# Materialize v0.73
## v0.73.0


[//]: # "NOTE(morsapaes) v0.73 shipped the ASSERT NOT NULL option for sinks
behind a feature flag."

#### Sources and sinks

* **Private preview.** Allow propagating comments in materialized views to the
    Avro schema of [Kafka sinks](/sql/create-sink/kafka/), as well as manually
    specifying comments using the new `[KEY|VALUE] DOC ON
    [TYPE|COLUMN] <identifier>` [connection option](/sql/create-sink/kafka/#syntax).

    **Example:**

	```mzsql
	CREATE TABLE t (c1 int, c2 text);
	COMMENT ON TABLE t IS 'materialize comment on t';
	COMMENT ON COLUMN t.c2 IS 'materialize comment on t.c2';

	CREATE SINK avro_sink
	  IN CLUSTER my_io_cluster
	  FROM t
	  INTO KAFKA CONNECTION kafka_connection (TOPIC 'test_avro_topic')
	  KEY (c1)
	  FORMAT AVRO USING CONFLUENT SCHEMA REGISTRY CONNECTION csr_connection
	  (
	    DOC ON TYPE t = 'top-level comment for avro record in both key and value schemas',
	    KEY DOC ON COLUMN t.c1 = 'comment on column only in key schema',
	    VALUE DOC ON COLUMN t.c1 = 'comment on column only in value schema'
	  )
	  ENVELOPE UPSERT;
	```

	**Key schema:**
	```json
	{
	  "type": "record",
	  "name": "row",
	  "doc": "this is a materialized view",
	  "fields" : [
	    {"name": "a", "type": "string", "doc": "this is column a"},
	    {"name": "b", "type": "string"}
	  ]
	}{
	  "type": "record",
	  "name": "row",
	  "doc": "top-level comment for avro record in both key and value schemas",
	  "fields": [
	    {
	      "name": "c1",
	      "type": [
	        "null",
	        "int"
	      ],
	      "doc": "comment on column only in key schema"
	    }
	  ]
	}
	```

	**Value schema:**

	```json
	{
	  "type": "record",
	  "name": "envelope",
	  "doc": "top-level comment for avro record in both key and value schemas",
	  "fields": [
	    {
	      "name": "c1",
	      "type": [
	        "null",
	        "int"
	      ],
	      "doc": "comment on column only in value schema"
	    },
	    {
	      "name": "c2",
	      "type": [
	        "null",
	        "string"
	      ],
	      "doc": "materialize comment on t.c2"
	    }
	  ]
	}
	```

#### Bug fixes and other improvements

* Allow the value of the `SASL MECHANISM` option for [Kafka connections](/sql/create-connection/#kafka)
to be specified in any case style. Previously, Materialize only accepted
uppercase case style (as required by `librdkafka`).