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• I need help with a SQL query. Fetching an entry, it's most recent revision and it's fields.

  - by Tigger ate my dad

  Hi there, I'm building a CMS for my own needs, and finished planning my database layout. Basically I am abstracting all possible data-models into "sections" and all entries into one table. The final layout is as follows: Database diagram: I have yet to be allowed to post images, so here is a link to a diagram of my database. Entries (section_entries) are children of their section (sections). I save all edits to the entries in a new revision (section_entries_revisions), and also track revisions on the sections (section_revisions), in order to match the values of a revision, to the fields of the section that existed when the entry-revision was made. The section-revisions can have a number of fields (section_revision_fields) that define the attributes of entries in the section. There is a many-to-many relationship between the fields (section_revision_fields) and the entry-revisions (section_entry_revisions), that stores the values of the attributes defined by the section revision. Feel free to ask questions if the diagram is confusing. Now, this is the most complex SQL I've ever worked with, and the task of fetching my data is a little daunting. Basically what i want help with, is fetching an entry, when the only known variables are; section_id, section_entry_id. The query should fetch the most recent revision of that entry, and the section_revision model corresponding to section_revision_id in the section_entry_revisions table. It should also fetch the values of the fields in the section-revision. I was hoping for a query result, where there would be as many rows as fields in the section. Each row would contain the information of the entry and the section, and then information for one of the fields (e.g. each row corresponding to a field and it's value). I tried to explain the best I could. Again, feel free to ask questions if my description somehow lacking. I hope someone is up for the challenge. Best regards. :-)

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• What is the Difference between onclick and href="javscript:function name ?

  - by Shyju

  Is there any difference between 1 : <a href="javascript:MyFunction()">Link1</a> and 2 : <a href="#" onclick="MyFunction()">Link2</a> ? Would one affect the page performance by any means ?

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• haw to connect to sql server db on server by domain name

  - by user353992

  haw can i connect to sql server database by domain name

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• Regex vs. string:find() for simple word boundary

  - by user576267

  Say I only need to find out whether a line read from a file contains a word from a finite set of words. One way of doing this is to use a regex like this: .*\y(good|better|best)\y.* Another way of accomplishing this is using a pseudo code like this: if ( (readLine.find("good") != string::npos) || (readLine.find("better") != string::npos) || (readLine.find("best") != string::npos) ) { // line contains a word from a finite set of words. } Which way will have better performance? (i.e. speed and CPU utilization)

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• How to detect READ_COMMITTED_SNAPSHOT is enabled?

  - by Chris Driver

  Hello, In MS SQL Server is there a way to detect whether a database has had its isolation level set via the T-SQL command ALTER DATABASE <database> SET READ_COMMITTED_SNAPSHOT ON; I cannot find a simple way to detect this in either T-SQL or via the Management Studio's GUI. TIA

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• want to extend from java.sql.ResultSet

  - by dora

  hi, i would like to create myRecordSet object that extends java.sql.ResultSet and to implement a method that returns UTC date from sql statement. how can i extend from java.sql.ResultSet, i need an example 10X

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• Does Flex/Actionsctipt/Flash implements a mechanism for reusing Sprites?

  - by php html

  I'm creating a game and I create sprites(enemies). I keep creating and destroying sprites. Flash/Flex has a garbage collector which handles the destruction of unused resources. Should I create an object pool to reuse them, or should I leave flash/flex to handle the creation/destruction of objects? Which option is better from the performance point of view?

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• Query does not subtract correctly

  - by Chris

  I have these two tables: SQL> SELECT * FROM TAB_A; MYDATE P4 D1 D2 P5 P6 --------- ---------- ---------- ----------- ----------- ----------- 30-OCT-12 949,324 4,437,654 10,203,116 25,303,632 13,900,078 SQL> SELECT * FROM TAB_B; MYDATE P4 D1 D2 P5 P6 --------- ---------- ---------- ----------- ----------- ----------- 30-OCT-12 937,796 4,388,477 10,091,811 25,028,402 13,755,882 I need to subtract their respective columns and store the results into a third table like so: SQL> INSERT INTO TAB_C (MYDATE, P4) SELECT SYSDATE,A.P4-B.P4 FROM TAB_A A,TAB_B B WHERE A.MYDATE=B.MYDATE; SQL> SELECT * FROM TAB_C; MYDATE P4 D1 D2 P5 P6 --------- ---------- ---------- ----------- ----------- ----------- 30-OCT-12 926,268 The result is wrong. Basic math: 949324-937796=11528. Numeric values are stored as number datatypes. What am I missing here?

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• Join two results sets to make one result set in T-SQL

  - by Michael Kniskern

  What would be the best approach to combine the two results sets in one result set in T-SQL? SQL statment #1: SELECT COUNT(t.col1) as 'Number of Responses', t.col2 as 'Department' FROM table t WHERE col3 IS NOT NULL GROUP BY t.col1 ORDER BY t.col1 SQL Statment #1: SELECT COUNT(t.col1) as 'Total number of participants', t.col2 as 'Department' FROM table t GROUP BY t.col1 ORDER by t.col1 Desired result set Number of Responses | Total Number of participants | Department

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• How to connect my APP to SQL Server?

  - by salhzmzm

  Hi I have 1 PC (MS Server 2003 + MS SQL Server 2008) and 2 PCs (MS SP2 + my APP) how I can let my APP connects to sql server 2008 on other PC My APP will connect to server to store data in SQL Server 2008 and read/delete/edit (basic operations) what is the best way to do that? NOTE: my APP is written in C# (.NET Platform)

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• linq to sql delete

  - by mazhar

  how would i delete in linq to sql with groupfeature object

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• How much slower is a try/catch block? [closed]

  - by Euclid

  Possible Duplicate: What is the real overhead of try/catch in C#? how much slower is a try catch block than a conditional? eg try { v = someArray[10]; } catch { v = defaultValue; } or if (null != someArray) { v = someArray[10]; } else { v = defaultValue; } is there much in it or isn't there a definative performance differance?

