NAME

   Kx - Perl extension for Kdb+ http://kx.com

SYNOPSIS

       use Kx;

       my $k = Kx->new(host=>'localhost', port=>2222);
       $k->connect() or die "Can't connect to Kdb+ server";

       my $rtn = $k->cmd('til 8');
       my $sum = $k->cmd('{x+y}', $k->int(5)->kval, $k->int(7)->kval);

       my $lst = $k->listof(5, Kx::KI());
       for (0 .. 4) {
           $lst->at($_, $_);
       }
       my $ktyp = Kx::kType($lst->kval);
       my $lst_perl = $lst->val;

DESCRIPTION

   Alpha code. Create a wrapper around Kdb+ and Q in Perl using the C
   interface to Kdb+

EXPORT

   None by default.

METHODS

New

       my $k = Kx->new(name=>'local22', host=>'localhost', port=>2222);

   Create a new Kx object. Set the connection paramaters to conect to
   'host' and 'port' as specified.

   No connection is made to the server until you call $k->connect()

   If you don't define a name it defaults to 'default'. Each subsequent
   call to new() will use the same 'default' connection.

   So once you make a connection later calls to new() with the same name
   will use the same connection without further connect() calls required.

       my $k = Kx->new(host=>'localhost', port=>2222);
       $k->connect() or die "Can't connect to Kdb+ server";

       # picks up previous default connection to localhost port 2222 and
       # will use it as well.
       my $k1 = Kx->new();

   Also username and passwords are supported. Just add the userpass
   attribute thus:

       $k = Kx->new(name=>'local22',
                    host=>'localhost',
                    port=>2222,
                    userpass=>'user:pass');

Connect

   To connect to the 'default' server.

       unless($k->connect()) {
           warn "Can't connect to Kdb+ server\n";
       }

   To connect to a defined server say 'local22'

       unless($k->connect('local22')) {
           warn "Can't connect to local22 Kdb+ server\n";
       }


Environment

   There are a number of environment details you can glean from the Kdb+
   server you are connected to. They are:

       my $arrayref = $k->tables;     # The tables defined
       my $arrayref = $k->funcs;      # The functions defined
       my $arrayref = $k->views;      # The views defined
       my $arrayref = $k->variables;  # The variables defined
       my $arrayref = $k->memory;     # The memory details \w

       my $dir = $k->cwd;              # The current working directory
       my $dir = $k->chdir($newdir);   # Set the cwd
       my $num = $k->GMToffset;        # Offset from GMT for times

   If you make changes that effects these environmental details then call
   the env() method to update what is known. This module doesn't
   continually hassle the server for these details.

       my @details = $k->env;  # Get the environment from the server

       $details[0] => [ tables     ]
       $details[1] => [ funcs      ]
       $details[2] => [ views      ]
       $details[3] => [ variables  ]
       $details[4] => 'GMToffset'
       $details[5] => 'releasedate'
       $details[6] => 'gmt'
       $details[7] => 'localtime'
       $details[8] => [ memory     ]
       $details[7] => 'cwd'

   You can also execute OS commands on the server end and gather the
   results like this.

       $arref = $k->oscmd("ls -l /");

TABLES

   You don't need to use this just use the cmd() interface if you like.
   However if your lazy like me.... read on

   Each of these accessors have a method name starting with 'T'. To help
   distinguish them as cooperating methods.

   Create a new table in Kdb+ named mytab with 3 columns col1, col2 and
   col3. The keys will be on col1 and col3 This equates to the Q command

       # Q command
       q)mytab:([col1:;col3:] col2:)

       # The long winded Perl way
       $k->Tnew(name=>'mytab',keys=>['col1','col3'],cols=>['col2']);

   To add data use Tinsert(). Each row is added in the order defined
   above. This line adds 1 into col1, 2 into col3 and 3 into col2 as the
   keys are always defined before the other columns.

       $k->Tinsert('mytab',1,2,3);

   To do a select over a table use Tselect(). Tselect() takes a variable
   name as its first argument. The select will be executed and assigned to
   the variable you define. This way no data is passed from Kdb+ to the
   client until it is needed.

