Kdb
Author: m | 2025-04-24
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It is possible to import C functions directly for use within the kdb process by dynamically loading modules. Below we will look at an example of compiling, importing and executing C functions on windows for kdb 3.0+.We will be adding two functions myavg, mysum which providemoving average and moving sum functions respectively. Yes, kdb does already mavg but read till the end and I think you will find the performance comparison interesting. The Interfacing Kdb with C and Extending with C page on the code KX website documents the C API extensively, we will give details for the core parts used in our example but you will want to read those pages thoroughly at a later stage. Download Example C Code Example of kdb C DLL Compilation Compiling a C DLL on Windows The steps to compile and load a C DLL are as follows: Download kdb C example code. It contains the following files: The latest version of header files provided by kx. k.h and and q.lib for windows 64. mymoving.c - C code that defines our actual functions mymoving.def - Declares the functions we will be providing Compile the code using comprun.bat this requires MS Visual Studio 2010 installed It uses "C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\vcvarsall.bat" amd64 to set the required environment variables for our compilation. Runs the command line compiler: cl /LD /DKXVER=3 mymoving.c mymoving.def q.lib Launch q running the script load-functions.q so that our DLL functions are loaded and defined. Now within q we can call our mytop, myavg functions. comprun.bat mymoving.c Loading a module load-functions.q In this q script we import functions from our DLL and assign them to variable names: mymoving is the name of our DLL which is in the current directory, you could place this in c:/q/w64 or specify a full path. 2: is the kdb function for loading native code. The right hand side e.g. (`mysum;2) specifies a function that exists and the number of arguments it accepts. Executing our C Code As you can see we get the same results using either our own function or kdb's builtin mavg. However our function is 46x quicker (users on linux report a much smaller 3x speed difference). There are a number of reasons why this is (nulls and partitioned data) but that's a topic for another post. If your having problems compiling or want advice either contact us or ask in our forums. We also provide kdb consulting services and have particular expertise in writing kdb+tick subscribers and feedhandlers. Related Tutorials. Kuiz KDB - Kuiz Klik Dengan Bijak - KDB - KDB! - KDB: Match Up! - CARI PADANAN KDB - KDB - Padankan KDB - KDB Maze - Kuiz KDB - CROSSWORD PUZZLE KDB kdb Database Browser and Query Tool Features. The kdb database query tool and database browser provided by RazorSQL includes a kdb Database Browser, a kdb SQL Editor, a kdb Edit Table Tool, import and export tools for importing and exporting kdb data, and other visual tools for working with kdb. The kdb database query tool and database browser provided by RazorSQL includes a kdb Database Browser, a kdb SQL Editor, a kdb Edit Table Tool, import and export tools for importing and exporting kdb data, and other visual tools for working with kdb. Listed below is more information. kdb Database Browser The kdb database query tool and database browser provided by RazorSQL includes a kdb Database Browser, a kdb SQL Editor, a kdb Edit Table Tool, import and export tools for importing and exporting kdb data, and other visual tools for working with kdb. Listed below is more information. kdb Database Browser Grafana KDB Backend Datasource What is KDB Backend Datasource? AquaQ's kdb Backend Datasource is a plugin that adds the ability to query kdb from Grafana. Visit KDB Deals www.kdbdeals.com Or Download KDB Deals Dropshipping App Portable Neckline Slimmer Massager System (KDB- ) This product is available exclusively on KDB Deals. KDB Overview - This is a complete quide to kdb from kx systems, aimed primarily at those learning independently. kdb, introduced in 2025, is the new generation of the kdb database KDB - Overview. This is a complete quide to kdb from kx systems, aimed primarily at those learning independently. kdb, introduced in 2025, is the new generation of the kdb database Home › Forums › kdb+ › How to download attachments from *.eml file Posted by on April 5, 2023 at 12:00 am How to download attachments from *.eml file using kdb code? 4 Replies Kdb+ can parse binary files as nicely shown at the recent KX meetup by formats can get complicated though so this can be a lot of work.If I wanted to do this task quickly I would either:a) Use a system call to a command line tool to extract the files on disk and then read them in from there.Writing them to current directory or using mktemp command to write in /var/tmpb) Wrap some exiting python code using EmbedPy to extract the email and attachments to JSON and read in to kdb+ this way.Similar to how I did for XML with discussions on the topic in Python world:(Note: I have not tested these for functionality or safety) Hi KPC,Looking at an example .eml file here. If you wanted to parse the attachments purely in KDB/Q without the use of Python libs (although I suggest using Python libs) I’d suggest something along the lines of:read0 the *.eml file. Depending on the contents and if you want to interpret new lines literally or not you may find “c”$read1 a more appropriate solutionUse regex to locate the contents of the attachment, content type and encoding type (from the example looks to default to b64)Decode the body of the attachment – for b64 decoding in KDB/Q it looks like this is a solutionb64Decode:{c:sum x=”=”;neg[c]_”c”$raze 256 vs’64 sv’0N 4#.Q.b6?x}?Post-process the data further into Q objects if it’s suitable. E.g. if the filetype is a json you may want to utilise the .j.k json deserialiser for QThe solution provided should be the preferred solution with embedPy. Adding to this there is a PyPiComments
