> On Nov 18, 2025, at 19:19, Vik Fearing <vik@postgresfriends.org> wrote:
>
>
> Because of position. Without making DEFINE a reserved keyword, how do you know that it isn't another variable in the
PATTERNclause?
>
Ah, thanks for the clarification. Now I got it.
I’m continue to review 0002.
5 - 0002 - parse_clause.c
```
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("FRAME must start at current row when row patttern recognition is used")));
```
Nit typo: patttern -> pattern
6 - 0002 - parse_clause.c
```
+ /* DEFINE variable name initials */
+ static char *defineVariableInitials = "abcdefghijklmnopqrstuvwxyz”;
```
This string can also be const, so “static const char *”
7 - 0002 - parse_clause.c
```
+ /*
+ * Create list of row pattern DEFINE variable name's initial. We assign
+ * [a-z] to them (up to 26 variable names are allowed).
+ */
+ restargets = NIL;
+ i = 0;
+ initialLen = strlen(defineVariableInitials);
+
+ foreach(lc, windef->rpCommonSyntax->rpDefs)
+ {
+ char initial[2];
+
+ restarget = (ResTarget *) lfirst(lc);
+ name = restarget->name;
```
Looks like “name” is not used inside “foreach”.
8 - 0002 - parse_clause.c
```
+ /*
+ * Create list of row pattern DEFINE variable name's initial. We assign
+ * [a-z] to them (up to 26 variable names are allowed).
+ */
+ restargets = NIL;
+ i = 0;
+ initialLen = strlen(defineVariableInitials);
+
+ foreach(lc, windef->rpCommonSyntax->rpDefs)
+ {
+ char initial[2];
```
I guess this “foreach” for build initial list can be combined into the previous foreach loop of checking duplication.
Ifan def has no dup, then assign an initial to it.
9 - 0002 - parse_clause.c
```
+static void
+transformPatternClause(ParseState *pstate, WindowClause *wc,
+ WindowDef *windef)
+{
+ ListCell *lc;
+
+ /*
+ * Row Pattern Common Syntax clause exists?
+ */
+ if (windef->rpCommonSyntax == NULL)
+ return;
```
Checking (windef->rpCommonSyntax == NULL) seems a duplicate, because transformPatternClause() is only called by
transformRPR(),and transformRPR() has done the check.
Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/