       $k->Tselect('a','select from mytab where col1>4');

   This is really just the same as

       # q command
       a:select from mytab where col1>4

   To get the details of the stored selection

       my $numrows = $k->Tnumrows('a');
       my $numcols = $k->Tnumcols('a');

   This only works on variables that are tables returned from a selection.

   Tget() Tindex() Tcol() and Theader() are only useful once you have done
   a Tget().

   Remember it is probably better to only pull back small tables less than
   say a few tens of thousand of rows as you'll eat up memory fast.

   You may have run a number of Tselects() and now wish to pull back the
   data. To do this use Tget()

       $k->Tget('table');   # table must be a table in the server

   Tget() can also be used with select type queries that return a table as
   their result. It also handles indexed tables better than the cmd()
   method.

   To get access to random values in the returned table from Tget().

       $val = $k->Tindex(row,col);

   This only works for simple tables holding scalars in each row. Don't
   try this if the index would point to a mulit-valued list. Actually it
   sort of works for lists and when it does $val is an array reference. If
   you have troubles use Tcol().

   To get the list of column names as Kdb+ knows them.

       my $header = $k->Theader();
           print "@$header\n";

   To get the meta data for a table as defined in KDB do this.

       my @meta = $k->Tmeta($table);
       foreach(@meta)
       {
           print "(name type) => (@$_)\n";
       }

   To get a Perl reference to a column of data from the table (as K is
   column oriented) do the following:

       my $colref = $k->Tcol(0);   # get the zeroth column
       print "Column 0 data is: @$colref\n";

   I advise against using this on large columns or tables as it is very
   memory inefficent. Better to use $k->cmd() interface to pull back
   exactly what you want first. The column reference above is a Perl copy
   of the data structure held in Kdb+ memory format in the client. This
   can be over 3 times larger in core than the Kdb+ data.

   If you need to access data via rows then use $k->Trow(). Given a row
   number it will return a reference to the row. The first row is at zero
   0.

       my $row = $k->Trow(0);   # get the zeroth row
       print "Row 0 data is: @$row\n";

   Finally to delete or remove a table by name from the server:

       $k->Tdelete('table');

   Here is a list of the complete table methods we have so far:

       $k->Tnew(name=>'thename',keys=>[],cols=>[]);
       $k->Tinsert('table',1,2,3);
       $k->Tbulkinsert('table',col1=>[],col2=>[],...);
       $k->Tget('select statement');
       $scalar = $k->Tindex($row,$col);
       $arref  = $k->Tcol(2);      # 3rd col vector
       $arref  = $k->Trow(2);      # 3rd row
       $arref  = $k->Theader;
       $x      = $k->Tnumrows;
       $y      = $k->Tnumcols;
       $k->Tselect('table','select statement');
       $k->Tsave('table','file');
       $k->Tappend('table','file');
       $k->Tload('table','file');
       $k->Tdelete('table');

   If you want a faster bulk insert function use:

       $k->Tfastbulkinsert('mytab',$col1,$col2,$col3...);

   Here col1 col2 etc are infact in core Kdb+ structures and must be in
   the same order as the declaration use when you used Tnew(). This is
   almost 3 times faster than Tbulkinsert but uses more memory in the
   client. See the test files that came with this module for more details
   on how it is used.

COMMANDS

   Execute the code on an already accessable Kdb+ server. The query is
   executed and the results are held in K structures in RAM. Example

       $return = $k->cmd('b:til 100');

   If you just what to send a command to the Kdb+ server and not wait then
   use the following. No return value is provided.

       $k->whenever('b:til 100');

   The cmd() method also allows up to two extra arguments that are
   normally K objects. You normally call cmd() this way when you have a
   function to call. Here is a dodgy example.

       my $data = $k->listof(length($arrsym), Kx::KG());  # list of bytes
       $data->setbin($arrsym);

       $result = $k->cmd('{[x]insert[`mytab](0;x;.z.z)}', $data->kval);

   The cmd() function will return a reference to an array if the Q command
   returns a list. It will return a simple scalar if the result is a
   scalar response from Q. It will return a hash reference if the return
   result from Q is either table/keyed table/dictionary. You need to know
   what you are doing so can know what the result is (or use Perl's
   ref()).

