ClickHouse/docs/en/operations/system-tables/events.md
Ivan Blinkov 258d2fd499
[docs] split various kinds of CREATE queries into separate articles (#12328)
* normalize

* split & adjust links

* re-normalize

* adjust ru links

* adjust ja/tr links

* partially apply e0d19d2aea

* reset contribs
2020-07-09 18:10:35 +03:00

4.5 KiB

system.events

Contains information about the number of events that have occurred in the system. For example, in the table, you can find how many SELECT queries were processed since the ClickHouse server started.

Columns:

  • event (String) — Event name.
  • value (UInt64) — Number of events occurred.
  • description (String) — Event description.

Example

SELECT * FROM system.events LIMIT 5
┌─event─────────────────────────────────┬─value─┬─description────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ Query                                 │    12 │ Number of queries to be interpreted and potentially executed. Does not include queries that failed to parse or were rejected due to AST size limits, quota limits or limits on the number of simultaneously running queries. May include internal queries initiated by ClickHouse itself. Does not count subqueries.                  │
│ SelectQuery                           │     8 │ Same as Query, but only for SELECT queries.                                                                                                                                                                                                                │
│ FileOpen                              │    73 │ Number of files opened.                                                                                                                                                                                                                                    │
│ ReadBufferFromFileDescriptorRead      │   155 │ Number of reads (read/pread) from a file descriptor. Does not include sockets.                                                                                                                                                                             │
│ ReadBufferFromFileDescriptorReadBytes │  9931 │ Number of bytes read from file descriptors. If the file is compressed, this will show the compressed data size.                                                                                                                                              │
└───────────────────────────────────────┴───────┴────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

See Also