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  • Taming Hopping Windows

    - by Roman Schindlauer
    At first glance, hopping windows seem fairly innocuous and obvious. They organize events into windows with a simple periodic definition: the windows have some duration d (e.g. a window covers 5 second time intervals), an interval or period p (e.g. a new window starts every 2 seconds) and an alignment a (e.g. one of those windows starts at 12:00 PM on March 15, 2012 UTC). var wins = xs     .HoppingWindow(TimeSpan.FromSeconds(5),                    TimeSpan.FromSeconds(2),                    new DateTime(2012, 3, 15, 12, 0, 0, DateTimeKind.Utc)); Logically, there is a window with start time a + np and end time a + np + d for every integer n. That’s a lot of windows. So why doesn’t the following query (always) blow up? var query = wins.Select(win => win.Count()); A few users have asked why StreamInsight doesn’t produce output for empty windows. Primarily it’s because there is an infinite number of empty windows! (Actually, StreamInsight uses DateTimeOffset.MaxValue to approximate “the end of time” and DateTimeOffset.MinValue to approximate “the beginning of time”, so the number of windows is lower in practice.) That was the good news. Now the bad news. Events also have duration. Consider the following simple input: var xs = this.Application                 .DefineEnumerable(() => new[]                     { EdgeEvent.CreateStart(DateTimeOffset.UtcNow, 0) })                 .ToStreamable(AdvanceTimeSettings.IncreasingStartTime); Because the event has no explicit end edge, it lasts until the end of time. So there are lots of non-empty windows if we apply a hopping window to that single event! For this reason, we need to be careful with hopping window queries in StreamInsight. Or we can switch to a custom implementation of hopping windows that doesn’t suffer from this shortcoming. The alternate window implementation produces output only when the input changes. We start by breaking up the timeline into non-overlapping intervals assigned to each window. In figure 1, six hopping windows (“Windows”) are assigned to six intervals (“Assignments”) in the timeline. Next we take input events (“Events”) and alter their lifetimes (“Altered Events”) so that they cover the intervals of the windows they intersect. In figure 1, you can see that the first event e1 intersects windows w1 and w2 so it is adjusted to cover assignments a1 and a2. Finally, we can use snapshot windows (“Snapshots”) to produce output for the hopping windows. Notice however that instead of having six windows generating output, we have only four. The first and second snapshots correspond to the first and second hopping windows. The remaining snapshots however cover two hopping windows each! While in this example we saved only two events, the savings can be more significant when the ratio of event duration to window duration is higher. Figure 1: Timeline The implementation of this strategy is straightforward. We need to set the start times of events to the start time of the interval assigned to the earliest window including the start time. Similarly, we need to modify the end times of events to the end time of the interval assigned to the latest window including the end time. The following snap-to-boundary function that rounds a timestamp value t down to the nearest value t' <= t such that t' is a + np for some integer n will be useful. For convenience, we will represent both DateTime and TimeSpan values using long ticks: static long SnapToBoundary(long t, long a, long p) {     return t - ((t - a) % p) - (t > a ? 0L : p); } How do we find the earliest window including the start time for an event? It’s the window following the last window that does not include the start time assuming that there are no gaps in the windows (i.e. duration < interval), and limitation of this solution. To find the end time of that antecedent window, we need to know the alignment of window ends: long e = a + (d % p); Using the window end alignment, we are finally ready to describe the start time selector: static long AdjustStartTime(long t, long e, long p) {     return SnapToBoundary(t, e, p) + p; } To find the latest window including the end time for an event, we look for the last window start time (non-inclusive): public static long AdjustEndTime(long t, long a, long d, long p) {     return SnapToBoundary(t - 1, a, p) + p + d; } Bringing it together, we can define the translation from events to ‘altered events’ as in Figure 1: public static IQStreamable<T> SnapToWindowIntervals<T>(IQStreamable<T> source, TimeSpan duration, TimeSpan interval, DateTime alignment) {     if (source == null) throw new ArgumentNullException("source");     // reason about DateTime and TimeSpan in ticks     long d = Math.Min(DateTime.MaxValue.Ticks, duration.Ticks);     long p = Math.Min(DateTime.MaxValue.Ticks, Math.Abs(interval.Ticks));     // set alignment to earliest possible window     var a = alignment.ToUniversalTime().Ticks % p;     // verify constraints of this solution     if (d <= 0L) { throw new ArgumentOutOfRangeException("duration"); }     if (p == 0L || p > d) { throw new ArgumentOutOfRangeException("interval"); }     // find the alignment of window ends     long e = a + (d % p);     return source.AlterEventLifetime(         evt => ToDateTime(AdjustStartTime(evt.StartTime.ToUniversalTime().Ticks, e, p)),         evt => ToDateTime(AdjustEndTime(evt.EndTime.ToUniversalTime().Ticks, a, d, p)) -             ToDateTime(AdjustStartTime(evt.StartTime.ToUniversalTime().Ticks, e, p))); } public static DateTime ToDateTime(long ticks) {     // just snap to min or max value rather than under/overflowing     return ticks < DateTime.MinValue.Ticks         ? new DateTime(DateTime.MinValue.Ticks, DateTimeKind.Utc)         : ticks > DateTime.MaxValue.Ticks         ? new DateTime(DateTime.MaxValue.Ticks, DateTimeKind.Utc)         : new DateTime(ticks, DateTimeKind.Utc); } Finally, we can describe our custom hopping window operator: public static IQWindowedStreamable<T> HoppingWindow2<T>(     IQStreamable<T> source,     TimeSpan duration,     TimeSpan interval,     DateTime alignment) {     if (source == null) { throw new ArgumentNullException("source"); }     return SnapToWindowIntervals(source, duration, interval, alignment).SnapshotWindow(); } By switching from HoppingWindow to HoppingWindow2 in the following example, the query returns quickly rather than gobbling resources and ultimately failing! public void Main() {     var start = new DateTimeOffset(new DateTime(2012, 6, 28), TimeSpan.Zero);     var duration = TimeSpan.FromSeconds(5);     var interval = TimeSpan.FromSeconds(2);     var alignment = new DateTime(2012, 3, 15, 12, 0, 0, DateTimeKind.Utc);     var events = this.Application.DefineEnumerable(() => new[]     {         EdgeEvent.CreateStart(start.AddSeconds(0), "e0"),         EdgeEvent.CreateStart(start.AddSeconds(1), "e1"),         EdgeEvent.CreateEnd(start.AddSeconds(1), start.AddSeconds(2), "e1"),         EdgeEvent.CreateStart(start.AddSeconds(3), "e2"),         EdgeEvent.CreateStart(start.AddSeconds(9), "e3"),         EdgeEvent.CreateEnd(start.AddSeconds(3), start.AddSeconds(10), "e2"),         EdgeEvent.CreateEnd(start.AddSeconds(9), start.AddSeconds(10), "e3"),     }).ToStreamable(AdvanceTimeSettings.IncreasingStartTime);     var adjustedEvents = SnapToWindowIntervals(events, duration, interval, alignment);     var query = from win in HoppingWindow2(events, duration, interval, alignment)                 select win.Count();     DisplayResults(adjustedEvents, "Adjusted Events");     DisplayResults(query, "Query"); } As you can see, instead of producing a massive number of windows for the open start edge e0, a single window is emitted from 12:00:15 AM until the end of time: Adjusted Events StartTime EndTime Payload 6/28/2012 12:00:01 AM 12/31/9999 11:59:59 PM e0 6/28/2012 12:00:03 AM 6/28/2012 12:00:07 AM e1 6/28/2012 12:00:05 AM 6/28/2012 12:00:15 AM e2 6/28/2012 12:00:11 AM 6/28/2012 12:00:15 AM e3 Query StartTime EndTime Payload 6/28/2012 12:00:01 AM 6/28/2012 12:00:03 AM 1 6/28/2012 12:00:03 AM 6/28/2012 12:00:05 AM 2 6/28/2012 12:00:05 AM 6/28/2012 12:00:07 AM 3 6/28/2012 12:00:07 AM 6/28/2012 12:00:11 AM 2 6/28/2012 12:00:11 AM 6/28/2012 12:00:15 AM 3 6/28/2012 12:00:15 AM 12/31/9999 11:59:59 PM 1 Regards, The StreamInsight Team