   Do not execute queries that return large 'keyed' tables as a copy of
   the table in unkeyed form is held to convert to a Perl Hash before
   being freed.

   Note: cmd() does not convert a keyed table to an unkeyed table in
   memory. It holds onto what was passed back from KDB+ as is. If you want
   get at the underlying K structure and change it use Tget() instead.
   Tget() will convert a keyed table to an unkeyed table and hold it in
   memory.

   If you have a Q script that you wish to run against the Kdb+ server you
   can use the do(file) method. Any error in your script that is caught
   will stop do(file) from proceeding. If you don't care when it is done
   then use dolater(file).

   Both do() and dolater() don't return anything useful. They just blindly
   execute each line of Q against the server. If you want to check each
   command and do stuff as a result then use cmd() and check the result.

   An example file name foo.txt holds the lines:

       t:([]a:();b:())
       insert[`t](`a;10.70)
       insert[`t](`b;-5.6)
       insert[`t](`c;21.73)

   You can run that file by doing this:

       $k->do("foo.txt");

ATOMS and STRUCTURES

   To create Kdb+ atoms locally in RAM use the following calls.

       my $d;
       $d=$k->bool(0);           # boolean
       $d=$k->byte(100);         # char
       $d=$k->char(ord('a'));    # char
       $d=$k->short(20);
       $d=$k->int(70);
       $d=$k->long(93939);
       $d=$k->real(20.44);        # remember 20.44 may look close as a real
       $d=$k->float(20.44);       # should look closer to 20.44 as a float
       $d=$k->sym('mysymbol');    # A Kdb+ symbol
       $d=$k->date(2007,4,22);    # integer encoded date year, month, day
       $d=$k->dt(time());         # Kdb+ datetime from Unix epoch
       $d=$k->tm(100);            # Time type in milliseconds

   These allow for fine grained control over the 'type' of K object you
   want. If you don't mind particularly about the type conversions then
   you can use perl2K() like this.

       $d = $k->perl2K('mysymbol');
       $d = $k->perl2K([qw/this will be a K list of symbols/]);
       $d = $k->perl2K({this => 1, that => 2, 'is a' => 'dict'});

   To get a Perl value back from a Kdb+ atom try this;

       my $val = $d->val();

   To get the internal value back from a Kdb+ atom try this;

       my $kval = $k->kval;  # used in $x->cmd('func', $kval)

   As a further comment on the date() method. When you look at the value
   retuned from a date() call it is in epoch seconds.

       my $date = $k->date(2007,4,22);
       print scalar localtime($date->val),"\n";

   Further more, KDB+ Datetimes are held as a C double in memory. The
   integral part is the number of days since 1/1/2000 and the fractional
   part is the fraction of the day. You have some control over how
   datetimes are returned from KDB+ back into Perl data structures. By
   default a conversion to Unix epoch seconds will be made. You can also
   get epoch seconds with milliseconds and you can also turn off
   conversion all together.

       Kx::__Z2epoch(0);   # turn off Kdb+ to Unix epoch conversion
       Kx::__Z2epoch(1);   # turn on Kdb+ to Unix epoch conversion (default)
       Kx::__Z2epoch(2);   # turn on Kdb+ to Unix epoch conversion plus millisecs

   These have immediate effects on how datetimes are converted into Perl
   data structures. These do not effect what is held in RAM after a call
   to KDB+ has been made, just how they are converted into Perl.

   These methods use the underlying functions as listed below. Don't use
   these unless you know what your doing. They are listed here for
   completeness and so you can use them if you really want. But don't.