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• Know More About Oracle Row Lock

  - by Liu Maclean(???)

  ??????Oracle??????????row lock,??ORACLE????????????????????,row lock???????????????????????????????,??Server Process?pin????block buffer????????? ????????,?process A ??update???????? Z?????????, ???????rollback???commit;??Process B??????DML??, ???????rowid???? Z???, ???????????process A????????ITL???,????????cleanout??,????????row???????????commit, ???????Process B????”enq: TX – row lock contention”??????? ????Process B????????????? ?????????Process A???????row,??Process B???????”enq: TX – row lock contention”???? ????????  ????????: SESSION A: SQL> select * from v$version; BANNER ---------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi PL/SQL Release 10.2.0.5.0 - Production CORE    10.2.0.5.0      Production TNS for Linux: Version 10.2.0.5.0 - Production NLSRTL Version 10.2.0.5.0 - Production SQL> select * from global_name; GLOBAL_NAME -------------------------------------------------------------------------------- www.oracledatabase12g.com SQL> create table maclean_lock(t1 int); Table created. SQL> insert into maclean_lock values (1); 1 row created. SQL> commit; Commit complete. SQL> select dbms_rowid.rowid_block_number(rowid),dbms_rowid.rowid_relative_fno(rowid) from maclean_lock; DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID) DBMS_ROWID.ROWID_RELATIVE_FNO(ROWID) ------------------------------------ ------------------------------------                                67642                                    1 SQL>  select distinct sid from v$mystat;        SID ----------        142 SQL> select pid,spid from v$process where addr = ( select paddr from v$session where sid=(select distinct sid from v$mystat));        PID SPID ---------- ------------         17 15636 ??SESSION A ????savepoint ,?update ?????????         SQL>  savepoint NONLOCK; Savepoint created. SQL> select * From v$Lock where sid=142; no rows selected SQL> set linesize 140 pagesize 1400 SQL>  update maclean_lock set t1=t1+2; 1 row updated. SQL> select * From v$Lock where sid=142; ADDR             KADDR                   SID TY        ID1        ID2      LMODE    REQUEST      CTIME      BLOCK ---------------- ---------------- ---------- -- ---------- ---------- ---------- ---------- ---------- ---------- 0000000091FC69F0 0000000091FC6A18        142 TM      55829          0          3          0          6          0 00000000914B4008 00000000914B4040        142 TX     393232        609          6          0          6          0         SQL> select dump(3,16) from dual; DUMP(3,16) -------------------------------------------------------------------------------- Typ=2 Len=2: c1,4 ALTER SYSTEM DUMP DATAFILE 1 BLOCK 67642;  Object id on Block? Y  seg/obj: 0xda16  csc: 0x00.234718  itc: 2  flg: O  typ: 1 - DATA      fsl: 0  fnx: 0x0 ver: 0x01  Itl           Xid                  Uba         Flag  Lck        Scn/Fsc 0x01   0x000a.00f.000001e0  0x00800075.02a6.29  C---    0  scn 0x0000.00234711 0x02   0x0007.018.000001fe  0x0080065c.017a.02  ----    1  fsc 0x0000.00000000 data_block_dump,data header at 0x81d185c =============== tsiz: 0x1fa0 hsiz: 0x14 pbl: 0x081d185c bdba: 0x0041083a      76543210 flag=-------- ntab=1 nrow=1 frre=-1 fsbo=0x14 fseo=0x1f9a avsp=0x1f83 tosp=0x1f83 0xe:pti[0]      nrow=1  offs=0 0x12:pri[0]     offs=0x1f9a block_row_dump: tab 0, row 0, @0x1f9a tl: 6 fb: --H-FL-- lb: 0x2  cc: 1 col  0: [ 2]  c1 04 end_of_block_dump ?? BLOCK DUMP ???? ??????XID=0x0007.018.000001fe ?transaction?? lb:0x1 ??SESSION B ,?????UPDATE?? ???enq: TX - row lock contention ?? SQL> select distinct sid from v$mystat;        SID ----------        140 SQL> select pid,spid from v$process where addr = ( select paddr from v$session where sid=(select distinct sid from v$mystat));        PID SPID ---------- ------------         24 15652 SQL> alter system set "_trace_events"='10000-10999:255:24'; System altered.         SQL> update maclean_lock set t1=t1+2; select * From v$Lock where sid=142 or sid=140 order by sid; SESSION C: SQL> select * From v$Lock where sid=142 or sid=140 order by sid; ADDR             KADDR                   SID TY        ID1        ID2      LMODE    REQUEST      CTIME      BLOCK ---------------- ---------------- ---------- -- ---------- ---------- ---------- ---------- ---------- ---------- 0000000091FC6B10 0000000091FC6B38        140 TM      55829          0          3          0         84          0 00000000924F4A58 00000000924F4A78        140 TX     458776        510          0          6         84          0 00000000914B51E8 00000000914B5220        142 TX     458776        510          6          0        312          1 0000000091FC69F0 0000000091FC6A18        142 TM      55829          0          3          0        312          0 ???? SESSION B SID=140 ?SESSION A ?TX ENQUEUE ?X mode?REQUEST SQL> oradebug dump systemstate 266; Statement processed. SESSION B waiter's enqueue lock       SO: 0x924f4a58, type: 5, owner: 