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  • Taming Hopping Windows

    - by Roman Schindlauer
    At first glance, hopping windows seem fairly innocuous and obvious. They organize events into windows with a simple periodic definition: the windows have some duration d (e.g. a window covers 5 second time intervals), an interval or period p (e.g. a new window starts every 2 seconds) and an alignment a (e.g. one of those windows starts at 12:00 PM on March 15, 2012 UTC). var wins = xs     .HoppingWindow(TimeSpan.FromSeconds(5),                    TimeSpan.FromSeconds(2),                    new DateTime(2012, 3, 15, 12, 0, 0, DateTimeKind.Utc)); Logically, there is a window with start time a + np and end time a + np + d for every integer n. That’s a lot of windows. So why doesn’t the following query (always) blow up? var query = wins.Select(win => win.Count()); A few users have asked why StreamInsight doesn’t produce output for empty windows. Primarily it’s because there is an infinite number of empty windows! (Actually, StreamInsight uses DateTimeOffset.MaxValue to approximate “the end of time” and DateTimeOffset.MinValue to approximate “the beginning of time”, so the number of windows is lower in practice.) That was the good news. Now the bad news. Events also have duration. Consider the following simple input: var xs = this.Application                 .DefineEnumerable(() => new[]                     { EdgeEvent.CreateStart(DateTimeOffset.UtcNow, 0) })                 .ToStreamable(AdvanceTimeSettings.IncreasingStartTime); Because the event has no explicit end edge, it lasts until the end of time. So there are lots of non-empty windows if we apply a hopping window to that single event! For this reason, we need to be careful with hopping window queries in StreamInsight. Or we can switch to a custom implementation of hopping windows that doesn’t suffer from this shortcoming. The alternate window implementation produces output only when the input changes. We start by breaking up the timeline into non-overlapping intervals assigned to each window. In figure 1, six hopping windows (“Windows”) are assigned to six intervals (“Assignments”) in the timeline. Next we take input events (“Events”) and alter their lifetimes (“Altered Events”) so that they cover the intervals of the windows they intersect. In figure 1, you can see that the first event e1 intersects windows w1 and w2 so it is adjusted to cover assignments a1 and a2. Finally, we can use snapshot windows (“Snapshots”) to produce output for the hopping windows. Notice however that instead of having six windows generating output, we have only four. The first and second snapshots correspond to the first and second hopping windows. The remaining snapshots however cover two hopping windows each! While in this example we saved only two events, the savings can be more significant when the ratio of event duration to window duration is higher. Figure 1: Timeline The implementation of this strategy is straightforward. We need to set the start times of events to the start time of the interval assigned to the earliest window including the start time. Similarly, we need to modify the end times of events to the end time of the interval assigned to the latest window including the end time. The following snap-to-boundary function that rounds a timestamp value t down to the nearest value t' <= t such that t' is a + np for some integer n will be useful. For convenience, we will represent both DateTime and TimeSpan values using long ticks: static long SnapToBoundary(long t, long a, long p) {     return t - ((t - a) % p) - (t > a ? 