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  1. Solution Center
  2. SOL-186

IDLE Connections

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    Details

    • Type: Explanation
    • Status: Published
    • Affects Version/s: EXASolution 4.2.0, EXASOL 6.0.0, Exasol 6.1.0, EXASolution 5.0.0
    • Fix Version/s: None
    • Component/s: None
    • Labels:
      None
    • Symptoms:

      IDLE sessions in EXA_ALL_SESSIONS...

      • What are they?
      • Are they slowing down my system?
    • Explanation:
      Hide

      Idle sessions should in most cases not have any visible performance impact.

      To be more specific, an idle session may be in one of the following states:

      Connected, inactive: In this state, the session will consume some RAM (TEMP_DB_RAM_USAGE). If resources get scarce, the database is allowed to silently disconnect the session (see below).

      Connected, active: Active in this context means that the session is using some volatile resource like a prepared statement, an open result set or an open transaction. Still minimal impact, but the session can not be silently disconnected. Open transactions will cause increasing storage usage on the backend when tables are repeatedly modified by other transactions!

      Disconnected: As mentioned above, the database may disconnect sessions in some cases. All session information is retained for about 24 hours, during this time our drivers are able to automatically reconnect to the session. Disconnected sessions have no impact at all, except for being visible in the session list.

      All in all, a manual cleanup process is either not necessary or would interrupt operations for the IDLE/active sessions...

      Currently, there is no way to discern the 'Connected' states through system tables; Disconnected sessions should have a TEMP_DB_RAM_USAGE of 0.0 in the current session list.

      See also SOL-296

      Show
      Idle sessions should in most cases not have any visible performance impact. To be more specific, an idle session may be in one of the following states: Connected, inactive: In this state, the session will consume some RAM (TEMP_DB_RAM_USAGE). If resources get scarce, the database is allowed to silently disconnect the session (see below). Connected, active: Active in this context means that the session is using some volatile resource like a prepared statement, an open result set or an open transaction. Still minimal impact, but the session can not be silently disconnected. Open transactions will cause increasing storage usage on the backend when tables are repeatedly modified by other transactions! Disconnected: As mentioned above, the database may disconnect sessions in some cases. All session information is retained for about 24 hours, during this time our drivers are able to automatically reconnect to the session. Disconnected sessions have no impact at all, except for being visible in the session list. All in all, a manual cleanup process is either not necessary or would interrupt operations for the IDLE/active sessions... Currently, there is no way to discern the 'Connected' states through system tables; Disconnected sessions should have a TEMP_DB_RAM_USAGE of 0.0 in the current session list. See also SOL-296
    • Category 1:
      Database Administration

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            • Assignee:
              CaptainEXA Captain EXASOL
              Reporter:
              CaptainEXA Captain EXASOL
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              • Created:
                Updated: