Posts
2012
- How does fby work? Nov 21
- What does it mean for a table to be a flipped dictionary? Oct 29
- How do I execute a q function call with parameters over IPC? Oct 10
- How do I use the functional forms of apply and amend? Feb 27
- How do I use the functional form of @ (at) apply? Feb 27
- How do I use the functional form of . (dot) apply? Feb 27
- How does each-both (aka multivalent each) work? Feb 26
- How can I capture STDOUT, STDERR and the exit status of a system command invoked from q? Jan 23
2011
- Why can’t I index some elements of a dictionary? Oct 23
- Why does the type of null returned by a failed dictionary key lookup vary? Oct 23
- When does : (amend) not modify its first argument? Aug 22
- What is q’s equivalent to sql’s ORDER BY? Aug 7
- How do I extract hours, minutes, or seconds from a time? Jul 30
- How do I parse a date and time? Jul 24
- How do I get the length of a list? Jul 19
- select sum size from a large table unexpectedly returns a negative number. Why? Jun 24
- Does the order of field constraints matter in the performance of a select query? Jun 4
- How do I set a breakpoint inside a q function? Jun 2
- How do I expose a subset of partitions and remove the rest from view? Jun 2
- I have a very large file to uncompress. zip and gzip do not work! Jun 2
- What exactly does column-oriented mean? May 31
- How do I convert a character to its ASCII code? May 22
- I’m in a hurry. Can multiple kdb processes write simultaneously to a splayed database? May 21
- How can I reorder column names of a splayed table on disk? May 19
- How do I split a list? May 13
- How can I find the data type of a given table column? May 4
- How do I set the return value of a function? Apr 27
- How can I test for the existence of a file or directory in q? Apr 22
- How do I remove a key from a dictionary? Apr 20
- I have a very big text file. Can I read a text file in chunks? Apr 14
- How do I select all columns in q? Apr 12
- How do I read in a text file? Apr 12
- How do I convert from symbol to integer? Apr 7
- How do I cast a string to a symbol? Apr 3
- How do I parse a ctrl-A delimited string? Apr 2
- How do I build a ctrl-A delimited string? Apr 2
- How can I measure the performance of my q code? Mar 27
- How do I declare a table column of type string (not symbol!)? Mar 27
- Can a table be partitioned but not be splayed? Mar 27
- What are some of the freely available software packages related to kdb? Mar 26
- q truncates the results in stdout. How can I fix it? Mar 26
- How do I use the timer? Mar 26
- What environment variables do I need to know about when kdb starts up? Mar 26
- I know k sits under q. By porting q code to k, will it run faster? Mar 26
- I defined an untyped list, but I get a type error when I add more than one element to it? How do I store mixed data in a list? Mar 25
- Does q have closures? Mar 25
- Why doesn’t ‘select from tablename where name = `ABC/A’ work? Mar 24
- What does ‘NUC mean? Mar 24
- How do I save a table to delimited text? Mar 24
- When I launch kdb with a directory, what exactly happens on start up and in what order? Mar 24
- I wish to keep sym file small. How can I find out if I will be introducing a new symbol before splaying the data out to disk? Mar 24
- How can I define my own infix functions? Mar 23
- Why doesn’t my query ‘select from reallybigtable’ ever return? Mar 23
- How do I store mixed data types in a single column of a table? Mar 22
- How does kdb compare to cloud computing? Mar 22
- How do I extract the milliseconds from a time? Mar 22
- Can I simply invoke garbage collect and clear the root namespace instead of restarting the process to reinitialize my database? Mar 21
- How portable is q code across operating systems? Mar 21
- Given a value, how do I get the null of that value’s type? Mar 21
- What are 0!, 1! and 2!? Mar 20
- How can I experiment on a production kdb while keeping the data free from accidental damage? Mar 20
- What is a virtual column? Mar 19
- What is the difference between the functions xcol and xcols? Mar 19
- What should I know about the sym file, and why back it up? Mar 19
- How do I get the day of the week? Mar 18
- Is the output of meta available for use in my program? Mar 18
- Who uses time series or column-oriented databases and why? Mar 17
- How do I delete a function in namespace .z? Mar 17
- How do I choose whether to make a field a symbol or string? Mar 17
- How can I group all (other) columns? Mar 16
- How can I slice a vector into a series of vectors of length n? Mar 16
- Can I retrieve kdb data from my web browser and save the query results to a csv file for viewing in a spreadsheet? Mar 16
- Is the q language simply syntactic sugar on top of k? Mar 16
- I noticed a list with a `s# prefix attached. What does this mean? Mar 16
- What does ‘\l .’ or ‘system “l .”‘ do? Mar 15
- How do I comment q code? Mar 15
- Can a historical database be partitioned on multiple levels – say, by date, then symbol? Mar 15
- ‘exit’ fails to terminate kdb console. How do I gracefully exit a kdb process? Mar 15
- How do i interpret the output of function .Q.w[]? Mar 14
- I’ve setup many views based on a single large table. How much of a performance penalty will I pay? Mar 13
- I want to keep kdb rdb super fast and prevent users from introducing large latencies by using a timeout argument of 2 seconds. is this a good idea? Mar 13
- How do I efficiently retrieve the first n rows of a query result? Mar 13
- How can I have kdb automatically load q code at startup in every session? Mar 13
- How can I set a trigger on a kdb table? Mar 13
- peach is great. Can I simply use it everywhere in place of each? Mar 12
- How do I load in a csv file into kdb with the headers as table fieldnames? Mar 12
- I’m purchasing new kdb server hardware. How should it be configured? Mar 12
- What are the implicit, default argument names to a function? Mar 12
- Why can’t kdb’s debugger tell me exactly which line in the function invoked the error? Mar 11
- Why doesn’t ‘\cd /fs/local/db;’ work? Mar 11
- What companion tools to kdb are useful? Mar 11
- How does ‘protected execution’ (or exception handling) work in q? Mar 10
- How can I find a listing of tables in a given namespace? Mar 10
- What is a dyadic function? Mar 10
- I understand white space matters in q code. Where does it matter? Mar 9
- How do I delete a column from a table? Mar 9
- I know SQL and don’t care to learn q. Can I still get my work done while benefiting from kdb’s speed? Mar 9
- How do I delete the nth row from a table? Mar 8
- What does it mean for a q function or table to be a ‘first class’ type? Mar 8
- What kdb connection libraries exist? Mar 8
- What are some of the hard limits of kdb I should know about? Mar 7
- Is q a purely functional language? Mar 7
- Is function overloading supported in q? Mar 7
- Why can’t I use exec on partitioned tables? Mar 6
- What’s the difference between kdb, kdb+, k, k4 and q? Mar 6
- What does error output ‘nyi mean? Mar 6
- I know kdb is a in-memory database. my dataset is over two terabytes in size. However my RAM is limited to 32GB. How will this work? Mar 6
- Can q script be compiled down to native code? Mar 5
- Is polymorphism supported in q? Mar 5
- How can I glue two tables side by side? Mar 4
- How do I sort? Mar 4
- What happens if I duplicate a partition name across multiple segments? Mar 4
- I’m used to sprinkling print statements to debug my code. How can I do the same in q? Mar 3
- How do I debug code in kdb? Mar 3
- What data structures does q provide out of the box? Mar 3
- Does q pass-by-value or pass-by-reference? Mar 2
- Is it possible to hold partitioned table and unpartitioned table named the same on a single kdb process? Mar 2