0L : p); } How do we find the earliest window including the start time for an event? It’s the window following the last window that does not include the start time assuming that there are no gaps in the windows (i.e. duration < interval), and limitation of this solution. To find the end time of that antecedent window, we need to know the alignment of window ends: long e = a + (d % p); Using the window end alignment, we are finally ready to describe the start time selector: static long AdjustStartTime(long t, long e, long p) {     return SnapToBoundary(t, e, p) + p; } To find the latest window including the end time for an event, we look for the last window start time (non-inclusive): public static long AdjustEndTime(long t, long a, long d, long p) {     return SnapToBoundary(t - 1, a, p) + p + d; } Bringing it together, we can define the translation from events to ‘altered events’ as in Figure 1: public static IQStreamable<T> SnapToWindowIntervals<T>(IQStreamable<T> source, TimeSpan duration, TimeSpan interval, DateTime alignment) {     if (source == null) throw new ArgumentNullException("source");     // reason about DateTime and TimeSpan in ticks     long d = Math.Min(DateTime.MaxValue.Ticks, duration.Ticks);     long p = Math.Min(DateTime.MaxValue.Ticks, Math.Abs(interval.Ticks));     // set alignment to earliest possible window     var a = alignment.ToUniversalTime().Ticks % p;     // verify constraints of this solution     if (d <= 0L) { throw new ArgumentOutOfRangeException("duration"); }     if (p == 0L || p > d) { throw new ArgumentOutOfRangeException("interval"); }     // find the alignment of window ends     long e = a + (d % p);     return source.AlterEventLifetime(         evt => ToDateTime(AdjustStartTime(evt.StartTime.ToUniversalTime().Ticks, e, p)),         evt => ToDateTime(AdjustEndTime(evt.EndTime.ToUniversalTime().Ticks, a, d, p)) -             ToDateTime(AdjustStartTime(evt.StartTime.ToUniversalTime().Ticks, e, p))); } public static DateTime ToDateTime(long ticks) {     // just snap to min or max value rather than under/overflowing     return ticks < DateTime.MinValue.Ticks         ? new DateTime(DateTime.MinValue.Ticks, DateTimeKind.Utc)         : ticks > DateTime.MaxValue.Ticks         ? new DateTime(DateTime.MaxValue.Ticks, DateTimeKind.Utc)         : new DateTime(ticks, DateTimeKind.Utc); } Finally, we can describe our custom hopping window operator: public static IQWindowedStreamable<T> HoppingWindow2<T>(     IQStreamable<T> source,     TimeSpan duration,     TimeSpan interval,     DateTime alignment) {     if (source == null) { throw new ArgumentNullException("source"); }     return SnapToWindowIntervals(source, duration, interval, alignment).SnapshotWindow(); } By switching from HoppingWindow to HoppingWindow2 in the following example, the query returns quickly rather than gobbling resources and ultimately failing! public void Main() {     var start = new DateTimeOffset(new DateTime(2012, 6, 28), TimeSpan.Zero);     var duration = TimeSpan.FromSeconds(5);     var interval = TimeSpan.FromSeconds(2);     var alignment = new DateTime(2012, 3, 15, 12, 0, 0, DateTimeKind.Utc);     var events = this.Application.DefineEnumerable(() => new[]     {         EdgeEvent.CreateStart(start.AddSeconds(0), "e0"),         EdgeEvent.CreateStart(start.AddSeconds(1), "e1"),         EdgeEvent.CreateEnd(start.AddSeconds(1), start.AddSeconds(2), "e1"),         EdgeEvent.CreateStart(start.AddSeconds(3), "e2"),         EdgeEvent.CreateStart(start.AddSeconds(9), "e3"),         EdgeEvent.CreateEnd(start.AddSeconds(3), start.AddSeconds(10), "e2"),         EdgeEvent.CreateEnd(start.AddSeconds(9), start.AddSeconds(10), "e3"),     }).ToStreamable(AdvanceTimeSettings.IncreasingStartTime);     var adjustedEvents = SnapToWindowIntervals(events, duration, interval, alignment);     var query = from win in HoppingWindow2(events, duration, interval, alignment)                 select win.Count();     DisplayResults(adjustedEvents, "Adjusted Events");     DisplayResults(query, "Query"); } As you can see, instead of producing a massive number of windows for the open start edge e0, a single window is emitted from 12:00:15 AM until the end of time: Adjusted Events StartTime EndTime Payload 6/28/2012 12:00:01 AM 12/31/9999 11:59:59 PM e0 6/28/2012 12:00:03 AM 6/28/2012 12:00:07 AM e1 6/28/2012 12:00:05 AM 6/28/2012 12:00:15 AM e2 6/28/2012 12:00:11 AM 6/28/2012 12:00:15 AM e3 Query StartTime EndTime Payload 6/28/2012 12:00:01 AM 6/28/2012 12:00:03 AM 1 6/28/2012 12:00:03 AM 6/28/2012 12:00:05 AM 2 6/28/2012 12:00:05 AM 6/28/2012 12:00:07 AM 3 6/28/2012 12:00:07 AM 6/28/2012 12:00:11 AM 2 6/28/2012 12:00:11 AM 6/28/2012 12:00:15 AM 3 6/28/2012 12:00:15 AM 12/31/9999 11:59:59 PM 1 Regards, The StreamInsight Team