0x92bb8dc8, flag: INIT/-/-/0x00       (enqueue) TX-00070018-000001FE    DID: 0001-0018-00000022       lv: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  res_flag: 0x6       req: X, lock_flag: 0x0, lock: 0x924f4a78, res: 0x925617c0       own: 0x92b76be0, sess: 0x92b76be0, proc: 0x92a737a0, prv: 0x925617e0 TX-00070018-000001FE=> TX 458776 510 SESSION A owner's enqueue lock       SO: 0x914b51e8, type: 40, owner: 0x92b796d0, flag: INIT/-/-/0x00       (trans) flg = 0x1e03, flg2 = 0xc0000, prx = 0x0, ros = 2147483647 bsn = 0xed5 bndsn = 0xee7 spn = 0xef7       efd = 3       file:xct.c lineno:1179       DID: 0001-0011-000000C2       parent xid: 0x0000.000.00000000       env: (scn: 0x0000.00234718  xid: 0x0007.018.000001fe  uba: 0x0080065c.017a.02  statement num=0  parent xid: xid: 0x0000.000.00000000  scn: 0x00 00.00234718 0sch: scn: 0x0000.00000000)       cev: (spc = 7818  arsp = 914e8310  ubk tsn: 1 rdba: 0x0080065c  useg tsn: 1 rdba: 0x00800069             hwm uba: 0x0080065c.017a.02  col uba: 0x00000000.0000.00             num bl: 1 bk list: 0x91435070)             cr opc: 0x0 spc: 7818 uba: 0x0080065c.017a.02       (enqueue) TX-00070018-000001FE    DID: 0001-0011-000000C2       lv: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  res_flag: 0x6       mode: X, lock_flag: 0x0, lock: 0x914b5220, res: 0x925617c0       own: 0x92b796d0, sess: 0x92b796d0, proc: 0x92a6ffd8, prv: 0x925617d0        xga: 0x8b7c6d40, heap: UGA       Trans IMU st: 2 Pool index 65535, Redo pool 0x914b58d0, Undo pool 0x914b59b8       Redo pool range [0x86de640 0x86de640 0x86e0e40]       Undo pool range [0x86dbe40 0x86dbe40 0x86de640]         ----------------------------------------         SO: 0x91435070, type: 39, owner: 0x914b51e8, flag: -/-/-/0x00         (List of Blocks) next index = 1         index   itli   buffer hint   rdba       savepoint         -----------------------------------------------------------             0      2   0x647f1fc8    0x41083a     0xee7 ?SESSION A? ROLLBACK ?savepoint: SQL> rollback to NONLOCK; Rollback complete. ????savepoint ??update??????? ??UPDATE???????? ROLLBACK: SQL> select * From v$Lock where sid=142 or sid=140; ADDR             KADDR                   SID TY        ID1        ID2      LMODE    REQUEST      CTIME      BLOCK ---------------- ---------------- ---------- -- ---------- ---------- ---------- ---------- ---------- ---------- 00000000924F4A58 00000000924F4A78        140 TX     458776        510          0          6        822          0 0000000091FC6B10 0000000091FC6B38        140 TM      55829          0          3          0        822          0 00000000914B51E8 00000000914B5220        142 TX     458776        510          6          0       1050          1 ???? SESSION A 142 ???SAVEPOINT ???????TM LOCK ????? ROLLBACK TO SAVEPOINT?????SESSION???TX LOCK!!!! ??????SESSION 142???TX ID1=458776 ID2=510, ????ROLLBACK TO SAVEPOINT?????????ABORT TRANSACTION ?? SESSION B  SID=140??  SESSION A ?? , ?????????SESSION B? update???HANG?? ?????????CACHE?????:  Object id on Block? Y  seg/obj: 0xda16  csc: 0x00.2347b7  itc: 2  flg: O  typ: 1 - DATA      fsl: 0  fnx: 0x0 ver: 0x01  Itl           Xid                  Uba         Flag  Lck        Scn/Fsc 0x01   0x000a.00f.000001e0  0x00800075.02a6.29  C---    0  scn 0x0000.00234711 0x02   0x0000.000.00000000  0x00000000.0000.00  ----    0  fsc 0x0000.00000000 data_block_dump,data header at 0x745d85c =============== tsiz: 0x1fa0 hsiz: 0x14 pbl: 0x0745d85c bdba: 0x0041083a      76543210 flag=-------- ntab=1 nrow=1 frre=-1 fsbo=0x14 fseo=0x1f9a avsp=0x1f83 tosp=0x1f83 0xe:pti[0]      nrow=1  offs=0 0x12:pri[0]     offs=0x1f9a block_row_dump: tab 0, row 0, @0x1f9a tl: 6 fb: --H-FL-- lb: 0x0  cc: 1 col  0: [ 2]  c1 02 end_of_block_dump ???? ITL=0x02? ?????????,col  0: [ 2]  c1 02 ????????? ?????????SESSION D ,??????row lock?? ?UPDATE???????? SESSION D: SQL> update maclean_lock set t1=t1+2; 1 row updated. SQL> rollback; Rollback complete. ??SESSION B ??????????? ?????ORACLE????????, ??????????? TX lock?? row lock , ????????2??? row lock?????????, ?TX lock????????ENQUEUE LOCK???? ?????????PROCESS K?DML???????????????????????,??????????TX LOCK, ????PROCESS Z?????????????????????????ROW LOCK????????, ???????OLTP?????????????????????? ??ROW LOCK?Release ??????TX?ENQUEUE LOCK,?????????Process J ????????????, Process K??????????? ,Process K?????????,???row piece?lb??0x0 ,?????ITL, Process Z???ITL???????Process J????XID,?????Process J?????TX lock, PROCESS K ???TX resource?Enqueue Waiter Linked List?????X mode(exclusive)?enqueue lock? ???Process J??TX lock?,Process J?????TX resource?Enqueue Waiter Linked List ???Process K??????,??POST?????Process K? TX lock??????, ???????row lock???????,????????? ?????????? ?????: SESSION A ???PID =17 ?????????????????? SESSION B ???PID =24 ??????? "_trace_events"='10000-10999:255:24';  KST trace ??????? Server Process??? SESSION A PID=17  ?? acqure?SX mode???TM Lock ,?? ????Transaction?????UNDO SEGMENT 7,???XID 7.24.510, ?acquire ?X mode? TX-00070018-000001fe ? ?????? 