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• Collaborative Filtering Program: What to do for a Pearson Score When There Isn't Enough Data

  - by Mike

  I'm building a recommendation engine using collaborative filtering. For similarity scores, I use a Pearson correlation. This is great most of the time, but sometimes I have users that only share a 1 or 2 fields. For example: User 1{ a: 4 b: 2 } User 2{ a: 4 b: 3 } Since this is only 2 data points, a Pearson correlation would always be 1 (a straight line or perfect correlation). This obviously isn't what I want, so what value should I use instead? I could just throw away all instances like this (give a correlation of 0), but my data is really sparse right now and I don't want to lose anything. Is there any similarity score I could use that would fit in with the rest of my similarity scores (all Pearson)?

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• Why & When should I use SPARSE COLUMN? (SQL SERVER 2008)

  - by priyanka.sarkar

  After going thru some tutorials on SQL SERVER 2008's new feature SPARSE COLUMN, I have found that it doesn't take any space if the column value is 0 or null but when there is a value, it takes 4 times the space a regular(non sparse) column holds. If my understanding is correct, then why I will go for that at the time of database design? And if I use that, then at what situation so I be? Also out of curiosity, how come no space get's reserve when a column is defined as sparse column(I mean to say, what is the internal implementation for that) Thanks in advance

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• Can you shrink the sparse disk image of a Mac OS X guest OS in VMWare Fusion?

  - by Paul D. Waite

  I use VMWare Fusion on my Mac to run a virtual Windows 7 machine, and the Microsoft IE compatibility Windows XP virtual machines. In VMWare Tools on the Windows guest OSes, there’s a “Shrink” option that lets you reduce the size of the sparse disk image used by the guest OS, to save hard drive space on your host OX. I’ve recently created another virtual machine, this time running Snow Leopard Server. I was wondering if I could shrink the spare disk image used by this machine too, but I can’t find a VMWare Tools app on the Mac guest OS, even though VMWare Tools have been installed (as VMWare’s Shared Folders feature is working). Is there any way to shrink the sparse disk image used by Mac OS X guest OSes in VMWare Fusion?

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• How do you synchronise huge sparse files (VM disk images) between machines?

  - by chrisdew

  Is there a command, such as rsync, which can synchronise huge, sparse, files from one linux server to another? It is very important that the destination file remains sparse. It may be longer (but not bigger) than the drive which contains it. Only changed blocks should be sent across the wire. I have tried rsync, but got no joy. groups.google.com/group/mailing.unix.rsync/browse_thread/thread/94f39271980513d3 If I write a programme to do this, am I just reinventing the wheel? http://www.finalcog.com/synchronise-block-devices Thanks, Chris.

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• Need help with testdisk output

  - by dan

  I had (note the past tense) an ubuntu 12.04 system with separate partitions for the base and /home directories. It started acting wonky, so I decided to do a reinstall with 12.10, intending just to do a reinstall to the base partition. After several seconds, I realize that the installer was repartitioning the drive and reinstalling, so I pulled the power cord. I'm now trying to recover as much as I can with testdisk, but it seems that testdisk is finding 100 unique partitions when I run it - they mostly tend to be HFS+ or solaris /home (which I think is just an ext4; I've never had solaris on the machine). I've pasted an abbreviated version of the testdisk output below (first ~100 lines, and then ~100 lines from the middle of the output). Is there a way to combine or recreate the partitions and then data recovery, or some other way maximize what I can recover (ideally as much of the file system as possible)? I really only care about what was in the /home directory - I'd rather not use photorec since I don't have another 2 TB HD lying around to recover to. Thanks, Dan Mon Dec 10 06:03:00 2012 Command line: TestDisk TestDisk 6.13, Data Recovery Utility, November 2011 Christophe GRENIER <[email protected]> http://www.cgsecurity.org OS: Linux, kernel 3.2.34-std312-amd64 (#2 SMP Sat Nov 17 08:06:32 UTC 2012) x86_64 Compiler: GCC 4.4 Compilation date: 2012-11-27T22:44:52 ext2fs lib: 1.42.6, ntfs lib: libntfs-3g, reiserfs lib: 0.3.1-rc8, ewf lib: none /dev/sda: LBA, HPA, LBA48, DCO support /dev/sda: size 3907029168 sectors /dev/sda: user_max 3907029168 sectors /dev/sda: native_max 3907029168 sectors Warning: can't get size for Disk /dev/mapper/control - 0 B - CHS 1 1 1, sector size=512 /dev/sr0 is not an ATA disk Hard disk list Disk /dev/sda - 2000 GB / 1863 GiB - CHS 243201 255 63, sector size=512 - WDC WD20EARS-00J2GB0, S/N:WD-WCAYY0075071, FW:80.00A80 Disk /dev/sdb - 1013 MB / 967 MiB - CHS 1014 32 61, sector size=512 - Generic Flash Disk, FW:8.07 Disk /dev/sr0 - 367 MB / 350 MiB - CHS 179470 1 1 (RO), sector size=2048 - PLDS DVD+/-RW DH-16AAS, FW:JD12 Partition table type (auto): Intel Disk /dev/sda - 2000 GB / 1863 GiB - WDC WD20EARS-00J2GB0 Partition table type: EFI GPT Analyse Disk /dev/sda - 2000 GB / 1863 GiB - CHS 243201 255 63 Current partition structure: Bad GPT partition, invalid signature. search_part() Disk /dev/sda - 2000 GB / 1863 GiB - CHS 243201 255 63 recover_EXT2: s_block_group_nr=0/14880, s_mnt_count=5/4294967295, s_blocks_per_group=32768, s_inodes_per_group=8192 recover_EXT2: s_blocksize=4096 recover_EXT2: s_blocks_count 487593984 recover_EXT2: part_size 3900751872 MS Data 2048 3900753919 3900751872 EXT4 Large file Sparse superblock, 1997 GB / 1860 GiB Linux Swap 3900755968 3907028975 6273008 SWAP2 version 1, 3211 MB / 3062 MiB Results P MS Data 2048 3900753919 3900751872 EXT4 Large file Sparse superblock, 1997 GB / 1860 GiB P Linux Swap 3900755968 3907028975 6273008 SWAP2 version 1, 3211 MB / 3062 MiB interface_write() 1 P MS Data 2048 3900753919 3900751872 2 P Linux Swap 3900755968 3907028975 6273008 search_part() Disk /dev/sda - 2000 GB / 1863 GiB - CHS 243201 255 63 recover_EXT2: s_block_group_nr=0/14880, s_mnt_count=5/4294967295, s_blocks_per_group=32768, s_inodes_per_group=8192 recover_EXT2: s_blocksize=4096 recover_EXT2: s_blocks_count 487593984 recover_EXT2: part_size 3900751872 MS Data 2048 3900753919 3900751872 EXT4 Large file Sparse superblock, 1997 GB / 1860 GiB block_group_nr 1 recover_EXT2: "e2fsck -b 32768 -B 4096 device" may be needed recover_EXT2: s_block_group_nr=1/14880, s_mnt_count=0/4294967295, s_blocks_per_group=32768, s_inodes_per_group=8192 recover_EXT2: s_blocksize=4096 recover_EXT2: s_blocks_count 487593984 recover_EXT2: part_size 3900751872 MS Data 2046 3900753917 3900751872 EXT4 Large file Sparse superblock Backup superblock, 1997 GB / 1860 GiB block_group_nr 1 recover_EXT2: "e2fsck -b 32768 -B 4096 device" may be needed recover_EXT2: s_block_group_nr=1/14880, s_mnt_count=0/4294967295, s_blocks_per_group=32768, s_inodes_per_group=8192 recover_EXT2: s_blocksize=4096 recover_EXT2: s_blocks_count 487593984 recover_EXT2: part_size 3900751872 MS Data 2048 3900753919 3900751872 EXT4 Large file Sparse superblock Backup superblock, 1997 GB / 1860 GiB block_group_nr 1 recover_EXT2: "e2fsck -b 32768 -B 4096 device" may be needed recover_EXT2: s_block_group_nr=1/14584, s_mnt_count=0/27, s_blocks_per_group=32768, s_inodes_per_group=8192 recover_EXT2: s_blocksize=4096 recover_EXT2: s_blocks_count 477915164 recover_EXT2: part_size 3823321312 MS Data 4094 3823325405 3823321312 EXT4 Large file Sparse superblock Backup superblock, 1957 GB / 1823 GiB block_group_nr 1 ....snip...... MS Data 2046 3900753917 3900751872 EXT4 Large file Sparse superblock Backup superblock, 1997 GB / 1860 GiB MS Data 2048 3900753919 3900751872 EXT4 Large file Sparse superblock, 1997 GB / 1860 GiB MS Data 4094 3823325405 3823321312 EXT4 Large file Sparse superblock Backup superblock, 1957 GB / 1823 GiB MS Data 4096 3823325407 3823321312 EXT4 Large file Sparse superblock Backup superblock, 1957 GB / 1823 GiB MS Data 7028840 7033383 4544 FAT12, 2326 KB / 2272 KiB Mac HFS 67856948 67862179 5232 HFS+ found using backup sector!, 2678 KB / 2616 KiB Mac HFS 67862176 67867407 5232 HFS+, 2678 KB / 2616 KiB Mac HFS 67862244 67867475 5232 HFS+ found using backup sector!, 2678 KB / 2616 KiB Mac HFS 67867404 67872635 5232 HFS+, 2678 KB / 2616 KiB Mac HFS 67867472 67872703 5232 HFS+, 2678 KB / 2616 KiB Mac HFS 67872700 67877931 5232 HFS+, 2678 KB / 2616 KiB Mac HFS 67937834 67948067 10234 [EasyInstall_OSX] HFS found using backup sector!, 5239 KB / 5117 KiB Mac HFS 67938012 67948155 10144 HFS+ found using backup sector!, 5193 KB / 5072 KiB Mac HFS 67948064 67958297 10234 [EasyInstall_OSX] HFS, 5239 KB / 5117 KiB Mac HFS 67948070 67958303 10234 [EasyInstall_OSX] HFS found using backup sector!, 5239 KB / 5117 KiB Mac HFS 67948152 67958295 10144 HFS+, 5193 KB / 5072 KiB Mac HFS 67958292 67968435 10144 HFS+, 5193 KB / 5072 KiB Mac HFS 67958300 67968533 10234 [EasyInstall_OSX] HFS, 5239 KB / 5117 KiB Mac HFS 67992596 67997827 5232 HFS+ found using backup sector!, 2678 KB / 2616 KiB Mac HFS 67997824 68003055 5232 HFS+, 2678 KB / 2616 KiB Mac HFS 67997892 68003123 5232 HFS+ found using backup sector!, 2678 KB / 2616 KiB Mac HFS 68003052 68008283 5232 HFS+, 2678 KB / 2616 KiB Mac HFS 68003120 68008351 5232 HFS+, 2678 KB / 2616 KiB Mac HFS 68008348 68013579 5232 HFS+, 2678 KB / 2616 KiB Solaris /home 84429840 123499141 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84429952 123499253 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84493136 123562437 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84493248 123562549 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84566088 123635389 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84566200 123635501 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84571232 123640533 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84571344 123640645 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84659952 123729253 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84660064 123729365 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84690504 123759805 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84690616 123759917 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84700424 123769725 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84700536 123769837 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84797720 123867021 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84797832 123867133 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84812544 123881845 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84812656 123881957 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84824552 123893853 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84824664 123893965 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84847528 123916829 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84847640 123916941 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84886840 123956141 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84886952 123956253 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84945488 124014789 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84945600 124014901 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84957992 124027293 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84958104 124027405 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84962240 124031541 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84962352 124031653 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84977168 124046469 39069302 UFS1, 20 GB / 18 GiB Solaris /home 84977280 124046581 39069302 UFS1, 20 GB / 18 GiB MS Data 174395467 178483851 4088385 ..... snip (it keeps going on for quite a while)