It is possible to import C functions directly for use within the kdb process by dynamically loading modules. Below we will look at an example of compiling, importing and executing C functions on windows for kdb 3.0+.We will be adding two functions myavg, mysum which providemoving average and moving sum functions respectively. Yes, kdb does already mavg but read till the end and I think you will find the performance comparison interesting. The Interfacing Kdb with C and Extending with C page on the code KX website documents the C API extensively, we will give details for the core parts used in our example but you will want to read those pages thoroughly at a later stage. Download Example C Code Example of kdb C DLL Compilation Compiling a C DLL on Windows The steps to compile and load a C DLL are as follows: Download kdb C example code. It contains the following files: The latest version of header files provided by kx. k.h and and q.lib for windows 64. mymoving.c - C code that defines our actual functions mymoving.def - Declares the functions we will be providing Compile the code using comprun.bat this requires MS Visual Studio 2010 installed It uses "C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\vcvarsall.bat" amd64 to set the required environment variables for our compilation. Runs the command line compiler: cl /LD /DKXVER=3 mymoving.c mymoving.def q.lib Launch q running the script load-functions.q so that our DLL functions are loaded and defined. Now within q we can call our mytop, myavg functions. comprun.bat mymoving.c Loading a module load-functions.q In this q script we import functions from our DLL and assign them to variable names: mymoving is the name of our DLL which is in the current directory, you could place this in c:/q/w64 or specify a full path. 2: is the kdb function for loading native code. The right hand side e.g. (`mysum;2) specifies a function that exists and the number of arguments it accepts. Executing our C Code As you can see we get the same results using either our own function or kdb's builtin mavg. However our function is 46x quicker (users on linux report a much smaller 3x speed difference). There are a number of reasons why this is (nulls and partitioned data) but that's a topic for another post. If your having problems compiling or want advice either contact us or ask in our forums. We also provide kdb consulting services and have particular expertise in writing kdb+tick subscribers and feedhandlers. Related Tutorials
2025-04-17Home › Forums › kdb+ › How to download attachments from *.eml file Posted by on April 5, 2023 at 12:00 am How to download attachments from *.eml file using kdb code? 4 Replies Kdb+ can parse binary files as nicely shown at the recent KX meetup by formats can get complicated though so this can be a lot of work.If I wanted to do this task quickly I would either:a) Use a system call to a command line tool to extract the files on disk and then read them in from there.Writing them to current directory or using mktemp command to write in /var/tmpb) Wrap some exiting python code using EmbedPy to extract the email and attachments to JSON and read in to kdb+ this way.Similar to how I did for XML with discussions on the topic in Python world:(Note: I have not tested these for functionality or safety) Hi KPC,Looking at an example .eml file here. If you wanted to parse the attachments purely in KDB/Q without the use of Python libs (although I suggest using Python libs) I’d suggest something along the lines of:read0 the *.eml file. Depending on the contents and if you want to interpret new lines literally or not you may find “c”$read1 a more appropriate solutionUse regex to locate the contents of the attachment, content type and encoding type (from the example looks to default to b64)Decode the body of the attachment – for b64 decoding in KDB/Q it looks like this is a solutionb64Decode:{c:sum x=”=”;neg[c]_”c”$raze 256 vs’64 sv’0N 4#.Q.b6?x}?Post-process the data further into Q objects if it’s suitable. E.g. if the filetype is a json you may want to utilise the .j.k json deserialiser for QThe solution provided should be the preferred solution with embedPy. Adding to this there is a PyPi
2025-04-01Recommendations against using \d in §12.7.13.1.8 Error Trap \e¶The \e [0|1] command displays or changes the behavior of a q process when an exception occurs during processing a client (i.e., remote) IPC request.In a fresh q session the default is 0, meaning that when an exception occurs the stack of the failing function is cleared and execution continues. This is the desired behavior for a production server, as you do not want wayward client requests to disable the process.In a development or testing scenario you can set this value to 1 to enable the familiar stack trace from the interactive console.13.1.9 Functions \f¶The \f [namespace] command displays a sorted list of symbolic names of functions in the current, or specified, working context. In a fresh q session,q)\f`symbol$()q)f:{x*x}q)g:{x*x*x}q)\f`s#`f`gq).jab.f:{[] 42}q)\f .jab,`f13.1.10 Garbage Collection \g¶\g commandFollowing is a description of q/kdb+ memory management provided by Charles Skelton, the KX CTO.Q/Kdb+ manages its own thread-local heap.Vectors always have a capacity and a used size (the count).There is no garbage since q/kdb+ uses reference counting. As soon as there are no references to an object, its memory is returned to the heap.During that return of memory, q/kdb+ checks if the capacity of the object is ≥64MB. If it is and \g is 1, the memory is returned immediately to the OS; otherwise, the memory is returned to the thread-local heap for reuse.Executing .Q.gc[] additionally attempts to coalesce pieces of the heap into their original allocation units and returns any units >=64MB to the OS.Beginning with 3.3 2015.08.23 – Linux only – unused pages in the heap are dropped from RSS during .Q.gc[].When q/kdb+ is denied additional address space from the OS, it will invoke .Q.gc[] and retry the request to the OS. Should that fail, it will exit with 'wsfull.When slave threads are configured and
2025-04-03