00070018-000001fe ???? 7- 24 - 510? XID ? 781F4B8A:007A569C    17   142 10704  83 ksqgtl: acquire TM-0000da15-00000000 mode=SX flags=GLOBAL|XACT why="contention" 781F4B92:007A569D    17   142 10704  19 ksqgtl: SUCCESS 781F4BB3:007A569E    17   142 10812   2 0x000000000041083A 0x0000000000000000 0x0000000000234717 781F4BBA:007A569F    17   142 10812   3 0x0000000000000000 0x0000000000000000 0x0000000000000000 781F4BC0:007A56A0    17   142 10812   4 0x0000000000000000 0x0000000000000000 0x0000000000000000 781F4BD3:007A56A1    17   142 10812   5 0x000000000041083A 0x0000000000000000 0x0000000000000000 781F4BFE:007A56A2    17   142 10811   1 0x000000000041083A 0x0000000000000000 0x0000000000234711 0x0000000000000002 781F4C06:007A56A3    17   142 10811   2 0x000000000041083A 0x0000000000000000 0x0000000000234718 0x00007FA074EDA560 781F4C26:007A56A4    17   142 10813   1 ktubnd: Bind usn 7 nax 1 nbx 0 lng 0 par 0 781F4C43:007A56A5    17   142 10813   2 ktubnd: Txn Bound xid: 7.24.510 781F4C4A:007A56A6    17   142 10704  83 ksqgtl: acquire TX-00070018-000001fe mode=X flags=GLOBAL|XACT why="contention" 781F4C51:007A56A7    17   142 10704  19 ksqgtl: SUCCESS ?????????? ???????? 781F4CBF:007A56A8    17   142 10005   1 KSL WAIT BEG [SQL*Net message to client] 1650815232/0x62657100 1/0x1 0/0x0 781F4CCC:007A56A9    17   142 10005   2 KSL WAIT END [SQL*Net message to client] 1650815232/0x62657100 1/0x1 0/0x0 time=13 781F4CDE:007A56AA    17   142 10005   1 KSL WAIT BEG [SQL*Net message from client] 1650815232/0x62657100 1/0x1 0/0x0 786BD85D:007A57E0    17   142 10005   2 KSL WAIT END [SQL*Net message from client] 1650815232/0x62657100 1/0x1 0/0x0 time=5016447 786BD966:007A57E1    17   142 10005   1 KSL WAIT BEG [SQL*Net message to client] 1650815232/0x62657100 1/0x1 0/0x0 786BD96E:007A57E2    17   142 10005   2 KSL WAIT END [SQL*Net message to client] 1650815232/0x62657100 1/0x1 0/0x0 time=8 SESSION B ???PID =24  ,??????? SX mode? TM lock,??row lock? acquire X mode?TX-00070018-000001fe ksqgtl: acquire TM-0000da15-00000000 mode=SX flags=GLOBAL|XACT why="contention" ksqgtl: SUCCESS 0x000000000041083A 0x0000000000000000 0x00000000002354F8 0x0000000000000000 0x0000000000000000 0x0000000000000000 0x0000000000000000 0x0000000000000000 0x0000000000000000 0x000000000041083A 0x0000000000000000 0x00000000002354F8 0x0000000000000001 0x000000000041083A 0x0000000000000000 0x00000000002354F8 0x0000000008A63780 0x0000000000000001 0x0000000000800861 0x0000000000000241 0x0000000000000001 0x000000000041083A 0x0000000000000001 0x0000000000000001 0x000000000041083A 0x0000000000000000 0x00000000002354F9 0x0000000000000002 ksqgtl: acquire TX-00070018-000001fe mode=X flags=GLOBAL|LONG why="row lock contention" C4048EBD:007F52B6    24   140 10005   2 KSL WAIT END [enq: TX - row lock contention] 1415053318/0x54580006 458776/0x70018 510/0x1fe time=2929879 C4048ED4:007F52B7    24   140 10005   1 KSL WAIT BEG [enq: TX - row lock contention] 1415053318/0x54580006 458776/0x70018 510/0x1fe C43146CA:007F535E    24   140 10005   2 KSL WAIT END [enq: TX - row lock contention] 1415053318/0x54580006 458776/0x70018 510/0x1fe time=2930676 ????????? ,PID=24 ??????ksqcmi???????? deadlock C43146D9:007F535F    24   140 10704 134 ksqcmi: performing local deadlock detection on TX-00070018-000001fe C43146F8:007F5360    24   140 10704 150 ksqcmi: deadlock not detected on TX-00070018-000001fe ?? ??? PID 17 ??ROLLBACK ???? ,????????: PID 17 ROLLBACK; D7A495BB:007F9D3E    17   142 10005   4 KSL POST SENT postee=24 loc='ksqrcl' id1=0 id2=0 name=   type=0 D7A495D8:007F9D3F    17   142 10444  12 ABORT TRANSACTION - xid: 0x0007.018.000001fe ??  PID 17 ??? TX resource?Enqueue Waiter linked List ???PID 24???,????KSL POST SENT ?? PID 24, ???ksqrcl???ENQUEUE LOCK ?PID 24??????KSL POST (KSL POST RCVD poster=17), ?ksqgtl???? TX-00070018-000001fe ?? ksqrcl??, ??PID 24???????? TX lock?USN ,??????? USN 3 XID 3.11.582 ,???acquire TX-0003000b-00000246 D7A49616:007F9D41    24   140 10005   3 KSL POST RCVD poster=17 loc='ksqrcl' id1=0 id2=0 name=   type=0 fac#=0 facpost=1 D7A4961C:007F9D42    24   140 10704  19 ksqgtl: SUCCESS D7A4967D:007F9D43    24   140 10704 117 ksqrcl: release TX-00070018-000001fe mode=X D7A496A5:007F9D44    24   140 10813   1 ktubnd: Bind usn 3 nax 1 nbx 0 lng 0 par 0 D7A496C2:007F9D45    24   140 10813   2 ktubnd: Txn Bound xid: 3.11.582 D7A496C7:007F9D46    24   140 10704  83 ksqgtl: acquire TX-0003000b-00000246 mode=X flags=GLOBAL|XACT why="contention" D7A496E4:007F9D47    24   140 10704  19 ksqgtl: SUCCESS ROW LOCK?Release ??????TX?ENQUEUE LOCK,?????????Process J ????????????, Process K??????????? ,Process K?????????,???row piece?lb??0×0 ,?????ITL,Process Z???ITL???????Process J????XID,?????Process J?????TX lock,PROCESS K ???TX resource?Enqueue Waiter Linked List?????X mode(exclusive)?enqueue lock? ???Process J??TX lock?,Process J?????TX resource?Enqueue Waiter Linked List ???Process K??????,??POST?????Process K? TX lock??????,???????row lock???????,?????????

