fix: trigger when IS NOT DISTINCT FROM

ir/inspector.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"regexp"
 	"sort"
 	"strconv"
 	"strings"
@@ -1555,6 +1556,39 @@ func (i *Inspector) normalizeTriggerCondition(rawCondition string) string {
 		}
 	}
 
+	// Use pg_query to normalize the expression for consistent formatting
+	// This handles complex expressions, case normalization, etc.
+	normalizedCondition := normalizeExpressionWithPgQuery(condition)
+	if normalizedCondition != "" {
+		condition = normalizedCondition
+	}
+
+	// Post-process to handle PostgreSQL's "NOT x IS DISTINCT FROM y" → "x IS NOT DISTINCT FROM y"
+	condition = i.normalizeNotDistinctFromPattern(condition)
+
+	return condition
+}
+
+// normalizeNotDistinctFromPattern converts "NOT x IS DISTINCT FROM y" to "x IS NOT DISTINCT FROM y"
+// This handles the specific case where pg_query.Deparse converts PostgreSQL's internal
+// "NOT (x IS DISTINCT FROM y)" representation to "NOT x IS DISTINCT FROM y"
+func (i *Inspector) normalizeNotDistinctFromPattern(condition string) string {
+	// Use regex to match: "NOT <expr> IS DISTINCT FROM <expr>"
+	// and convert to: "<expr> IS NOT DISTINCT FROM <expr>"
+
+	// Pattern explanation:
+	// ^NOT\s+ - starts with "NOT" followed by whitespace
+	// (.+?) - non-greedy capture of left expression
+	// \s+IS\s+DISTINCT\s+FROM\s+ - " IS DISTINCT FROM " with flexible whitespace
+	// (.+)$ - capture the right expression to end of string
+	re := regexp.MustCompile(`^NOT\s+(.+?)\s+IS\s+DISTINCT\s+FROM\s+(.+)$`)
+
+	if matches := re.FindStringSubmatch(condition); matches != nil {
+		left := strings.TrimSpace(matches[1])
+		right := strings.TrimSpace(matches[2])
+		return fmt.Sprintf("%s IS NOT DISTINCT FROM %s", left, right)
+	}
+
 	return condition
 }
 

ir/parser.go

@@ -1411,6 +1411,20 @@ func (p *Parser) parseAExpr(expr *pg_query.A_Expr) string {
 		return fmt.Sprintf("%s IN %s", left, right)
 	}
 
+	// Handle DISTINCT FROM expressions
+	if expr.Kind == pg_query.A_Expr_Kind_AEXPR_DISTINCT {
+		left := p.extractExpressionText(expr.Lexpr)
+		right := p.extractExpressionText(expr.Rexpr)
+		return fmt.Sprintf("%s IS DISTINCT FROM %s", left, right)
+	}
+
+	// Handle NOT DISTINCT FROM expressions
+	if expr.Kind == pg_query.A_Expr_Kind_AEXPR_NOT_DISTINCT {
+		left := p.extractExpressionText(expr.Lexpr)
+		right := p.extractExpressionText(expr.Rexpr)
+		return fmt.Sprintf("%s IS NOT DISTINCT FROM %s", left, right)
+	}
+
 	// Simplified implementation for basic expressions
 	if len(expr.Name) > 0 {
 		if str := expr.Name[0].GetString_(); str != nil {

testdata/diff/create_trigger/add_trigger_when_distinct/diff.sql

@@ -0,0 +1,11 @@
+CREATE OR REPLACE TRIGGER products_description_trigger
+    BEFORE UPDATE ON products
+    FOR EACH ROW
+    WHEN (NEW.description IS DISTINCT FROM OLD.description)
+    EXECUTE FUNCTION log_description_change();
+
+CREATE OR REPLACE TRIGGER products_status_trigger
+    BEFORE UPDATE ON products
+    FOR EACH ROW
+    WHEN (NEW.status IS NOT DISTINCT FROM OLD.status)
+    EXECUTE FUNCTION skip_status_change();

