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  • Method flags as arguments or as member variables?

    - by Martin
    I think the title "Method flags as arguments or as member variables?" may be suboptimal, but as I'm missing any better terminology atm., here goes: I'm currently trying to get my head around the problem of whether flags for a given class (private) method should be passed as function arguments or via member variable and/or whether there is some pattern or name that covers this aspect and/or whether this hints at some other design problems. By example (language could be C++, Java, C#, doesn't really matter IMHO): class Thingamajig { private ResultType DoInternalStuff(FlagType calcSelect) { ResultType res; for (... some loop condition ...) { ... if (calcSelect == typeA) { ... } else if (calcSelect == typeX) { ... } else if ... } ... return res; } private void InteralStuffInvoker(FlagType calcSelect) { ... DoInternalStuff(calcSelect); ... } public void DoThisStuff() { ... some code ... InternalStuffInvoker(typeA); ... some more code ... } public ResultType DoThatStuff() { ... some code ... ResultType x = DoInternalStuff(typeX); ... some more code ... further process x ... return x; } } What we see above is that the method InternalStuffInvoker takes an argument that is not used inside this function at all but is only forwarded to the other private method DoInternalStuff. (Where DoInternalStuffwill be used privately at other places in this class, e.g. in the DoThatStuff (public) method.) An alternative solution would be to add a member variable that carries this information: class Thingamajig { private ResultType DoInternalStuff() { ResultType res; for (... some loop condition ...) { ... if (m_calcSelect == typeA) { ... } ... } ... return res; } private void InteralStuffInvoker() { ... DoInternalStuff(); ... } public void DoThisStuff() { ... some code ... m_calcSelect = typeA; InternalStuffInvoker(); ... some more code ... } public ResultType DoThatStuff() { ... some code ... m_calcSelect = typeX; ResultType x = DoInternalStuff(); ... some more code ... further process x ... return x; } } Especially for deep call chains where the selector-flag for the inner method is selected outside, using a member variable can make the intermediate functions cleaner, as they don't need to carry a pass-through parameter. On the other hand, this member variable isn't really representing any object state (as it's neither set nor available outside), but is really a hidden additional argument for the "inner" private method. What are the pros and cons of each approach?

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  • How can you tell which columns are unused in ALL_TAB_COLS?

    - by thecoop
    When you query the ALL_TAB_COLS view on Oracle 9i, it lists columns marked as UNUSED as well as the 'active' table columns. There doesn't seem to be a field that explicitly says whether a column is UNUSED, or any view I can join to that lists the unused columns in a table. How can I easily find out which are the unused columns, so I can filter them out of ALL_TAB_COLS?

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  • Table Variables: an empirical approach.