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• BIDS Helper 1.6 Beta Release (now with SQL 2012 support!)

  - by Darren Gosbell

  The beta for BIDS Helper 1.6 was just released. We have not updated the version notification just yet as we would like to get some feedback on people's experiences with the SQL 2012 version. So if you are using SQL 2012, go grab it and let us know how you go (you can post a comment on this blog post or on the BIDS Helper site itself). This is the first release that supports SQL 2012 and consequently also the first release that runs in Visual Studio 2010. A big thanks to Greg Galloway for doing the bulk of the work on this release. Please note that if you are doing an xcopy deploy that you will need to unblock the files you download or you will get a cryptic error message. This appears to be caused by a security update to either Visual Studio or the .Net framework – the xcopy deploy instructions have been updated to show you how to do this. Below are the notes from the release page. ====== This beta release is the first to support SQL Server 2012 (in addition to SQL Server 2005, 2008, and 2008 R2). Since it is marked as a beta release, we are looking for bug reports in the next few months as you use BIDS Helper on real projects. In addition to getting all existing BIDS Helper functionality working appropriately in SQL Server 2012 (SSDT), the following features are new... Analysis Services Tabular Smart Diff Tabular Actions Editor Tabular HideMemberIf Tabular Pre-Build Fixes and Updates The Unused Datasets feature for Reporting Services now accounts for new features in Reporting Services 2008 R2 like Lookups and new features in Reporting Services 2012. SSIS: emit an informational message when a variable has an expression defined and EvaluateAsExpression = False SSAS: roles reports points to wrong server SSIS - Variable Copy / Move broken in v1.5 "Unused DataSets Report" not showing up in Context menu on VS2005 if Solution Folders used SSAS Tabular: Create a UI for managing actions SSAS Tabular: Smart Diff improvements for new schema and Tabular models SSIS: Copy/Move Variable Erroring due to custom Control Flow item Icon SSIS Performance Visualization Index out of range fixing bugs in AggManager when aggregation design IDs don't match names The exe downloads are a self extracting installer, the zip downloads allow for an xcopy deploy. Make sure to note the updated xcopy deploy instructions for SQL Server 2012.

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• Improving the performance of XSL

  - by Rachel

  In the below XSL for the variable "insert-data", I have an input param with the structure, <insert-data> <data compareIndex="4" nodeName="d1e1"> <a/> </data> <data compareIndex="5" nodeName="d1e1"> <b/> </data> <data compareIndex="7" nodeName="d1e2"> <a/> </data> <data compareIndex="9" nodeName="d1e2"> <b/> </data> </insert-data> where "nodeName" is the id of a node and "compareIndex" is the position of the text content relative to the node having id "$nodeName". I am using the below XSL to select all the text nodes(generate-id) that satisfy the above condition and construct a data xml. The below implementation works perfectly but the time taken for the execution is in min. Is there a better way of implementing or is there any in-efficient operation being used. From my observation the code where the preceding text length is calculated consumes the major time. Please share your thoughts to improve the performance of the XSL. I am using Java SAXON XSL transformer. <xsl:variable name="insert-data" as="element()*"> <xsl:for-each select="$insert-file/insert-data/data"> <xsl:sort select="xsd:integer(@index)"/> <xsl:variable name="compareIndex" select="xsd:integer(@compareIndex)" /> <xsl:variable name="nodeName" select="@nodeName" /> <xsl:variable name="nodeContent" as="node()"> <xsl:copy-of select="node()"/> </xsl:variable> <xsl:for-each select="$main-root/*//text()[ancestor::*[@id = $nodeName]]"> <xsl:variable name="preTextLength" as="xsd:integer" select="sum((preceding::text())[. ancestor::*[@id = $nodeName]]/string-length(.))" /> <xsl:variable name="currentTextLength" as="xsd:integer" select="string-length(.)" /> <xsl:variable name="sum" select="$preTextLength + $currentTextLength" as="xsd:integer"></xsl:variable> <xsl:variable name="split-index" select="$compareIndex - $preTextLength" as="xsd:integer"></xsl:variable> <xsl:if test="($sum ge $compareIndex) and ($compareIndex gt $preTextLength)"> <data split-index="{$split-index}" text-id="{generate-id(.)}"> <xsl:copy-of select="$nodeContent"/> </data> </xsl:if> </xsl:for-each> </xsl:for-each> </xsl:variable>

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• HttpClient multithread performance

