Search Results

Search found 4640 results on 186 pages for 'unique'.

Page 72/186 | < Previous Page | 68 69 70 71 72 73 74 75 76 77 78 79  | Next Page >

  • Using a Linq-To-SQL class automagically generates the connection string for me; is there a way to ma

    - by Sergio Tapia
    I'm just beginning to use Linq-to-SQL and it's just wonderful to use. The problem is, this software is going to be run on a lot of machines and each machine will have a unique connection string. Is there a way for me to manually set the connection the Linq-to-SQL (.dbml) uses? The way I'm doing things now is creating the .dbml file, and in the graphic designer I'm dragging tables from the Server Explorer to the white board of the .dbml.

    Read the article

  • Create multiple modal windows with javascript (+jQuery), what is the best practice to indentify wind

    - by Kirzilla
    Hello, When creating every instance of Window object I should bind close button of each window to closing this window. But how should I identify windows? Should I create unique id for each Window instance or maybe another way? What is the best way to create such identifiers, maybe some kind of singleton object with id parameter which should be incremented each time when window is created? Thank you.

    Read the article

  • Generate money type fields using code first EF CTP5

    - by BBHorus
    In this blog post: EF4 Code First Control Unicode and Decimal Precision, Scale with Attributes, Dane Morgridge used attributes to control the creation of different types on your database. ...And I found this pretty unique BTW!!! How do I generate money type fields in my resulting database using code first API of EF CTP5, if is possible to do it from your model, using conventions or attributes? Sorry about my English is not my main language. Thanks in advance.

    Read the article

  • Searches (and general querying) with HBase and/or Cassandra (best practices?)

    - by alexeypro
    I have User model object with quite few fields (properties, if you wish) in it. Say "firstname", "lastname", "city" and "year-of-birth". Each user also gets "unique id". I want to be able to search by them. How do I do that properly? How to do that at all? My understanding (will work for pretty much any key-value storage -- first goes key, then value) u:123456789 = serialized_json_object ("u" as a simple prefix for user's keys, 123456789 is "unique id"). Now, thinking that I want to be able to search by firstname and lastname, I can save in: f:Steve = u:384734807,u:2398248764,u:23276263 f:Alex = u:12324355,u:121324334 so key is "f" - which is prefix for firstnames, and "Steve" is actual firstname. For "u:Steve" we save as value all user id's who are "Steve's". That makes every search very-very easy. Querying by few fields (properties) -- say by firstname (i.e. "Steve") and lastname (i.e. "l:Anything") is still easy - first get list of user ids from "f:Steve", then list from "l:Anything", find crossing user ids, an here you go. Problems (and there are quite a few): Saving, updating, deleting user is a pain. It has to be atomic and consistent operation. Also, if we have size of value limited to some value - then we are in (potential) trouble. And really not of an answer here. Only zipping the list of user ids? Not too cool, though. What id we want to add new field to search by. Eventually. Say by "city". We certainly can do the same way "c:Los Angeles" = ..., "c:Chicago" = ..., but if we didn't foresee all those "search choices" from the very beginning, then we will have to be able to create some night job or something to go by all existing User records and update those "c:CITY" for them... Quite a big job! Problems with locking. User "u:123" updates his name "Alex", and user "u:456" updates his name "Alex". They both have to update "f:Alex" with their id's. That means either we get into overwriting problem, or one update will wait for another (and imaging if there are many of them?!). What's the best way of doing that? Keeping in mind that I want to search by many fields? P.S. Please, the question is about HBase/Cassandra/NoSQL/Key-Value storages. Please please - no advices to use MySQL and "read about" SELECTs; and worry about scaling problems "later". There is a reason why I asked MY question exactly the way I did. :-)

    Read the article

  • Is there an equivalent of "OPTION(RECOMPILE)" or "WITH RECOMPILE" for an entire connection?

    - by kamens
    I'm curious. Is there any way to prevent SQL query execution plans from being cached for an entire connection's duration? Can I run a command that basically says, "use OPTION(RECOMPILE) for all subsequent commands until I tell you to stop doing so?" I'm acutely aware of all the performance trade-offs here, and I know this is not a step to be taken lightly. However, I'm in a unique situation where this behavior may be advantageous.

    Read the article

  • Is the Angular templateCache shared between apps? Is it persistent?

    - by alexp
    If I have two Angular apps that run on the same domain, will/can they share data in the templateCache? Or is the cache unique to each main application module? In general I'm trying to understand what dictates when a new templateCache is created. Furthermore I'm not clear on whether or in what way the templateCache is persistent? Looking in local storage and cookies, I don't see where anything is getting stored.