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• Why does mmap() fail with ENOMEM on a 1TB sparse file?

  - by metadaddy

  I've been working with large sparse files on openSUSE 11.2 x86_64. When I try to mmap() a 1TB sparse file, it fails with ENOMEM. I would have thought that the 64 bit address space would be adequate to map in a terabyte, but it seems not. Experimenting further, a 1GB file works fine, but a 2GB file (and anything bigger) fails. I'm guessing there might be a setting somewhere to tweak, but an extensive search turns up nothing. Here's some sample code that shows the problem - any clues? #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <sys/types.h> #include <unistd.h> int main(int argc, char *argv[]) { char * filename = argv[1]; int fd; off_t size = 1UL << 40; // 30 == 1GB, 40 == 1TB fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666); ftruncate(fd, size); printf("Created %ld byte sparse file\n", size); char * buffer = (char *)mmap(NULL, (size_t)size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if ( buffer == MAP_FAILED ) { perror("mmap"); exit(1); } printf("Done mmap - returned 0x0%lx\n", (unsigned long)buffer); strcpy( buffer, "cafebabe" ); printf("Wrote to start\n"); strcpy( buffer + (size - 9), "deadbeef" ); printf("Wrote to end\n"); if ( munmap(buffer, (size_t)size) < 0 ) { perror("munmap"); exit(1); } close(fd); return 0; }

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• What is the best algorithm for solving a band-diagonal matrix?

  - by Goose Bumper

  I'm trying to figure out the best way to solve a pentadiagonal matrix. Is there something faster than gaussian elimination?

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• Multiplying two matrices from two text files with unknown dimensions

  - by wes schwertner

  This is my first post here. I've been working on this c++ question for a while now and have gotten nowhere. Maybe you guys can give me some hints to get me started. My program has to read two .txt files each containing one matrix. Then it has to multiply them and output it to another .txt file. My confusion here though is how the .txt files are setup and how to get the dimensions. Here is an example of matrix 1.txt. #ivalue #jvalue value 1 1 1.0 2 2 1 The dimension of the matrix is 2x2. 1.0 0 0 1 Before I can start multiplying these matrices I need to get the i and j value from the text file. The only way I have found out to do this is int main() { ifstream file("a.txt"); int numcol; float col; for(int x=0; x<3;x++) { file>>col; cout<<col; if(x==1) //grabs the number of columns numcol=col; } cout<<numcol; } The problem is I don't know how to get to the second line to read the number of rows. And on top of that I don't think this will give me accurate results for other matrices files. Let me know if anything is unclear. UPDATE Thanks! I got getline to work correctly. But now I am running into another problem. In matrix B it is setup like: #ivalue #jvalue Value 1 1 0.1 1 2 0.2 2 1 0.3 2 2 0.4 I need to let the program know that it needs to go down 4 lines, maybe even more (The matrices dimensions are unknown. My matrix B example is a 2x2, but it could be a 20x20). I have a while(!file.eof()) loop my program to let it loop until the end of file. I know I need a dynamic array for multiplying, but would I need one here also? #include <iostream> #include <fstream> using namespace std; int main() { ifstream file("a.txt"); //reads matrix A while(!file.eof()) { int temp; int numcol; string numrow; float row; float col; for(int x=0; x<3;x++) { file>>col; if(x==1) { numcol=col; //number of columns } } string test; getline(file, test); //next line to get rows for(int x=0; x<3; x++) { file>>test; if(x==1) { numrow=test; //sets number of rows } } cout<<numrow; cout<<numcol<<endl; } ifstream file1("b.txt"); //reads matrix 2 while(!file1.eof()) { int temp1; int numcol1; string numrow1; float row1; float col1; for(int x=0; x<2;x++) { file1>>col1; if(x==1) numcol1=col1; //sets number of columns } string test1; getline(file1, test1); //In matrix B there are four rows. getline(file1, test1); //These getlines go down a row. getline(file1, test1); //Need help here. for(int x=0; x<2; x++) { file1>>test1; if(x==1) numrow1=test1; } cout<<numrow1; cout<<numcol1<<endl; } }

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• How do I mount a sparse disk image permanently?

  - by Mike

  On Mac OS X 10.6.7, when I mount a sparse disk image (either by double-clicking it or using hdid from the command line), the image: Appears on my desktop Needs to be re-mounted every time I log in I'd like to set up the equivalent of an /etc/fstab which will mount the image when the system boots, and make it permanent - so I don't have to worry if my symbolic links will resolve or not. Is this more trouble than it's worth on a Mac? I noticed that there is no /etc/fstab, and /etc/fstab.hd contains a dire warning: IGNORE THIS FILE. This file does nothing, contains no useful data, and might go away in future releases. Do not depend on this file or its contents. I tried sudo hdid -notremovable <image>, which seemed like half of what I wanted (according to man hdid), but it failed with an error: hdid: attach failed - no mountable file systems.