  - by pepper

  I have an application which downloads more than 4500 html pages from 62 target hosts using HttpClient (4.1.3 or 4.2-beta). It runs on Windows 7 64-bit. Processor - Core i7 2600K. Network bandwidth - 54 Mb/s. At this moment it uses such parameters: DefaultHttpClient and PoolingClientConnectionManager; Also it hasIdleConnectionMonitorThread from http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html; Maximum total connections = 80; Default maximum connections per route = 5; For thread management it uses ForkJoinPool with the parallelism level = 5 (Do I understand correctly that it is a number of working threads?) In this case my network usage (in Windows task manager) does not rise above 2.5%. To download 4500 pages it takes 70 minutes. And in HttpClient logs I have such things: DEBUG ForkJoinPool-2-worker-1 [org.apache.http.impl.conn.PoolingClientConnectionManager]: Connection released: [id: 209][route: {}-http://stackoverflow.com][total kept alive: 6; route allocated: 1 of 5; total allocated: 10 of 80] Total allocated connections do not raise above 10-12, in spite of that I've set it up to 80 connections. If I'll try to rise parallelism level to 20 or 80, network usage remains the same but a lot connection time-outs will be generated. I've read tutorials on hc.apache.org (HttpClient Performance Optimization Guide and HttpClient Threading Guide) but they does not help. Task's code looks like this: public class ContentDownloader extends RecursiveAction { private final HttpClient httpClient; private final HttpContext context; private List<Entry> entries; public ContentDownloader(HttpClient httpClient, List<Entry> entries){ this.httpClient = httpClient; context = new BasicHttpContext(); this.entries = entries; } private void computeDirectly(Entry entry){ final HttpGet get = new HttpGet(entry.getLink()); try { HttpResponse response = httpClient.execute(get, context); int statusCode = response.getStatusLine().getStatusCode(); if ( (statusCode >= 400) && (statusCode <= 600) ) { logger.error("Couldn't get content from " + get.getURI().toString() + "\n" + response.toString()); } else { HttpEntity entity = response.getEntity(); if (entity != null) { String htmlContent = EntityUtils.toString(entity).trim(); entry.setHtml(htmlContent); EntityUtils.consumeQuietly(entity); } } } catch (Exception e) { } finally { get.releaseConnection(); } } @Override protected void compute() { if (entries.size() <= 1){ computeDirectly(entries.get(0)); return; } int split = entries.size() / 2; invokeAll(new ContentDownloader(httpClient, entries.subList(0, split)), new ContentDownloader(httpClient, entries.subList(split, entries.size()))); } } And the question is - what is the best practice to use multi threaded HttpClient, may be there is a some rules for setting up ConnectionManager and HttpClient? How can I use all of 80 connections and raise network usage? If necessary, I will provide more code.

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• SQL Saturday is Coming to Nashville! Won't You?

  - by KKline

  How 'Bout a Little Context? Let me be direct with you. I love SQL Saturday . If it were a woman , I'd marry it. (Avoiding all extraneous thoughts of what my real wife would say, etc etc). Check out this fun Flickr Feed from the recent SQL Saturday in Chicago or these picks by Jorge Segara ( blog | twitter ) to see the sort of fun that's in store. But who can argue with a day of free SQL Server training and a chance to network with great presenters and a wide swath of your peers? Keynotes are more...(read more)

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• Two free SQL Server events I'll be presenting at in UK. Come and say hi!

  - by Mladen Prajdic

  SQLBits: April 7th - April 9th 2011 in Brighton, UK Free community event on Saturday (April 9th) with a paid conference day on Friday (April 8th) and a Pre Conference day full of day long seminars (April 7th). It'll be a huge event with over 800 attendees and over 20 MVPs. I'll be presenting on Saturday April 9th.     SQL in the City: July 15th 2011 in London, UK One day of free SQL Server training sponsored by Redgate. Other MVP's that'll be presenting there are Steve Jones (website|twitter), Brad McGehee (blog|twitter) and Grant Fritchey (blog|twitter)   At both conferences I'll be presenting about database testing. In the sessions I'll cover a few things from my book The Red Gate Guide to SQL Server Team based Development like what do we need for testing, how to go about it, what are some of the obstacles we have to overcome, etc… If you're around there come and say Hi!

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• Optimizing python code performance when importing zipped csv to a mongo collection