    Read the article

  • VSS Linked file's original location.

    - by Biju Joseph N
    A common file may be used in one more projects and such files will be shown as a linked file in VSS database. Actually such files are kept at a unique location within the database. Is there a way to get the original storage location of a linked file ?

    Read the article

  • Advantage of creating a generic repository vs. specific repository for each object?

    - by LuckyLindy
    We are developing an ASP.NET MVC application, and are now building the repository/service classes. I'm wondering if there are any major advantages to creating a generic IRepository interface that all repositories implement, vs. each Repository having its own unique interface and set of methods. For example: a generic IRepository interface might look like (taken from this answer): public interface IRepository : IDisposable { T[] GetAll<T>(); T[] GetAll<T>(Expression<Func<T, bool>> filter); T GetSingle<T>(Expression<Func<T, bool>> filter); T GetSingle<T>(Expression<Func<T, bool>> filter, List<Expression<Func<T, object>>> subSelectors); void Delete<T>(T entity); void Add<T>(T entity); int SaveChanges(); DbTransaction BeginTransaction(); } Each Repository would implement this interface (e.g. CustomerRepository:IRepository, ProductRepository:IRepository, etc). The alternate that we've followed in prior projects would be: public interface IInvoiceRepository : IDisposable { EntityCollection<InvoiceEntity> GetAllInvoices(int accountId); EntityCollection<InvoiceEntity> GetAllInvoices(DateTime theDate); InvoiceEntity GetSingleInvoice(int id, bool doFetchRelated); InvoiceEntity GetSingleInvoice(DateTime invoiceDate, int accountId); //unique InvoiceEntity CreateInvoice(); InvoiceLineEntity CreateInvoiceLine(); void SaveChanges(InvoiceEntity); //handles inserts or updates void DeleteInvoice(InvoiceEntity); void DeleteInvoiceLine(InvoiceLineEntity); } In the second case, the expressions (LINQ or otherwise) would be entirely contained in the Repository implementation, whoever is implementing the service just needs to know which repository function to call. I guess I don't see the advantage of writing all the expression syntax in the service class and passing to the repository. Wouldn't this mean easy-to-messup LINQ code is being duplicated in many cases? For example, in our old invoicing system, we call InvoiceRepository.GetSingleInvoice(DateTime invoiceDate, int accountId) from a few different services (Customer, Invoice, Account, etc). That seems much cleaner than writing the following in multiple places: rep.GetSingle(x => x.AccountId = someId && x.InvoiceDate = someDate.Date); The only disadvantage I see to using the specific approach is that we could end up with many permutations of Get* functions, but this still seems preferable to pushing the expression logic up into the Service classes. What am I missing?

    Read the article

  • Comparison of web template engines

    - by Mark
    Post a snippet of code from your favorite templating engine, with the name of the engine and a link to its homepage; show off its basic syntax and maybe some neat features about it that makes it unique. Hopefully this will give people an idea of what's out there and make it easier for them to decide on an engine.

    Read the article

  • ASP.NET MVC: customized design per domain

    - by Feryt
    Hi. I'm thinking about ASP.NET MVC 2 project which should display the same Domain Model(with different data) in different mark-up or page design(selected by url domain). I'm not sure which one ot these to use : set of views per unique domain + one default? use areas? any other idea? How would you do that? Thank you.

    Read the article

  • Are GUIDs the ultimate ID?

    - by mafutrct
    I noticed some people don't bother having the usual incremented number as ID but instead simply generate a GUID. The advantages include: Quick and easy No need to keep track of previous IDs Guaranteed to be unique even across machines without knowledge of each other Some disadvantages are: Possibly performance bottleneck Uses a large number of bytes My understanding is that using a GUID is beneficial in most cases, except if optimization for time or space is an issue. Did I miss something? Or do you agree with this idea?

    Read the article

  • How can one extract rdf:about or rdf:ID properties from triples using SPARQL?

    - by lennyks
    It seemed a trivial matter at the beginning but so far I have not managed to get the unique identifier for a given resource using SPARQL. What I mean is given, e.g., rdf:Description rdf:about="http://..." and then some properties identifying this resource, what I want to do is to first find this very resource and then retrieve all the triples given some URI. I have tried naïve approaches by writing statements in a WHERE clause such as: ?x rdf:about ?y and ?x rdfs:about ?y I hope I am being precise.