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  • Many user stories share the same technical tasks: what to do?

    - by d3prok
    A little introduction to my case: As part of a bigger product, my team is asked to realize a small IDE for a DSL. The user of this product will be able to make function calls in the code and we are also asked to provide some useful function libraries. The team, together with the PO, put on the wall a certain number of user stories regarding the various libraries for the IDE user. When estimating the first of those stories, the team decided that the function call mechanism would have been an engaging but not completely obvious task, so the estimate for that user story raised up from a simple 3 to a more dangerous 5. Coming to the problem: The team then moved to the user stories regarding the other libraries, actually 10 stories, and added those 2 points of "function call mechanism" thing to each of those user story. This immediately raised up the total points for the product of 20 points! Everyone in the team knows that each user story could be picked up by the PO for the next iteration at any time, so we shouldn't isolate that part in one user story, but those 20 points feel so awfully unrealistic! I've proposed a solution, but I'm absolutely not satisfied: We created a "Design story" and put those annoying 2 points over it. However when we came to realize and demonstrate it to our customers, we were unable to show something really valuable for them about that story! Here the problem is whether we should ignore the principle of having isolated user stories (without any dependency between them). What would you do, or even better what have you done, in situations like this? (a small foot-note: following a suggestion I've moved this question from stackoverflow)

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  • SQL SERVER – Signal Wait Time Introduction with Simple Example – Wait Type – Day 2 of 28

    - by pinaldave
    In this post, let’s delve a bit more in depth regarding wait stats. The very first question: when do the wait stats occur? Here is the simple answer. When SQL Server is executing any task, and if for any reason it has to wait for resources to execute the task, this wait is recorded by SQL Server with the reason for the delay. Later on we can analyze these wait stats to understand the reason the task was delayed and maybe we can eliminate the wait for SQL Server. It is not always possible to remove the wait type 100%, but there are few suggestions that can help. Before we continue learning about wait types and wait stats, we need to understand three important milestones of the query life-cycle. Running - a query which is being executed on a CPU is called a running query. This query is responsible for CPU time. Runnable – a query which is ready to execute and waiting for its turn to run is called a runnable query. This query is responsible for Signal Wait time. (In other words, the query is ready to run but CPU is servicing another query). Suspended – a query which is waiting due to any reason (to know the reason, we are learning wait stats) to be converted to runnable is suspended query. This query is responsible for wait time. (In other words, this is the time we are trying to reduce). In simple words, query execution time is a summation of the query Executing CPU Time (Running) + Query Wait Time (Suspended) + Query Signal Wait Time (Runnable). Again, it may be possible a query goes to all these stats multiple times. Let us try to understand the whole thing with a simple analogy of a taxi and a passenger. Two friends, Tom and Danny, go to the mall together. When they leave the mall, they decide to take a taxi. Tom and Danny both stand in the line waiting for their turn to get into the taxi. This is the Signal Wait Time as they are ready to get into the taxi but the taxis are currently serving other customer and they have to wait for their turn. In other word they are in a runnable state. Now when it is their turn to get into the taxi, the taxi driver informs them he does not take credit cards and only cash is accepted. Neither Tom nor Danny have enough cash, they both cannot get into the vehicle. Tom waits outside in the queue and Danny goes to ATM to fetch the cash. During this time the taxi cannot wait, they have to let other passengers get into the taxi. As Tom and Danny both are outside in the queue, this is the Query Wait Time and they are in the suspended state. They cannot do anything till they get the cash. Once Danny gets the cash, they are both standing in the line again, creating one more Signal Wait Time. This time when their turn comes they can pay the taxi driver in cash and reach their destination. The time taken for the taxi to get from the mall to the destination is running time (CPU time) and the taxi is running. I hope this analogy is bit clear with the wait stats. You can check the Signalwait stats using following query of Glenn Berry. -- Signal Waits for instance SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%signal (cpu) waits], CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%resource waits] FROM sys.dm_os_wait_stats OPTION (RECOMPILE); Higher the Signal wait stats are not good for the system. Very high value indicates CPU pressure. In my experience, when systems are running smooth and without any glitch the Signal wait stat is lower than 20%. Again, this number can be debated (and it is from my experience and is not documented anywhere). In other words, lower is better and higher is not good for the system. In future articles we will discuss in detail the various wait types and wait stats and their resolution. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Single Wait Time Introduction with Simple Example – Wait Type – Day 2 of 28