       Kx::kb(integer)     => Create boolean 0|1
       Kx::kg(integer)     => Create a byte/char
       Kx::kh(integer)     => Create a short
       Kx::ki(integer)     => Create and integer
       Kx::kj(longval)     => Create a long
       Kx::ke(realval)     => Create a real
       Kx::kf(floatval)    => Create a float
       Kx::kc(charval)     => Create a char from an int ord()
       Kx::ks(symbol)      => Create a symbol from a string
       Kx::kd(date)        => Create a date - See K dates
       Kx::kz(datetime)    => Create a datetime - See K dates
       Kx::kt(time)        => Create a time

       Kx::p2k($ref)       => return a K structure describing the Reference
       Kx::k2p(K)          => return a Perl structure from a Kdb+ structure

       Kx::k2pscalar(K)    => return a scalar from a Kdb+ atom
       Kx::k2parray(K)     => return an array from a Kdb+ list
       Kx::k2phash(K)      => return a hash from a Kdb+ dict/table

       Kx::phash2k($href)  => return a Kdb+ dict from a Perl hash ref
       Kx::parray2k($aref) => return a Kdb+ list from a Perl array ref
       Kx::pscalar2k($srf) => return a Kdb+ atom from a Perl scalar ref

   Example:

       # Simple create
       my $bool = $k->bool(0);
       print "My boolean in K is ",$bool->val,"\n";

LISTS

 Simple Lists

   These list functions create in memory local lists outside of any 'q'
   running process. These will allow you to create very large simple lists
   without blowing out all your memory.

   To create a simple Kdb+ list of a single type use the listof()
   function. The type of the list is passed in as the second aregument and
   can be one of:

       Kx::KC()  char
       Kx::KD()  date yyyy mm dd
       Kx::KE()  real
       Kx::KF()  float
       Kx::KG()  byte
       Kx::KH()  short
       Kx::KI()  integer
       Kx::KJ()  long
       Kx::KM()  month
       Kx::KS()  symbol (internalised string)
       Kx::KT()  time
       Kx::KU()  minute
       Kx::KV()  second
       Kx::KZ()  datetime epoch seconds

   Example simple lists:

       my $list = $k->listof(20,Kx::KS());      # List of 20 symbols
       for( my $i=0; $i < 20; $i++)
       {
           $list->at($i,"symbol$i");
       }

       # To get at the 4th element
       my $sym = $list->at(3);     # symbol3

       my $perl_list = $list->list;
       print "Symbols are @$perl_list\n";

       # dates
       $d = $k->listof(20,Kx::KD());
       for( my $i=0; $i < 20; $i++)
       {
           $d->at($i,2007,4,$i+1);  # 20070401 -> 20070421
       }

       # Add an extra date to the end of the list
       my $day = $k->date(2007,4,30);
       $d->joinatom($day->kval);

   There is also another method defined setbin() that sets binary data
   into a list of bytes. You can use this to save serialised Perl data
   structures into Kdb+ tables (much like a blob or text field in SQL
   DBs). Here is an example:

       use Kx;
       use Compress::Zlib qw/compress uncompress/;
       use Data::Dumper;
       $Data::Dumper::Indent = 0; # no newlines, important

       my $k = Kx->new(host=>"localhost", port=>2222, check_for_errors=>1);
       $k->connect() or die "Can't connect to Kdb+ server";

       # create new table in q
       $k->Tnew(name=>'mytab',cols=>[qw/id data ts/]);

       # Build a large complicated Perl structure.
       my $arr = { a=>['a','b','c',1,2,3], b=>'this is a test'};
       for (0..10000) {
           $arr->{$_} = {$_ => $_};
           $arr->{"a$_"} = [$_, $_];
       }

       # Serialise it as a compressed piece of data
       my $arrsym =  Dumper($arr);
       print "Dumper size is: ", length $arrsym, "\n";
       $arrsym = compress( $arrsym );
       print "Compress Dumper size is: ", length $arrsym, "\n";

       # An in memory Kdb+ list of bytes to hold the compressed data
       my $data = $k->listof(length($arrsym),Kx::KG());  # list of length bytes
       $data->setbin($arrsym);

       # Insert it into a table using a function call.
       $k->cmd('{[x]insert[`mytab](0;x;.z.z)}',$data->kval);

       # Select a single row from the table, and return it's data
       $binary = $k->cmd('(select data from mytab where id=0)[0;`data]');

       # Get the data back into Perl string form
       $arrsym = uncompress($binary);
       #print $arrsym,"\n";

       # Eval the string into a Perl data structure the hard way
       my $VAR1;
       eval $arrsym;
       print $VAR1->{'b'},"\n";

 Mixed Lists

       # The zero in line below says its to be a mixed list
       my $list = $k->listof(40,0); # mixed list 40 elements
       $list->at(0,$k->float(22.22));

       $list->at(1,$k->sym('this is a test'));
       .
       .
       $list->at(39,$k->date(2007,2,28));

   This is handy for creating multiple arguments to a KDB+ function call.