    - by Phil Factor
    It isn’t entirely a pleasant experience to publish an article only to have it described on Twitter as ‘Horrible’, and to have it criticized on the MVP forum. When this happened to me in the aftermath of publishing my article on Temporary tables recently, I was taken aback, because these critics were experts whose views I respect. What was my crime? It was, I think, to suggest that, despite the obvious quirks, it was best to use Table Variables as a first choice, and to use local Temporary Tables if you hit problems due to these quirks, or if you were doing complex joins using a large number of rows. What are these quirks? Well, table variables have advantages if they are used sensibly, but this requires some awareness by the developer about the potential hazards and how to avoid them. You can be hit by a badly-performing join involving a table variable. Table Variables are a compromise, and this compromise doesn’t always work out well. Explicit indexes aren’t allowed on Table Variables, so one cannot use covering indexes or non-unique indexes. The query optimizer has to make assumptions about the data rather than using column distribution statistics when a table variable is involved in a join, because there aren’t any column-based distribution statistics on a table variable. It assumes a reasonably even distribution of data, and is likely to have little idea of the number of rows in the table variables that are involved in queries. However complex the heuristics that are used might be in determining the best way of executing a SQL query, and they most certainly are, the Query Optimizer is likely to fail occasionally with table variables, under certain circumstances, and produce a Query Execution Plan that is frightful. The experienced developer or DBA will be on the lookout for this sort of problem. In this blog, I’ll be expanding on some of the tests I used when writing my article to illustrate the quirks, and include a subsequent example supplied by Kevin Boles. A simplified example. We’ll start out by illustrating a simple example that shows some of these characteristics. We’ll create two tables filled with random numbers and then see how many matches we get between the two tables. We’ll forget indexes altogether for this example, and use heaps. We’ll try the same Join with two table variables, two table variables with OPTION (RECOMPILE) in the JOIN clause, and with two temporary tables. It is all a bit jerky because of the granularity of the timing that isn’t actually happening at the millisecond level (I used DATETIME). However, you’ll see that the table variable is outperforming the local temporary table up to 10,000 rows. Actually, even without a use of the OPTION (RECOMPILE) hint, it is doing well. What happens when your table size increases? The table variable is, from around 30,000 rows, locked into a very bad execution plan unless you use OPTION (RECOMPILE) to provide the Query Analyser with a decent estimation of the size of the table. However, if it has the OPTION (RECOMPILE), then it is smokin’. Well, up to 120,000 rows, at least. It is performing better than a Temporary table, and in a good linear fashion. What about mixed table joins, where you are joining a temporary table to a table variable? You’d probably expect that the query analyzer would throw up its hands and produce a bad execution plan as if it were a table variable. After all, it knows nothing about the statistics in one of the tables so how could it do any better? Well, it behaves as if it were doing a recompile. And an explicit recompile adds no value at all. (we just go up to 45000 rows since we know the bigger picture now)   Now, if you were new to this, you might be tempted to start drawing conclusions. Beware! We’re dealing with a very complex beast: the Query Optimizer. It can come up with surprises What if we change the query very slightly to insert the results into a Table Variable? We change nothing else and just measure the execution time of the statement as before. Suddenly, the table variable isn’t looking so much better, even taking into account the time involved in doing the table insert. OK, if you haven’t used OPTION (RECOMPILE) then you’re toast. Otherwise, there isn’t much in it between the Table variable and the temporary table. The table variable is faster up to 8000 rows and then not much in it up to 100,000 rows. Past the 8000 row mark, we’ve lost the advantage of the table variable’s speed. Any general rule you may be formulating has just gone for a walk. What we can conclude from this experiment is that if you join two table variables, and can’t use constraints, you’re going to need that Option (RECOMPILE) hint. Count Dracula and the Horror Join. These tables of integers provide a rather unreal example, so let’s try a rather different example, and get stuck into some implicit indexing, by using constraints. What unusual words are contained in the book ‘Dracula’ by Bram Stoker? Here we get a table of all the common words in the English language (60,387 of them) and put them in a table. We put them in a Table Variable with the word as a primary key, a Table Variable Heap and a Table Variable with a primary key. We then take all the distinct words used in the book ‘Dracula’ (7,558 of them). We then create