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• Error installing scipy on Mountain Lion with Xcode 4.5.1

  - by Xster

  Environment: Mountain Lion 10.8.2, Xcode 4.5.1 command line tools, Python 2.7.3, virtualenv 1.8.2 and numpy 1.6.2 When installing scipy with pip install -e "git+https://github.com/scipy/scipy#egg=scipy-dev" on a fresh virtualenv. llvm-gcc: scipy/sparse/linalg/eigen/arpack/ARPACK/FWRAPPERS/veclib_cabi_c.c In file included from /System/Library/Frameworks/vecLib.framework/Headers/vecLib.h:43, from /System/Library/Frameworks/Accelerate.framework/Headers/Accelerate.h:20, from scipy/sparse/linalg/eigen/arpack/ARPACK/FWRAPPERS/veclib_cabi_c.c:2: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:51:23: error: immintrin.h: No such file or directory In file included from /System/Library/Frameworks/vecLib.framework/Headers/vecLib.h:43, from /System/Library/Frameworks/Accelerate.framework/Headers/Accelerate.h:20, from scipy/sparse/linalg/eigen/arpack/ARPACK/FWRAPPERS/veclib_cabi_c.c:2: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h: In function ‘vceilf’: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:53: error: incompatible types in return /System/Library/Frameworks/vecLib.framework/Headers/vfp.h: In function ‘vfloorf’: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:54: error: incompatible types in return /System/Library/Frameworks/vecLib.framework/Headers/vfp.h: In function ‘vintf’: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:55: error: ‘_MM_FROUND_TRUNC’ undeclared (first use in this function) /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:55: error: (Each undeclared identifier is reported only once /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:55: error: for each function it appears in.) /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:55: error: incompatible types in return /System/Library/Frameworks/vecLib.framework/Headers/vfp.h: In function ‘vnintf’: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:56: error: ‘_MM_FROUND_NINT’ undeclared (first use in this function) /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:56: error: incompatible types in return In file included from /System/Library/Frameworks/vecLib.framework/Headers/vecLib.h:43, from /System/Library/Frameworks/Accelerate.framework/Headers/Accelerate.h:20, from scipy/sparse/linalg/eigen/arpack/ARPACK/FWRAPPERS/veclib_cabi_c.c:2: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:51:23: error: immintrin.h: No such file or directory In file included from /System/Library/Frameworks/vecLib.framework/Headers/vecLib.h:43, from /System/Library/Frameworks/Accelerate.framework/Headers/Accelerate.h:20, from scipy/sparse/linalg/eigen/arpack/ARPACK/FWRAPPERS/veclib_cabi_c.c:2: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h: In function ‘vceilf’: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:53: error: incompatible types in return /System/Library/Frameworks/vecLib.framework/Headers/vfp.h: In function ‘vfloorf’: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:54: error: incompatible types in return /System/Library/Frameworks/vecLib.framework/Headers/vfp.h: In function ‘vintf’: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:55: error: ‘_MM_FROUND_TRUNC’ undeclared (first use in this function) /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:55: error: (Each undeclared identifier is reported only once /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:55: error: for each function it appears in.) /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:55: error: incompatible types in return /System/Library/Frameworks/vecLib.framework/Headers/vfp.h: In function ‘vnintf’: /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:56: error: ‘_MM_FROUND_NINT’ undeclared (first use in this function) /System/Library/Frameworks/vecLib.framework/Headers/vfp.h:56: error: incompatible types in return error: Command "/usr/bin/llvm-gcc -fno-strict-aliasing -Os -w -pipe -march=core2 -msse4 -fwrapv -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -Iscipy/sparse/linalg/eigen/arpack/ARPACK/SRC -I/Users/xiao/.virtualenv/lib/python2.7/site-packages/numpy/core/include -c scipy/sparse/linalg/eigen/arpack/ARPACK/FWRAPPERS/veclib_cabi_c.c -o build/temp.macosx-10.4-x86_64-2.7/scipy/sparse/linalg/eigen/arpack/ARPACK/FWRAPPERS/veclib_cabi_c.o" failed with exit status 1 Is it supposed to be looking for headers from my system frameworks? Is the development version of scipy no longer good for the latest version of Mountain Lion/Xcode?

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• HPCM 11.1.2.x - Outline Optimisation for Calculation Performance

  - by Jane Story

  When an HPCM application is first created, it is likely that you will want to carry out some optimisation on the HPCM application’s Essbase outline in order to improve calculation execution times. There are several things that you may wish to consider. Because at least one dense dimension for an application is required to deploy from HPCM to Essbase, “Measures” and “AllocationType”, as the only required dimensions in an HPCM application, are created dense by default. However, for optimisation reasons, you may wish to consider changing this default dense/sparse configuration. In general, calculation scripts in HPCM execute best when they are targeting destinations with one or more dense dimensions. Therefore, consider your largest target stage i.e. the stage with the most assignment destinations and choose that as a dense dimension. When optimising an outline in this way, it is not possible to have a dense dimension in every target stage and so testing with the dense/sparse settings in every stage is the key to finding the best configuration for each individual application. It is not possible to change the dense/sparse setting of individual cloned dimensions from EPMA. When a dimension that is to be repeated in multiple stages, and therefore cloned, is defined in EPMA, every instance of that dimension has the same storage setting. However, such manual changes may not be preserved in all cases. Please see below for full explanation. However, once the application has been deployed from EPMA to HPCM and from HPCM to Essbase, it is possible to make the dense/sparse changes to a cloned dimension directly in Essbase. This can be done by editing the properties of the outline in Essbase Administration Services (EAS) and manually changing the dense/sparse settings of individual dimensions. There are two methods of deployment from HPCM to Essbase from 11.1.2.1. There is a “replace” deploy method and an “update” deploy method: “Replace” will delete the Essbase application and replace it. If this method is chosen, then any changes made directly on the Essbase outline will be lost. If you use the update deploy method (with or without archiving and reloading data), then the Essbase outline, including any manual changes you have made (i.e. changes to dense/sparse settings of the cloned dimensions), will be preserved. Notes If you are using the calculation optimisation technique mentioned in a previous blog to calculate multiple POVs (https://blogs.oracle.com/pa/entry/hpcm_11_1_2_optimising) and you are calculating all members of that POV dimension (e.g. all months in the Period dimension) then you could consider making that dimension dense. Always review Block sizes after all changes! The maximum block size recommended in the Essbase Database Administrator’s Guide is 100k for 32 bit Essbase and 200k for 64 bit Essbase. However, calculations may perform better with a larger than recommended block size provided that sufficient memory is available on the Essbase server. Test different configurations to determine the most optimal solution for your HPCM application. Please note that this blog article covers HPCM outline optimisation only. Additional performance tuning can be achieved by methodically testing database settings i.e data cache, index cache and/or commit block settings. For more information on Essbase tuning best practices, please review these items in the Essbase Database Administrators Guide. For additional information on the commit block setting, please see the previous PA blog article https://blogs.oracle.com/pa/entry/essbase_11_1_2_commit

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• CodePlex Daily Summary for Saturday, March 27, 2010