testdata/diff/create_trigger/add_trigger_when_distinct/new.sql

@@ -0,0 +1,34 @@
+CREATE TABLE public.products (
+    id serial PRIMARY KEY,
+    name text NOT NULL,
+    description text,
+    status text,
+    updated_at timestamp DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE OR REPLACE FUNCTION public.log_description_change()
+RETURNS trigger AS $$
+BEGIN
+    NEW.updated_at = CURRENT_TIMESTAMP;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION public.skip_status_change()
+RETURNS trigger AS $$
+BEGIN
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER products_description_trigger
+    BEFORE UPDATE ON public.products
+    FOR EACH ROW
+    WHEN (NEW.description IS DISTINCT FROM OLD.description)
+    EXECUTE FUNCTION public.log_description_change();
+
+CREATE TRIGGER products_status_trigger
+    BEFORE UPDATE ON public.products
+    FOR EACH ROW
+    WHEN (NEW.status IS NOT DISTINCT FROM OLD.status)
+    EXECUTE FUNCTION public.skip_status_change();

testdata/diff/create_trigger/add_trigger_when_distinct/old.sql

@@ -0,0 +1,22 @@
+CREATE TABLE public.products (
+    id serial PRIMARY KEY,
+    name text NOT NULL,
+    description text,
+    status text,
+    updated_at timestamp DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE OR REPLACE FUNCTION public.log_description_change()
+RETURNS trigger AS $$
+BEGIN
+    NEW.updated_at = CURRENT_TIMESTAMP;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION public.skip_status_change()
+RETURNS trigger AS $$
+BEGIN
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;

testdata/diff/create_trigger/add_trigger_when_distinct/plan.json

@@ -0,0 +1,26 @@
+{
+  "version": "1.0.0",
+  "pgschema_version": "1.1.1",
+  "created_at": "1970-01-01T00:00:00Z",
+  "source_fingerprint": {
+    "hash": "98db11096a7a86d2175ff6821924a2b64dddbf240681f23079c0d912d3ea22b5"
+  },
+  "groups": [
+    {
+      "steps": [
+        {
+          "sql": "CREATE OR REPLACE TRIGGER products_description_trigger\n    BEFORE UPDATE ON products\n    FOR EACH ROW\n    WHEN (NEW.description IS DISTINCT FROM OLD.description)\n    EXECUTE FUNCTION log_description_change();",
+          "type": "table.trigger",
+          "operation": "create",
+          "path": "public.products.products_description_trigger"
+        },
+        {
+          "sql": "CREATE OR REPLACE TRIGGER products_status_trigger\n    BEFORE UPDATE ON products\n    FOR EACH ROW\n    WHEN (NEW.status IS NOT DISTINCT FROM OLD.status)\n    EXECUTE FUNCTION skip_status_change();",
+          "type": "table.trigger",
+          "operation": "create",
+          "path": "public.products.products_status_trigger"
+        }
+      ]
+    }
+  ]
+}

testdata/diff/create_trigger/add_trigger_when_distinct/plan.sql

@@ -0,0 +1,11 @@
+CREATE OR REPLACE TRIGGER products_description_trigger
+    BEFORE UPDATE ON products
+    FOR EACH ROW
+    WHEN (NEW.description IS DISTINCT FROM OLD.description)
+    EXECUTE FUNCTION log_description_change();
+
+CREATE OR REPLACE TRIGGER products_status_trigger
+    BEFORE UPDATE ON products
+    FOR EACH ROW
+    WHEN (NEW.status IS NOT DISTINCT FROM OLD.status)
+    EXECUTE FUNCTION skip_status_change();

testdata/diff/create_trigger/add_trigger_when_distinct/plan.txt

@@ -0,0 +1,24 @@
+Plan: 1 to modify.
+
+Summary by type:
+  tables: 1 to modify
+
+Tables:
+  ~ products
+    + products_description_trigger (trigger)
+    + products_status_trigger (trigger)
+
+DDL to be executed:
+--------------------------------------------------
+
+CREATE OR REPLACE TRIGGER products_description_trigger
+    BEFORE UPDATE ON products
+    FOR EACH ROW
+    WHEN (NEW.description IS DISTINCT FROM OLD.description)
+    EXECUTE FUNCTION log_description_change();
+
+CREATE OR REPLACE TRIGGER products_status_trigger
+    BEFORE UPDATE ON products
+    FOR EACH ROW
+    WHEN (NEW.status IS NOT DISTINCT FROM OLD.status)
+    EXECUTE FUNCTION skip_status_change();