    Read the article

  • Printing Instance ID to NSLog?

    - by fuzzygoat
    In the dealloc method for a class how would I print out the ID (or some other unique identifier) for the instance being deallocated? - (void)dealloc { NSLog(@"_deallocing: ??"); [super dealloc]; } Is this possible? I am just trying to get a little more feedback in the console as an aid to learning. many thanks -gary-

    Read the article

  • convert perl map with multiple key to c++

    - by YY
    I want to convert a code from perl to c++, and my problem is multi key map in perl! example: perl: $address{name}{familyName} = $someAddress; and keys are not unique. I want similar data structure in c++ using map or ...!? also I want to search and obtain values with first key for example I want such %keys{name} in c++ .

    Read the article

  • SET game odds simulation (MATLAB)

    - by yuk
    Here is an interesting problem for your weekend. :) I recently find the great card came - SET. Briefly, there are 81 cards with the four features: symbol (oval, squiggle or diamond), color (red, purple or green), number (one, two or three) or shading (solid, striped or open). The task is to find (from selected 12 cards) a SET of 3 cards, in which each of the four features is either all the same on each card or all different on each card (no 2+1 combination). In my free time I've decided to code it in MATLAB to find a solution and to estimate odds of having a set in randomly selected cards. Here is the code: %% initialization K = 12; % cards to draw NF = 4; % number of features (usually 3 or 4) setallcards = unique(nchoosek(repmat(1:3,1,NF),NF),'rows'); % all cards: rows - cards, columns - features setallcomb = nchoosek(1:K,3); % index of all combinations of K cards by 3 %% test tic NIter=1e2; % number of test iterations setexists = 0; % test results holder % C = progress('init'); % if you have progress function from FileExchange for d = 1:NIter % C = progress(C,d/NIter); % cards for current test setdrawncardidx = randi(size(setallcards,1),K,1); setdrawncards = setallcards(setdrawncardidx,:); % find all sets in current test iteration for setcombidx = 1:size(setallcomb,1) setcomb = setdrawncards(setallcomb(setcombidx,:),:); if all(arrayfun(@(x) numel(unique(setcomb(:,x))), 1:NF)~=2) % test one combination setexists = setexists + 1; break % to find only the first set end end end fprintf('Set:NoSet = %g:%g = %g:1\n', setexists, NIter-setexists, setexists/(NIter-setexists)) toc 100-1000 iterations are fast, but be careful with more. One million iterations takes about 15 hours on my home computer. Anyway, with 12 cards and 4 features I've got around 13:1 of having a set. This is actually a problem. The instruction book said this number should be 33:1. And it was recently confirmed by Peter Norvig. He provides the Python code, but I didn't test it. So can you find an error?

    Read the article

  • JQuery Treeview causes browser crash with certain parameters

    - by IP
    I have the following code, which causes Chrome and Safari to crash (Aw Snap in Chrome) jQuery(".filetree").treeview({ animated: "fast", collapsed: true, unique: true, persist: "cookie", toggle: function() { } }); If I change it to this: jQuery(".filetree").treeview({ animated: "fast", toggle: function() { } }); It doesn't crash...any ideas?