  CodePlex Daily Summary for Saturday, March 27, 2010New ProjectsAlter gear SQL index Management: SQL Index management displays a list of indexes available for the chosen database and allows you to select an individual / group of indexes to be r...ASP League Ladder System: An ASP ladder / league system for online gaming league or real life leagues also.Augmented Reality Strategy Simulator: Augmented Reality Strategy Simulator is a software suite to promote computer aided strategy planning. Sports team can visualize their strategy usin...Boo syntax highlighting for Visual Studio 2010: Simple syntax hightlighting VSX add-in for Boo language in Visual Studio 2010.easySan: easySan zur einfachen Mitgliedsverwaltung im BRKFsUnit: FsUnit makes unit-testing with F# more enjoyable. It adds a special syntax to your favorite .NET testing framework.Laughing Dog XNA Framework: Laughing Dog is a simple to use, component based 2D framework for XNA game development. At present it is very early in development and as such is f...miniTodo: WPFでMVVMの練習にてきとうに作ったTODOアプリ 実用は無理です。My Common Library on .NET with CSharp: My Common Library on .NET with CSharp, it conclude database assecc, encrypt string, data caching, StringUtility, thank you for your view.Native code wrapping using c# : fsutil sparse commands: Ever thought about creating HUGE FILES for future use but felt bad for the wasted memory? Well, SPARSE FILES are the ANSWER! This FSUTIL SPARSE CO...Open SOA Platform: A centralized system for administering applications throught a SOA Enterprise Service Bus: Runtime environment (PROD, DEV, ...) , application and s...P-DBMS: Network and Database ProjectPraiseSight: PraiseSight is supposed to become a practical tool for churches to catalog an present their songs, lyrics and presentations on a beamer. The soluti...Pretty Good Frontend: Pretty Good Frontend is a sample frontend for ConfigMgr (SCCM) 2007 and MDT 2010 Zero Touch. S3Appender (Appender for Log4Net that Uses Amazon S3 For Storing Log Files): The S3Appender is a log4net appender that stores log events in either a MemoryStream or FileStream and sends them to S3 based on time intervals and...sEmit: sEmit (sms emitter) is an application written in C# which was built to send text messages. The project was founded in May 2009 by cansik. It works ...Silverlight RIA Tools: A tool set that generates a full RIA Solutions in Silverlightthommo cannon: Cannon for shooting down ThommosTianjin Polytechnic University Online Judge: Online Judge System Built on Microsoft technologies. Vision & Scope: A distributed OJ Solution on Windows and Cloud. Technologies used or planed...Tinare: Tinare is an byte encryption and decryption alogrithm. The input key is a string password.TinyPlug: Small Plugin Manager, written in C# Allows a project to define supported interfaces, and at runtime add plugins which support (inherit) these in...Utility niconv helps to convert text from one encoding to another: .NET implementation of GUN iconv console converter utility. The niconv program converts text from one encoding to another encoding. In the future r...WareFeed - Software Business Analytics: WareFeed is a simple but effective Software Business Analytics tool written in PHP and compatible others languages such as .NET, Java or Python. It...Y36API1: Semestralni projekt na Y36APINew ReleasesAlter gear SQL index Management: Setup 1.0.0: setup for first alpha releaseASP League Ladder System: ASPLeagueRelease_0_4_1: Release v 0.41Augmented Reality Strategy Simulator: Augmented Reality Strategy Simulator: Version 1.0 InstallerAutoAudit: AutoAudit 1.10e: Version 1.10e will be the final iteration of version 1 development. Version 2 will begin adding switches and options. Pleae email your suggestio...Boo syntax highlighting for Visual Studio 2010: Boo syntax VS 2010 - alpha: First release TODO: Multiline comments!Chargify.NET: Chargify.NET 0.6: Updated library, using Metered Components and updated Product information.Composer: V1.0.326.1000 Alpha: Initial Alpha release. Should be stable, with minor issues.CoNatural Components: CoNatural Components 1.6: Code fixes: Created helper classes to generate source code for type mapper/materializer. Fixed issue in optimized type materializer when loading ...CRM External View: 1.2: New Features in v1.2 release Password protected views. No more using Web Data Access role from v1. Filtering capabilities Caching for performan...Designit Video Embed Package: Release 1.1.0 beta1: You can now either have the video embeded directly in the template or have a preview in template that opens the video in a lightbox window.FsUnit: FsUnit 0.9.0 for NUnit: This release is for F# 2.0 and NUnit 2.5+.Laughing Dog XNA Framework: Laughing Dog 0.0.1: Laughing Dog - Alpla - v 0.0.1 First released version of the Laughing Dog framework.LiveUpload to Facebook: LiveUpload to Facebook 3.2: Version 3.2Become a fan on Facebook! Features Quickly and easily upload your photos and videos to Facebook, including any people tags added in Win...MapWindow6: MapWindow 6.0 msi March 26: This version adds the Join feature for creating a new "featureset" with attributes that are joined with attributes from a Excel data label named 'D...Mobile Broadband Logging Monitor: Mobile Broadband Logging Monitor 1.2.2: This edition supports: Newer and older editions of Birdstep Technology's EasyConnect HUAWEI Mobile Partner MWConn User defined location for s...Multiplayer Quiz: Release 1_6_351_0: A beta release of the next version. Please leave any errors in discussions or comments.Native code wrapping using c# : fsutil sparse commands: Fsutil sparse file native code - c sharp wrapper: Project Description A C# code wrapping a native code-Sparse files1 The code is about SPARSE files- the abillity to create huge files (for future us...Nice Libraries: 1.30 build 50325.01: Release 1.30 build 50325.01Pretty Good Frontend: Pretty Good Frontend binaries v1.0: This is the first public release of the Pretty Good Frontend binariesPylor: Pylor 0.1 alpha: This is the very first published version. I hope I can put a sample project soon.Quick Performance Monitor: Version 1.1 refresh: There was a typo or two in the sample batch file. Corrected now.Rapidshare Episode Downloader: RED v0.8.3: 0.8.1 introduced the ability to advance to the next episode. In 0.8.2 a bug was found that if episode number is less then 10, then the preceding 0...RapidWebDev - .NET Enterprise Software Development Infrastructure: RapidWebDev 1.52: RapidWebDev is an infrastructure helps to develop enterprise software solutions in Microsoft .NET easily and productively. This is the release vers...thommo cannon: game: gamethommo cannon: setup: setupthommo cannon: test: testTinare: Tinare DLL: Tinare DLL is a dynamic-link library written in C# which provides the functions to encrypt and decrypt a byte stream with tinare.WeatherBar: WeatherBar 2.1 [No Installation]: Minor changes to release 2.0 (http://weatherbar.codeplex.com/releases/view/42490). Fixed the bug that caused an exception to be thrown if the user...Most Popular ProjectsMetaSharpRawrWBFS ManagerASP.NET Ajax LibrarySilverlight ToolkitMicrosoft SQL Server Product Samples: DatabaseAJAX Control ToolkitLiveUpload to FacebookWindows Presentation Foundation (WPF)ASP.NETMost Active ProjectsRawrjQuery Library for SharePoint Web ServicesBlogEngine.NETMicrosoft Biology FoundationFarseer Physics Enginepatterns & practices: Composite WPF and SilverlightLINQ to TwitterTable2ClassFluent Ribbon Control SuiteNB_Store - Free DotNetNuke Ecommerce Catalog Module

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• DBCC CHECKDB on VVLDB and latches (Or: My Pain is Your Gain)

  - by Argenis

    Does your CHECKDB hurt, Argenis? There is a classic blog series by Paul Randal [blog|twitter] called “CHECKDB From Every Angle” which is pretty much mandatory reading for anybody who’s even remotely considering going for the MCM certification, or its replacement (the Microsoft Certified Solutions Master: Data Platform – makes my fingers hurt just from typing it). Of particular interest is the post “Consistency Options for a VLDB” – on it, Paul provides solid, timeless advice (I use the word “timeless” because it was written in 2007, and it all applies today!) on how to perform checks on very large databases. Well, here I was trying to figure out how to make CHECKDB run faster on a restored copy of one of our databases, which happens to exceed 7TB in size. The whole thing was taking several days on multiple systems, regardless of the storage used – SAS, SATA or even SSD…and I actually didn’t pay much attention to how long it was taking, or even bothered to look at the reasons why - as long as it was finishing okay and found no consistency errors. Yes – I know. That was a huge mistake, as corruption found in a database several days after taking place could only allow for further spread of the corruption – and potentially large data loss. In the last two weeks I increased my attention towards this problem, as we noticed that CHECKDB was taking EVEN LONGER on brand new all-flash storage in the SAN! I couldn’t really explain it, and were almost ready to blame the storage vendor. The vendor told us that they could initially see the server driving decent I/O – around 450Mb/sec, and then it would settle at a very slow rate of 10Mb/sec or so. “Hum”, I thought – “CHECKDB is just not pushing the I/O subsystem hard enough”. Perfmon confirmed the vendor’s observations. Dreaded @BlobEater What was CHECKDB doing all the time while doing so little I/O? Eating Blobs. It turns out that CHECKDB was taking an extremely long time on one of our frankentables, which happens to be have 35 billion rows (yup, with a b) and sucks up several terabytes of space in the database. We do have a project ongoing to purge/split/partition this table, so it’s just a matter of time before we deal with it. But the reality today is that CHECKDB is coming to a screeching halt in performance when dealing with this particular table. Checking sys.dm_os_waiting_tasks and sys.dm_os_latch_stats showed that LATCH_EX (DBCC_OBJECT_METADATA) was by far the top wait type. I remembered hearing recently about that wait from another post that Paul Randal made, but that was related to computed-column indexes, and in fact, Paul himself reminded me of his article via twitter. But alas, our pathologic table had no non-clustered indexes on computed columns. I knew that latches are used by the database engine to do internal synchronization – but how could I help speed this up? After all, this is stuff that doesn’t have a lot of knobs to tweak. (There’s a fantastic level 500 talk by Bob Ward from Microsoft CSS [blog|twitter] called “Inside SQL Server Latches” given at PASS 2010 – and you can check it out here. DISCLAIMER: I assume no responsibility for any brain melting that might ensue from watching Bob’s talk!) Failed Hypotheses Earlier on this week I flew down to Palo Alto, CA, to visit our Headquarters – and after having a great time with my Monkey peers, I was relaxing on the plane back to Seattle watching a great talk by SQL Server MVP and fellow MCM Maciej Pilecki [twitter] called “Masterclass: A Day in the Life of a Database Transaction” where he discusses many different topics related to transaction management inside SQL Server. Very good stuff, and when I got home it was a little late – that slow DBCC CHECKDB that I had been dealing with was way in the back of my head. As I was looking at the problem at hand earlier on this week, I thought “How about I set the database to read-only?” I remembered one of the things Maciej had (jokingly) said in his talk: “if you don’t want locking and blocking, set the database to read-only” (or something to that effect, pardon my loose memory). I immediately killed the CHECKDB which had been running painfully for days, and set the database to read-only mode. Then I ran DBCC CHECKDB against it. It started going really fast (even a bit faster than before), and then throttled down again to around 10Mb/sec. All sorts of expletives went through my head at the time. Sure enough, the same latching scenario was present. Oh well. I even spent some time trying to figure out if NUMA was hurting performance. Folks on Twitter made suggestions in this regard (thanks, Lonny! [twitter]) …Eureka? This past Friday I was still scratching my head about the whole thing; I was ready to start profiling with XPERF to see if I could figure out which part of the engine was to blame and then get Microsoft to look at the evidence. After getting a bunch of good news I’ll blog about separately, I sat down for a figurative smack down with CHECKDB before the weekend. And then the light bulb went on. A sparse column. I thought that I couldn’t possibly be experiencing the same scenario that Paul blogged about back in March showing extreme latching with non-clustered indexes on computed columns. Did I even have a non-clustered index on my sparse column? As it turns out, I did. I had one filtered non-clustered index – with the sparse column as the index key (and only column). To prove that this was the problem, I went and setup a test. Yup, that'll do it The repro is very simple for this issue: I tested it on the latest public builds of SQL Server 2008 R2 SP2 (CU6) and SQL Server 2012 SP1 (CU4). First, create a test database and a test table, which only needs to contain a sparse column: CREATE DATABASE SparseColTest; GO USE SparseColTest; GO CREATE TABLE testTable (testCol smalldatetime SPARSE NULL); GO INSERT INTO testTable (testCol) VALUES (NULL); GO 1000000 That’s 1 million rows, and even though you’re inserting NULLs, that’s going to take a while. In my laptop, it took 3 minutes and 31 seconds. Next, we run DBCC CHECKDB against the database: DBCC CHECKDB('SparseColTest') WITH NO_INFOMSGS, ALL_ERRORMSGS; This runs extremely fast, as least on my test rig – 198 milliseconds. Now let’s create a filtered non-clustered index on the sparse column: CREATE NONCLUSTERED INDEX [badBadIndex] ON testTable (testCol) WHERE testCol IS NOT NULL; With the index in place now, let’s run DBCC CHECKDB one more time: DBCC CHECKDB('SparseColTest') WITH NO_INFOMSGS, ALL_ERRORMSGS; In my test system this statement completed in 11433 milliseconds. 11.43 full seconds. Quite the jump from 198 milliseconds. I went ahead and dropped the filtered non-clustered indexes on the restored copy of our production database, and ran CHECKDB against that. We went down from 7+ days to 19 hours and 20 minutes. Cue the “Argenis is not impressed” meme, please, Mr. LaRock. My pain is your gain, folks. Go check to see if you have any of such indexes – they’re likely causing your consistency checks to run very, very slow. Happy CHECKDBing, -Argenis ps: I plan to file a Connect item for this issue – I consider it a pretty serious bug in the engine. After all, filtered indexes were invented BECAUSE of the sparse column feature – and it makes a lot of sense to use them together. Watch this space and my twitter timeline for a link.

