sequences

Distributed sequence number generation?

由 霸气de小男生 提交于 2019-11-26 10:05:23
问题 I\'ve generally implemented sequence number generation using database sequences in the past. e.g. Using Postgres SERIAL type http://www.neilconway.org/docs/sequences/ I\'m curious though as how to generate sequence numbers for large distributed systems where there is no database. Does anybody have any experience or suggestions of a best practice for achieving sequence number generation in a thread safe manner for multiple clients? 回答1: OK, this is a very old question, which I'm first seeing

Auto-increment in Oracle without using a trigger

由 ￡可爱￡侵袭症＋ 提交于 2019-11-26 08:19:33
问题 What are the other ways of achieving auto-increment in oracle other than use of triggers? 回答1: As far as I can recall from my Oracle days, you can't achieve Auto Increment columns without using TRIGGER. Any solutions out there to make auto increment column involves TRIGGER and SEQUENCE (I'm assuming you already know this, hence the no trigger remarks). 回答2: You can create and use oracle sequences. The syntax and details are at http://www.techonthenet.com/oracle/sequences.php Also read the

mysql - making a mechanism similar to Oracle's seqences

由 ﹥＞﹥吖頭↗ 提交于 2019-11-26 04:01:09
问题 MySQL provides an automatic mechanism to increment record IDs. This is OK for many purposes, but I need to be able to use sequences as offered by ORACLE. Obviously, there is no point in creating a table for that purpose. The solution SHOULD be simple: 1) Create a table to hosts all the needed sequences, 2) Create a function that increases the value of a specific sequence and returns the new value, 3) Create a function that returns the current value of a sequence. In theory, it looks simple...

Comprehension for flattening a sequence of sequences? [duplicate]

由 ◇◆丶佛笑我妖孽 提交于 2019-11-26 03:43:47
问题 This question already has an answer here: How to make a flat list out of list of lists? 45 answers If I have sequence of sequences (maybe a list of tuples) I can use itertools.chain() to flatten it. But sometimes I feel like I would rather write it as a comprehension. I just can\'t figure out how to do it. Here\'s a very construed case: Let\'s say I want to swap the elements of every pair in a sequence. I use a string as a sequence here: >>> from itertools import chain >>> seq = \'012345\' >>

Sequence-zip function for c++11?

由 这一生的挚爱 提交于 2019-11-26 01:39:35
问题 With the new range-based for loop we can write code like for(auto x: Y) {} Which IMO is a huge improvement from (for ex.) for(std::vector<int>::iterator x=Y.begin(); x!=Y.end(); ++x) {} Can it be used to loop over two simultaneous loops, like Pythons zip function? For those unfamiliar with Python, the code: Y1 = [1,2,3] Y2 = [4,5,6,7] for x1,x2 in zip(Y1,Y2): print x1,x2 Gives as output (1,4) (2,5) (3,6) 回答1: Warning: boost::zip_iterator and boost::combine as of Boost 1.63.0 (2016 Dec 26)

How to write the Fibonacci Sequence?

由 三世轮回 提交于 2019-11-25 22:28:32
问题 I had originally coded the program wrongly. Instead of returning the Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 should = only those numbers between 1 & 20), I have written for the program to display all Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 displays = First 20 Fibonacci numbers). I thought I had a sure-fire code. I also do not see why this is happening. startNumber = int(raw_input(\"Enter the start number here \")) endNumber = int(raw_input

Sequence-zip function for c++11?

由 断了今生、忘了曾经 提交于 2019-11-25 19:09:39
With the new range-based for loop we can write code like for(auto x: Y) {} Which IMO is a huge improvement from (for ex.) for(std::vector<int>::iterator x=Y.begin(); x!=Y.end(); ++x) {} Can it be used to loop over two simultaneous loops, like Pythons zip function? For those unfamiliar with Python, the code: Y1 = [1,2,3] Y2 = [4,5,6,7] for x1,x2 in zip(Y1,Y2): print x1,x2 Gives as output (1,4) (2,5) (3,6) Warning: boost::zip_iterator and boost::combine as of Boost 1.63.0 (2016 Dec 26) will cause undefined behavior if the length of the input containers are not the same (it may crash or iterate
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