    Read the article

  • INNER JOIN code calculated value with SELECT statement

    - by sp-1986
    I have the following stored procedure which will generate mon to sun and then creates a temp table with a series of 'weeks' (start and end weeks) : USE [test_staff] GO /****** Object: StoredProcedure [dbo].[sp_timesheets_all_staff_by_week_by_job_grouping_by_site] Script Date: 03/21/2012 09:04:49 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE PROCEDURE [dbo].[sp_timesheets_all_staff_by_week_by_job_grouping_by_site] ( @grouping_ref int, @week_ref int ) AS CREATE TABLE #WeeklyList ( Start_Week date, End_Week date, week_ref int --month_name date ) DECLARE @REPORT_DATE DATETIME, @WEEK_BEGINING VARCHAR(10) SELECT @REPORT_DATE = '2011-01-19T00:00:00' --SELECT @REPORT_DATE = GETDATE() -- should grab the date now. SELECT @WEEK_BEGINING = 'MONDAY' IF @WEEK_BEGINING = 'MONDAY' SET DATEFIRST 1 ELSE IF @WEEK_BEGINING = 'TUESDAY' SET DATEFIRST 2 ELSE IF @WEEK_BEGINING = 'WEDNESDAY' SET DATEFIRST 3 ELSE IF @WEEK_BEGINING = 'THURSDAY' SET DATEFIRST 4 ELSE IF @WEEK_BEGINING = 'FRIDAY' SET DATEFIRST 5 ELSE IF @WEEK_BEGINING = 'SATURDAY' SET DATEFIRST 6 ELSE IF @WEEK_BEGINING = 'SUNDAY' SET DATEFIRST 7 DECLARE @WEEK_START_DATE DATETIME, @WEEK_END_DATE DATETIME --GET THE WEEK START DATE SELECT @WEEK_START_DATE = @REPORT_DATE - (DATEPART(DW, @REPORT_DATE) - 1) --GET THE WEEK END DATE SELECT @WEEK_END_DATE = @REPORT_DATE + (7 - DATEPART(DW, @REPORT_DATE)) PRINT 'Week Start: ' + CONVERT(VARCHAR, @WEEK_START_DATE) PRINT 'Week End: ' + CONVERT(VARCHAR, @WEEK_END_DATE) DECLARE @Interval int = datediff(WEEK,getdate(),@WEEK_START_DATE)+1 --SELECT Start_Week=@WEEK_START_DATE --, End_Week=@WEEK_END_DATE --INTO #WeekList INSERT INTO #WeeklyList SELECT Start_Week=@WEEK_START_DATE, End_Week=@WEEK_END_DATE WHILE @Interval <= 0 BEGIN set @WEEK_START_DATE=DATEADD(WEEK,1,@WEEK_START_DATE) set @WEEK_END_DATE=DATEADD(WEEK,1,@WEEK_END_DATE) INSERT INTO #WeeklyList values (@WEEK_START_DATE,@WEEK_END_DATE) SET @Interval += 1; END SELECT CONVERT(VARCHAR(11), Start_Week, 106) AS 'month_name', CONVERT(VARCHAR(11), End_Week, 106) AS 'End', DATEDIFF(DAY, 0, Start_Week) / 7 AS week_ref -- create the unique week reference number --'VIEW' AS month_name FROM #WeeklyList In this section i am creating the week_ref DATEDIFF(DAY, 0, Start_Week) / 7 AS week_ref -- create the unique week reference number I then need to combine it with this select code: DECLARE @YearString char(3) = CONVERT(char(3), SUBSTRING(CONVERT(char(5), @week_ref), 1, 3)) DECLARE @MonthString char(2) = CONVERT(char(2), SUBSTRING(CONVERT(char(5), @week_ref), 4, 2)) --Convert: DECLARE @Year int = CONVERT(int, @YearString) + 1200 DECLARE @Month int = CONVERT(int, @MonthString) **--THIS FILTERS THE REPORT** SELECT ts.staff_member_ref, sm.common_name, sm.department_name, DATENAME(MONTH, ts.start_dtm) + ' ' + DATENAME(YEAR, ts.start_dtm) AS month_name, ts.timesheet_cat_ref, cat.desc_long AS timesheet_cat_desc, grps.grouping_ref, grps.description AS grouping_desc, ts.task_ref, tsks.task_code, tsks.description AS task_desc, ts.site_ref, sits.description AS site_desc, ts.site_ref AS Expr1, CASE WHEN ts .status = 0 THEN 'Pending' WHEN ts .status = 1 THEN 'Booked' WHEN ts .status = 2 THEN 'Approved' ELSE 'Invalid Status' END AS site_status, ts.booked_time AS booked_time_sum, start_dtm, CONVERT(varchar(20), start_dtm, 108) + ' ' + CONVERT(varchar(20), start_dtm, 103) AS start_dtm_text, booked_time, end_dtm, CONVERT(varchar(20), end_dtm, 108) + ' ' + CONVERT(varchar(20), end_dtm, 103) AS end_dtm_text FROM timesheets AS ts INNER JOIN timesheet_categories AS cat ON ts.timesheet_cat_ref = cat.timesheet_cat_ref INNER JOIN timesheet_tasks AS tsks ON ts.task_ref = tsks.task_ref INNER JOIN timesheet_task_groupings AS grps ON tsks.grouping_ref = grps.grouping_ref INNER JOIN timesheet_sites AS sits ON ts.site_ref = sits.site_ref INNER JOIN vw_staff_members AS sm ON ts.staff_member_ref = sm.staff_member_ref WHERE (ts.status IN (1, 2)) AND (cat.is_leave_category = 0) GROUP BY ts.staff_member_ref, sm.common_name, sm.department_name, DATENAME(MONTH, ts.start_dtm), DATENAME(YEAR, ts.start_dtm), ts.timesheet_cat_ref, cat.desc_long, grps.grouping_ref, grps.description, ts.status, ts.booked_time, ts.task_ref, tsks.task_code, tsks.description, ts.site_ref, sits.description, ts.start_dtm, ts.end_dtm ORDER BY sm.common_name, timesheet_cat_desc, tsks.task_code, site_desc DROP TABLE #WeeklyList GO I want to pass the week_ref into the SELECT statement (refer to comment - THIS FILTERS THE REPORT) but the problem is week_ref isnt a valid column as its derived by code. Any ideas?