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• Creating SparseImages for Pivot

  - by John Conwell

  Learning how to programmatically make collections for Microsoft Live Labs Pivot has been a pretty interesting ride. There are very few examples out there, and the folks at MS Live Labs are often slow on any feedback.  But that is what Reflector is for, right? Well, I was creating these InfoCard images (similar to the Car images in the "New Cars" sample collection that that MS created for Pivot), and wanted to put a Tag Cloud into the info card.  The problem was the size of the tag cloud might vary in order for all the tags to fit into the tag cloud (often times being bigger than the info card itself).  This was because the varying word lengths and calculated font sizes. So, to fix this, I made the tag cloud its own separate image from the info card.  Then, I would create a sparse image out of the two images, where the tag cloud fit into a small section of the info card.  This would allow the user to see the info card, but then zoom into the tag cloud and see all the tags at a normal resolution.  Kind'a cool. But...I couldn't find one code example (not one!) of how to create a sparse image.  There is one page on the SeaDragon site (http://www.seadragon.com/developer/creating-content/deep-zoom-tools/) that gives over the API for creating images and collections, and it sparsely goes over how to create a sparse image, but unless you are familiar with the API already, the documentation doesn't help very much. The key is the Image.ViewportWidth and Image.ViewportOrigin properties of the image that is getting super imposed on the main image.  I'll walk through the code below.  I've setup a couple Point structs to represent the parent and sub image sizes, as well as where on the parent I want to position the sub image.  Next, create the parent image.  This is pretty straight forward.  Then I create the sub image.  Then I calculate several ratios; the height to width ratio of the sub image, the width ratio of the sub image to the parent image, the height ratio of the sub image to the parent image, then the X and Y coordinates on the parent image where I want the sub image to be placed represented as a ratio of the position to the parent image size. After all these ratios have been calculated, I use them to calculate the Image.ViewportWidth and Image.ViewportOrigin values, then pass the image objects into the SparseImageCreator and call Create. The key thing that was really missing from the API documentation page is that when setting up your sub images, everything is expressed in a ratio in relation to the main parent image.  If I had known this, it would have saved me a lot of trial and error time.  And how did I figure this out?  Reflector of course!  There is a tool called Deep Zoom Composer that came from MS Live Labs which can create a sparse image.  I just dug around the tool's code until I found the method that create sparse images.  But seriously...look at the API documentation from the SeaDragon size and look at the code below and tell me if the documentation would have helped you at all.  I don't think so!   public static void WriteDeepZoomSparseImage(string mainImagePath, string subImagePath, string destination) {     Point parentImageSize = new Point(720, 420);     Point subImageSize = new Point(490, 310);     Point subImageLocation = new Point(196, 17);     List<Image> images = new List<Image>();     //create main image     Image mainImage = new Image(mainImagePath);     mainImage.Size = parentImageSize;     images.Add(mainImage);     //create sub image     Image subImage = new Image(subImagePath);     double hwRatio = subImageSize.X/subImageSize.Y;            // height width ratio of the tag cloud     double nodeWidth = subImageSize.X/parentImageSize.X;        // sub image width to parent image width ratio     double nodeHeight = subImageSize.Y / parentImageSize.Y;    // sub image height to parent image height ratio     double nodeX = subImageLocation.X/parentImageSize.X;       //x cordinate position on parent / width of parent     double nodeY = subImageLocation.Y / parentImageSize.Y;     //y cordinate position on parent / height of parent     subImage.ViewportWidth = (nodeWidth < double.Epsilon) ? 1.0 : (1.0 / nodeWidth);     subImage.ViewportOrigin = new Point(         (nodeWidth < double.Epsilon) ? -1.0 : (-nodeX / nodeWidth),         (nodeHeight < double.Epsilon) ? -1.0 : ((-nodeY / nodeHeight) / hwRatio));     images.Add(subImage);     //create sparse image     SparseImageCreator creator = new SparseImageCreator();     creator.Create(images, destination); }

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• Sparse Array in C! How accomplish it? Can I alloc only parts of an array?

  - by drigoSkalWalker

  Hi guys! The first question is: "How I do a simple sparse array in C (with one dimension only)?" {with my own hands, without libraries.} And the last one: "Can I allocate only parts of an array?" like *array; then use malloc to allocate some mem for this; so, We free the index that we don't want. Can I do it? Thanks so much!

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• How do I translate this Matlab bsxfun call to R?

  - by claytontstanley

  I would also (fingers crossed) like the solution to work with R Sparse Matrices in the Matrix package. >> A = [1,2,3,4,5] A = 1 2 3 4 5 >> B = [1;2;3;4;5] B = 1 2 3 4 5 >> bsxfun(@times, A, B) ans = 1 2 3 4 5 2 4 6 8 10 3 6 9 12 15 4 8 12 16 20 5 10 15 20 25 >> EDIT: I would like to do a matrix multiplication of these sparse vectors, and return a sparse array: > class(NRowSums) [1] "dsparseVector" attr(,"package") [1] "Matrix" > class(NColSums) [1] "dsparseVector" attr(,"package") [1] "Matrix" > NRowSums * NColSums (I think) w/o using a non-sparse variable to temporarily store data.

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• Paste multiple lines before a line in vim?

  - by Umar

  How do I copy multiple lines and paste them as a block before a line? As an example I have the following code and I want to copy and paste the three lines after the if statement to after the else statement but before the line below it. [row col] = find(H); if (nargin < 4) delqmn = sparse(row, col, 0, M, N); % diff of msgs from bits to checks delrmn = sparse(row, col, 0, M, N);% diff of msgs from checks to bits rmn0 = sparse(row, col, 0, M, N);% msgs from checks to bits (p=0) else // Insert 3 lines after if statement here qn0 = 1-r;% pseudoposterior probabilities qn1 = r;% pseudoposterior probabilities Thanks

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• Ways to setup a ZFS pool on a device without possibility to create/manage partitions?

  - by Karl Richter

  I have a NAS where I don't have a possibility to create and manage partitions (maybe I could with some hacks that I don't want to make). What ways to setup multiple ZFS pools with one partition each (for starters - just want to use deduplication) exist? The setup should work with the NAS, i.e. over network (I'd mount the images via NFS or cifs). My ideas and associated issues so far: sparse files mounted over loop device (specifying sparse file directly as ZFS vdev doesn't work, see Can I choose a sparse file as vdev for a zfs pool?): problem that the name/number of the assigned loop device is anything but constant, not sure how increasing the number loop device with kernel parameter affects performance (there has to be a reason to limit it to 8 in the default value, right?)

