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Restore 4.1's doc update for virtual table system_views.clients 

patch by Tibor Répási; reviewed by Ekaterina Dimitrova, Michael Semb Wever for CASSANDRA-18303, CASSANDRA-17344
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Tibor Répási 2023-03-06 15:10:14 +01:00 committed by Mick Semb Wever
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94
doc/modules/cassandra/pages/operating/virtualtables.adoc
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@ -112,18 +112,80 @@ We shall discuss some of the virtual tables in more detail next.
=== Clients Virtual Table
The `clients` virtual table lists all active connections (connected
clients) including their ip address, port, connection stage, driver
clients) including their ip address, port, client_options, connection stage, driver
name, driver version, hostname, protocol version, request count, ssl
enabled, ssl protocol and user name:
....
cqlsh:system_views> select * from system_views.clients;
address | port | connection_stage | driver_name | driver_version | hostname | protocol_version | request_count | ssl_cipher_suite | ssl_enabled | ssl_protocol | username
-----------+-------+------------------+-------------+----------------+-----------+------------------+---------------+------------------+-------------+--------------+-----------
127.0.0.1 | 50628 | ready | null | null | localhost | 4 | 55 | null | False | null | anonymous
127.0.0.1 | 50630 | ready | null | null | localhost | 4 | 70 | null | False | null | anonymous
cqlsh> EXPAND ON ;
Now Expanded output is enabled
cqlsh> SELECT * FROM system_views.clients;
(2 rows)
@ Row 1
------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
address | 127.0.0.1
port | 50687
client_options | {'CQL_VERSION': '3.4.6', 'DRIVER_NAME': 'DataStax Python Driver', 'DRIVER_VERSION': '3.25.0'}
connection_stage | ready
driver_name | DataStax Python Driver
driver_version | 3.25.0
hostname | localhost
protocol_version | 5
request_count | 16
ssl_cipher_suite | null
ssl_enabled | False
ssl_protocol | null
username | anonymous
@ Row 2
------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
address | 127.0.0.1
port | 50688
client_options | {'CQL_VERSION': '3.4.6', 'DRIVER_NAME': 'DataStax Python Driver', 'DRIVER_VERSION': '3.25.0'}
connection_stage | ready
driver_name | DataStax Python Driver
driver_version | 3.25.0
hostname | localhost
protocol_version | 5
request_count | 4
ssl_cipher_suite | null
ssl_enabled | False
ssl_protocol | null
username | anonymous
@ Row 3
------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
address | 127.0.0.1
port | 50753
client_options | {'APPLICATION_NAME': 'TestApp', 'APPLICATION_VERSION': '1.0.0', 'CLIENT_ID': '55b3efbd-c56b-469d-8cca-016b860b2f03', 'CQL_VERSION': '3.0.0', 'DRIVER_NAME': 'DataStax Java driver for Apache Cassandra(R)', 'DRIVER_VERSION': '4.13.0'}
connection_stage | ready
driver_name | DataStax Java driver for Apache Cassandra(R)
driver_version | 4.13.0
hostname | localhost
protocol_version | 5
request_count | 18
ssl_cipher_suite | null
ssl_enabled | False
ssl_protocol | null
username | anonymous
@ Row 4
------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
address | 127.0.0.1
port | 50755
client_options | {'APPLICATION_NAME': 'TestApp', 'APPLICATION_VERSION': '1.0.0', 'CLIENT_ID': '55b3efbd-c56b-469d-8cca-016b860b2f03', 'CQL_VERSION': '3.0.0', 'DRIVER_NAME': 'DataStax Java driver for Apache Cassandra(R)', 'DRIVER_VERSION': '4.13.0'}
connection_stage | ready
driver_name | DataStax Java driver for Apache Cassandra(R)
driver_version | 4.13.0
hostname | localhost
protocol_version | 5
request_count | 7
ssl_cipher_suite | null
ssl_enabled | False
ssl_protocol | null
username | anonymous
(4 rows)
....
Some examples of how `clients` can be used are:
@ -139,23 +201,29 @@ listed however cannot be run to create a virtual table. As an example
describe the `system_views.clients` virtual table:
....
cqlsh:system_views> DESC TABLE system_views.clients;
CREATE TABLE system_views.clients (
cqlsh> DESCRIBE TABLE system_views.clients;
/*
Warning: Table system_views.clients is a virtual table and cannot be recreated with CQL.
Structure, for reference:
VIRTUAL TABLE system_views.clients (
address inet,
port int,
client_options frozen<map<text, text>>,
connection_stage text,
driver_name text,
driver_version text,
hostname text,
port int,
protocol_version int,
request_count bigint,
ssl_cipher_suite text,
ssl_enabled boolean,
ssl_protocol text,
username text,
PRIMARY KEY (address, port)) WITH CLUSTERING ORDER BY (port ASC)
AND compaction = {'class': 'None'}
AND compression = {};
PRIMARY KEY (address, port)
) WITH CLUSTERING ORDER BY (port ASC)
AND comment = 'currently connected clients';
*/
....
=== Caches Virtual Table