A question on forums.oracle.com asked: can we recover a database further in time then the time of backup of the last controlfile. Nice question…my gut feeling immediately says : YES we can. But…I do not have a proof of it, and one quick search on the internet did not supply a adequate answer. So…then I […]
Continue ReadingDistribution of values in a column
Distribution of data For calculating the right execution-plan Oracle often needs the distribution of values for a column. For an outlier value a index can easily be used. For a value that is present in half the rows a index might be less effective. For a similar exercise I needed the distribution of values myself. […]
Continue ReadingCreating an ACL
A very simple example of creating an ACL for a principal and a host: Creating the ACLS (qith the associated principal) itself. exec dbms_network_acl_admin.create_acl( acl=>’print_permissions.xml’, description=>’Gebruikt voor Print functionaliteit’, principal=>’APEX_230100′, is_grant=>TRUE, privilege=>’connect’); Associating a host to the ACL: exec dbms_network_acl_admin.assign_acl( acl=>’print_permissions.xml’, host=>’machine-name.domain.domain’, lower_port=>8010, upper_port=>8010); This is a starting point. You can go from here … […]
Continue ReadingAssembly and opcodes
Intro When a program is compiled (and linked) it will no longer contains readable lines of code. Instead it will consist of opcodes (operation codes). I would like to see whether I can find out what dome opcodes mean. You might say “just look at the intel or AMD manual and there you go”…but where […]
Continue ReadingOEM : No Data
This is reaaly memory for myself 🙂 We often encounter sql performance screens where OEM says “Unable to Retrieve Data” What we do : create a job (in OEM) that deploys Database Management PL/SQL packages In OEM main Menu Click Enterprise –> Job –> Library –> Select Job Type “Deploy Database Management PL/SQL Packages” –> […]
Continue ReadingOracle system statistics
Oracle System Statistics When I look at the system statistics I’m not really getting any wiser. There a re really a lot of statistics: SQL> select count(*) from v$sysstat; COUNT(*) ———- 2252 SQL> Above from a Oracle 21c instance. I do not want to see them all. I would like to see the change in […]
Continue Readingsar usage
I like to use the linux utility sar (system activity reporter (?)) I gives a fast and quite complete overview over the performance of a linux system. SAR has a lot of possibilitys. I just highlight a few of them to remember how the syntax is 🙂 CPU information of today oracle@lqas4342:~$sar Linux 4.18.0-425.13.1.el8_7.x86_64 (lqas4342.mod.nl) […]
Continue ReadingORAENV_ASK
Just a reminder I keep forgetting what the environment variable is called: ORA_ASKENV ORA_ENVASK ORAASK_ENV ORAENV_ASK This is _the_ variable: ORAENV_ASK=NO ORAENV_ASK=YES Happy scripting
Continue Readingtcpdump
Just a write up of the filters I sometimes use/need. (work in progress…) Filtering _out_ ssh: tcpdump “port ! ssh” Just seeing ICMP packets: tcpdump “icmp” Filtering on port _and_ host: tcpdump “port ssh && host host-name”
Continue Readingansible reboot after updating packages
When installing security/kernel packages the system must be rebooted. It would be a bit silly to reboot always. So..without further ado…you can solve this for example with the following playbook: [martijn@fedora basis]$ cat update_all.yaml — – name: Update alle hosts hosts: all become: true tasks: – name: install dnf tools dnf: state: present name: dnf-utils […]
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