PostgreSQL: size of a row

Source: Measure the size of a PostgreSQL table row

  SELECT l.what, l.nr AS "bytes/ct"
     , CASE WHEN is_size THEN pg_size_pretty(nr) END AS bytes_pretty
     , CASE WHEN is_size THEN nr / x.ct END          AS bytes_per_row
FROM  (
   SELECT min(tableoid)        AS tbl      -- same as 'public.tbl'::regclass::oid
        , count(*)             AS ct
        , sum(length(t::text)) AS txt_len  -- length in characters
   FROM   radius_db.radacct t  -- provide table name *once*
   ) x
 , LATERAL (
   VALUES
      (true , 'core_relation_size'               , pg_relation_size(tbl))
    , (true , 'visibility_map'                   , pg_relation_size(tbl, 'vm'))
    , (true , 'free_space_map'                   , pg_relation_size(tbl, 'fsm'))
    , (true , 'table_size_incl_toast'            , pg_table_size(tbl))
    , (true , 'indexes_size'                     , pg_indexes_size(tbl))
    , (true , 'total_size_incl_toast_and_indexes', pg_total_relation_size(tbl))
    , (true , 'live_rows_in_text_representation' , txt_len)
    , (false, '------------------------------'   , NULL)
    , (false, 'row_count'                        , ct)
    , (false, 'live_tuples'                      , pg_stat_get_live_tuples(tbl))
    , (false, 'dead_tuples'                      , pg_stat_get_dead_tuples(tbl))
   ) l(is_size, what, nr);
 

mod_perl: how to use environment variable

In httpd.conf:

PerlSetEnv PG_FLG 1

In mod_perl code:

sub is_pure_pg {
    return exists $ENV{PG_FLG};
}

PostgreSQL: rotate pgbouncer logs

Simplest method: switch to syslog

vi /etc/pgbouncer/pgbouncer.ini

; logfile = /var/log/pgbouncer.log
syslog = 1

psql -p6432 -Upostgres -d pgbouncer -c reload

PostgreSQL: split record returned by function into columns

Source: PostgreSQL function or stored procedure that outputs multiple columns?

SELECT a, (func(a)).* FROM table1;

Git: undo push

Source: How to undo (almost) anything with Git

git revert <SHA>

MacOS 10.12: auto mount network drive

Since 10.12, auto-mounting a network drive via Login Items asks to confirm the login and password each time we log in. Very unpleasant.
To get rid of that behavior:

1. Remove the network drive from the Login Items
2. Drag and drop the network drive to the dock

Then, network drive automatically mounted and no more password asked at each login!

[EDIT] The login / password dialog showing up whenever we log in has been fixed in 10.12.2 at last.

MacOS 10.12: screensaver stuck at: Loading photos

rm ~/Library/Preferences/com.apple.screensaver.plist

Git: list files changed in a branch

git checkout my_branch
git diff --name-only master...

Git: branching and merging for newbies

Git Branching - Basic Branching and Merging

Git: merge --no-ff

Source: What is the difference between `git merge` and `git merge --no-ff`?

Git: visualize

http://kentnguyen.com/development/visualized-git-practices-for-team/

PostgeSQL: pool sizing

About Pool Sizing

Git: use external diff command

git difftool --extcmd=diff sql/mbqt_prov_api.sql

PostgreSQL: remove all Bucardo triggers from a schema

do
$$
declare
    _row record;
    _query text;
begin
    for _row in SELECT tgname, tgrelid::regclass as table_name FROM pg_trigger where tgname ~ 'bucardo' and tgrelid::regclass::text ~ 'shared_db' loop
        _query := format('drop trigger %s on %s', _row.tgname, _row.table_name);
        raise notice '%', _query;
        execute _query;
    end loop;
end
$$;

Google Drive web hosting is shutting down

An alternative is to use Google Firebase.