  - by mark

  I need to import a zipped csv into a mongo collection, but there is a catch - every record contains a timestamp in Pacific Time, which must be converted to the local time corresponding to the (longitude,latitude) pair found in the same record. The code looks like so: def read_csv_zip(path, timezones): with ZipFile(path) as z, z.open(z.namelist()[0]) as input: csv_rows = csv.reader(input) header = csv_rows.next() check,converters = get_aux_stuff(header) for csv_row in csv_rows: if check(csv_row): row = { converter[0]:converter[1](value) for converter, value in zip(converters, csv_row) if allow_field(converter) } ts = row['ts'] lng, lat = row['loc'] found_tz_entry = timezones.find_one(SON({'loc': {'$within': {'$box': [[lng-tz_lookup_radius, lat-tz_lookup_radius],[lng+tz_lookup_radius, lat+tz_lookup_radius]]}}})) if found_tz_entry: tz_name = found_tz_entry['tz'] local_ts = ts.astimezone(timezone(tz_name)).replace(tzinfo=None) row['tz'] = tz_name else: local_ts = (ts.astimezone(utc) + timedelta(hours = int(lng/15))).replace(tzinfo = None) row['local_ts'] = local_ts yield row def insert_documents(collection, source, batch_size): while True: items = list(itertools.islice(source, batch_size)) if len(items) == 0: break; try: collection.insert(items) except: for item in items: try: collection.insert(item) except Exception as exc: print("Failed to insert record {0} - {1}".format(item['_id'], exc)) def main(zip_path): with Connection() as connection: data = connection.mydb.data timezones = connection.timezones.data insert_documents(data, read_csv_zip(zip_path, timezones), 1000) The code proceeds as follows: Every record read from the csv is checked and converted to a dictionary, where some fields may be skipped, some titles be renamed (from those appearing in the csv header), some values may be converted (to datetime, to integers, to floats. etc ...) For each record read from the csv, a lookup is made into the timezones collection to map the record location to the respective time zone. If the mapping is successful - that timezone is used to convert the record timestamp (pacific time) to the respective local timestamp. If no mapping is found - a rough approximation is calculated. The timezones collection is appropriately indexed, of course - calling explain() confirms it. The process is slow. Naturally, having to query the timezones collection for every record kills the performance. I am looking for advises on how to improve it. Thanks. EDIT The timezones collection contains 8176040 records, each containing four values: > db.data.findOne() { "_id" : 3038814, "loc" : [ 1.48333, 42.5 ], "tz" : "Europe/Andorra" } EDIT2 OK, I have compiled a release build of http://toblerity.github.com/rtree/ and configured the rtree package. Then I have created an rtree dat/idx pair of files corresponding to my timezones collection. So, instead of calling collection.find_one I call index.intersection. Surprisingly, not only there is no improvement, but it works even more slowly now! May be rtree could be fine tuned to load the entire dat/idx pair into RAM (704M), but I do not know how to do it. Until then, it is not an alternative. In general, I think the solution should involve parallelization of the task. EDIT3 Profile output when using collection.find_one: >>> p.sort_stats('cumulative').print_stats(10) Tue Apr 10 14:28:39 2012 ImportDataIntoMongo.profile 64549590 function calls (64549180 primitive calls) in 1231.257 seconds Ordered by: cumulative time List reduced from 730 to 10 due to restriction <10> ncalls tottime percall cumtime percall filename:lineno(function) 1 0.012 0.012 1231.257 1231.257 ImportDataIntoMongo.py:1(<module>) 1 0.001 0.001 1230.959 1230.959 ImportDataIntoMongo.py:187(main) 1 853.558 853.558 853.558 853.558 {raw_input} 1 0.598 0.598 370.510 370.510 ImportDataIntoMongo.py:165(insert_documents) 343407 9.965 0.000 359.034 0.001 ImportDataIntoMongo.py:137(read_csv_zip) 343408 2.927 0.000 287.035 0.001 c:\python27\lib\site-packages\pymongo\collection.py:489(find_one) 343408 1.842 0.000 274.803 0.001 c:\python27\lib\site-packages\pymongo\cursor.py:699(next) 343408 2.542 0.000 271.212 0.001 c:\python27\lib\site-packages\pymongo\cursor.py:644(_refresh) 343408 4.512 0.000 253.673 0.001 c:\python27\lib\site-packages\pymongo\cursor.py:605(__send_message) 343408 0.971 0.000 242.078 0.001 c:\python27\lib\site-packages\pymongo\connection.py:871(_send_message_with_response) Profile output when using index.intersection: >>> p.sort_stats('cumulative').print_stats(10) Wed Apr 11 16:21:31 2012 ImportDataIntoMongo.profile 41542960 function calls (41542536 primitive calls) in 2889.164 seconds Ordered by: cumulative time List reduced from 778 to 10 due to restriction <10> ncalls tottime percall cumtime percall filename:lineno(function) 1 0.028 0.028 2889.164 2889.164 ImportDataIntoMongo.py:1(<module>) 1 0.017 0.017 2888.679 2888.679 ImportDataIntoMongo.py:202(main) 1 2365.526 2365.526 2365.526 2365.526 {raw_input} 1 0.766 0.766 502.817 502.817 ImportDataIntoMongo.py:180(insert_documents) 343407 9.147 0.000 491.433 0.001 ImportDataIntoMongo.py:152(read_csv_zip) 343406 0.571 0.000 391.394 0.001 c:\python27\lib\site-packages\rtree-0.7.0-py2.7.egg\rtree\index.py:384(intersection) 343406 379.957 0.001 390.824 0.001 c:\python27\lib\site-packages\rtree-0.7.0-py2.7.egg\rtree\index.py:435(_intersection_obj) 686513 22.616 0.000 38.705 0.000 c:\python27\lib\site-packages\rtree-0.7.0-py2.7.egg\rtree\index.py:451(_get_objects) 343406 6.134 0.000 33.326 0.000 ImportDataIntoMongo.py:162(<dictcomp>) 346 0.396 0.001 30.665 0.089 c:\python27\lib\site-packages\pymongo\collection.py:240(insert) EDIT4 I have parallelized the code, but the results are still not very encouraging. I am convinced it could be done better. See my own answer to this question for details.