a table variable and insert into it all those uncommon words that are in ‘Dracula’. i.e. all the words in Dracula that aren’t matched in the list of common words. To do this we use a left outer join, where the right-hand value is null. The results show a huge variation, between the sublime and the gorblimey. If both tables contain a Primary Key on the columns we join on, and both are Table Variables, it took 33 Ms. If one table contains a Primary Key, and the other is a heap, and both are Table Variables, it took 46 Ms. If both Table Variables use a unique constraint, then the query takes 36 Ms. If neither table contains a Primary Key and both are Table Variables, it took 116383 Ms. Yes, nearly two minutes!! If both tables contain a Primary Key, one is a Table Variables and the other is a temporary table, it took 113 Ms. If one table contains a Primary Key, and both are Temporary Tables, it took 56 Ms.If both tables are temporary tables and both have primary keys, it took 46 Ms. Here we see table variables which are joined on their primary key again enjoying a  slight performance advantage over temporary tables. Where both tables are table variables and both are heaps, the query suddenly takes nearly two minutes! So what if you have two heaps and you use option Recompile? If you take the rogue query and add the hint, then suddenly, the query drops its time down to 76 Ms. If you add unique indexes, then you've done even better, down to half that time. Here are the text execution plans.So where have we got to? Without drilling down into the minutiae of the execution plans we can begin to create a hypothesis. If you are using table variables, and your tables are relatively small, they are faster than temporary tables, but as the number of rows increases you need to do one of two things: either you need to have a primary key on the column you are using to join on, or else you need to use option (RECOMPILE) If you try to execute a query that is a join, and both tables are table variable heaps, you are asking for trouble, well- slow queries, unless you give the table hint once the number of rows has risen past a point (30,000 in our first example, but this varies considerably according to context). Kevin’s Skew In describing the table-size, I used the term ‘relatively small’. Kevin Boles produced an interesting case where a single-row table variable produces a very poor execution plan when joined to a very, very skewed table. In the original, pasted into my article as a comment, a column consisted of 100000 rows in which the key column was one number (1) . To this was added eight rows with sequential numbers up to 9. When this was joined to a single-tow Table Variable with a key of 2 it produced a bad plan. This problem is unlikely to occur in real usage, and the Query Optimiser team probably never set up a test for it. Actually, the skew can be slightly less extreme than Kevin made it. The following test showed that once the table had 54 sequential rows in the table, then it adopted exactly the same execution plan as for the temporary table and then all was well. Undeniably, real data does occasionally cause problems to the performance of joins in Table Variables due to the extreme skew of the distribution. We've all experienced Perfectly Poisonous Table Variables in real live data. As in Kevin’s example, indexes merely make matters worse, and the OPTION (RECOMPILE) trick does nothing to help. In this case, there is no option but to use a temporary table. However, one has to note that once the slight de-skew had taken place, then the plans were identical across a huge range. Conclusions Where you need to hold intermediate results as part of a process, Table Variables offer a good alternative to temporary tables when used wisely. They can perform faster than a temporary table when the number of rows is not great. For some processing with huge tables, they can perform well when only a clustered index is required, and when the nature of the processing makes an index seek very effective. Table Variables are scoped to the batch or procedure and are unlikely to hang about in the TempDB when they are no longer required. They require no explicit cleanup. Where the number of rows in the table is moderate, you can even use them in joins as ‘Heaps’, unindexed. Beware, however, since, as the number of rows increase, joins on Table Variable heaps can easily become saddled by very poor execution plans, and this must be cured either by adding constraints (UNIQUE or PRIMARY KEY) or by adding the OPTION (RECOMPILE) hint if this is impossible. Occasionally, the way that the data is distributed prevents the efficient use of Table Variables, and this will require using a temporary table instead. Tables Variables require some awareness by the developer about the potential hazards and how to avoid them. If you are not prepared to do any performance monitoring of your code or fine-tuning, and just want to pummel out stuff that ‘just runs’ without considering namby-pamby stuff such as indexes, then stick to Temporary tables. If you are likely to slosh about large numbers of rows in temporary tables without considering the niceties of processing just what is required and no more, then temporary tables provide a safer and less fragile means-to-an-end for you.

