fix: support create index if not exists

The flag `if_not_exists` was ignored when deparsing a create index
statement.

Author: tomquist

__fixtures__/misc.sql

@@ -19,4 +19,6 @@ create table if not exists users (
   handle text not null,
   created_at timestamp not null default now(),
   updated_at timestamp not null default now()
-)
+);
+
+CREATE INDEX CONCURRENTLY IF NOT EXISTS index_email_logs_on_created_at ON public.email_logs USING btree (created_at DESC);

packages/deparser/__tests__/__snapshots__/kitchen-sink.test.ts.snap

@@ -246734,7 +246734,7 @@ exports[`misc 15`] = `
         ],
       },
     },
-    "stmt_len": undefined,
+    "stmt_len": 238,
     "stmt_location": 629,
   },
 }
@@ -246747,9 +246747,44 @@ name text NOT NULL,
 handle text NOT NULL,
 created_at timestamp NOT NULL DEFAULT ( now() ),
 updated_at timestamp NOT NULL DEFAULT ( now() )
-)"
+);"
 `;
 
+exports[`misc 17`] = `
+{
+  "RawStmt": {
+    "stmt": {
+      "IndexStmt": {
+        "accessMethod": "btree",
+        "concurrent": true,
+        "idxname": "index_email_logs_on_created_at",
+        "if_not_exists": true,
+        "indexParams": [
+          {
+            "IndexElem": {
+              "name": "created_at",
+              "nulls_ordering": "SORTBY_NULLS_DEFAULT",
+              "ordering": "SORTBY_DESC",
+            },
+          },
+        ],
+        "relation": {
+          "inh": true,
+          "location": 944,
+          "relname": "email_logs",
+          "relpersistence": "p",
+          "schemaname": "public",
+        },
+      },
+    },
+    "stmt_len": 123,
+    "stmt_location": 868,
+  },
+}
+`;
+
+exports[`misc 18`] = `"CREATE INDEX CONCURRENTLY IF NOT EXISTS index_email_logs_on_created_at ON public.email_logs ( created_at DESC );"`;
+
 exports[`parens 1`] = `
 {
   "RawStmt": {

packages/deparser/src/deparser.ts

@@ -1510,6 +1510,9 @@ export default class Deparser {
     if (node.concurrent) {
       output.push('CONCURRENTLY');
     }
+    if (node.if_not_exists) {
+      output.push('IF NOT EXISTS');
+    }
 
     if (node.idxname) {
       output.push(node.idxname);