ORA-00855 PGA_AGGREGATE_TARGET cannot be set because of insufficient physical memory
I have been investigated a case with ORA-00855 recently, and decided to share my findings about this error in this post.
Заметки¶
X$ tables: table-level callbacks and column definitions (without parsing)
Thus far, I have reviewed the kqftab structure which is used to build the majority of tables shown in X$KQFTA.
It is not clear yet where actual columns are coming from.
Let us find out in this post.
Virtual X$ tables
Some X$ tables are not coming from the kqftab structure.
Let us find out their origin.
X$ tables: reading X$KQFTA from Oracle binary
Explaining how to read the X$KQFTA structure listing X$ tables.
How to trace specific SQL statement executed by certain user
A question about the subject appeared on Oracle-L today here asking how to trace a known SQL statement executed by a certain user. This post is written to demonstrate my solution to this problem.
Mythbusters: VARRAY faster than CLOB
There has been a tweet recently saying that VARRAY is faster than CLOB.
I found that it is generally not the case, and conducted additional tests to support this statement in this post.
Using credentials with database links in 21c
Since 21c it is now possible to use credential objects in database links. This post demonstrates the new capability.
gridSetup.sh executeConfigTools fails with PRVG-13606 : chrony daemon is not synchronized with any external time source
Encountered an error related to clock synchronization checks ran during Grid Infrastructure configuration. This post demonstrates how the issue was analyzed and resolved.
Setting database session to read only in 21c
Oracle introduced a new parameter read_only in 21c which is not documented in Database Reference yet at the time of this writing.
It allows to enable read-only mode for a user session, preventing any writes.
This post demonstrates how it works.
ORA-7445 kpdbfSourceFileSearch with NFSv3 without noac option
Creating a pluggable database (PDB) by plugging an unplugged PDB in 19.12 can fail with the ORA-7445 kpdbfSourceFileSearch error.
Somehow there is no information about this error on MOS, so that I am sharing it in this post along with the solution that helped in my case.