On 2/27/15 2:49 PM, Alvaro Herrera wrote:
Tomas Vondra wrote:
1) change the order of columns in "SELECT *"
- display columns so that related ones grouped together
(irrespectedly whether they were added later, etc.)
FWIW, I find the ordering more important for things like \d than SELECT *.
Hey, after we get this done the next step is allowing different logical
ordering for different uses! ;P
- keep columns synced with COPY
- requires user interface (ALTER TABLE _ ALTER COLUMN _ SET ORDER _)
Not sure about the "ORDER #" syntax. In ALTER ENUM we have "AFTER
<value>" and such .. I'd consider that instead.
+1. See also Gavin's suggestion of ALTER COLUMN (a, b, c) SET ORDER ...
2) optimization of physical order (efficient storage / tuple deforming)
- more efficient order for storage (deforming)
- may be done manually by reordering columns in CREATE TABLE
- should be done automatically (no user interface required)
A large part of it can be done automatically: for instance, not-nullable
fixed length types ought to come first, because that enables the
I would think that eliminating wasted space due to alignment would be
more important than optimizing attcacheoff, at least for a database that
doesn't fit in memory. Even if it does fit in memory I suspect memory
bandwidth is more important than clock cycles.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
