E.8 MON$STATEMENTS

MON$STATEMENTS displays statements prepared for execution.

Column NameData TypeDescription

MON$STATEMENT_ID

BIGINT

Statement identifier

MON$ATTACHMENT_ID

BIGINT

Connection identifier

MON$TRANSACTION_ID

BIGINT

Transaction identifier

MON$STATE

SMALLINT

Statement state:

0 - idle 1 - active 2 - stalled

MON$TIMESTAMP

TIMESTAMP

The date and time when the statement was prepared

MON$SQL_TEXT

BLOB TEXT

Statement text in SQL

MON$STAT_ID

INTEGER

Statistics identifier

MON$EXPLAINED_PLAN

BLOB TEXT

Explained execution plan

MON$STATEMENT_TIMEOUT

INTEGER

Connection-level statement timeout in milliseconds. When 0 is reported the timeout of MON$ATTACHMENT.MON$STATEMENT_TIMEOUT for this connection applies.

MON$IDLE_TIMER

TIMESTAMP WITH TIME ZONE

Statement timer expiration time

The STALLED state indicates that, at the time of the snapshot, the statement had an open cursor and was waiting for the client to resume fetching rows.

Display active queries, excluding those running in your connection

  1. SELECT
  2.   ATT.MON$USER,
  3.   ATT.MON$REMOTE_ADDRESS,
  4.   STMT.MON$SQL_TEXT,
  5.   STMT.MON$TIMESTAMP
  6. FROM MON$ATTACHMENTS ATT
  7. JOIN MON$STATEMENTS STMT ON ATT.MON$ATTACHMENT_ID = STMT.MON$ATTACHMENT_ID
  8. WHERE ATT.MON$ATTACHMENT_ID <> CURRENT_CONNECTION
  9. AND STMT.MON$STATE = 1

E.8.1 Using MON$STATEMENTS to Cancel a Query

Monitoring tables are read-only. However, the server has a built-in mechanism for deleting (and only deleting) records in the MON$STATEMENTS table, which makes it possible to cancel a running query.

Notes

  • If no statements are currently being executed in the connection, any attempt to cancel queries will not proceed

  • After a query is cancelled, calling execute/fetch API functions will return an error with the isc_cancelled code

  • Subsequent queries from this connection will proceed as normal

  • Cancellation of the statement does not occur synchronously, it only marks the request for cancellation, and the cancellation itself is done asynchronously by the server

ExampleCancelling all active queries for the specified connection:

  1. DELETE FROM MON$STATEMENTS
  2.   WHERE MON$ATTACHMENT_ID = 32