Create new project on Firebase console :

Select Storage :

Import your files :

Edit your template in Blogger :

Copy the Firebase URL of the file you want to use in Blogger :

Replace your Google Drive URL :

Save your template and you will get an error about token :

To workaround the token issue, go to the Google URL shortener, and paste the Firebase URL :

Copy the short URL :

Replace the Firebase URL with the shortened one in Blogger :

[2021-09-05 Edit]
syntaxhighlighter has stopped working for some time now. The Web Dev Tools console in FF shows the following error:
The resource from “https://goo.gl/kQztrh” was blocked due to MIME type (“text/html”) mismatch (X-Content-Type-Options: nosniff).
So, it seems as if something changed either in the Google shortener behavior, or maybe in FF itself.
Let's try to re-use the original URLs instead of the shortened ones. As the Blogspot UI changed, you now need to go to "Themes", and click the "Customize" button.

Then select the "Edit HTML" menu item.

But using, e.g. "https://firebasestorage.googleapis.com/v0/b/syntaxhighlighter-2b128.appspot.com/o/scripts%2FshBrushPhp.js?alt=media&token=1533c104-e33b-43fa-b299-c2dd8c8f81ab" instead of "https://goo.gl/kQztrh" brings back the old error:

which is actually caused by the use of "&token=" instead of "&token=".
Once all the URLs have been substituted and the "&token=" occurences replaced, we're back in tracks :)

PostgreSQL: Find a table columns type

From http://dba.stackexchange.com/questions/75015/query-to-return-output-column-names-and-data-types-of-a-query-table-or-view:

SELECT attname, format_type(atttypid, atttypmod) AS type
FROM   pg_attribute
WHERE  attrelid = 'foo'::regclass
AND    attnum > 0
AND    NOT attisdropped
ORDER  BY attnum;

OSX: Installing Sierra over El Capitan

Information found here:

• Direct Update to macOS Sierra using Clover
• ​NVIDIA GeForce GTX 260 + Sierra 
• Sierra Desktop/Realtek AppleHDA Audio 

Install Sierra:

• Update Clover from Clover Configurator, then reboot

• Mount EFI partition like in OSX: use Clover Configurator 

• Copy kext to inject from 10.11

cp -R /Volumes/EFI/EFI/CLOVER/kexts/10.11/* /Volumes/EFI/EFI/CLOVER/kexts/Other

• Copy NVDAStartup.kext from El Capitan, to avoid a kernel panic on Sierra install

cp -R /Volumes/osx/System/Library/Extensions/NVDAStartup.kext /Volumes/EFI/EFI/CLOVER/kexts/Other

• Download Sierra from Mac App Store 

• Reboot and choose Boot macOS Install option. Before running the install, press spacebar and tick Without cache + Inject kexts. This will install and start Sierra. 

• When Sierra up, re-mount EFI partition 
• Remove Sierra NVDAStartup.kext

rm -R /Volumes/osx/System/Library/Extensions/NVDAStartup.kext

• Copy NVDAStartup.kext from EFI partition to Desktop 

• Install NVDAStartup.kext with KextBeast 

• Reboot

Then install audio drivers:

• Re-mount EFI partition
• Run audio_cloverALC command to install Toleda AppleHDA 
• Reboot, et voila

Emacs: disable auto-indent of new lines

This is a new feature from Emacs 24.4.
To revert to the old behavior, you need to disable electric-indent-mode.

(when (fboundp 'electric-indent-mode) (electric-indent-mode -1))

See http://emacs.stackexchange.com/questions/5939/how-to-disable-auto-indentation-of-new-lines

CentOS 6 / wkhtmltopdf: extra spaces added in strings when generating PDF from HTML

The tip on this page solved it for me:

sudo wget http://pastebin.com/raw.php?i=AmfYN3er -O /etc/fonts/conf.d/10-wkhtmltopdf.conf

grep extract

Suppose you want 150 lines after the line containing "2016-05-31 11:06:39.265" from file postgresql-31.csv:

grep -A150 '2016-05-31 11:06:39.265' postgresql-31.csv > /tmp/postgresql-31.csv.extract