    - by pinaldave
    In this post, let’s delve a bit more in depth regarding wait stats. The very first question: when do the wait stats occur? Here is the simple answer. When SQL Server is executing any task, and if for any reason it has to wait for resources to execute the task, this wait is recorded by SQL Server with the reason for the delay. Later on we can analyze these wait stats to understand the reason the task was delayed and maybe we can eliminate the wait for SQL Server. It is not always possible to remove the wait type 100%, but there are few suggestions that can help. Before we continue learning about wait types and wait stats, we need to understand three important milestones of the query life-cycle. Running - a query which is being executed on a CPU is called a running query. This query is responsible for CPU time. Runnable – a query which is ready to execute and waiting for its turn to run is called a runnable query. This query is responsible for Single Wait time. (In other words, the query is ready to run but CPU is servicing another query). Suspended – a query which is waiting due to any reason (to know the reason, we are learning wait stats) to be converted to runnable is suspended query. This query is responsible for wait time. (In other words, this is the time we are trying to reduce). In simple words, query execution time is a summation of the query Executing CPU Time (Running) + Query Wait Time (Suspended) + Query Single Wait Time (Runnable). Again, it may be possible a query goes to all these stats multiple times. Let us try to understand the whole thing with a simple analogy of a taxi and a passenger. Two friends, Tom and Danny, go to the mall together. When they leave the mall, they decide to take a taxi. Tom and Danny both stand in the line waiting for their turn to get into the taxi. This is the Signal Wait Time as they are ready to get into the taxi but the taxis are currently serving other customer and they have to wait for their turn. In other word they are in a runnable state. Now when it is their turn to get into the taxi, the taxi driver informs them he does not take credit cards and only cash is accepted. Neither Tom nor Danny have enough cash, they both cannot get into the vehicle. Tom waits outside in the queue and Danny goes to ATM to fetch the cash. During this time the taxi cannot wait, they have to let other passengers get into the taxi. As Tom and Danny both are outside in the queue, this is the Query Wait Time and they are in the suspended state. They cannot do anything till they get the cash. Once Danny gets the cash, they are both standing in the line again, creating one more Single Wait Time. This time when their turn comes they can pay the taxi driver in cash and reach their destination. The time taken for the taxi to get from the mall to the destination is running time (CPU time) and the taxi is running. I hope this analogy is bit clear with the wait stats. You can check the single wait stats using following query of Glenn Berry. -- Signal Waits for instance SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%signal (cpu) waits], CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%resource waits] FROM sys.dm_os_wait_stats OPTION (RECOMPILE); Higher the single wait stats are not good for the system. Very high value indicates CPU pressure. In my experience, when systems are running smooth and without any glitch the single wait stat is lower than 20%. Again, this number can be debated (and it is from my experience and is not documented anywhere). In other words, lower is better and higher is not good for the system. In future articles we will discuss in detail the various wait types and wait stats and their resolution. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Developing web application with time zones support

    - by outcoldman
    When you develop web application you should know that client PCs can be located anywhere on earth. Even if you develop app just for your country users you should remember it (in Russia now we have 9 time zones, before 28 of March we had 11 time zones). On big sites with many members do it very easy – you can place field “time zone” in member profile, in Sharepoint I saw this solution, and many enterprise app do it like this. But if we have simple website with blog publications or website with news and we don’t have member profiles on server, how we can support user’s time zones? I thought about this question because I wanted to develop time zone support on my own site. My case is ASP.NET MVC app and MS SQL Server DB. First, I started from learning which params we have at HTTP headers, but it doesn’t have information about it. So we can’t use regional settings and methods DateTime.ToLocalTime and DateTime.ToUniversalTime until we get user time zone on server. If we used our app before without time zones support we need to change dates from local time zone to UTC time zone (something like Greenwich Mean Time). Read more...(Redirect to http://outcoldman.ru)

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  • Opening Time-Machine OSX backup files on Windows 7?

    - by user39279
    Hi, Have Time Machine backups on a Western Digital External HD. The Time Machine backups were done on my now dead Mac G4 running OSX Leopard- I am waiting on a new iMac but in the meantime I need to access some of my backup files urgently. I have a laptop running Windows 7 so is there any safe way of accessing some of the files from the Time Machine backup on my laptop and still be able to do a full restore when the iMac arrives? Thanks -

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  • How do I restore a non-system hard drive using Time Machine under OSX?

