizing protective copying of utility statements

I wrote:
> (In any case, if someone does get excited about this, they
> could rearrange things to push the copyObject calls into the
> individual arms of the switch in ProcessUtility. Personally
> though I doubt it could be worth the code bloat.)

It occurred to me to try making the copying code look like

if (readOnlyTree)
{
switch (nodeTag(parsetree))
{
case T_TransactionStmt:
/* stmt is immutable anyway, no need to copy */
break;
default:
pstmt = copyObject(pstmt);
parsetree = pstmt->utilityStmt;
break;
}
}

This didn't move the needle at all, in fact it seems maybe a
shade slower:

tps = 23502.288878 (without initial connection time)
tps = 23643.821923 (without initial connection time)
tps = 23082.976795 (without initial connection time)
tps = 23547.527641 (without initial connection time)

So I think this confirms my gut feeling that copyObject on a
TransactionStmt is negligible. To the extent that the prior
measurement shows a real difference, it's probably a chance effect
of changing code layout elsewhere.

regards, tom lane