[Monetdb-developers] what should happen when appending to a nil bat?
Consider this scenario: mil>var a := new(oid,void).insert(0@0,nil); mil>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] mil>var b := new(oid,oid).insert(0@0,1@0); mil>b.print(); #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, 1@0 ] mil>a.append(b); mil>a.print();
The question is, what should the result be?
As I see it, there are two possibilities: #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] [ 1@0, nil ] or #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, nil ] [ 1@0, 1@0 ]
The former keeps the nil tail (the tail of a was void without seqbase and stays that way), whereas the latter materializes the tail so that the tail value of b gets inserted.
Opinions?
To me, the second possibility seems better, since the tail value of 'b' is preserved.
But how about a third possibility: reject such 'append' and require a explicit type casting?
Regards,
Jennie
On Wed, Dec 21, 2005 at 01:08:26PM +0100, Sjoerd Mullender wrote:
Consider this scenario: mil>var a := new(oid,void).insert(0@0,nil); mil>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] mil>var b := new(oid,oid).insert(0@0,1@0); mil>b.print(); #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, 1@0 ] mil>a.append(b); mil>a.print();
The question is, what should the result be?
As I see it, there are two possibilities: #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] [ 1@0, nil ] or #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, nil ] [ 1@0, 1@0 ]
The former keeps the nil tail (the tail of a was void without seqbase and stays that way), whereas the latter materializes the tail so that the tail value of b gets inserted.
Opinions?
-- Sjoerd Mullender
I also vote for the second alternative.
If/where desired the first result can then achieved by
a.append(b.mark(nil));
Stefan
On Wed, Dec 21, 2005 at 01:26:08PM +0100, Ying Zhang wrote:
To me, the second possibility seems better, since the tail value of 'b' is preserved.
But how about a third possibility: reject such 'append' and require a explicit type casting?
Regards,
Jennie
On Wed, Dec 21, 2005 at 01:08:26PM +0100, Sjoerd Mullender wrote:
Consider this scenario: mil>var a := new(oid,void).insert(0@0,nil); mil>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] mil>var b := new(oid,oid).insert(0@0,1@0); mil>b.print(); #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, 1@0 ] mil>a.append(b); mil>a.print();
The question is, what should the result be?
As I see it, there are two possibilities: #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] [ 1@0, nil ] or #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, nil ] [ 1@0, 1@0 ]
The former keeps the nil tail (the tail of a was void without seqbase and stays that way), whereas the latter materializes the tail so that the tail value of b gets inserted.
Opinions?
-- Sjoerd Mullender
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In the current example the head is oid. The same question however arises with void|void bats. Both cases should be treated equally.
I therefore also vote for the second alternative as the sequence construction in XQuery e.g. uses append/insert and expects the behaviour of the second version. Otherwise values will get lost as their reference (1@0) is replaced by nil values.
Jan
PS: Is their a difference between append and insert in this scenario?
I also vote for the second alternative.
If/where desired the first result can then achieved by
a.append(b.mark(nil));
Stefan
On Wed, Dec 21, 2005 at 01:26:08PM +0100, Ying Zhang wrote:
To me, the second possibility seems better, since the tail value of 'b' is preserved.
But how about a third possibility: reject such 'append' and require a explicit type casting?
Regards,
Jennie
On Wed, Dec 21, 2005 at 01:08:26PM +0100, Sjoerd Mullender wrote:
Consider this scenario: mil>var a := new(oid,void).insert(0@0,nil); mil>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] mil>var b := new(oid,oid).insert(0@0,1@0); mil>b.print(); #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, 1@0 ] mil>a.append(b); mil>a.print();
The question is, what should the result be?
As I see it, there are two possibilities: #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] [ 1@0, nil ] or #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, nil ] [ 1@0, 1@0 ]
The former keeps the nil tail (the tail of a was void without seqbase and stays that way), whereas the latter materializes the tail so that the tail value of b gets inserted.
Opinions?
-- Sjoerd Mullender
This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click _______________________________________________ Monetdb-developers mailing list Monetdb-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/monetdb-developers
Jan Rittinger wrote:
In the current example the head is oid. The same question however arises with void|void bats. Both cases should be treated equally.
I therefore also vote for the second alternative as the sequence construction in XQuery e.g. uses append/insert and expects the behaviour of the second version. Otherwise values will get lost as their reference (1@0) is replaced by nil values.
Jan
PS: Is their a difference between append and insert in this scenario?
Most cases of append are implemented internally using the equivalent of insert. Hence my earlier reply which crossed yours.
I got to this because a problem I'm facing in my XML Update code. The problem I have is described in bug #1385067: "bug appending to [void,void] bat".
I also vote for the second alternative.
If/where desired the first result can then achieved by a.append(b.mark(nil));
Stefan
On Wed, Dec 21, 2005 at 01:26:08PM +0100, Ying Zhang wrote:
To me, the second possibility seems better, since the tail value of 'b' is preserved.
But how about a third possibility: reject such 'append' and require a explicit type casting?