    - by richardtallent
    I dropped one of the external drives on my Mac Pro and it started making noises... so I bought a replacement drive. No biggie, that's why I have Time Machine, right? So now that I have the new drive up and initialized, how do I actually restore the drive from backup? Time Machine is intuitive when it comes to restoring the system drive or restoring individual folders/files on the same literal device, but I'm a bit stuck in how to properly restore an entire drive that is not the boot drive. I saw one suggestion to use the same volume name as the old drive and then go into Time Machine. Haven't tried that since the information is unconfirmed. For now, I just went to the Time Machine volume, found the latest backup folder for that volume, and I'm copying the files via Finder. Of couse, I expect this to work just fine, but I feel like I'm missing something if that's the "proper" way to do this.

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  • How can I set the date format to my country setting?

    - by Jamina Meissner
    I am German, but I use only English software. Hence, I am also using English Ubuntu. It's not because I don't know how to install German Ubuntu. It's because I prefer to work with English software environment. However, I would like to keep date & time format in German format, just as I use a German keyboard layout in English Ubuntu. I can set the time format to 24h time. But how can I set the date format to German time format? It is irritating for me to have the day number before the time numbers: In other words, instead of "Oct 14 15:16" I want it to display "14 Okt" or (if only English language is available) "14 Oct 15:16" or "14th Oct 15:16". At least, the number of the day should be displayed before the month. In Windows, it was no problem to choose time/date/currency settings according to a chosen country. Where can I do this in Ubuntu? The best would be if I could freely enter the date/time format myself with variables (DD.MM hh.mm.ss etc). I found answers for Ubuntu 11.04, but not for Ubuntu 12.04. I am using Ubuntu 12.04, 64-bit. Keep in mind that I am a beginner. So I'd like to be able to do this via GUI, if possible. EDIT: I found the answer in a forum. Go to System Settings... and choose Language Support. There are two tabs, Language and Reginal Formats. You are by default on the Language tab. On the Language tab, click Install / Remove Languages. A window with a list of languages opens. Mark the language(s) you want to add for your time/date/currency format. Click Apply Changes. Ubuntu will now download and install the additional language files, as well as help files of other applications in this language. So don't be irritated. When Ubuntu has finished applying the changes, switch to Regional Formats tab. (Do not change the Language for menus and windows on the Language tab if you only want to change the date/time/unit format). There you can choose from the dropdown list the language for your preferred format for date/time/currency/unit. Log out and log in again to have the changes take effect.

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  • Logic - Time measurement

    - by user73384
    To measure the following for tasks- Last execution time and maximum execution time for each task. CPU load/time consumed by each task over a defined period informed by application at run time. Maximum CPU load consumed by each task. Tasks have following characteristics- First task runs as background – Event information for entering only Second task - periodic – Event information for entering and exiting from task Third task is interrupt , can start any time – no information available from this task Forth task highest priority interrupt , can start any time – Event information for entering and exiting from task Should use least possible execution time and memory. 32bit increment timer available for time counting. Lets prepare and discuss the logic, It’s OK to have limitations …! Questions on understanding problem statement are welcome

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  • How can we plan projects realistically while accounting for support issues?

    - by Thomas Clayson
    We're having a problem at work: we're trying to schedule work so that we can assess time scales and get deadline dates. The problem is that it's difficult to plan for a project without knowing everything that's going to happen. For instance, right now we've planned all our projects through the start of December, however in that time we will have various in house and external meetings, teleconferences and extra work. It's all well and good to say that a project will take three weeks, but if there is a week's worth of interruption in that time then the date of completion will be pushed back a week. The problem is 3 fold: When we schedule projects the time scales are taken literally. If we estimate three weeks, the deadline is set for three week's time, the client is told, and there is no room for extension. Interim work and such means that we lose productive time working on the project. Sometimes clients don't have the time that we need to take to do the work, so they'll sometimes come to us and say they need a project done by the end of the month even when we think that the work will take two months - not to mention we already have work to be doing. We have a Gantt chart which we are trying to fill in with all the projects we have and we fill in timesheets, but they're not compared to the Gantt chart at all. This makes it difficult to say "Well, we scheduled 3 weeks for this project, but we've lost a week here so the deadline has to move back a week." It's also not professional to keep missing deadlines we've communicated to the client. How do other people deal with this type of situation? How do you manage the planning of projects? How much "extra" time do you schedule into a project to account for non-project work that occurs during a project? How do you deal with support issues and bugs and stuff? Things you can't account for during planning? UPDATE Lots of good answers thank you.