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  • Environment variables in Weblogic Managed Server with SSL nodemanager

    - by Eric Darchis
    We have a C legacy application start with JNI that requires environment variables. Not java -Djava.library.path -Dvar=foo as these are purely java. I need real environment variables. When we setup our domains, we usually use the SSH method to start the node managers. This works fine and the env variables are set properly. Recently the sysadmin has decided for a few reasons to use the SSL mode for nodemanagers. The servers start but the environment variables are not set. I checked with "pargs -e" (this is a Solaris machine) that the env variable was indeed not present from the nodemanager and for the managed server. Is SSL starting the managed server without running the .sh scripts or I am missing a parameter somewhere ?

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  • Placement of Variables in Puppet module

    - by Michael Duffy
    Hi guys; I've got a puppet module to setup several Gigaspaces PU's. Each of these have quite a few variables to be placed within the configuration file templates. We're also using several different environments so these variables are repeated several times to contain the values for each environment. My question is where the best place to store these variables would be? A class of their own, an external .pp I import, or something other?

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  • cannot unset env variables from script

    - by w00t
    Hi, I am trying to unset all environment variables from within a script. The script runs fine but if I run env it still shows all the variables set. If I run the command from CLI, it works and the variables are unset. unset `env | awk -F= '/^\w/ {print $1}' | xargs` Have any idea how to run this from a script? Also, have any idea how to source /etc/profile from a script? This doesn't work either. I need to set variables with same names but different paths, depending on the instances my users need.

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  • How do you use environment variables, such as %CommonProgramFiles%, in the PATH and have them recogn

    - by Brad Knowles
    I'm trying to add C:\Program Files\Common Files\xxx\xxx to the system PATH environment variable by appending %CommonProgramFiles%\xxx\xxx to the existing path. After rebooting, I open a command prompt and check the PATH. It expands correctly. However, when using Process Explorer from Sysinternals to view the Environment variables on services.exe, it shows the unexpanded version. Coincidentally, the paths using %SystemRoot% expand and are recognized just fine. I've tried altering the PATH through the Environment Variables window from System Properties and through direct Registry manipulation, neither seems to work. Is it possible to use other environment variables, besides %SystemRoot% in PATH and have services.exe understand it?

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  • "service"-command and environment variables

    - by varesa
    I am trying to start a service that requires a env. variable to be set to certain path. I set this variable in "/etc/profile.d/". However when I start this service using the service command, it doesn't work. man service: service runs a System V init script in as predictable environment as possible, removing most environment variables and with current working directory set to /. So it seems that service is removing my variables. How should I set the variables up to keep them from being removed. Or is that something i should not do. I could start the service manually using the init-scripts, or even hardcode the path into the script, but I'd like to know how to use it with the service command.

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  • perl: Run remote perl script through SSH and query environment variables on remote machine

    - by kakyo
    I'm running a perl script through SSH, in the perl script I query environment variables using $ENV{MY_VAR_NAME} and it works fine when run locally. But through SSH, all environment variables become unset. I also tried to run system("source ~/.bash_profile"); at the beginning of my script to no avail. Any tips? EDIT: Rephrasing my question. I have machine A and B. I ran my perl on machine B, trying to get the environment variables on B and it worked. Then I ssh from A to B running the same script, i.e., using this code ssh user@B perl myscript.pl This time the environment variables on B are all blank. Any tips? UPDATE: I found that running the above script, ~/.bashrc on Machine B was invoked, but after setting environment variables in ~/.bashrc, run the above command again and still I don't see any environment variables. Also, if my perl script contains only echo $ENV{PATH} Then I get /usr/bin:/bin:/usr/sbin:/sbin

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  • Alternative ways of setting environment variables through PuTTy?

    - by A T
    Connecting via SSH to a SPARC server but am unable to set environmental variables through the usual PuTTy way, which gives me this error: Server refused to set environment variables I also noticed that export and set techniques don't work from the prompt; the only which works is: $ PATH=/everyones_passwords_in_plain_text/:$PATH How do I automatically run that line on every connect to this server?

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  • APPDATA and LOCALAPPDATA environment variables are not set on a profile in Windows 7 Pro 32bit

    - by Timur Fanshteyn
    I am having problem with a user account on a Windows 7 machine (local install, admin user account) APPDATA and LOCALAPPDATA environment are not set. Another user on the same machine, (also a local account, but without admin rights) has the variables set. This started to happen recently, however, I can not figure out if there was something installed on the machine to cause this. This is creating issues with applications that are trying to expand the variables to store local files. Thank you for the help.

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  • How to set environment variables for Xfce windowing environment

    - by GreenMatt
    We're using Ubuntu 12.04.1 with Xfce 4.8. We have a script which sets environment variables needed by our software. In the past, I figured out how to run this script in the Xfce start up so that these environment variables are set up and available to gui based programs launched via icons. Recently an OS upgrade wiped out this setting and I can't remember or find how to do this. I've tried sourcing the script from ~/.profile, ~/.xinitrc, and ~/.config/xfce4/xinitrc, but no luck.

