[Logitech MX Vertical] starts to creep its cursor

Symptom

Even if you do not touch the mouse, its cursor creeps over the screen.

Solution

Switch it off and on again possibly waiting a couple of seconds inbetween.

[DB2 LUW] Single multiple key records

Goal

Say you have a table without primary key imposed but there are records sporting the same value over a select number of attributes and want to only one record of those to remain within the table, you cannot use a function like ROWID in Oracle because DB2 LUW does not expose such a function/(pseudo) column (see how-to-delete-multiple-records-of-key)

Solution

Use sort of subquery, i.e.

delete from (select rownumber() over (partition by <list of attributes over which uniqueness is supposed to be>) as RN
               from <table>) as T
      where T.RN > 1;

Example

delete from (select rownumber() over (partition by TABLE_NAME,
                                                   ROW_SCAN_NUMBER,
                                                   DWH_REG_TIME) as RN
               from ADW_ETL.ETL_OGG_ROW_SCAN) as T
      where T.RN > 1;

[Db2 LUW] When is a table reorg needed?

Some operations on a table of a Db2 instance let the table in an unusable state. I shall try to list the operations. Please be aware the list is probably not complete!

Require reorg

• drop at least one column
• increase the size of a decimal column

Do not require reorg

• add columns (at least 5 are possible, did not test more)
• increase the size of a varchar column

[Db2 LUW] buggy (left) outer join?!?

Problem

Following queries lose against DB2 v11.1.1.1 fixpack number 1(Linux) lose the left row without match on the right side.

with G as
    (select   *
        from ADW_ETL.ETL_GDT_UNIQUE_KEY
        where TABLE_NAME in('BAP_KOMMUNIKATION',
                            'BAP_GESCHAEFTSVORFALL',
                            'BAP_GFSCHRITT',
                            'BAP_GFSCHRITTADD',
                            'BAP_AUFTRAG',
                            'BAP_AUFTRAGPRODUKT')
    )
  select   G.TABLE_NAME,
      C.FLAG_ACTIVE,
      G.STORE_FLAG,
      G.OGG_PACKER_FREQUENCY,
      C.DWH_TIME_DELAY,
      I.*
    from G
    left outer join ADW_STATMON.DWH_ODS_CTRL C
    on G.TABLE_NAME = C.DWH_ODSCTRL_GDT_NAME
    left outer join ADW_STATMON.DWH_INBOUND_REG I
    on I.DWH_TRG_TABLE_NAME = G.TABLE_NAME
    where nvl(I.DWH_REG_TS, current_timestamp) >= current_timestamp - 9
;

with G as
    (select   *
        from ADW_ETL.ETL_GDT_UNIQUE_KEY
        where TABLE_NAME in('BAP_KOMMUNIKATION',
                            'BAP_GESCHAEFTSVORFALL',
                            'BAP_GFSCHRITT',
                            'BAP_GFSCHRITTADD',
                            'BAP_AUFTRAG',
                            'BAP_AUFTRAGPRODUKT')
    )
  select   G.TABLE_NAME,
      C.FLAG_ACTIVE,
      G.STORE_FLAG,
      G.OGG_PACKER_FREQUENCY,
      C.DWH_TIME_DELAY,
      I.*
    from G
    left outer join ADW_STATMON.DWH_ODS_CTRL C
    on G.TABLE_NAME = C.DWH_ODSCTRL_GDT_NAME
    left outer join ADW_STATMON.DWH_INBOUND_REG I
    on I.DWH_TRG_TABLE_NAME = G.TABLE_NAME
    where I.DWH_REG_TS                         >= current_timestamp - 9
       or I.DWH_REG_TS                         is null
;

I am pretty sure it is not iso standard behavior, and to me counterintuitive for sure.

Solution

Either pack the filtering into with constructs or move the filter on the outer table (the one not necessarily retaining its records) into the on clause. Example for the latter:

with G as
    (select   *
        from ADW_ETL.ETL_GDT_UNIQUE_KEY
        where TABLE_NAME in('BAP_KOMMUNIKATION',
                            'BAP_GESCHAEFTSVORFALL',
                            'BAP_GFSCHRITT',
                            'BAP_GFSCHRITTADD',
                            'BAP_AUFTRAG',
                            'BAP_AUFTRAGPRODUKT')
    )
  select   G.TABLE_NAME,
      C.FLAG_ACTIVE,
      G.STORE_FLAG,
      G.OGG_PACKER_FREQUENCY,
      C.DWH_TIME_DELAY,
      I.*
    from G
    left outer join ADW_STATMON.DWH_ODS_CTRL C
    on G.TABLE_NAME = C.DWH_ODSCTRL_GDT_NAME
    left outer join ADW_STATMON.DWH_INBOUND_REG I
    on I.DWH_TRG_TABLE_NAME = G.TABLE_NAME
    and I.DWH_REG_TS >= current_timestamp - 9
;

[git] Get the unpushed commits of a local repository and their commit timestamp using zsh

Run within the local repository

_LOG="$(git log)"
for _COMMIT in "${(@f)$(git cherry -v)}"
# '${(@f)VARIABLE}' splits VARIABLE (can be command substitution) at linebreaks (otherwise it would get split into words)
do
    _DATE_STRING=$(echo "${_LOG}" | grep -A2 ${_COMMIT[(w)2]} | grep -F Date)
    # (w) spilts into words, [..2] takes the second element
    echo "${_DATE_STRING}  ${_COMMIT}"
done

or as oneliner

_LOG="$(git log)" ; for _COMMIT in "${(@f)$(git cherry -v)}" ; do _DATE_STRING=$(echo "${_LOG}" | grep -A2 ${_COMMIT[(w)2]} | grep -F Date) ; echo "${_DATE_STRING}  ${_COMMIT}" ; done

[Db2 LUW] Source for arbitrary record

I sometimes are in need for a source of an arbitrary record, e. g. to test some function. In Oracle you can use DUAL. In Db2 LUW (to make it clear what DB I am referring to, I know LUW is officially not used anymore by IBM) there is a compatibility vector thing which provides DUAL as well. But it is not installed, switched on, activated or whatever one has to do to make it usable, one can use SYSIBM.SYSDUMMY1.

[screen] Howto scroll back

screen

is a terminal multiplexer pretty useful when you want to have several terminals over one single remote connection and also if you want disconnects not effect your sessions.

However, when in screen you cannot just scroll back. Longtime I just thought it would not be possible but it is. You need to enter scrollback/copy mode by [ctrl]-[a] [esc].