Better docs for virtual columns in Kafka/RabbitMQ/NATS/FileLog

docs/en/engines/table-engines/integrations/kafka.md

@@ -238,19 +238,19 @@ Example:
 
 ## Virtual Columns {#virtual-columns}
 
-- `_topic` — Kafka topic.
-- `_key` — Key of the message.
-- `_offset` — Offset of the message.
-- `_timestamp` — Timestamp of the message.
-- `_timestamp_ms` — Timestamp in milliseconds of the message.
-- `_partition` — Partition of Kafka topic.
-- `_headers.name` — Array of message's headers keys.
-- `_headers.value` — Array of message's headers values.
+- `_topic` — Kafka topic. Data type: `LowCardinality(String)`.
+- `_key` — Key of the message. Data type: `String`.
+- `_offset` — Offset of the message. Data type: `UInt64`.
+- `_timestamp` — Timestamp of the message Data type: `Nullable(DateTime)`.
+- `_timestamp_ms` — Timestamp in milliseconds of the message. Data type: `Nullable(DateTime64(3))`.
+- `_partition` — Partition of Kafka topic. Data type: `UInt64`.
+- `_headers.name` — Array of message's headers keys. Data type: `Array(String)`.
+- `_headers.value` — Array of message's headers values. Data type: `Array(String)`.
 
 Additional virtual columns when `kafka_handle_error_mode='stream'`:
 
-- `_raw_message` - Raw message that couldn't be parsed successfully.
-- `_error` - Exception message happened during failed parsing.
+- `_raw_message` - Raw message that couldn't be parsed successfully. Data type: `String`.
+- `_error` - Exception message happened during failed parsing. Data type: `String`.
 
 Note: `_raw_message` and `_error` virtual columns are filled only in case of exception during parsing, they are always empty when message was parsed successfully.
 

docs/en/engines/table-engines/integrations/nats.md

@@ -163,14 +163,14 @@ If you want to change the target table by using `ALTER`, we recommend disabling
 
 ## Virtual Columns {#virtual-columns}
 
-- `_subject` - NATS message subject.
+- `_subject` - NATS message subject. Data type: `String`.
 
 Additional virtual columns when `kafka_handle_error_mode='stream'`:
 
-- `_raw_message` - Raw message that couldn't be parsed successfully.
-- `_error` - Exception message happened during failed parsing.
+- `_raw_message` - Raw message that couldn't be parsed successfully. Data type: `Nullable(String)`.
+- `_error` - Exception message happened during failed parsing. Data type: `Nullable(String)`.
 
-Note: `_raw_message` and `_error` virtual columns are filled only in case of exception during parsing, they are always empty when message was parsed successfully.
+Note: `_raw_message` and `_error` virtual columns are filled only in case of exception during parsing, they are always `NULL` when message was parsed successfully.
 
 
 ## Data formats support {#data-formats-support}

docs/en/engines/table-engines/integrations/rabbitmq.md

@@ -184,19 +184,19 @@ Example:
 
 ## Virtual Columns {#virtual-columns}
 
-- `_exchange_name` - RabbitMQ exchange name.
-- `_channel_id` - ChannelID, on which consumer, who received the message, was declared.
-- `_delivery_tag` - DeliveryTag of the received message. Scoped per channel.
-- `_redelivered` - `redelivered` flag of the message.
-- `_message_id` - messageID of the received message; non-empty if was set, when message was published.
-- `_timestamp` - timestamp of the received message; non-empty if was set, when message was published.
+- `_exchange_name` - RabbitMQ exchange name. Data type: `String`.
+- `_channel_id` - ChannelID, on which consumer, who received the message, was declared. Data type: `String`.
+- `_delivery_tag` - DeliveryTag of the received message. Scoped per channel. Data type: `UInt64`.
+- `_redelivered` - `redelivered` flag of the message. Data type: `UInt8`.
+- `_message_id` - messageID of the received message; non-empty if was set, when message was published. Data type: `String`.
+- `_timestamp` - timestamp of the received message; non-empty if was set, when message was published. Data type: `UInt64`.
 
 Additional virtual columns when `kafka_handle_error_mode='stream'`:
 
-- `_raw_message` - Raw message that couldn't be parsed successfully.
-- `_error` - Exception message happened during failed parsing.
+- `_raw_message` - Raw message that couldn't be parsed successfully. Data type: `Nullable(String)`.
+- `_error` - Exception message happened during failed parsing. Data type: `Nullable(String)`.
 
-Note: `_raw_message` and `_error` virtual columns are filled only in case of exception during parsing, they are always empty when message was parsed successfully.
+Note: `_raw_message` and `_error` virtual columns are filled only in case of exception during parsing, they are always `NULL` when message was parsed successfully.
 
 ## Data formats support {#data-formats-support}
 

docs/en/engines/table-engines/special/filelog.md

@@ -94,12 +94,12 @@ If you want to change the target table by using `ALTER`, we recommend disabling
 
 ## Virtual Columns {#virtual-columns}
 
-- `_filename` - Name of the log file.
-- `_offset` - Offset in the log file.
+- `_filename` - Name of the log file. Data type: `LowCardinality(String)`.
+- `_offset` - Offset in the log file. Data type: `UInt64`.
 
 Additional virtual columns when `kafka_handle_error_mode='stream'`:
 
-- `_raw_record` - Raw record that couldn't be parsed successfully.
-- `_error` - Exception message happened during failed parsing.
+- `_raw_record` - Raw record that couldn't be parsed successfully. Data type: `Nullable(String)`.
+- `_error` - Exception message happened during failed parsing. Data type: `Nullable(String)`.
 
-Note: `_raw_record` and `_error` virtual columns are filled only in case of exception during parsing, they are always empty when message was parsed successfully.
+Note: `_raw_record` and `_error` virtual columns are filled only in case of exception during parsing, they are always `NULL` when message was parsed successfully.