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  • APPPATH and LOCALAPPPATH environment variables are not set on a profile in Windows 7 Pro 32bit

    - by Timur Fanshteyn
    I am having problem with a user account on a Windows 7 machine (local install, admin user account) APPPATH and LOCALAPPPATH environment are not set. Another user on the same machine, (also a local account, but without admin rights) has the variables set. This started to happen recently, however, I can not figure out if there was something installed on the machine to cause this. This is creating issues with applications that are trying to expand the variables to store local files. Thank you for the help.

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  • Is it possible to get all member variables in flash(AS3)?

    - by Parris
    Hi, I am trying grab all the member variables in AS3, and then foreach one i would like to process it in various ways. I would need the name and then if it is a collection of some type I would like to loop through that collection as well. I am attempting to essentially serialize in a somewhat custom fashion. Thanks!

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  • How to remove unused usings from class file ?

    - by Samir R. Bhogayta
    When we create a .cs file means code file class is automatically create. That .cs file means class has default usings for namespace. using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls; We don't use all namespaces  in that class so we have to remove unused namespaces from file. We can remove  namespace manually but it takes time and need full knowledge of class library so we can use Visual Studio . Step 1:  Right Click in .cs File. Step 2:  Move on Organize usings. Step 3: Click on Remove Unused Usings. After that we have only those namespaces in the file these are using.  

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  • How to clean unused app files

    - by Ando
    I've finished working on a web app and looking back at the process, I can see that a lot of extra files have been accumulated - backup css, php files, javascripts, images. I'm using an MVC workflow (codeigniter) and I would like to clean the app from unused files. There are also libraries which I've downloaded but referenced some of the files in my code, yet I've kept the unused files too. Total mess really, I'll take a note for the next app to become more organized. There is also a fair security concern regarding these sorts of situations, plus I think that it would be better to omit all the extra files when search engines are indexing the app. Has anyone been in that situation and what is the safest/fastest way to clean the app? My setup: MVC Codeigniter - Netbeans - Mac

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  • Saving Variables In An ASP Page

    - by Or Betzalel
    I'm trying to convert a game I made (WindowsFormApplication) to an ASP Page. My Problem is that I have a lot "private" variables in my WindowFormApplication and those variables are important for the game. But when after I Declare all my variables (in my Page_Load), they turn null no matter what I do(click a button, refresh the page). Is there anyway to save my variables between buttons (other than Session, because I'd have to create like 6 more sessions)

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  • MATLAB: Automatic detection of relations between workspace variables through functions

    - by Peterstone
    Hi all, I´m trying to write a function what detect this relation between the variables I have got in the workspace: v1 - fft(v2) = 0 Where v1, v2 are variables of my workspace. Sometimes I need to know which variables have a certain numerical relation. If I have thirty, I don´t want to be looking for this relation in "manual way", just itroducing a sentence for each pair of different variables. I would like a function in which I introuce (or I modify this function every time I need it) the sentence (for instance what I wrote before) and the function show me the pair of variables a I am looking for. Does anyone know how to do it? Thank you so much!

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  • Prolog singleton variables in Python

    - by Rubens
    I'm working on a little set of scripts in python, and I came to this: line = "a b c d e f g" a, b, c, d, e, f, g = line.split() I'm quite aware of the fact that these are decisions taken during implementation, but shouldn't (or does) python offer something like: _, _, var_needed, _, _, another_var_needed, _ = line.split() as well as Prolog does offer, in order to exclude the famous singleton variables. I'm not sure, but wouldn't it avoid unnecessary allocation? Or creating references to the result of the split call does not count up as overhead? EDIT: Sorry, my point here is: in Prolog, as far as I'm concerned, in an expression like: test(L, N) :- test(L, 0, N). test([], N, N). test([_|T], M, N) :- V is M + 1, test(T, V, N). The variable represented by _ is not accessible, for what I suppose the reference to the value that does exist in the list [_|T] is not even created. But, in Python, if I use _, I can use the last value assigned to _, and also, I do suppose the assignment occurs for each of the variables _ -- which may be considered an overhead. My question here is if shouldn't there be (or if there is) a syntax to avoid such unnecessary attributions.

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