Hello, I hate to re-ask this again (sorry to be repetitive!)... I really could use some help with this, if anyone is familiar with table inheritance as it applies to my questions....
Thanks! - Greg >Hello, > >I am playing with the "INHERITS" functionality of create table to >determine its suitability to my needs and I've hit a roadblock (hopefully >minor)... > >If I have two tables like this: > >CREATE TABLE tablea ( > id SERIAL >); > >CREATE TABLE tableb () INHERITS (tablea); > >#1. Now first of all, I notice that if I insert something into tableb, it >appears in tablea and if I insert something in tablea, it does not appear >in tableb... Is this correct and will the use of the "SERIAL" type >cause any confusion or can I insert rows in each table without being >concerned about any internal ramifications of this? > >#2. If I do "explain select id from tablea where id=4", I get something >like this: > > QUERY PLAN >------------------------------------------------------- > Seq Scan on jobdata (cost=0.00..1.04 rows=1 width=4) > Filter: (id = 4) > > >...If, however, I do "explain select id from tableb where id=4": > >------------------------------------- >------------------------------------------------ > Result (cost=0.00..2.08 rows=2 width=4) > -> Append (cost=0.00..2.08 rows=2 width=4) > -> Seq Scan on jobdata_revisions (cost=0.00..1.04 rows=1 width=4) > Filter: (id = 4) > -> Seq Scan on jobdata jobdata_revisions (cost=0.00..1.04 >rows=1 width=4) > Filter: (id = 4) > > >I'm a bit mystified by the results of tableb, I don't understand what the >"Append" and the second "Seq Scan" is for... More importantly, I'm not >sure how to optimize this properly... > >Any ideas what I can do here?... > >Thanks! > >- Greg > ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
