fix(postgres): fix compilation of array string join and map/struct fi…

…eld extraction

ibis/backends/postgres/compiler.py

@@ -315,7 +315,7 @@ def visit_StructField(self, op, *, arg, field):
         #
         # but also postgres should really support anonymous structs
         return self.cast(
-            self.f.json_extract(self.f.to_jsonb(arg), sge.convert(f"f{idx:d}")),
+            self.f.jsonb_extract_path(self.f.to_jsonb(arg), sge.convert(f"f{idx:d}")),
             op.dtype,
         )
 
@@ -336,11 +336,18 @@ def visit_MapLength(self, op, *, arg):
         return self.f.cardinality(self.f.akeys(arg))
 
     def visit_MapGet(self, op, *, arg, key, default):
-        return self.if_(self.f.exist(arg, key), self.f.json_extract(arg, key), default)
+        return self.if_(
+            self.f.exist(arg, key),
+            self.f.jsonb_extract_path_text(self.f.to_jsonb(arg), key),
+            default,
+        )
 
     def visit_MapMerge(self, op, *, left, right):
         return sge.DPipe(this=left, expression=right)
 
+    def visit_ArrayStringJoin(self, op, *, arg, sep):
+        return self.f.anon.array_to_string(arg, sep)
+
     def visit_TypeOf(self, op, *, arg):
         typ = self.cast(self.f.pg_typeof(arg), dt.string)
         return self.if_(

ibis/backends/tests/snapshots/test_sql/test_union_aliasing/postgres/out.sql

@@ -20,8 +20,8 @@ WITH "t5" AS (
       FROM (
         SELECT
           "t1"."field_of_study",
-          CAST(TO_JSONB("t1"."__pivoted__") -> 'f1' AS VARCHAR) AS "years",
-          CAST(TO_JSONB("t1"."__pivoted__") -> 'f2' AS BIGINT) AS "degrees"
+          CAST(JSONB_EXTRACT_PATH(TO_JSONB("t1"."__pivoted__"), 'f1') AS VARCHAR) AS "years",
+          CAST(JSONB_EXTRACT_PATH(TO_JSONB("t1"."__pivoted__"), 'f2') AS BIGINT) AS "degrees"
         FROM (
           SELECT
             "t0"."field_of_study",