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  • SQL - Converting 24-hour ("military") time (2145) to "AM/PM time" (9:45 pm)

    - by CheeseConQueso
    I have 2 fields I'm working with that are stored as smallint military structured times. Edit I'm running on IBM Informix Dynamic Server Version 10.00.FC9 beg_tm and end_tm Sample values beg_tm 545 end_tm 815 beg_tm 1245 end_tm 1330 Sample output beg_tm 5:45 am end_tm 8:15 am beg_tm 12:45 pm end_tm 1:30 pm I had this working in Perl, but I'm looking for a way to do it with SQL and case statements. Is this even possible? EDIT Essentially, this formatting has to be used in an ACE report. I couldn't find a way to format it within the output section using simple blocks of if(beg_tm>=1300) then beg_tm = vbeg_tm - 1200 Where vbeg_tm is a declared char(4) variable EDIT This works for hours =1300 (EXCEPT FOR 2230 !!) select substr((beg_tm-1200),0,1)||":"||substr((beg_tm-1200),2,2) from mtg_rec where beg_tm>=1300; This works for hours < 1200 (sometimes.... 10:40 is failing) select substr((mtg_rec.beg_tm),0,(length(cast(beg_tm as varchar(4)))-2))||":"||(substr((mtg_rec.beg_tm),2,2))||" am" beg_tm from mtg_rec where mtg_no = 1; EDIT Variation of casting syntax used in Jonathan Leffler's expression approach SELECT beg_tm, cast((MOD(beg_tm/100 + 11, 12) + 1) as VARCHAR(2)) || ':' || SUBSTRING(cast((MOD(beg_tm, 100) + 100) as CHAR(3)) FROM 2) || SUBSTRING(' am pm' FROM (MOD(cast((beg_tm/1200) as INT), 2) * 3) + 1 FOR 3), end_tm, cast((MOD(end_tm/100 + 11, 12) + 1) as VARCHAR(2)) || ':' || SUBSTRING(cast((MOD(end_tm, 100) + 100) as CHAR(3)) FROM 2) || SUBSTRING(' am pm' FROM (MOD(cast((end_tm/1200) as INT), 2) * 3) + 1 FOR 3) FROM mtg_rec where mtg_no = 39;

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  • Flash, getURL works from time to time

    - by Sergey
    I'm not a flasher, but i did a menu for site on flash i have about 10 buttons working like hyperlink using getURL. So, problem is: it works perfectly on my netbook (Win XP - Mozilla/Chrome/IE - last flash player) it works perfectly on my wife's laptop (Vista - Mozilla/chrome/IE - last flash player) But it does not work at all on my employer's computers (XP/Vista - Mozilla/Chrome - last flash player) I'm using swfobject (i'm not sure what version is, but i think it's 2.x) Do you have any ideas?

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  • ScheduledThreadPoolExecutor executing a wrong time because of CPU time discrepancy

    - by richs
    I'm scheduling a task using a ScheduledThreadPoolExecutor object. I use the following method: public ScheduledFuture<?> schedule(Runnable command, long delay,TimeUnit unit) and set the delay to 30 seconds (delay = 30,000 and unit=TimeUnit.MILLISECONDS). Sometimes my task occurs immediately and other times it takes 70 seconds. I believe the ScheduledThreadPoolExecutor uses CPU specific clocks. When i run tests comparing System.currentTimeMillis(), System.nanoTime() [which is CPU specific] i see the following schedule: 1272637682651ms, 7858346157228410ns execute: 1272637682667ms, 7858386270968425ns difference is 16ms but 4011374001ns (or 40,113ms) so it looks like there is discrepancy between two CPU clocks of 40 seconds How do i resolve this issue in java code? Unfortunately this is a clients machine and i can't modify their system.

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  • quick approach to migrate classic asp project to asp.net

    - by Buzz
    Recently we got a requirement for converting a classic asp project to asp.net. This one is really a very old project created around 2002/2003. It consists of around 50 asp pages. I found very little documentation for this project, FSD and design documents for only a few modules. Just giving a quick look into this project my head start to hurt. It is really a mess. I checked the records and found none of the developers who worked on this project work for the company anymore. My real pain is that this is an urgent requirement and I have to provide an estimated deadline to my supervisor. I found a similar question classic-asp-to-asp-net, but I need some more insight on how to convert this classic asp project to asp.net in the quickest possible way.

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  • Should you ever re-estimate user stories?

    - by f1dave
    My current project is having a 'discussion' which is split down the middle- "this story is more complex than we originally thought, we should re-estimate" vs "you should never re-estimate as you only ever estimate up and never down". Can anyone shed some light on whether you ever should re-estimate? IMHO I'd imagine you could bring up an entirely new card for a new requirement or story, but going back and re-estimating on backlog items seems to skew the concept of relative sizing and will only ever 'inflate' your backlog.

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  • Can I trust the Basic schedule equation?

    - by Steve Campbell
    I've been reading Steve McConnell's demystifying the black art of estimating book, and he gives an equation for estimating nominal schedule based on Person-months of effort: ScheduleInMonths = 3.0 x EffortInMonths ^ (1/3) Per the book, this is very accurate (within 25%), although the 3.0 factor above varies depending on your organization (typically between 2 and 4). It is supposedly easy to use historical projects in your organization to derive an appropriate factor for your use. I am trying to reconcile the equation against Agile methods, using 2-6 week cycles which are often mini-projects that have a working deliverable at the end. If I have a team of 5 developers over 4 weeks (1 month), then EffortInMonths = 5 Person Months. The algorithm then outputs a schedule of 3.0 x 5^(1/3) = 5 months. 5 months is much more than 25% different than 1 month. If I lower the 3.0 factor to 0.6, then the algorthim works (outputs a schedule of approx 1 month). The lowest possible factor mentioned in the book through is 2.0. Whats going on here? I want to trust this equation for estimating a "traditional" non-agile project, but I cannot trust it when it does not reconcile with my (agile) experience. Can someone help me understand?