    Read the article

  • problem with piping in my own implementation of shell

    - by codemax
    Hey guys, i am implementing my own shell. I want to involve piping. i searched here and i got a code. But it is not working.Can any one help me? this is my code #include <sys/types.h> #include <sys/wait.h> #include <sys/ipc.h> #include <fcntl.h> #include <unistd.h> #include <string.h> #include <iostream> #include <cstdlib> using namespace std; char temp1[81][81],temp2[81][81] ,*cmdptr1[40], *cmdptr2[40]; void process(char**,int); int arg_count, count; int arg_cnt[2]; int pip,tok; char input[81]; int fds[2]; void process( char* cmd[])//, int arg_count ) { pid_t pid; pid = fork(); //char path[81]; //getcwd(path,81); //strcat(path,"/"); //strcat(path,cmd[0]); if(pid < 0) { cout << "Fork Failed" << endl; exit(-1); } else if( pid == 0 ) { execvp( cmd[0] , cmd ); } else { wait(NULL); } } void pipe(char **cmd1, char**cmd2) { cout<<endl<<endl<<"in pipe"<<endl; for(int i=0 ; i<arg_cnt[0] ; i++) { cout<<cmdptr1[i]<<" "; } cout<<endl; for(int i=0 ; i<arg_cnt[1] ; i++) { cout<<cmdptr2[i]<<" "; } pipe(fds); if (fork() == 0 ) { dup2(fds[1], 1); close(fds[0]); close(fds[1]); process(cmd1); } if (fork() == 0) { dup2(fds[0], 0); close(fds[0]); close(fds[1]); process(cmd2); } close(fds[0]); close(fds[1]); wait(NULL); } void pipecommand(char** cmd1, char** cmd2) { cout<<endl<<endl; for(int i=0 ; i<arg_cnt[0] ; i++) { cout<<cmd1[i]<<" "; } cout<<endl; for(int i=0 ; i<arg_cnt[1] ; i++) { cout<<cmd2[i]<<" "; } int fds[2]; // file descriptors pipe(fds); // child process #1 if (fork() == 0) { // Reassign stdin to fds[0] end of pipe. dup2(fds[0], STDIN_FILENO); close(fds[1]); close(fds[0]); process(cmd2); // child process #2 if (fork() == 0) { // Reassign stdout to fds[1] end of pipe. dup2(fds[1], STDOUT_FILENO); close(fds[0]); close(fds[1]); // Execute the first command. process(cmd1); } wait(NULL); } close(fds[1]); close(fds[0]); wait(NULL); } void splitcommand1() { tok++; int k,done=0,no=0; arg_count = 0; for(int i=count ; input[i] != '\0' ; i++) { k=0; while(1) { count++; if(input[i] == ' ') { break; } if((input[i] == '\0')) { done = 1; break; } if(input[i] == '|') { pip = 1; done = 1; break; } temp1[arg_count][k++] = input[i++]; } temp1[arg_count][k++] = '\0'; arg_count++; if(done == 1) { break; } } for(int i=0 ; i<arg_count ; i++) { cmdptr1[i] = temp1[i]; } arg_cnt[tok] = arg_count; } void splitcommand2() { tok++; cout<<"count is :"<<count<<endl; int k,done=0,no=0; arg_count = 0; for(int i=count ; input[i] != '\0' ; i++) { k=0; while(1) { count++; if(input[i] == ' ') { break; } if((input[i] == '\0')) { done = 1; break; } if(input[i] == '|') { pip = 1; done = 1; cout<<"PIP"; break; } temp2[arg_count][k++] = input[i++]; } temp2[arg_count][k++] = '\0'; arg_count++; if(done == 1) { break; } } for(int i=0 ; i<arg_count ; i++) { cmdptr2[i] = temp2[i]; } arg_cnt[tok] = arg_count; } int main() { cout<<endl<<endl<<"Welcome to unique shell !!!!!!!!!!!"<<endl; tok=-1; while(1) { cout<<endl<<"***********UNIQUE**********"<<endl; cin.getline(input,81); count = 0,pip=0; splitcommand1(); if(pip == 1) { count++; splitcommand2(); } cout<<endl<<endl; if(strcmp(cmdptr1[0], "exit") == 0 ) { cout<<endl<<"EXITING UNIQUE SHELL"<<endl; exit(0); } //cout<<endl<<"Arg count is :"<<arg_count<<endl; if(pip == 1) { cout<<endl<<endl<<"in main :"; for(int i=0 ; i<arg_cnt[0] ; i++) { cout<<cmdptr1[i]<<" "; } cout<<endl; for(int i=0 ; i<arg_cnt[1] ; i++) { cout<<cmdptr2[i]<<" "; } pipe(cmdptr1, cmdptr2); } else { process (cmdptr1);//,arg_count); } } } I know it is not well coded. But try to help me :(

