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Creating tables on disk

Received: by 10.114.61.1 with SMTP id j1mr67617waa.7.1216940345039; Thu, 24 Jul 2008 15:59:05 -0700 (PDT)Date: Thu, 24 Jul 2008 15:59:04 -0700 (PDT)X-IP: 141.162.101.50User-Agent: G2/1.0X-Google-Token: QbwmywwAAACPtUqvQDob7pb3j9K_m4PmX-HTTP-UserAgent...

sk by New Contributor
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filesystem tree as a table

In q/k, how does one determine a complete filesystem tree for a drive,stored as a table with fields corresponding with the depth of eachbranch of the tree? In addition other file info i.e size, date, type,etc. would be great, the more the better.

k_os_tao by New Contributor
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Function From String

Content-Disposition: inline Hello,I want to invoke a function on the q server side. For this reason, I would like to pass a string over to q server that can be interpreted as a function. Later I shall invoke the function remotely. Is this possible?Re...

Deducing non-existence & inserting only key columns

Content-Disposition: inline Hello,This is what I tried:q)a:([b:();c:()]d:())q)a b c| d---| - q)meta ac| t f a -| -----b|c| d|q)`a upsert (`first;1;"first item") \ for type discovery `aq)`a insert (`second;2;"second item") ,1q)ab c| d --------| ------...

string replace/substitute

Content-Disposition: inlinehi all,how can i substitue a substring with another. eg. if i have a: q) a:"ab\"\"de\"\"\"\"fg"then i want a function f: q) f[a;"\"\"";"\""] "ab\"de\"\"fg"ta, jack

effbiae by New Contributor
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How to release memory?

Hello,I used the personal developer edition and load 3million rows data tothe table, but the memory usage without any reduce after I deletedthe data from the table.Somebody help me?

Limitation on personal q server (other than time)?

Content-Disposition: inlineHello,Is there a size restriction on the data or limitation on number of operations when using the personal edition?I get a crash at exactly the same data insert point. However, the statement is valid (I checked independent...

Saving as splayed with custom name for "sym" file

HiWhat's the easiest way to save a splayed table where you can use acustom name for the sym file?Doing this one-liner:`:dir/table/ set tablemeans that the file containing the enumerated symbols is always called"sym".Thanks

guydowman by New Contributor
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NUMERIC(11) data type equivalent?

Content-Disposition: inlineHello,I want to persist a NUMERIC(11) data. I used long as the type for the q table.When I append a record with a value 4300000002, I get an error in the insertq)`4300000002What is the equivalent data type in q in this case...

Table with only composite primary key?

Content-Disposition: inlineHello,Why does the following q statement result in a 'parse error?q)d:([a:`int$();b:`long$();c:`symbol$()])'parseq)I think with this statement I am creating a table d with 3 columns a,b&c and a composite key with all of the...

Duplicate column names in tables.

Hi,I'm just getting started in q, so please forgive me if this is a sillyquestion.In some (most?) cases, it appears that q prohibits duplicate columnnames, or at least attempts to avoid accidental introduction of them,while in others (well, at least ...

dict lookup via c

Content-Disposition: inlinehi,i create a dict in c: K d=xD(x,y);how do i look up a value in d?or does d have to be sent to a server and run a query on it?ta, jack

effbiae by New Contributor
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k/kdb 3.2

"Inherited" a product with a K/KDB 3.2 database in it. Need to connectto a table via the K console to fetch some data and having syntaxproblems.Ignoring that there may be security in place to prevent theconnection, knowing that the K server is listen...

"writing compilers is a snap in q."

Content-Disposition: inlinein "q for mortals 2", jeffry claims "writing compilers is a snap in q."are there any examples? searching for 'compiler' doesn't get me anywhere.ta, jack

effbiae by New Contributor
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aggregate function

how can i create my own aggregate function in q?to try something i did following:-f1:{100+first x}when i do:-select f1 field from table1where field is an int, it gives �type error....but if i do:-.q.f1: {first x+100}.Q[`a0],:.q.f1thenselect f1 field ...

Shiv by New Contributor
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SSH and command line 'Q'

I have a problem which is not directly to do with q, but to do withthe use of q under SSH.My local machine is a windows laptop, and I'm trying to run q on aremote machine which is a multi core linux box. I access the remotelinux box via SSH using the...

non-sprayed table does not support partition ?

Hi, all:I have a table with hundreds millions unique symbols, it's hard tobeen stored as sprayded.q)t:([] url:`symbol$(); referer:`symbol$())how to partition the non-sprayed table ?Best Regards,Davies

by Not applicable
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MapReduce

Content-Disposition: inlinehi guys,anyone thought about MapReduce (google's core-ish distributed query engine) http://labs.google.com/papers/mapreduce.htmland if it would be easy to do and generalize in q? i haven't readmuch about distributed program...

effbiae by New Contributor
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Infix functions, f:+/* and bitwise XOR

Hi, I am a Q newbie and would like to find answers to 3 questions:Q1: How do I make a dyadic function infix?The only way I've found that seems to work is to append the both-eachadverb. Is this the only way? q)op:{y+10*x} q)1 2 3 op' 7 8 9 17 28 39Q2:...

Swee_Heng by New Contributor
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my interest is in k

Content-Disposition: inlinehi guys,i'm new, my interest is mainly in k. is this the forum?is there a k wiki or faq or something that would have eg. example ofquicksort in k?ta, jack

effbiae by New Contributor
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Dictionary Performance Slow On Occasion

q)m: (til 5000)!(til 5000) / a trivial mappingq)v: 1000 50#(537?100) / a 2D list of values to mapq)\t m[v] / <== this takes a surprisinglylong time190q)\t m[raze v] / 1D list - same amount of mappingas m[v] but MASSIVELY faster0As you can see, applyi...

how to deal with parted table?

Hi, all:I create a parted table, just like in /kx/kdb+/taq/tq.q, the directorylooks like:rohan/|-- 2008.05.08| `-- log| |-- agent| |-- bid| |-- code| |-- date| |-- ip| |-- length| |-- method| |-- nreferer| |-- nurl| |-- pt| |-- referer| |-- sid| |-- ...

by Not applicable
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Interprocess Communication - Fedora

Content-Disposition: inline I have 2 machines on the same local network.When both machines run Windows XP, I can start a q process on each machine and establish interprocess communication in either direction.When one machine runs XP and the other run...

tavmem by New Contributor
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help... how to start up kdb gui

I have looked at kdb a couple years ago.. but even though it fulfilledmy purposes their licensing simply was so strict that I lost interest.Anyway I was pleasently surprised by their recent step even though Idon't think it will achieve what they are ...

trigger in Kdb+ ??

Hello Frends!!Old k system have trigger for global variable ( x..t: "bla-bla" )In Kdb+ its possible ??With best regards.

kgforth by New Contributor
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webserver questions

1) Have any performance metrics been posted or documented for the kdb+webserver?2) Is there a way to firewall against lambda injections?3) Has anybody written a json de/serializer?Thanks,James

jksmith by New Contributor
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