identifier quotes and variadic udfs

plugins/exasol/skills/exasol-database/SKILL.md

@@ -49,10 +49,10 @@ After the connection is established, determine the task type and load **only** t
 Multiple routes can apply — load all that match.
 
 8. **Before writing any SQL** (applies to routes 2–7):
-   - Check all identifiers (column names, table names, aliases) against the **reserved keyword list in `references/exasol-sql.md`** (Common Traps section)
-   - Double-quote any identifier that appears in that list
-   - If a query fails with a syntax error that may be caused by a reserved keyword, fetch the live list: `exapump sql "SELECT KEYWORD FROM EXA_SQL_KEYWORDS WHERE RESERVED ORDER BY KEYWORD"`
-   - This is critical — Exasol reserves many common words (e.g., `YEAR`, `PROFILE`, `FILE`, `POSITION`) that are unreserved in other databases
+   - **Always double-quote every identifier** (column names, table names, schema names) in SELECT, FROM, WHERE, GROUP BY, ORDER BY, and JOIN clauses — without exception
+   - This preserves mixed-case names and prevents reserved-keyword errors in a single rule
+   - Do NOT quote SQL keywords, functions, or aliases — only object identifiers
+   - If a query fails with a syntax error, fetch the live reserved keyword list: `exapump sql "SELECT KEYWORD FROM EXA_SQL_KEYWORDS WHERE RESERVED ORDER BY KEYWORD"`
 
 ## Related Skills
 

plugins/exasol/skills/exasol-database/references/exasol-sql.md

@@ -44,7 +44,7 @@ SELECT "myColumn" FROM "myTable";  -- works
 SELECT mycolumn FROM myTable;      -- ERROR: "MYTABLE" not found
 ```
 
-**Rule of thumb:** Don't use quoted identifiers unless you have a specific reason. Let everything be uppercase.
+**Rule of thumb:** Never use quoted identifiers in DDL statements. Always double-quote **every** identifier in SELECT (and all DML) statements — columns, tables, schemas — unconditionally, not just reserved words.
 
 ---
 

plugins/exasol/skills/exasol-udfs/SKILL.md

@@ -5,7 +5,7 @@ description: "Exasol User Defined Functions (UDFs) and Script Language Container
 
 # Exasol UDFs & Script Language Containers
 
-Trigger when the user mentions **UDF**, **user defined function**, **CREATE SCRIPT**, **ExaIterator**, **SCALAR**, **SET EMITS**, **BucketFS**, **script language container**, **SLC**, **exaslct**, **custom packages**, **GPU UDF**, **ctx.emit**, **ctx.next**, or any UDF/SLC-related topic.
+Trigger when the user mentions **UDF**, **user defined function**, **CREATE SCRIPT**, **ExaIterator**, **SCALAR**, **SET EMITS**, **BucketFS**, **script language container**, **SLC**, **exaslct**, **custom packages**, **GPU UDF**, **ctx.emit**, **ctx.next**, **variadic script**, **dynamic parameters**, **EMITS(...)**, **default_output_columns**, or any UDF/SLC-related topic.
 
 ## When to Use UDFs
 
@@ -135,6 +135,57 @@ run <- function(ctx) {
 /
 ```
 
+## Variadic Scripts (Dynamic Parameters)
+
+Use `...` to accept any number of input columns, output columns, or both.
+
+### Dynamic Input
+
+```sql
+CREATE OR REPLACE PYTHON3 SCALAR SCRIPT schema.to_json(...) RETURNS VARCHAR(2000000) AS
+import simplejson
+def run(ctx):
+    obj = {}
+    for i in range(0, exa.meta.input_column_count, 2):
+        obj[ctx[i]] = ctx[i+1]   # caller passes: name, value, name, value, ...
+    return simplejson.dumps(obj)
+/
+
+SELECT to_json('fruit', fruit, 'price', price) FROM products;
+```
+
+- Access by index: `ctx[i]` — **0-based in Python/Java, 1-based in Lua/R**
+- Parameter names inside a variadic script are always `0`, `1`, `2`, ... — never the original column names
+- `exa.meta.input_column_count` — total number of input columns
+- `exa.meta.input_columns[i].name / .sql_type` — per-column metadata
+
+### Dynamic Output (`EMITS(...)`)
+
+Declare `EMITS(...)` in `CREATE SCRIPT`. At call time, columns must be provided one of two ways:
+
+| Method | Where specified | Use when |
+|--------|----------------|----------|
+| **EMITS in SELECT** | Caller's SQL query | Output structure depends on data values |
+| **`default_output_columns()`** | Script body | Output structure derivable from input column count/types alone |
+
+```sql
+-- EMITS in SELECT (required when output depends on data content)
+SELECT split_csv(line) EMITS (a VARCHAR(100), b VARCHAR(100), c VARCHAR(100)) FROM t;
+```
+
+```python
+# default_output_columns() — called before run(), no ctx/data access available
+def default_output_columns():
+    parts = []
+    for i in range(exa.meta.input_column_count):
+        parts.append("c" + exa.meta.input_columns[i].name + " " + exa.meta.input_columns[i].sql_type)
+    return ",".join(parts)
+```
+
+If neither is provided, the query fails with:
+> *The script has dynamic return arguments. Either specify the return arguments in the query via EMITS or implement the method default_output_columns in the UDF.*
+
+
 ## ExaIterator API Quick Reference
 
 ### Python