Using perf to analyze any(almost) internal gpdb functions

On my previous post I have shown how to investigate particular function execution, actually I've just borrowed a ready to use piece of code here: Profiling with perf In this post you will see how to go much deeper Let's consider this fuction ExecInitSeqScan as an example You can see this function exported in ../gpdb/src/include/executor/nodeSeqscan.h …

Capture all GPDB SQLs by means of perf utility

I decided to play around a bit with perf utility for debugging greenplum internals First of all you need to install perf itself as sudo yum install perf Then to use some comprehensive features I need to recompile GPDP with debug enabled (I'll try to strip debuginfo as a separate file on one of following …

Greenplum installation on CentOS 7 from source code

Recently I decided to install a popular MPP database Greenplum from"scratch" on some cloud env (http://cloud.yandex.ru). Compiler First of all you would need a "modern" C-compiler and tools, so: sudo yum install centos-release-scl sudo yum install devtoolset-9-gcc* SCL stands for "software collection". You can initialize the collection of your choice as following: scl enable devtoolset-9 …

Ideal CPU eater with connect by

It is a common knowledge that huge "connect by" can lead to some kind of out of memory exception. However there is some variant of similar issue that consumes almost zero PGA/TEMP please see below: select distinct id from (select id from (select 1 id from dual union all select 2 from dual union all …

Function call arguments representation , in CPU registries

$rdi - 1st argument $rsi - 2nd argument $rdx - 3nd argument $rcx - 4th argument $rax - return value

Oracle FGA internals (Part 4).Complex (column) expression.

On a previous post we considered a case of FGA set for some quite simple condition. Let's set up a new scene for further experimentation/ideation. Clean up old policies and set a new one (that includes condition on the table column/s) begin dbms_fga.drop_policy(object_schema =>'FGA_OWNER' , object_name => 'TBL_FGA', policy_name =>'TBL_FGA' ); end; / begin dbms_fga.add_policy(object_schema …

Oracle FGA internals (Part 3). More complex but still simple condition.

On my previous post we stopped at comparison of noaudit case with a very basic FGA audit setting (actually kind of "No OPeration"). Today I am going to consider slightly more complex case. Let's clean up our audit 1st begin dbms_fga.drop_policy(object_schema =>'FGA_OWNER' , object_name => 'TBL_FGA', policy_name =>'TBL_FGA' ); end; / and set up a …

Oracle FGA internals (Part 2). Simple audit condition.

On my previous post we have set the scene up and raised a couple of questions. Let's start with our new agenda, I have connected to my Oracle session via GDB (debugger). Like gdb -p 12345 and set up a few break points (inside Oracle's codebase) b opifch b selexe0 b expeal Where opifch - …

Oracle FGA internals (Part 1)

Oracle FGA stands for Fine Grained Audit, see for instance here: Official docs or here: Tim Hall's oracle-base site The main question (or concern) for my use case was how switching on FGA on some object/objects may affect executions of queries from an application itselfs that should not be audited. Let's start setting up the …

Terminator to Vagrant box connection

I have the following config piece in my Vagrant file: config.ssh.host = '192.168.1.201' config.vm.network "forwarded_port", id: "ssh", host_ip: "192.168.1.201", guest: 22, host: 25 config.ssh.host port to be used by internal Vagrant ssh config.vm.network "forwarded_port" - VM's port forwarding settings. to connect to this Vagrant box from popular Terminator ssh client I need to point out …