Fix CAST alias and large float formatting in EXPLAIN output (#95)

* Fix CAST alias and large float formatting in EXPLAIN output

- Always show alias for CAST expressions when wrapped in AliasedExpr,
  regardless of whether CAST uses AS syntax (CAST(x AS Type)) or comma
  syntax (CAST(x, 'Type'))

- Use scientific notation for very large floats (>= 1e21) in EXPLAIN
  output to match ClickHouse's behavior

- Update next-test command to show test with most pending statements
  instead of fewest

These changes fix 69 test files with numerous explain_todo statements.

* Add total pending statements count to next-test output

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: kyleconroy

cmd/next-test/main.go

@@ -79,10 +79,10 @@ func main() {
 		return
 	}
 
-	// Sort by explain_todo count (fewest first), then by query size
+	// Sort by explain_todo count (most first), then by query size
 	sort.Slice(todoTests, func(i, j int) bool {
 		if todoTests[i].explainTodoLen != todoTests[j].explainTodoLen {
-			return todoTests[i].explainTodoLen < todoTests[j].explainTodoLen
+			return todoTests[i].explainTodoLen > todoTests[j].explainTodoLen
 		}
 		return todoTests[i].querySize < todoTests[j].querySize
 	})
@@ -116,5 +116,12 @@ func main() {
 		}
 	}
 
+	// Calculate total pending statements across all tests
+	totalStatements := 0
+	for _, t := range todoTests {
+		totalStatements += t.explainTodoLen
+	}
+
 	fmt.Printf("\nRemaining explain_todo tests: %d\n", len(todoTests))
+	fmt.Printf("Total pending statements: %d\n", totalStatements)
 }

internal/explain/expressions.go

@@ -503,12 +503,8 @@ func explainAliasedExpr(sb *strings.Builder, n *ast.AliasedExpr, depth int) {
 		Node(sb, e.Then, depth+2)
 		Node(sb, e.Else, depth+2)
 	case *ast.CastExpr:
-		// CAST expressions - show alias only for CAST(x AS Type) syntax, not CAST(x, 'Type')
-		if e.UsedASSyntax {
-			explainCastExprWithAlias(sb, e, n.Alias, indent, depth)
-		} else {
-			explainCastExpr(sb, e, indent, depth)
-		}
+		// CAST expressions always show the alias from the AliasedExpr wrapper
+		explainCastExprWithAlias(sb, e, n.Alias, indent, depth)
 	case *ast.ArrayAccess:
 		// Array access - show alias only when array is not a literal
 		// ClickHouse hides alias when array access is on a literal

internal/explain/format.go

@@ -21,15 +21,16 @@ func FormatFloat(val float64) string {
 	if math.IsNaN(val) {
 		return "nan"
 	}
-	// Use scientific notation for very small numbers (< 1e-6)
-	// This matches ClickHouse's behavior where numbers like 0.0000001 (-1e-7)
-	// are displayed in scientific notation
+	// Use scientific notation for very small numbers (< 1e-6) or very large numbers (>= 1e21)
+	// This matches ClickHouse's behavior
 	absVal := math.Abs(val)
-	if absVal > 0 && absVal < 1e-6 {
+	if (absVal > 0 && absVal < 1e-6) || absVal >= 1e21 {
 		s := strconv.FormatFloat(val, 'e', -1, 64)
-		// Remove leading zeros from exponent (e-07 -> e-7)
+		// Remove leading zeros from exponent (e-07 -> e-7, e+07 -> e+7)
 		s = strings.Replace(s, "e-0", "e-", 1)
 		s = strings.Replace(s, "e+0", "e+", 1)
+		// Remove the + from positive exponents (e+21 -> e21)
+		s = strings.Replace(s, "e+", "e", 1)
 		return s
 	}
 	// Use decimal notation for normal-sized numbers

parser/testdata/00541_kahan_sum/metadata.json

@@ -1,6 +1 @@
-{
-  "explain_todo": {
-    "stmt3": true,
-    "stmt4": true
-  }
-}
+{}

parser/testdata/00700_decimal_casts/metadata.json

@@ -1,6 +1 @@
-{
-  "explain_todo": {
-    "stmt121": true,
-    "stmt122": true
-  }
-}
+{}

parser/testdata/00700_decimal_casts_2/metadata.json

@@ -1,8 +1 @@
-{
-  "explain_todo": {
-    "stmt86": true,
-    "stmt89": true,
-    "stmt92": true,
-    "stmt95": true
-  }
-}
+{}

parser/testdata/00700_decimal_math/metadata.json

@@ -1,7 +1 @@
-{
-  "explain_todo": {
-    "stmt17": true,
-    "stmt27": true,
-    "stmt7": true
-  }
-}
+{}

parser/testdata/01013_hex_float/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt5": true
-  }
-}
+{}

parser/testdata/01262_low_cardinality_remove/metadata.json

@@ -1,7 +1 @@
-{
-  "explain_todo": {
-    "stmt11": true,
-    "stmt6": true,
-    "stmt9": true
-  }
-}
+{}

parser/testdata/01322_cast_keep_nullable/metadata.json

@@ -1 +1 @@
-{"explain_todo":{"stmt11":true,"stmt12":true,"stmt7":true,"stmt8":true}}
+{}