Utility Methods

   $k->dump0() will return a string describing the under lying K
   structure.

   Kx::dump($k) will print out the K structure of $k

   $sym = Kx::makesym("string") will convert a simple string into a quoted
   symbol suitable for usage in KDB+

   make_C() will convert its argument into a suitable string quoted as a
   KDB+ character list.

       my $c = Kx::make_C("now is\tthe \n time for \n help");

   There is also make_s():

       my $sym = Kx::make_s("a symbol"); # `$"a symbol"
       my $sym = Kx::make_s(undef);      # a null symbol `

Kx::LIST

   You may wish to tie a Perl array to a Kdb+ variable. Well, you can do
   that as well. Try something like this:

       use Kx;

       my %config = (
           host=>"localhost",
           port=>2222,
           userpass=>'user:pass',    # optional
           type=>'symbol',
           list=>'d',
           create=>1
       );
       tie(@a, 'Kx::LIST', %config);

       # push lost of stuff on an array
       my @array = (qw/aaaa bbbbb ccccc ddddddddd e f j h i j k l/) x 30000
       ;
       push(@a,@array);
       push(@a,@array);
       push(@a,@array);
       print "\@a has ", scalar(@a)," elements\n";

       # Store
       $a[3] = "Help me";
       print "Elementt 3 is ",$a[3],"\n";

   All the functions defined in perltie for lists are included.

   Note: 'type' is a Kdb+ type as defined in Types below - it is the type
   for the array. Only simple types are allowed at the moment.

Kx::HASH

   You may wish to tie a Perl hash to a Kdb+ variable. Well, you can do
   that as well. Try something like this:

       use Kx;

       my %config = (
               host=>"localhost",
               port=>2222,
               userpass=>'user:pass', # optional
               ktype=>'symbol',
               vtype=>'int',
               dict=>'x',
               create=>1
       );
       tie(%x, 'Kx::HASH', %config);

       print "Size of hash x is :". scalar %x ."\n";
       for(0..5) {
           $x{"a$_"} = $_;
       }

       %y = %x;

       for(0..5) {
           print $y{"a$_"}," " if exists $y{"a$_"};
       }
       print "\n";

       while(($k,$v) = each %x) {
           print "Key=>$k is $v\n";
       }
       untie(%x);

   All the functions defined in perltie for hashs are included.

   Note: ktype is a Kdb+ type as defined in Types below - it is the 'key'
   type for the hash. vtype is also defined in Types - it is the value
   type. Only simple types are allowed at the moment.

SEE ALSO

   http://kx.com

   http://code.kx.com

   See the test code under the 't' directory of this module for more
   details on how to call each method.

AUTHORS

     * Mark Pfeiffer <[email protected]>

     * Stephan Loyd <[email protected]>

COPYRIGHT AND LICENSE

   Copyright (C) 2007 by Mark Pfeiffer

   This library is free software; you can redistribute it and/or modify it
   under the same terms as Perl itself, either Perl version 5.8.6 or, at
   your option, any later version of Perl 5 you may have available.

   This code is not affiliated with KxSystems in anyway. It is just a
   simple interface to their code. Any functionality that is of any use is
   due to the hard work of the people at KxSystems.

   This is Alpha code. Use at your own risk. It is availble only for
   testing at the moment. It has not been fully tested. For example nulls,
   inf and the like. Your kms may vary.

   If this code is useful then please drop me a line and let me know. I
   would also like to be acknowledged in any products you may make from
   this. I get a bit of a buzz out of it.

   The LICENSE file in the package is the Perl 5 license.

BUGS

   Plenty and to be expected. Please send me any bugs you find. Patches
   are even better and will always be acknowledged.

   Once the code has been tested for a while I'll move it to beta. Don't
   hold your breath though.

   All spelling mistakes are mine ;-)

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