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• SQL SERVER – Weekly Series – Memory Lane – #038

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 CASE Statement in ORDER BY Clause – ORDER BY using Variable This article is as per request from the Application Development Team Leader of my company. His team encountered code where the application was preparing string for ORDER BY clause of the SELECT statement. Application was passing this string as variable to Stored Procedure (SP) and SP was using EXEC to execute the SQL string. This is not good for performance as Stored Procedure has to recompile every time due to EXEC. sp_executesql can do the same task but still not the best performance. SSMS – View/Send Query Results to Text/Grid/Files Results to Text – CTRL + T Results to Grid – CTRL + D Results to File – CTRL + SHIFT + F 2008 Introduction to SPARSE Columns Part 2 I wrote about Introduction to SPARSE Columns Part 1. Let us understand the concept of the SPARSE column in more detail. I suggest you read the first part before continuing reading this article. All SPARSE columns are stored as one XML column in the database. Let us see some of the advantage and disadvantage of SPARSE column. Deferred Name Resolution How come when table name is incorrect SP can be created successfully but when an incorrect column is used SP cannot be created? 2009 Backup Timeline and Understanding of Database Restore Process in Full Recovery Model In general, databases backup in full recovery mode is taken in three different kinds of database files. Full Database Backup Differential Database Backup Log Backup Restore Sequence and Understanding NORECOVERY and RECOVERY While doing RESTORE Operation if you restoring database files, always use NORECOVER option as that will keep the database in a state where more backup file are restored. This will also keep database offline also to prevent any changes, which can create itegrity issues. Once all backup file is restored run RESTORE command with a RECOVERY option to get database online and operational. Four Different Ways to Find Recovery Model for Database Perhaps, the best thing about technical domain is that most of the things can be executed in more than one ways. It is always useful to know about the various methods of performing a single task. Two Methods to Retrieve List of Primary Keys and Foreign Keys of Database When Information Schema is used, we will not be able to discern between primary key and foreign key; we will have both the keys together. In the case of sys schema, we can query the data in our preferred way and can join this table to another table, which can retrieve additional data from the same. Get Last Running Query Based on SPID PID is returns sessions ID of the current user process. The acronym SPID comes from the name of its earlier version, Server Process ID. 2010 SELECT * FROM dual – Dual Equivalent Dual is a table that is created by Oracle together with data dictionary. It consists of exactly one column named “dummy”, and one record. The value of that record is X. You can check the content of the DUAL table using the following syntax. SELECT * FROM dual Identifying Statistics Used by Query Someone asked this question in my training class of query optimization and performance tuning.  “Can I know which statistics were used by my query?” 2011 SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 14 of 31 What are the basic functions for master, msdb, model, tempdb and resource databases? What is the Maximum Number of Index per Table? Explain Few of the New Features of SQL Server 2008 Management Studio Explain IntelliSense for Query Editing Explain MultiServer Query Explain Query Editor Regions Explain Object Explorer Enhancements Explain Activity Monitors SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 15 of 31 What is Service Broker? Where are SQL server Usernames and Passwords Stored in the SQL server? What is Policy Management? What is Database Mirroring? What are Sparse Columns? What does TOP Operator Do? What is CTE? What is MERGE Statement? What is Filtered Index? Which are the New Data Types Introduced in SQL SERVER 2008? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 16 of 31 What are the Advantages of Using CTE? How can we Rewrite Sub-Queries into Simple Select Statements or with Joins? What is CLR? What are Synonyms? What is LINQ? What are Isolation Levels? What is Use of EXCEPT Clause? What is XPath? What is NOLOCK? What is the Difference between Update Lock and Exclusive Lock? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 17 of 31 How will you Handle Error in SQL SERVER 2008? What is RAISEERROR? What is RAISEERROR? How to Rebuild the Master Database? What is the XML Datatype? What is Data Compression? What is Use of DBCC Commands? How to Copy the Tables, Schema and Views from one SQL Server to Another? How to Find Tables without Indexes? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 18 of 31 How to Copy Data from One Table to Another Table? What is Catalog Views? What is PIVOT and UNPIVOT? What is a Filestream? What is SQLCMD? What do you mean by TABLESAMPLE? What is ROW_NUMBER()? What are Ranking Functions? What is Change Data Capture (CDC) in SQL Server 2008? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 19 of 31 How can I Track the Changes or Identify the Latest Insert-Update-Delete from a Table? What is the CPU Pressure? How can I Get Data from a Database on Another Server? What is the Bookmark Lookup and RID Lookup? What is Difference between ROLLBACK IMMEDIATE and WITH NO_WAIT during ALTER DATABASE? What is Difference between GETDATE and SYSDATETIME in SQL Server 2008? How can I Check that whether Automatic Statistic Update is Enabled or not? How to Find Index Size for Each Index on Table? What is the Difference between Seek Predicate and Predicate? What are Basics of Policy Management? What are the Advantages of Policy Management? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 20 of 31 What are Policy Management Terms? What is the ‘FILLFACTOR’? Where in MS SQL Server is ’100’ equal to ‘0’? What are Points to Remember while Using the FILLFACTOR Argument? What is a ROLLUP Clause? What are Various Limitations of the Views? What is a Covered index? When I Delete any Data from a Table, does the SQL Server reduce the size of that table? What are Wait Types? How to Stop Log File Growing too Big? If any Stored Procedure is Encrypted, then can we see its definition in Activity Monitor? 2012 Example of Width Sensitive and Width Insensitive Collation Width Sensitive Collation: A single-byte character (half-width) represented as single-byte and the same character represented as a double-byte character (full-width) are when compared are not equal the collation is width sensitive. In this example we have one table with two columns. One column has a collation of width sensitive and the second column has a collation of width insensitive. Find Column Used in Stored Procedure – Search Stored Procedure for Column Name Very interesting conversation about how to find column used in a stored procedure. There are two different characters in the story and both are having a conversation about how to find column in the stored procedure. Here are two part story Part 1 | Part 2 SQL SERVER – 2012 Functions – FORMAT() and CONCAT() – An Interesting Usage Generate Script for Schema and Data – SQL in Sixty Seconds #021 – Video In simple words, in many cases the database move from one place to another place. It is not always possible to back up and restore databases. There are possibilities when only part of the database (with schema and data) has to be moved. In this video we learn that we can easily generate script for schema for data and move from one server to another one. INFORMATION_SCHEMA.COLUMNS and Value Character Maximum Length -1 I often see the value -1 in the CHARACTER_MAXIMUM_LENGTH column of INFORMATION_SCHEMA.COLUMNS table. I understand that the length of any column can be between 0 to large number but I do not get it when I see value in negative (i.e. -1). Any insight on this subject? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Achieve Named Criteria with multiple tables in EJB Data control

  - by Deepak Siddappa

  In EJB create a named criteria using sparse xml and in named criteria wizard, only attributes related to the that particular entities will be displayed.  So here we can filter results only on particular entity bean. Take a scenario where we need to create Named Criteria based on multiple tables using EJB. In BC4J we can achieve this by creating view object based on multiple tables. So in this article, we will try to achieve named criteria based on multiple tables using EJB.Implementation StepsCreate Java EE Web Application with entity based on Departments and Employees, then create a session bean and data control for the session bean.Create a Java Bean, name as CustomBean and add below code to the file. Here in java bean from both Departments and Employees tables three fields are taken. public class CustomBean { private BigDecimal departmentId; private String departmentName; private BigDecimal locationId; private BigDecimal employeeId; private String firstName; private String lastName; public CustomBean() { super(); } public void setDepartmentId(BigDecimal departmentId) { this.departmentId = departmentId; } public BigDecimal getDepartmentId() { return departmentId; } public void setDepartmentName(String departmentName) { this.departmentName = departmentName; } public String getDepartmentName() { return departmentName; } public void setLocationId(BigDecimal locationId) { this.locationId = locationId; } public BigDecimal getLocationId() { return locationId; } public void setEmployeeId(BigDecimal employeeId) { this.employeeId = employeeId; } public BigDecimal getEmployeeId() { return employeeId; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getFirstName() { return firstName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getLastName() { return lastName; } } Open the sessionEJb file and add the below code to the session bean and expose the method in local/remote interface and generate a data control for that. Note:- Here in the below code "em" is a EntityManager. public List<CustomBean> getCustomBeanFindAll() { String queryString = "select d.department_id, d.department_name, d.location_id, e.employee_id, e.first_name, e.last_name from departments d, employees e\n" + "where e.department_id = d.department_id"; Query genericSearchQuery = em.createNativeQuery(queryString, "CustomQuery"); List resultList = genericSearchQuery.getResultList(); Iterator resultListIterator = resultList.iterator(); List<CustomBean> customList = new ArrayList(); while (resultListIterator.hasNext()) { Object col[] = (Object[])resultListIterator.next(); CustomBean custom = new CustomBean(); custom.setDepartmentId((BigDecimal)col[0]); custom.setDepartmentName((String)col[1]); custom.setLocationId((BigDecimal)col[2]); custom.setEmployeeId((BigDecimal)col[3]); custom.setFirstName((String)col[4]); custom.setLastName((String)col[5]); customList.add(custom); } return customList; } Open the DataControls.dcx file and create sparse xml for customBean. In sparse xml navigate to Named criteria tab -> Bind Variable section, create two binding variables deptId,fName. In sparse xml navigate to Named criteria tab ->Named criteria, create a named criteria and map the query attributes to the bind variables. In the ViewController create a file jspx page, from data control palette drop customBeanFindAll->Named Criteria->CustomBeanCriteria->Query as ADF Query Panel with Table. Run the jspx page and enter values in search form with departmentId as 50 and firstName as "M". Named criteria will filter the query of a data source and display the result like below.