    Read the article

  • Tweet's xml format

    - by Anand Kulkarni
    I get ' top tweets ' from twitter as an RSS feed in xml format . There is a guid field in that xml format. There is a long 11 digit number at the end of guid field , is it unique for every tweet ?

    Read the article

  • PostgreSQL - fetch the row which has the Max value for a column

    - by Joshua Berry
    I'm dealing with a Postgres table (called "lives") that contains records with columns for time_stamp, usr_id, transaction_id, and lives_remaining. I need a query that will give me the most recent lives_remaining total for each usr_id There are multiple users (distinct usr_id's) time_stamp is not a unique identifier: sometimes user events (one by row in the table) will occur with the same time_stamp. trans_id is unique only for very small time ranges: over time it repeats remaining_lives (for a given user) can both increase and decrease over time example: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 07:00 | 1 | 1 | 1 09:00 | 4 | 2 | 2 10:00 | 2 | 3 | 3 10:00 | 1 | 2 | 4 11:00 | 4 | 1 | 5 11:00 | 3 | 1 | 6 13:00 | 3 | 3 | 1 As I will need to access other columns of the row with the latest data for each given usr_id, I need a query that gives a result like this: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 11:00 | 3 | 1 | 6 10:00 | 1 | 2 | 4 13:00 | 3 | 3 | 1 As mentioned, each usr_id can gain or lose lives, and sometimes these timestamped events occur so close together that they have the same timestamp! Therefore this query won't work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp) AS max_timestamp FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp = b.time_stamp Instead, I need to use both time_stamp (first) and trans_id (second) to identify the correct row. I also then need to pass that information from the subquery to the main query that will provide the data for the other columns of the appropriate rows. This is the hacked up query that I've gotten to work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp || '*' || trans_id) AS max_timestamp_transid FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp_transid = b.time_stamp || '*' || b.trans_id ORDER BY b.usr_id Okay, so this works, but I don't like it. It requires a query within a query, a self join, and it seems to me that it could be much simpler by grabbing the row that MAX found to have the largest timestamp and trans_id. The table "lives" has tens of millions of rows to parse, so I'd like this query to be as fast and efficient as possible. I'm new to RDBM and Postgres in particular, so I know that I need to make effective use of the proper indexes. I'm a bit lost on how to optimize. I found a similar discussion here. Can I perform some type of Postgres equivalent to an Oracle analytic function? Any advice on accessing related column information used by an aggregate function (like MAX), creating indexes, and creating better queries would be much appreciated! P.S. You can use the following to create my example case: create TABLE lives (time_stamp timestamp, lives_remaining integer, usr_id integer, trans_id integer); insert into lives values ('2000-01-01 07:00', 1, 1, 1); insert into lives values ('2000-01-01 09:00', 4, 2, 2); insert into lives values ('2000-01-01 10:00', 2, 3, 3); insert into lives values ('2000-01-01 10:00', 1, 2, 4); insert into lives values ('2000-01-01 11:00', 4, 1, 5); insert into lives values ('2000-01-01 11:00', 3, 1, 6); insert into lives values ('2000-01-01 13:00', 3, 3, 1);

    Read the article

  • help optimize sql query

    - by msony
    I have tracking table tbl_track with id, session_id, created_date fields I need count unique session_id for one day here what i got: select count(0) from ( select distinct session_id from tbl_track where created_date between getdate()-1 and getdate() group by session_id )tbl im feeling that it could be better solution for it

    Read the article

< Previous Page | 68 69 70 71 72 73 74 75 76 77 78 79  | Next Page >