Message-ID: <9009934.post@talk.nabble.com>
Date: Fri, 16 Feb 2007 10:35:13 -0800 (PST)
From: chrisj <chrisj.wood@sympatico.ca>
To: pgsql-sql@postgresql.org
Subject: Re: can someone explain confusing array indexing nomenclature
In-Reply-To: <200702161034.43399.achill@matrix.gatewaynet.com>
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References: <8971770.post@talk.nabble.com>
	<200702151224.12455.achill@matrix.gatewaynet.com>
	<8989242.post@talk.nabble.com>
	<200702161034.43399.achill@matrix.gatewaynet.com>


I am quite sure the [2] is not discarded, easy enough to test but I don't
have access to PG at the moment.


Achilleas Mantzios wrote:
>=20
> =CE=A3=CF=84=CE=B9=CF=82 =CE=A0=CE=AD=CE=BC=CF=80=CF=84=CE=B7 15 =CE=A6=
=CE=B5=CE=B2=CF=81=CE=BF=CF=85=CE=AC=CF=81=CE=B9=CE=BF=CF=82 2007 18:55, =
=CE=BF/=CE=B7 chrisj =CE=AD=CE=B3=CF=81=CE=B1=CF=88=CE=B5:
>> Thanks Achilleas,
>>
>> I see what you are saying, but if we consider just the index "[2]" for a
>> moment,
>> it means something different depending upon the context  (in one case it
>> means "2" and in the other case it means "1:2") and the context is
>> determined by the format of indexes on other dimensions.
>>
>> I believe I understand....but incredibly confusing.
>>
>=20
> Now that i think about it again, i speculate that the [2] is discarded.
>=20
>> - chris
>>
>> Achilleas Mantzios wrote:
>> > =CE=9E=C2=A3=CE=9F=C2=84=CE=9E=CE=89=CE=9F=C2=82 =CE=9E=EF=BF=BD=CE=9E=
=CE=85=CE=9F=C2=84=CE=9E=C2=AC=CE=9F=C2=81=CE=9F=C2=84=CE=9E=C2=B7 14 =CE=
=9E=C2=A6=CE=9E=CE=85=CE=9E=C2=B2=CE=9F=C2=81=CE=9E=CE=8F=CE=9F=C2=85=CE=9E=
=C2=AC=CE=9F=C2=81=CE=9E=CE=89=CE=9E=CE=8F=CE=9F=C2=82 2007 21:31, =CE=9E=
=CE=8F/=CE=9E=C2=B7
>> chrisj=20
> =CE=9E=C2=AD=CE=9E=C2=B3=CE=9F=C2=81=CE=9E=C2=B1=CE=9F=C2=88=CE=9E=CE=85:
>> >> given the following table:
>> >>
>> >> protocal2=3D> select * from sal_emp ;
>> >>  name  |      pay_by_quarter       |                 schedule
>> >>
>> -------+---------------------------+------------------------------------
>> >>--- ---- Bill  | {10000,10000,10000,10000} |
>> >> {{meeting,lunch},{training,presentation}}
>> >>  Carol | {20000,25000,25000,25000} |
>> >> {{breakfast,consulting},{meeting,lunch}}
>> >> (2 rows)
>> >>
>> >> why do the following two queries yield different results??
>> >>
>> >> protocal2=3D> SELECT schedule[1][2] FROM sal_emp WHERE name =3D 'Bill=
';
>> >>  schedule
>> >> ----------
>> >>  lunch
>> >> (1 row)
>> >>
>> >> protocal2=3D> SELECT schedule[1:1][2] FROM sal_emp WHERE name =3D 'Bi=
ll';
>> >>      schedule
>> >> -------------------
>> >>  {{meeting,lunch}}
>> >> (1 row)
>> >
>> > The [n:m] notation denotes a slice of the array (not element).
>> > So schedule[1][2] is the Array element on 2nd col of 1st row,
>> > while schedule[1:1][2] could mean
>> > the second row of the subarray schedule[1:1][1:2].
>> > So these two are foundamentally different things.
>> > In my 7.4 even if you gave
>> > SELECT schedule[1:1][888] FROM sal_emp WHERE name =3D 'Bill';
>> > you would still get  {{meeting,lunch}} as a result.
>> > (Right or wrong is another story).
>> > Anyway the first time you query for a "text",
>> > the second time you query for a "text[]", so you should expect
>> > different results.
>> > --
>> > Achilleas Mantzios
>> >
>> > ---------------------------(end of
>> broadcast)---------------------------
>> > TIP 3: Have you checked our extensive FAQ?
>> >
>> >                http://www.postgresql.org/docs/faq
>=20
> --=20
> Achilleas Mantzios
>=20
> ---------------------------(end of broadcast)---------------------------
> TIP 3: Have you checked our extensive FAQ?
>=20
>                http://www.postgresql.org/docs/faq
>=20
>=20

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