How to Upgrade AWS RDS PostgreSQL With Extensions

One of the client just received notifications about end of support for AWS PostgreSQL RDS 9.5. They do have a couple of PostgreSQL RDS 9.5 in AWS. Some of them are using PostGIS extensions.

This post demonstrates step by step how to upgrade AWS PostgreSQL RDS 9.5.23-R1 to AWS PostgreSQL RDS 9.6.20-R1. Certainly the upgrading method in this post can be applied to other versions as well like AWS PostgreSQL RDS 10, 11 and 12, etc.

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Failed to connect to ASM instance. The connection is closed: The connection is closed

One client OEM reports the following incidents intermittently from OEM 13c.

Host=racnode1.virtuallab
Target type=Automatic Storage Management
Target name=+ASM1_racnode1.virtuallab
Categories=Availability
Message=Failed to connect to ASM instance. The connection is closed: The connection is closed
Severity=Fatal
Event reported time=20/12/2020 09:19:01AM EST
Target Lifecycle Status=Test
Operating System=LINUX
Platform=X86_64
Associated Incident Id=12345
Associated Incident Status=New
Associated Incident Owner=oracle
Associated Incident Acknowledged By Owner=No
Associated Incident Priority=High
Associated Incident Escalation Level=0
Event Type=Target Availability
Event name=Status
Availability status=Down

Let’s do some investigations, and provide the easy workaround if patches are unavailable to some clients.

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How to Check Process Memory Usage in Linux

This post demonstrates how to check a process memory usage in Linux. While there are system resource issues, it is always helpful to identify the root cause by checking suspected process memory usage, which can be memory leaking from time to time.

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ORA-24327: need explicit attach before authenticating a user (DBD ERROR: OCISessionBegin)

One of the OEM agent log has the following error, and some of the jobs fail due to the database connection issues:

$ grep ORA-24327 *
gcagent.log.16:em_error=Could not connect to dbsnmp/(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=racnode1.virtuallab)(Port=1521))(CONNECT_DATA=(SID=RACTESTDB1))): ORA-24327: need explicit attach before authenticating a user (DBD ERROR: OCISessionBegin)

The output from CA( Corrective Action) job:

Connector descriptor is (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=racnode1.virtuallab)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=RACTESTDB)(SERVER=DEDICATED)))
Could not connect to SYSTEM/(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=racnode1.virtuallab)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=RACTESTDB)(SERVER=DEDICATED))):ORA-24327: need explicit attach before authenticating a user (DBD ERROR: OCISessionBegin)

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Find Oracle SQL Execution History Details

DBAs are always asked about the database performance issues, which are mostly caused by some SQL queries’ execution plan changes.

This post demonstrates how to get a SQL query performance details like executions, disk/physical read/write, cpu time, elapsed time and waiting time, etc.

With the help of those statistics of a specific SQL query, DBA can easily identify the issue, and remediate it by applying SQL plan baselines.

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