I need a sample DELETE Query where SQL Server by default takes an X lock at Page Level and not at Row Level. BACKGROUND: In our purging SP, we are using DELETE Query with ROWLOCK hint and I want to proof to my manager that if we remove that ROWLOCK Hint, SQL Server might go to acquire locks at PAGE Level. We are suspecting that LOCK ESCALATION is happening because of the ROWLOCK hint which we have explicitly mentioned in the DELETE Query.
We currently have some indexes where ALLOW_PAGELOCKS is set to off. This presumably was done in order to reduce deadlocks. However I doubt that it would really had an effect back then.   Now I am trying to understand WHEN SQL Server actually chooses to start locking pages rather than keys in a clustered index. I asked Jonathan Keyhaisas recently and he told me that this could happen if I am touching rows on several subsequent pages. However I didn't manage to get any exclusive page locks by updating rows in a clustered index with a sample query.   Could you help me understand page locks better with a sample query and table? I am running SQL Server 2008 SP4.  Thanks in advance  Martin
Which $n$ can be expressed as $x^2 − y^2$? Which $n$ can be expressed as $x^2 − y^2$?  Attempt: Any number which is odd or or which is a multiple of 4. Why would you use an assignment in a condition? In many languages assignments are legal in conditions. I never understood the reason behind this. Why would you write:  if (var1 = var2) {   ... }   instead of:  var1 = var2; if (var1) {   ... } Simulating a Brownian Excursion using a Brownian Bridge? I'm using Linux (centos) machine, I already connected to the other system using ssh. Now my question is how can I copy files from one system to another system?  Suppose, in my environment, I have two system like System A and System B. I'm using System A machine and some other using System B machine.  How can I copy a file from System B to System A? And, copy a file from System A to System B? Strange characters when the output of `ls` is redirected to a file I want to list the components of the current working directory in a text file  ls -1 &gt; textfile   Output looks fine with more.   1010661085645 1010729039145 1010747080245 1010849051345 1010859053445 1011046075845   However when I view this textfile with emacs, several strange characters appear  [0m[01;34m1010661085645[0m [01;34m1010729039145[0m [01;34m1010747080245[0m [01;34m1010849051345[0m [01;34m1010859053445[0m [01;34m1011046075845[0m   Can anyone explain what is going on here? I am looping over the features of a shapefile containing multiple polygons. If  certain criteria are met, I want to save the current feature in a new shapefile.  I am doing this using GDAL 1.10.0 with Python 2.7.3  The code runs, creates the files I want, calculates the area correctly. In the shapefile that is created, the attribute table contains the propoer fields ('name' and FID). Two things are wrong:   No polygons are visible (in ArcMap). This seems to me particularly weird, because the polygons seem to me proper, in the sense that they are closed (and the area is calculated properly).  The coordinate system seems off (in Arc Catalog there appears in the bottom -20,9667 0,0000 (are these degrees??)), despite the fact that I am creating a projection file (they are in German national grid 3)   Any hints as to what the problems could be? I tried to put the relevant excerpt of the code below:  from osgeo import gdal, gdalnumeric, ogr, osr, gdalconst  ### prepare shapefile into which to save driver = ogr.GetDriverByName('ESRI Shapefile') path_matched = r'.../.../path' datasource = driver.CreateDataSource(path_matched) lyr_matched = 'matched_%s' % cur_id  # from above # Remove output shapefile if it already exists name_shpfile = lyr_matched + '.shp' if os.path.exists(os.path.join(path_matched, name_shpfile)):     driver.DeleteDataSource(os.path.join(path_matched, name_shpfile)) layer = datasource.CreateLayer(lyr_matched, geom_type=ogr.wkbPolygon) #layer.ResetReading() field_name = ogr.FieldDefn("name", ogr.OFTString) layer.CreateField(field_name)  ### prepare file in which I want to write the areas of matched polygons path_area = path_matched file_area = 'matched_area_%s.txt' % (cur_id) fobj_area = open(os.path.join(path_area, file_area), 'w')  ### original shape file containing all polygons shp = ogr.Open(shp_all)  # os fobj from above lyr = shp.GetLayer()  # loop over polygons in original shameful for FID in featList:     feat = lyr.GetFeature(FID)      # this is from the shapefile      cur_name = feat.GetField(1)      # ... work on conditions ...      