From: chrisj <chrisj.wood@sympatico.ca>
To: pgsql-sql@postgresql.org
Subject: Re: can someone explain confusing array indexing nomenclature
Date: Sat, 24 Feb 2007 15:04:51 -0800 (PST)
Message-ID: <9138745.post@talk.nabble.com> (raw)
In-Reply-To: <200702200942.18500.achill@matrix.gatewaynet.com>
References: <8971770.post@talk.nabble.com>
<200702151224.12455.achill@matrix.gatewaynet.com>
<8989242.post@talk.nabble.com>
<200702161034.43399.achill@matrix.gatewaynet.com>
<9009934.post@talk.nabble.com>
<200702200942.18500.achill@matrix.gatewaynet.com>
I guess you could say the [2] is discarded since the value "2" is at the top
or beyond the top of the range.
Achilleas Mantzios wrote:
>
> Στις Παρασκευή 16 Φεβρουάριος 2007 20:35, ο/η chrisj έγραψε:
>> I am quite sure the [2] is not discarded, easy enough to test but I don't
>> have access to PG at the moment.
>
> Well it should, since
>
> dynacom=# SELECT
> (CAST( '{{meeting,lunch},{training,presentation}}' as text[][]))[1:1];
> text
> -------------------
> {{meeting,lunch}}
> (1 row)
>
> dynacom=# SELECT
> (CAST( '{{meeting,lunch},{training,presentation}}' as text[][]))[1:1][1];
> text
> -------------
> {{meeting}}
> (1 row)
>
> dynacom=# SELECT
> (CAST( '{{meeting,lunch},{training,presentation}}' as text[][]))[1:1][2];
> text
> -------------------
> {{meeting,lunch}}
> (1 row)
>
> dynacom=# SELECT
> (CAST( '{{meeting,lunch},{training,presentation}}' as text[][]))[1:1][3];
> text
> -------------------
> {{meeting,lunch}}
> (1 row)
>
> dynacom=# SELECT
> (CAST( '{{meeting,lunch},{training,presentation}}' as
> text[][]))[1:1][1000];
> text
> -------------------
> {{meeting,lunch}}
> (1 row)
>
> dynacom=#
>
>>
>> Achilleas Mantzios wrote:
>> > Στις Πέμπτη 15 Φεβρουάριος 2007 18:55, ο/η chrisj έγραψε:
>> >> 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.
>> >
>> > Now that i think about it again, i speculate that the [2] is discarded.
>> >
>> >> - chris
>> >>
>> >> Achilleas Mantzios wrote:
>> >> > Ξ£ΟΞΉΟ Ξ�Ξ΅ΟΞ¬ΟΟΞ· 14 ΦΡβΟΞΏΟ Ξ¬ΟΞΉΞΏΟ 2007 21:31, ΞΏ/Ξ·
>> >>
>> >> chrisj
>> >
>> > ΞΞ³ΟΞ±ΟΞ΅:
>> >> >> given the following table:
>> >> >>
>> >> >> protocal2=> 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=> SELECT schedule[1][2] FROM sal_emp WHERE name = 'Bill';
>> >> >> schedule
>> >> >> ----------
>> >> >> lunch
>> >> >> (1 row)
>> >> >>
>> >> >> protocal2=> SELECT schedule[1:1][2] FROM sal_emp WHERE name =
>> 'Bill';
>> >> >> 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 = '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
>> >
>> > --
>> > Achilleas Mantzios
>> >
>> > ---------------------------(end of
>> broadcast)---------------------------
>> > TIP 3: Have you checked our extensive FAQ?
>> >
>> > http://www.postgresql.org/docs/faq
>
> --
> Achilleas Mantzios
>
> ---------------------------(end of broadcast)---------------------------
> TIP 7: You can help support the PostgreSQL project by donating at
>
> http://www.postgresql.org/about/donate
>
>
--
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To: pgsql-sql@postgresql.org
Cc: chrisj.wood@sympatico.ca
Subject: Re: can someone explain confusing array indexing nomenclature
In-Reply-To: <9138745.post@talk.nabble.com>
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