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Database¶

Can’t Change Permissions on Extension¶

Error¶

… could not execute query: ERROR:  must be owner of extension lo
Command was: COMMENT ON EXTENSION …

Cause¶

pg_restore skips creation of the object itself, in this case lo, because it already exists. However, it still tries to change the comment but doesn’t have the permissions.

Solution - Remove Comment¶

Remove the comments from the affected extensions to ensure future dumps won’t contain COMMENT ON … statements.

Usually these two are affected:

COMMENT ON EXTENSION lo IS NULL;
COMMENT ON EXTENSION plpgsql IS NULL;

Hint

Remove the comment in database template1 to ensure new databases don’t contain it. (A CREATE DATABASE xy copies that DB.)

Workaround - Don’t Restore Comments¶

Use pg_restore’s --no-comments to skip restore of comments.

Postgres Connection Timeout¶

Error¶

HikariPool-1 - Connection is not available, request timed out after 30001ms.

often seen in connection with:

PersistenceException: org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection

Cause¶

HikariCP, the connection pool used by Nice, has a fixed number of connections available. The error tells us that no connection could be obtained within the given time. This could be because all connections are in use, because connecting to the server failed, or some other other issue lead to delays.

Analysis¶

Low Memory¶

In the vast majority of cases, this error is printed because the application is low on memory. In such a scenario, the GC is using most of the available resources, slowing down everything to a near-halt delaying the return of DB connections.

Solutions:

Create a memory dump for later analysis
Creating a Memory Dump Manually

Too Few Connections¶

First, check how the connections are used …:
```
$ tco db-queries ${installation}
```

… and check how many DB connections are available:

$ tco config ${installation}
agogis:
…
  installations:
    agogis:
      branch: releases/3.6
      env: !merge
        hibernate.main.hikari.maximumPoolSize: 15    # <---
      db_server: db3.tocco.cust.vshn.net
      enable_performance_monitoring: true
…

hibernate.main.hikari.maximumPoolSize is the maximum number of connections available. The value currently defaults to 6.

Take a look at HikariCP’s github page.

Take a look at how the connections are used

tco db-queries ${installation}