Regards,
Jennie
On Wed, Dec 21, 2005 at 01:08:26PM +0100, Sjoerd Mullender wrote:
Consider this scenario: mil>var a := new(oid,void).insert(0@0,nil); mil>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] mil>var b := new(oid,oid).insert(0@0,1@0); mil>b.print(); #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, 1@0 ] mil>a.append(b); mil>a.print();
The question is, what should the result be?
As I see it, there are two possibilities: #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] [ 1@0, nil ] or #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, nil ] [ 1@0, 1@0 ]
The former keeps the nil tail (the tail of a was void without seqbase and stays that way), whereas the latter materializes the tail so that the tail value of b gets inserted.
Opinions?
-- Sjoerd Mullender
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Note that this solution also means that when you insert a non-nil value into a nil column, the column should get materialized as well (this is currently not the case):
mil>var a := new(oid,void).insert(0@0,nil); mil>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] mil>a.insert(1@0,1@0); mil>a.print(); #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, nil ] [ 1@0, 1@0 ]
Stefan Manegold wrote:
I also vote for the second alternative.
If/where desired the first result can then achieved by
a.append(b.mark(nil));
Stefan
On Wed, Dec 21, 2005 at 01:26:08PM +0100, Ying Zhang wrote:
To me, the second possibility seems better, since the tail value of 'b' is preserved.
But how about a third possibility: reject such 'append' and require a explicit type casting?
Regards,
Jennie
On Wed, Dec 21, 2005 at 01:08:26PM +0100, Sjoerd Mullender wrote:
Consider this scenario: mil>var a := new(oid,void).insert(0@0,nil); mil>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] mil>var b := new(oid,oid).insert(0@0,1@0); mil>b.print(); #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, 1@0 ] mil>a.append(b); mil>a.print();
The question is, what should the result be?
As I see it, there are two possibilities: #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] [ 1@0, nil ] or #-----------------# # h t # name # oid oid # type #-----------------# [ 0@0, nil ] [ 1@0, 1@0 ]
The former keeps the nil tail (the tail of a was void without seqbase and stays that way), whereas the latter materializes the tail so that the tail value of b gets inserted.
Opinions?
-- Sjoerd Mullender
This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click _______________________________________________ Monetdb-developers mailing list Monetdb-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/monetdb-developers
Note that the void type has more hidden semantics that are not yet mentioned in behaviours 1 and 2...
Some people use/have used insert(nil) meaning to say insert(lastoid++) - For example:
MonetDB>var a := new(oid,void); MonetDB>a.insert(oid(0),nil); MonetDB>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] MonetDB>a.reverse().seqbase(oid(0)); MonetDB>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, 0@0 ] MonetDB>a.insert(oid(1),nil); MonetDB>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, 0@0 ] [ 1@0, 1@0 ]
Note that this latter result is inconsistent with the decision for option 2!! (while it is consistent with that of option 1 - seqbase is nil!)
| Note that this solution also means that when you insert a non-nil value | into a nil column, the column should get materialized as well (this is | currently not the case):
BTW, in principle nil-values could be represented in other ways to avoid materialisation - e.g., a bit-vector, or a list of all nil-values; this may be interesting alternatives when columns contain only a small number of nil values (though affecting all current operators of course).
Arjen
| | mil>var a := new(oid,void).insert(0@0,nil); | mil>a.print(); | #-----------------# | # h t # name | # oid void # type | #-----------------# | [ 0@0, nil ] | mil>a.insert(1@0,1@0); | mil>a.print(); | #-----------------# | # h t # name | # oid oid # type | #-----------------# | [ 0@0, nil ] | [ 1@0, 1@0 ]
On Wed, Dec 21, 2005 at 09:31:43PM +0100, Arjen P. de Vries wrote:
Note that the void type has more hidden semantics that are not yet mentioned in behaviours 1 and 2...
Some people use/have used insert(nil) meaning to say insert(lastoid++) - For example:
MonetDB>var a := new(oid,void); MonetDB>a.insert(oid(0),nil); MonetDB>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, nil ] MonetDB>a.reverse().seqbase(oid(0)); MonetDB>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, 0@0 ] MonetDB>a.insert(oid(1),nil); MonetDB>a.print(); #-----------------# # h t # name # oid void # type #-----------------# [ 0@0, 0@0 ] [ 1@0, 1@0 ]
Note that this latter result is inconsistent with the decision for option 2!! (while it is consistent with that of option 1 - seqbase is nil!)
| Note that this solution also means that when you insert a non-nil value | into a nil column, the column should get materialized as well (this is | currently not the case):
BTW, in principle nil-values could be represented in other ways to avoid materialisation - e.g., a bit-vector, or a list of all nil-values; this may be interesting alternatives when columns contain only a small number of nil values (though affecting all current operators of course).
but the way we will go with X100 ;-)
Arjen
| | mil>var a := new(oid,void).insert(0@0,nil); | mil>a.print(); | #-----------------# | # h t # name | # oid void # type | #-----------------# | [ 0@0, nil ] | mil>a.insert(1@0,1@0); | mil>a.print(); | #-----------------# | # h t # name | # oid oid # type | #-----------------# | [ 0@0, nil ] | [ 1@0, 1@0 ]
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participants (6)
-
Arjen P. de Vries -
Jan Rittinger -
Niels Nes -
Sjoerd Mullender -
Stefan Manegold -
Ying Zhang