diff options
Diffstat (limited to 'src/backend/executor/README')
| -rw-r--r-- | src/backend/executor/README | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/src/backend/executor/README b/src/backend/executor/README index ddbd62b4dba..05f197bc75b 100644 --- a/src/backend/executor/README +++ b/src/backend/executor/README @@ -124,7 +124,7 @@ For example, "a + b" (one OpExpr, with two Var expressions) would be represented as two steps to fetch the Var values, and one step for the evaluation of the function underlying the + operator. The steps for the Vars would have their resvalue/resnull pointing directly to the appropriate -arg[] and argnull[] array elements in the FunctionCallInfoData struct that +args[].value .isnull elements in the FunctionCallInfoBaseData struct that is used by the function evaluation step, thus avoiding extra work to copy the result values around. @@ -145,7 +145,7 @@ sub-expressions. Each ExecInitExprRec() call has to specify where that subexpression's results are to be stored (via the resv/resnull parameters). This allows the above scenario of evaluating a (sub-)expression directly into -fcinfo->arg/argnull, but also requires some care: target Datum/isnull +fcinfo->args[].value/isnull, but also requires some care: target Datum/isnull variables may not be shared with another ExecInitExprRec() unless the results are only needed by steps executing before further usages of those target Datum/isnull variables. Due to the non-recursiveness of the @@ -158,7 +158,7 @@ not enough space. Because of that it is *not* allowed to point directly into any of the steps during expression initialization. Therefore, the resv/resnull for a subexpression usually point to some storage that is palloc'd separately from the steps array. For instance, the -FunctionCallInfoData for a function call step is separately allocated +FunctionCallInfoBaseData for a function call step is separately allocated rather than being part of the ExprEvalStep array. The overall result of a complete expression is typically returned into the resvalue/resnull fields of the ExprState node itself. |