if condition = true:         myPoly = ogr.Geometry(type=ogr.wkbPolygon)         cur_poly = feat.GetGeometryRef()         myPoly.AddGeometry(cur_poly)         cur_spat_ref = cur_poly.GetSpatialReference()          cur_area =  cur_poly.GetArea()         cur_area_string = "%s \t %f \n" % (gw_name_EZG, cur_area)         fobj_area.write(cur_area_string)          featur_dfn = layer.GetLayerDefn()         feature_abc = ogr.Feature(featur_dfn)         feature_abc.SetGeometry(myPoly)         feature_abc.SetField("name", cur_name)         feature_abc.SetFID(FID)         layer.CreateFeature(feature_abc)         myPoly.Destroy()         feature.Destroy()   # generate projection file prj_filename = lyr_matched + '.prj' file = open(os.path.join(path_matched, prj_filename), 'w') targetSR = cur_spat_ref targetSR.MorphToESRI() file.write(targetSR.ExportToWkt()) file.close()   datasource.Destroy() Ubuntu installation is slow, why? I am currently installing Ubuntu 12.04.3. Everything was going fine until I came across this...     Installing System   It is sssooooooo close to being finished! Like 1/6 of the way there! I just wanted to know if this is normal or if something is wrong. I'm installing it through a flash drive if that helps   Also,what will happen if I press the skip button that pops up when I click Installing System? How to find and replace using sed on records starting with Specific number How to calculate the sum of sequence $$\frac{1}{\binom{n}{1}}+\frac{1}{\binom{n}{2}}+\frac{1}{\binom{n}{3}}+\cdots+\frac{1}{\binom{n}{n}}=？$$ How about its limit? Excel 2010 on multi monitor screen MVC DateTime binding with incorrect date format How to launch a command on network connection/disconnection? When should end punctuation go inside quotes? RSA is not designed to be used on long blocks of plaintext like a block cipher, but I need to use it to send a large (encrypted) message.  How can I do this? When documenting a style file, it would be nice to be able to easily put side by side different examples of code, side-by-side with the output they produce.  What recommendations to people have to do this efficiently, and &aelig;sthetically? Is there is any reason to make the permissions on an overridden C++ virtual function different from the base class?  Is there any danger in doing so?  For example:  class base {     public:         virtual int foo(double) = 0; }  class child : public base {     private:         virtual int foo(double); }   The  says that it is a bad idea, but doesn't say why.  I have seen this idiom in some code and I believe that the author was attempting to make the class final, based on an assumption that it is not possible to override a private member function.  However,  shows an example of overriding private functions.  Of course  recommends against doing so.  My concrete questions:   Is there any technical problem with using a different permission for virtual methods in derived classes vs base class? Is there any legitimate reason to do so? Profile page "activity" tab is broken I'm including \usepackage{hyperref} so that each instance of \ref (as well as each page number in the index and the table of contents) automatically links to that page.  When I'm viewing the document (in ) and I click a link, I jump to the linked page.  Is there any easy way to go "back" to where I was before I clicked the link?  (And is the answer any different when using Adobe Acrobat reader?) How do I uninstall Ubuntu? How do I format drive and unistall Ubuntu 11.10?  I wanted a dual boot and was given an option to overwrite Windows XP partition and said yes.  Format options don't work.  I tried a few dos prompts and probably not using correct fdisk.  Format options state drive is busy closed all windows.  Tried to boot windows XP and disk says its corrupt. How do I apply differential cryptanalysis to a block cipher? I have read a lot of summaries of block ciphers particularly with regards to the NIST competitions stating that reduced-round block ciphers are – for example – vulnerable to differential cryptanalysis.  I have a general idea that the application of differential cryptanalysis is to look at the difference between inputs;  makes that fairly clear. However, I could take any two inputs for any given block cipher and I am pretty certain I'd be staring at random differences.    I am aware this is the idea of a well written block cipher; however, assuming a broken or vulnerable cipher (feel free to provide simple examples) how do I go about choosing differences to try?  Are there any clues in algorithm design that would inform a decision on which values to choose?  How does being vulnerable to differential cryptanalysis impact a cipher in the wild?  If all I have are differences between known plain-texts and known keys as my analysis and a captured ciphertext as my data to exploit, what can I actually deduce?