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• SQL SERVER – 2008 – Introduction to Snapshot Database – Restore From Snapshot

  - by pinaldave

  Snapshot database is one of the most interesting concepts that I have used at some places recently. Here is a quick definition of the subject from Book On Line: A Database Snapshot is a read-only, static view of a database (the source database). Multiple snapshots can exist on a source database and can always reside on the same server instance as the database. Each database snapshot is consistent, in terms of transactions, with the source database as of the moment of the snapshot’s creation. A snapshot persists until it is explicitly dropped by the database owner. If you do not know how Snapshot database work, here is a quick note on the subject. However, please refer to the official description on Book-on-Line for accuracy. Snapshot database is a read-only database created from an original database called the “source database”. This database operates at page level. When Snapshot database is created, it is produced on sparse files; in fact, it does not occupy any space (or occupies very little space) in the Operating System. When any data page is modified in the source database, that data page is copied to Snapshot database, making the sparse file size increases. When an unmodified data page is read in the Snapshot database, it actually reads the pages of the original database. In other words, the changes that happen in the source database are reflected in the Snapshot database. Let us see a simple example of Snapshot. In the following exercise, we will do a few operations. Please note that this script is for demo purposes only- there are a few considerations of CPU, DISK I/O and memory, which will be discussed in the future posts. Create Snapshot Delete Data from Original DB Restore Data from Snapshot First, let us create the first Snapshot database and observe the sparse file details. USE master GO -- Create Regular Database CREATE DATABASE RegularDB GO USE RegularDB GO -- Populate Regular Database with Sample Table CREATE TABLE FirstTable (ID INT, Value VARCHAR(10)) INSERT INTO FirstTable VALUES(1, 'First'); INSERT INTO FirstTable VALUES(2, 'Second'); INSERT INTO FirstTable VALUES(3, 'Third'); GO -- Create Snapshot Database CREATE DATABASE SnapshotDB ON (Name ='RegularDB', FileName='c:\SSDB.ss1') AS SNAPSHOT OF RegularDB; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO Now let us see the resultset for the same. Now let us do delete something from the Original DB and check the same details we checked before. -- Delete from Regular Database DELETE FROM RegularDB.dbo.FirstTable; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO When we check the details of sparse file created by Snapshot database, we will find some interesting details. The details of Regular DB remain the same. It clearly shows that when we delete data from Regular/Source DB, it copies the data pages to Snapshot database. This is the reason why the size of the snapshot DB is increased. Now let us take this small exercise to  the next level and restore our deleted data from Snapshot DB to Original Source DB. -- Restore Data from Snapshot Database USE master GO RESTORE DATABASE RegularDB FROM DATABASE_SNAPSHOT = 'SnapshotDB'; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Clean up DROP DATABASE [SnapshotDB]; DROP DATABASE [RegularDB]; GO Now let us check the details of the select statement and we can see that we are successful able to restore the database from Snapshot Database. We can clearly see that this is a very useful feature in case you would encounter a good business that needs it. I would like to request the readers to suggest more details if they are using this feature in their business. Also, let me know if you think it can be potentially used to achieve any tasks. Complete Script of the afore- mentioned operation for easy reference is as follows: USE master GO -- Create Regular Database CREATE DATABASE RegularDB GO USE RegularDB GO -- Populate Regular Database with Sample Table CREATE TABLE FirstTable (ID INT, Value VARCHAR(10)) INSERT INTO FirstTable VALUES(1, 'First'); INSERT INTO FirstTable VALUES(2, 'Second'); INSERT INTO FirstTable VALUES(3, 'Third'); GO -- Create Snapshot Database CREATE DATABASE SnapshotDB ON (Name ='RegularDB', FileName='c:\SSDB.ss1') AS SNAPSHOT OF RegularDB; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Delete from Regular Database DELETE FROM RegularDB.dbo.FirstTable; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Restore Data from Snapshot Database USE master GO RESTORE DATABASE RegularDB FROM DATABASE_SNAPSHOT = 'SnapshotDB'; GO -- Select from Regular and Snapshot Database SELECT * FROM RegularDB.dbo.FirstTable; SELECT * FROM SnapshotDB.dbo.FirstTable; GO -- Clean up DROP DATABASE [SnapshotDB]; DROP DATABASE [RegularDB]; GO Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Backup and Restore, SQL Data Storage, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• What's up with stat on MacOSX/Darwin? Or filesystems without names...

  - by Charles Stewart

  In response to a question I asked on SO, Give the mount point of a path, one respondant suggested using stat to get the device name associated with the volume of a given path. This works nicely on Linux, but gives crazy results on MacOSX 10.4. For my system, df and mount give: cas cas$ df Filesystem 512-blocks Used Avail Capacity Mounted on /dev/disk0s3 58342896 49924456 7906440 86% / devfs 194 194 0 100% /dev fdesc 2 2 0 100% /dev <volfs> 1024 1024 0 100% /.vol automount -nsl [166] 0 0 0 100% /Network automount -fstab [170] 0 0 0 100% /automount/Servers automount -static [170] 0 0 0 100% /automount/static /dev/disk2s1 163577856 23225520 140352336 14% /Volumes/Snapshot /dev/disk2s2 409404102 5745938 383187960 1% /Volumes/Sparse cas cas$ mount /dev/disk0s3 on / (local, journaled) devfs on /dev (local) fdesc on /dev (union) <volfs> on /.vol automount -nsl [166] on /Network (automounted) automount -fstab [170] on /automount/Servers (automounted) automount -static [170] on /automount/static (automounted) /dev/disk2s1 on /Volumes/Snapshot (local, nodev, nosuid, journaled) /dev/disk2s2 on /Volumes/Sparse (asynchronous, local, nodev, nosuid) Trying to get the devices from the mount points, though: cas cas$ df | grep -e/ | awk '{print $NF}' | while read line; do echo $line $(stat -f"%Sdr" $line); done / disk0s3r /dev ???r /dev ???r /.vol ???r /Network ???r /automount/Servers ???r /automount/static ???r /Volumes/Snapshot disk2s1r /Volumes/Sparse disk2s2r Here, I'm feeding each of the mount points scraped from df to stat, outputting the results of the "%Sdr" format string, which is supposed to be the device name: Cf. stat(1) man page: The special output specifier S may be used to indicate that the output, if applicable, should be in string format. May be used in combination with: ... dr Display actual device name. What's going on? Is it a bug in stat, or some Darwin VFS weirdness? Postscript Per Andrew McGregor, try passing "%Sd" to stat for more weirdness. It lists some apparently arbitrary subset of files from CWD...

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• What's up with stat on Mac OS X/Darwin? Or filesystems without names...

  - by Charles Stewart

  In response to a question I asked on SO, Give the mount point of a path, one respondant suggested using stat to get the device name associated with the volume of a given path. This works nicely on Linux, but gives crazy results on Mac OS X 10.4. For my system, df and mount give: cas cas$ df Filesystem 512-blocks Used Avail Capacity Mounted on /dev/disk0s3 58342896 49924456 7906440 86% / devfs 194 194 0 100% /dev fdesc 2 2 0 100% /dev <volfs> 1024 1024 0 100% /.vol automount -nsl [166] 0 0 0 100% /Network automount -fstab [170] 0 0 0 100% /automount/Servers automount -static [170] 0 0 0 100% /automount/static /dev/disk2s1 163577856 23225520 140352336 14% /Volumes/Snapshot /dev/disk2s2 409404102 5745938 383187960 1% /Volumes/Sparse cas cas$ mount /dev/disk0s3 on / (local, journaled) devfs on /dev (local) fdesc on /dev (union) <volfs> on /.vol automount -nsl [166] on /Network (automounted) automount -fstab [170] on /automount/Servers (automounted) automount -static [170] on /automount/static (automounted) /dev/disk2s1 on /Volumes/Snapshot (local, nodev, nosuid, journaled) /dev/disk2s2 on /Volumes/Sparse (asynchronous, local, nodev, nosuid) Trying to get the devices from the mount points, though: cas cas$ df | grep -e/ | awk '{print $NF}' | while read line; do echo $line $(stat -f"%Sdr" $line); done / disk0s3r /dev ???r /dev ???r /.vol ???r /Network ???r /automount/Servers ???r /automount/static ???r /Volumes/Snapshot disk2s1r /Volumes/Sparse disk2s2r Here, I'm feeding each of the mount points scraped from df to stat, outputting the results of the "%Sdr" format string, which is supposed to be the device name: Cf. stat(1) man page: The special output specifier S may be used to indicate that the output, if applicable, should be in string format. May be used in combination with: ... dr Display actual device name. What's going on? Is it a bug in stat, or some Darwin VFS weirdness? Postscript Per Andrew McGregor, try passing "%Sd" to stat for more weirdness. It lists some apparently arbitrary subset of files from CWD...

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• What's up with stat on Macos/Darwin? Or filesystems without names...