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  • How to explain to non-technical person why the task will take much longer then they think?

    - by Mag20
    Almost every developer has to answer questions from business side like: Why is going to take 2 days to add this simple contact form? When developer estimates this task, they may divide it into steps: make some changes to Database optimize DB changes for speed add front end HTML write server side code add validation add client side javascript use unit tests make sure SEO is setup is working implement email confirmation refactor and optimize the code for speed ... These maybe hard to explain to non-technical person, who basically sees the whole task as just putting together some HTML and creating a table to store the data. To them it could be 2 hours MAX. So is there a better way to explain why the estimate is high to non-developer?

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  • How to handle estimates for programmers joining the team?

    - by Jordan
    Iteration has already started, new programmer joins the team, task X has already been estimated to be 30 hours by a different developer. What is the best practice in this situation? new developer runs with the given estimate (the idea being that any discrepancy will be corrected for when velocity is calculated?) new developer re-estimates task? (if so, what if it's significantly higher and no longer fits in the iteration?) throw our hands up and go back to waterfall? something else entirely?

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  • Quantitfying a cost for a software project

    - by The Elite Gentleman
    Disclaimer: I didn't know exactly where to put this question. If you feel that this question is not suitable for Programmers @ StackExchange, feel free to migrate it. Background: Broadening my last question, there is a request for tender for a software system that's open and I have decided to take it on. I am a software developer & engineer by profession and, in this tender process, I have to put on the pricing for my bid. I have been provided a documentation consisting of functional and non-functional requirements only. I have to put a project manager's cap on and think of all aspects, e.g. cost for implementation for the project, resources needed, etc. My question is: Is there a project framework that I can follow that breaks the project cycle into steps and corresponding cost aspect or how would I go about best calculating/approximating the cost for the project?

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  • How to force a clock update using ntp?

    - by ysap
    I am running Ubuntu on an ARM based embedded system that lacks a battery backed RTC. The wake-up time is somewhere during 1970. Thus, I use the NTP service to update the time to the current time. I added the following line to /etc/rc.local file: sudo ntpdate -s time.nist.gov However, after startup, it still takes a couple of minutes until the time is updated, during which period I cannot work effectively with tar and make. How can I force a clock update at any given time? UPDATE 1: The following (thanks to Eric and Stephan) works fine from command line, but fails to update the clock when put in /etc/rc.local: $ date ; sudo service ntp stop ; sudo ntpdate -s time.nist.gov ; sudo service ntp start ; date Thu Jan 1 00:00:58 UTC 1970 * Stopping NTP server ntpd [ OK ] * Starting NTP server [ OK ] Thu Feb 14 18:52:21 UTC 2013 What am I doing wrong? UPDATE 2: I tried following the few suggestions that came in response to the 1st update, but nothing seems to actually do the job as required. Here's what I tried: Replace the server to us.pool.ntp.org Use explicit paths to the programs Remove the ntp service altogether and leave just sudo ntpdate ... in rc.local Remove the sudo from the above command in rc.local Using the above, the machine still starts at 1970. However, when doing this from command line once logged in (via ssh), the clock gets updated as soon as I invoke ntpdate. Last thing I did was to remove that from rc.local and place a call to ntpdate in my .bashrc file. This does update the clock as expected, and I get the true current time once the command prompt is available. However, this means that if the machine is turned on and no user is logged in, then the time never gets updates. I can, of course, reinstall the ntp service so at least the clock is updated within a few minutes from startup, but then we're back at square 1. So, is there a reason why placing the ntpdate command in rc.local does not perform the required task, while doing so in .bashrc works fine?

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  • Best way to restore individual folders via Time Machine after clean Lion install?

    - by A4J
    I'm doing a clean erase and install of Lion, and am looking for the best way to restore individual folders into my home directory via Time Machine. I've done a dummy run, clean Lion install, then 'browse other disks' in Time Machine, navigate to my home folder and 'restore' what I need, such as pictures/music and folders inside the .library folder (such as Mail and Keychains). However this method seems to give you odd permissions, like this: http://i43.tinypic.com/15y82v4.png Hence I wondered if anyone knows what the best method is to restore files and folders after a clean install. N.b I do not want to use the migration assistant, or 'restore OS from Time Machine' - as I specifically want to do a clean install, and just copy over what I need (some folders will be moved onto a separate disk to the OS, and some will remain on the same disk). Thanks in advance.

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  • Is it reasonable to use my Time Machine backup to migrate to a new primary hard drive?

    - by Michael Haren
    I'm planning to upgrade my MacBook's harddrive. I already use Time Machine to back up the system to an external drive. Is it reasonable to use Time Machine to restore my system to the new laptop drive, once I install it? I mean, a restore like this really ought to be fine, right? That's the point of it, after all! I know imaging the drive would be more appropriate but this plan seems a whole lot easier (albeit probably slower), with practically no risk since my original drive won't be involved. A second question would then be, are there any considerations to be made when doing a Time Machine restore?

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