Thread: can someone explain confusing array indexing nomenclature

can someone explain confusing array indexing nomenclature

From

chrisj

Date:

14 February 2007, 15:31:56

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)

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Re: can someone explain confusing array indexing nomenclature

From

Achilleas Mantzios

Date:

15 February 2007, 06:24:24

Στις Τετάρτη 14 Φεβρουάριος 2007 21:31, ο/η chrisj έγραψε:
> 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

Re: can someone explain confusing array indexing nomenclature

From

chrisj

Date:

15 February 2007, 12:56:10

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.

- chris


Achilleas Mantzios wrote:
>
> Στις Τετάρτη 14 Φεβρουάριος 2007 21:31, ο/η chrisj έγραψε:
>> 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
>
>

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Re: can someone explain confusing array indexing nomenclature

From

Achilleas Mantzios

Date:

16 February 2007, 10:31:06

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 Ξ¦Ξ΅Ξ²ΟΞΏΟΞ¬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

Re: can someone explain confusing array indexing nomenclature

From

chrisj

Date:

16 February 2007, 14:35:20

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:
>
> 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 Ξ¦Ξ΅Ξ²ΟΞΏΟΞ¬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
>
>

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Re: can someone explain confusing array indexing nomenclature

From

Achilleas Mantzios

Date:

20 February 2007, 03:42:28

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 Ξ¦Ξ΅Ξ²ΟΞΏΟΞ¬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

Re: can someone explain confusing array indexing nomenclature

From

Bruce Momjian

Date:

20 February 2007, 10:26:20

Yes, it is confusing.  I have an update to the array documentation that
should clarify it --- attached.

---------------------------------------------------------------------------

Achilleas Mantzios wrote:
> ???? ????????? 16 ??????????? 2007 20:35, ?/? chrisj ??????:
> > 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:
> > > ???? ?????? 15 ??????????? 2007 18:55, ?/? chrisj ??????:
> > >> 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:
> > >> > ???????? ?????????????? 14 ?????????????????????? 2007 21:31, ??/??
> > >>
> > >> chrisj
> > >
> > > ????????????:
> > >> >> 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

--
  Bruce Momjian  <bruce@momjian.us>          http://momjian.us
  EnterpriseDB                               http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +
Index: doc/src/sgml/array.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/array.sgml,v
retrieving revision 1.56
diff -c -c -r1.56 array.sgml
*** doc/src/sgml/array.sgml    1 Feb 2007 00:28:16 -0000    1.56
--- doc/src/sgml/array.sgml    20 Feb 2007 03:43:28 -0000
***************
*** 243,260 ****
  (1 row)
  </programlisting>

!   We could also have written:

  <programlisting>
- SELECT schedule[1:2][1] FROM sal_emp WHERE name = 'Bill';
- </programlisting>
-
-   with the same result.  An array subscripting operation is always taken to
-   represent an array slice if any of the subscripts are written in the form
-   <literal><replaceable>lower</replaceable>:<replaceable>upper</replaceable></literal>.
-   A lower bound of 1 is assumed for any subscript where only one value
-   is specified, as in this example:
- <programlisting>
  SELECT schedule[1:2][2] FROM sal_emp WHERE name = 'Bill';

                   schedule
--- 243,256 ----
  (1 row)
  </programlisting>

!   If any dimmension is written as a slice, i.e contains a colon, then all
!   dimmensions are treated as slices.  If a dimmension is missing, it is
!   assumed to be <literal>[1:1]</>.  If a dimmension has only a single
!   number (no colon), that dimmension is treated as being from <literal>1</>
!   to the number specified.  For example, <literal>[2]</> is treated as
!   <literal>[1:2], as in this example:

  <programlisting>
  SELECT schedule[1:2][2] FROM sal_emp WHERE name = 'Bill';

                   schedule

Re: can someone explain confusing array indexing nomenclature

From

chrisj

Date:

24 February 2007, 19:04:56

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 Ξ¦Ξ΅Ξ²ΟΞΏΟΞ¬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
>
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