Month: August 2010

Tips N’ Tricks – using GNU Screen as shell

I'm quite often doing stuff on remote machines, and quite frequently I start some long-running job, when I remember that I didn't ran it via screen – so it will break, if my network connection will die.

Is there any sane way to start screen automatically? YES.

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Waiting for 9.1 – concat, concat_ws, right, left, reverse

On 24th of August, Takahiro Itagaki committed patch:

Log Message:
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Add string functions: concat(), concat_ws(), left(), right(), and reverse().
 
Pavel Stehule, reviewed by me.

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How to manage changes to your database?

Every now and then somebody asks how to make diff of database schemata.

Usual background is like: we have production database, and development database, and we want to see what is different on development to be able to change production in the same way.

Personally I think that such approach is inherently flawed. Why?

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Waiting for 9.1 – Recognize functional dependency on primary keys.

Yesterday (August, 7th), Tom Lane committed:

Log Message:
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Recognize functional dependency on primary keys.  This allows a table's
other columns to be referenced without listing them in GROUP BY, so long as
the primary key column(s) are listed in GROUP BY.
 
Eventually we should also allow functional dependency on a UNIQUE constraint
when the columns are marked NOT NULL, but that has to wait until NOT NULL
constraints are represented in pg_constraint, because we need to have
pg_constraint OIDs for all the conditions needed to ensure functional
dependency.
 
Peter Eisentraut, reviewed by Alex Hunsaker and Tom Lane

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Waiting for 9.1 – Reduced lock levels for ALTER TABLE

On 28th of July, Simon Riggs committed patch which:

Log Message:
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Reduce LOCK levels OF CREATE TRIGGER AND SOME ALTER TABLE, CREATE RULE actions.
Avoid hard-coding lockmode used FOR many altering DDL commands, allowing easier
future changes OF LOCK levels. Implementation OF initial analysis ON DDL
sub-commands, so that many LOCK levels are now at ShareUpdateExclusiveLock OR
ShareRowExclusiveLock, allowing certain DDL NOT TO block reads/writes.
FIRST OF NUMBER OF planned changes IN this area; additional docs required
WHEN FULL project complete.

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