  - by Charles Stewart

  In response to a question I asked on SO, Give the mount point of a path, one respondant suggested using stat to get the device name associated with the volume of a given path. This works nicely on Linux, but gives crazy results on Macos 10.4. For my system, df and mount give: cas cas$ df Filesystem 512-blocks Used Avail Capacity Mounted on /dev/disk0s3 58342896 49924456 7906440 86% / devfs 194 194 0 100% /dev fdesc 2 2 0 100% /dev 1024 1024 0 100% /.vol automount -nsl [166] 0 0 0 100% /Network automount -fstab [170] 0 0 0 100% /automount/Servers automount -static [170] 0 0 0 100% /automount/static /dev/disk2s1 163577856 23225520 140352336 14% /Volumes/Snapshot /dev/disk2s2 409404102 5745938 383187960 1% /Volumes/Sparse cas cas$ mount /dev/disk0s3 on / (local, journaled) devfs on /dev (local) fdesc on /dev (union) on /.vol automount -nsl [166] on /Network (automounted) automount -fstab [170] on /automount/Servers (automounted) automount -static [170] on /automount/static (automounted) /dev/disk2s1 on /Volumes/Snapshot (local, nodev, nosuid, journaled) /dev/disk2s2 on /Volumes/Sparse (asynchronous, local, nodev, nosuid) Trying to get the devices from the mount points, though: cas cas$ df | grep -e/ | awk '{print $NF}' | while read line; do echo $line $(stat -f"%Sdr" $line); done / disk0s3r /dev ???r /dev ???r /.vol ???r /Network ???r /automount/Servers ???r /automount/static ???r /Volumes/Snapshot disk2s1r /Volumes/Sparse disk2s2r Here, I'm feeding each of the mount points scraped from df to stat, outputing the results of the "%Sdr" format string, which is supposed to be the device name: Cf. stat(1) man page: The special output specifier S may be used to indicate that the output, if applicable, should be in string format. May be used in combination with: ... dr Display actual device name. What's going on? Is it a bug in stat, or some Darwin VFS weirdness? Postscript Per Andrew McGregor, try passing "%Sd" to stat for more weirdness. It lists some apparently arbitrary subset of files from CWD...

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• SQL SERVER – Weekly Series – Memory Lane – #037

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Convert Text to Numbers (Integer) – CAST and CONVERT If table column is VARCHAR and has all the numeric values in it, it can be retrieved as Integer using CAST or CONVERT function. List All Stored Procedure Modified in Last N Days If SQL Server suddenly start behaving in un-expectable behavior and if stored procedure were changed recently, following script can be used to check recently modified stored procedure. If a stored procedure was created but never modified afterwards modified date and create a date for that stored procedure are same. Count Duplicate Records – Rows Validate Field For DATE datatype using function ISDATE() We always checked DATETIME field for incorrect data type. One of the user input date as 30/2/2007. The date was sucessfully inserted in the temp table but while inserting from temp table to final table it crashed with error. We had now task to validate incorrect date value before we insert in final table. Jr. Developer asked me how can he do that? We check for incorrect data type (varchar, int, NULL) but this is incorrect date value. Regular expression works fine with them because of mm/dd/yyyy format. 2008 Find Space Used For Any Particular Table It is very simple to find out the space used by any table in the database. Two Convenient Features Inline Assignment – Inline Operations Here is the script which does both – Inline Assignment and Inline Operation DECLARE @idx INT = 0 SET @idx+=1 SELECT @idx Introduction to SPARSE Columns SPARSE column are better at managing NULL and ZERO values in SQL Server. It does not take any space in database at all. If column is created with SPARSE clause with it and it contains ZERO or NULL it will be take lesser space then regular column (without SPARSE clause). SP_CONFIGURE – Displays or Changes Global Configuration Settings If advanced settings are not enabled at configuration level SQL Server will not let user change the advanced features on server. Authorized user can turn on or turn off advance settings. 2009 Standby Servers and Types of Standby Servers Standby Server is a type of server that can be brought online in a situation when Primary Server goes offline and application needs continuous (high) availability of the server. There is always a need to set up a mechanism where data and objects from primary server are moved to secondary (standby) server. BLOB – Pointer to Image, Image in Database, FILESTREAM Storage When it comes to storing images in database there are two common methods. I had previously blogged about the same subject on my visit to Toronto. With SQL Server 2008, we have a new method of FILESTREAM storage. However, the answer on when to use FILESTREAM and when to use other methods is still vague in community. 2010 Upper Case Shortcut SQL Server Management Studio I select the word and hit CTRL+SHIFT+U and it SSMS immediately changes the case of the selected word. Similar way if one want to convert cases to lower case, another short cut CTRL+SHIFT+L is also available. The Self Join – Inner Join and Outer Join Self Join has always been a noteworthy case. It is interesting to ask questions about self join in a room full of developers. I often ask – if there are three kinds of joins, i.e.- Inner Join, Outer Join and Cross Join; what type of join is Self Join? The usual answer is that it is an Inner Join. However, the reality is very different. Parallelism – Row per Processor – Row per Thread – Thread 0  If you look carefully in the Properties window or XML Plan, there is “Thread 0?. What does this “Thread 0” indicate? Well find out from the blog post. How do I Learn and How do I Teach The blog post has raised three very interesting questions. How do you learn? How do you teach? What are you learning or teaching? Let me try to answer the same. 2011 SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 7 of 31 What are Different Types of Locks? What are Pessimistic Lock and Optimistic Lock? When is the use of UPDATE_STATISTICS command? What is the Difference between a HAVING clause and a WHERE clause? What is Connection Pooling and why it is Used? What are the Properties and Different Types of Sub-Queries? What are the Authentication Modes in SQL Server? How can it be Changed? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 8 of 31 Which Command using Query Analyzer will give you the Version of SQL Server and Operating System? What is an SQL Server Agent? Can a Stored Procedure call itself or a Recursive Stored Procedure? How many levels of SP nesting is possible? What is Log Shipping? Name 3 ways to get an Accurate Count of the Number of Records in a Table? What does it mean to have QUOTED_IDENTIFIER ON? What are the Implications of having it OFF? What is the Difference between a Local and a Global Temporary Table? What is the STUFF Function and How Does it Differ from the REPLACE Function? What is PRIMARY KEY? What is UNIQUE KEY Constraint? What is FOREIGN KEY? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 9 of 31 What is CHECK Constraint? What is NOT NULL Constraint? What is the difference between UNION and UNION ALL? What is B-Tree? How to get @@ERROR and @@ROWCOUNT at the Same Time? What is a Scheduled Job or What is a Scheduled Task? What are the Advantages of Using Stored Procedures? What is a Table Called, if it has neither Cluster nor Non-cluster Index? What is it Used for? Can SQL Servers Linked to other Servers like Oracle? What is BCP? When is it Used? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 10 of 31 What Command do we Use to Rename a db, a Table and a Column? What are sp_configure Commands and SET Commands? How to Implement One-to-One, One-to-Many and Many-to-Many Relationships while Designing Tables? What is Difference between Commit and Rollback when Used in Transactions? What is an Execution Plan? When would you Use it? How would you View the Execution Plan? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 11 of 31 What is Difference between Table Aliases and Column Aliases? Do they Affect Performance? What is the difference between CHAR and VARCHAR Datatypes? What is the Difference between VARCHAR and VARCHAR(MAX) Datatypes? What is the Difference between VARCHAR and NVARCHAR datatypes? Which are the Important Points to Note when Multilanguage Data is Stored in a Table? How to Optimize Stored Procedure Optimization? What is SQL Injection? How to Protect Against SQL Injection Attack? How to Find Out the List Schema Name and Table Name for the Database? What is CHECKPOINT Process in the SQL Server? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Day 12 of 31 How does Using a Separate Hard Drive for Several Database Objects Improves Performance Right Away? How to Find the List of Fixed Hard Drive and Free Space on Server? Why can there be only one Clustered Index and not more than one? What is Difference between Line Feed (\n) and Carriage Return (\r)? Is It Possible to have Clustered Index on Separate Drive From Original Table Location? What is a Hint? How to Delete Duplicate Rows? Why the Trigger Fires Multiple Times in Single Login? 2012 CTRL+SHIFT+] Shortcut to Select Code Between Two Parenthesis Shortcut key is CTRL+SHIFT+]. This key can be very useful when dealing with multiple subqueries, CTE or query with multiple parentheses. When exercised this shortcut key it selects T-SQL code between two parentheses. Monday Morning Puzzle – Query Returns Results Sometimes but Not Always I am beginner with SQL Server. I have one query, it sometime returns a result and sometime it does not return me the result. Where should I start looking for a solution and what kind of information I should send to you so you can help me with solving. I have no clue, please guide me. Remove Debug Button in SSMS – SQL in Sixty Seconds #020 – Video Effect of Case Sensitive Collation on Resultset Collation is a very interesting concept but I quite often see it is heavily neglected. I have seen developer and DBA looking for a workaround to fix collation error rather than understanding if the side effect of the workaround. Switch Between Two Parenthesis using Shortcut CTRL+] Earlier this week I wrote a blog post about CTRL+SHIFT+] Shortcut to Select Code Between Two Parenthesis, I received quite a lot of positive feedback from readers. If you are a regular reader of the blog post, you must be aware that I appreciate the learning shared by readers. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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