gianm commented on a change in pull request #6094: Introduce SystemSchema tables (#5989) URL: https://github.com/apache/incubator-druid/pull/6094#discussion_r221369584
########## File path: docs/content/querying/sql.md ########## @@ -481,6 +486,88 @@ SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = 'druid' AND TABLE_ |COLLATION_NAME|| |JDBC_TYPE|Type code from java.sql.Types (Druid extension)| +## SYSTEM SCHEMA + +The SYS schema provides visibility into Druid segments, servers and tasks. +For example to retrieve all segments for datasource "wikipedia", use the query: +```sql +SELECT * FROM sys.segments WHERE datasource = 'wikipedia' +``` + +### SEGMENTS table +Segments table provides details on all Druid segments, whether they are published yet or not. + + +|Column|Notes| +|------|-----| +|segment_id|Unique segment identifier| +|datasource|Name of datasource| +|start|Interval start time (in ISO 8601 format)| +|end|Interval end time (in ISO 8601 format)| +|size|Size of segment in bytes| +|version|Version number (generally an ISO8601 timestamp corresponding to when the segment set was first started)| +|partition_num|Partition number (an integer, unique within a datasource+interval+version; may not necessarily be contiguous)| +|num_replicas|Number replicas of this segment currently being served| +|is_published|True if this segment has been published to the metadata store| +|is_available|True if this segment is currently being served by any server| +|is_realtime|True if this segment is being served on a realtime server| +|payload|Jsonified datasegment payload| + +### SERVERS table +Servers table lists all data servers(any server that hosts a segment). It includes both historicals and peons. + +|Column|Notes| +|------|-----| +|server|Server name in the form host:port| Review comment: It does support concatenating, but I think we should keep this here. It's basically the primary key of the server table, and is used for joins with the segment_servers table. The other fields (host, plaintext_port, etc) are provided too as conveniences. With system tables, since they're all generated dynamically anyway, it's ok to have some redundancy when it makes the user experience more convenient. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@druid.apache.org For additional commands, e-mail: commits-h...@druid.apache.org