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• ListView slow performance

  - by Mohamed Hemdan

  I've created a list of recipes using Listview/customcursoradapter. A custom layout includes a photo for the recipe , Now I've some problems with the performance of viewing and scrolling the Listview although it has only 10 records (Target is 150). sometimes i get this error java.lang.OutOfMemoryError: bitmap size exceeds VM budget , I've tried to implement the Async task but i failed to do it. Is there any way i can overcome this problem? Your help is highly appreciated !! Here is my GetView method public View getView(int position, View convertView, ViewGroup parent) { View row = super.getView(position, convertView, parent); Cursor cursbbn = getCursor(); if (row == null) { LayoutInflater inflater = (LayoutInflater) localContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE); row = inflater.inflate(R.layout.listtype, null); } String Title = cursbbn.getString(2); String SandID=cursbbn.getString(1); String Readyin = cursbbn.getString(4); String Faovoites=cursbbn.getString(8); TextView titler=(TextView)row.findViewById(R.id.listmaintitle); TextView readyinr=(TextView)row.findViewById(R.id.listreadyin); int colorPos = position % colors.length; row.setBackgroundColor(colors[colorPos]); titler.setText(Title); readyinr.setText(Readyin); ImageView picture = (ImageView) row.findViewById(R.id.imageView1); Bitmap bitImg1 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0001); Bitmap bitImg2 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0002); Bitmap bitImg3 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0003); Bitmap bitImg4 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0004); Bitmap bitImg5 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0005); Bitmap bitImg6 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0006); Bitmap bitImg7 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0007); Bitmap bitImg8 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0008); Bitmap bitImg9 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0009); Bitmap bitImg10 = BitmapFactory.decodeResource(localContext.getResources(), R.drawable.rec0010); if(SandID.contentEquals("0001")) picture.setImageBitmap(getRoundedCornerImage(bitImg1)); if(SandID.contentEquals("0002")) picture.setImageBitmap(getRoundedCornerImage(bitImg2)); if(SandID.contentEquals("0003")) picture.setImageBitmap(getRoundedCornerImage(bitImg3)); if(SandID.contentEquals("0004")) picture.setImageBitmap(getRoundedCornerImage(bitImg4)); if(SandID.contentEquals("0005")) picture.setImageBitmap(getRoundedCornerImage(bitImg5)); if(SandID.contentEquals("0006")) picture.setImageBitmap(getRoundedCornerImage(bitImg6)); if(SandID.contentEquals("0007")) picture.setImageBitmap(getRoundedCornerImage(bitImg7)); if(SandID.contentEquals("0008")) picture.setImageBitmap(getRoundedCornerImage(bitImg8)); if(SandID.contentEquals("0009")) picture.setImageBitmap(getRoundedCornerImage(bitImg9)); if(SandID.contentEquals("0010")) picture.setImageBitmap(getRoundedCornerImage(bitImg10)); return row; } And This is the error : 05-02 03:11:55.898: E/AndroidRuntime(376): FATAL EXCEPTION: main 05-02 03:11:55.898: E/AndroidRuntime(376): java.lang.OutOfMemoryError: bitmap size exceeds VM budget 05-02 03:11:55.898: E/AndroidRuntime(376): at android.graphics.BitmapFactory.nativeDecodeAsset(Native Method) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:460) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:336) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.graphics.BitmapFactory.decodeResource(BitmapFactory.java:359) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.graphics.BitmapFactory.decodeResource(BitmapFactory.java:385) 05-02 03:11:55.898: E/AndroidRuntime(376): at master.chef.mediamaster.AlternateRowCursorAdapter.getView(AlternateRowCursorAdapter.java:83) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.widget.AbsListView.obtainView(AbsListView.java:1409) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.widget.ListView.makeAndAddView(ListView.java:1745) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.widget.ListView.fillUp(ListView.java:700) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.widget.ListView.fillGap(ListView.java:646) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.widget.AbsListView.trackMotionScroll(AbsListView.java:3399) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.widget.AbsListView.onTouchEvent(AbsListView.java:2233) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.widget.ListView.onTouchEvent(ListView.java:3446) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.View.dispatchTouchEvent(View.java:3885) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:903) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:942) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:942) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:942) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:942) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:942) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:942) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:942) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:942) 05-02 03:11:55.898: E/AndroidRuntime(376): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1691) 05-02 03:11:55.898: E/AndroidRuntime(376): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1125) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.app.Activity.dispatchTouchEvent(Activity.java:2096) 05-02 03:11:55.898: E/AndroidRuntime(376): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2194) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.view.ViewRoot.handleMessage(ViewRoot.java:1878) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.os.Handler.dispatchMessage(Handler.java:99) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.os.Looper.loop(Looper.java:123) 05-02 03:11:55.898: E/AndroidRuntime(376): at android.app.ActivityThread.main(ActivityThread.java:3683) 05-02 03:11:55.898: E/AndroidRuntime(376): at java.lang.reflect.Method.invokeNative(Native Method) 05-02 03:11:55.898: E/AndroidRuntime(376): at java.lang.reflect.Method.invoke(Method.java:507) 05-02 03:11:55.898: E/AndroidRuntime(376): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 05-02 03:11:55.898: E/AndroidRuntime(376): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 05-02 03:11:55.898: E/AndroidRuntime(376): at dalvik.system.NativeStart.main(Native Method)

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• How optimize code with introspection + heavy alloc on iPhone

  - by mamcx

  I have a problem. I try to display a UITable that could have 2000-20000 records (typicall numbers.) I have a SQLite database similar to the Apple contacts application. I do all the tricks I know to get a smoth scroll, but I have a problem. I load the data in 50 recods blocks. Then, when the user scroll, request next 50 until finish the list. However, load that 50 records cause a notable "pause" in loading and scrolling. Everything else works fine. I cache the data, have opaque cells, draw it by code, etc... I swap the code loading the same data in dicts and have a performance boost but wonder if I could keep my object oriented aproach and improve the actual code. This is the code I think have the performance problem: -(NSArray *) loadAndFill: (NSString *)sql theClass: (Class)cls { [self openDb]; NSMutableArray *list = [NSMutableArray array]; NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; DbObject *ds; Class myClass = NSClassFromString([DbObject getTableName:cls]); FMResultSet *rs = [self load:sql]; while ([rs next]) { ds = [[myClass alloc] init]; NSDictionary *props = [ds properties]; NSString *fieldType = nil; id fieldValue; for (NSString *fieldName in [props allKeys]) { fieldType = [props objectForKey: fieldName]; fieldValue = [self ValueForField:rs Name:fieldName Type:fieldType]; [ds setValue:fieldValue forKey:fieldName]; } [list addObject :ds]; [ds release]; } [rs close]; [pool drain]; return list; } And I think the main culprit is: -(id) ValueForField: (FMResultSet *)rs Name:(NSString *)fieldName Type:(NSString *)fieldType { id fieldValue = nil; if ([fieldType isEqualToString:@"i"] || // int [fieldType isEqualToString:@"I"] || // unsigned int [fieldType isEqualToString:@"s"] || // short [fieldType isEqualToString:@"S"] || // unsigned short [fieldType isEqualToString:@"f"] || // float [fieldType isEqualToString:@"d"] ) // double { fieldValue = [NSNumber numberWithInt: [rs longForColumn:fieldName]]; } else if ([fieldType isEqualToString:@"B"]) // bool or _Bool { fieldValue = [NSNumber numberWithBool: [rs boolForColumn:fieldName]]; } else if ([fieldType isEqualToString:@"l"] || // long [fieldType isEqualToString:@"L"] || // usigned long [fieldType isEqualToString:@"q"] || // long long [fieldType isEqualToString:@"Q"] ) // unsigned long long { fieldValue = [NSNumber numberWithLong: [rs longForColumn:fieldName]]; } else if ([fieldType isEqualToString:@"c"] || // char [fieldType isEqualToString:@"C"] ) // unsigned char { fieldValue = [rs stringForColumn:fieldName]; //Is really a boolean? if ([fieldValue isEqualToString:@"0"] || [fieldValue isEqualToString:@"1"]) { fieldValue = [NSNumber numberWithInt: [fieldValue intValue]]; } } else if ([fieldType hasPrefix:@"@"] ) // Object { NSString *className = [fieldType substringWithRange:NSMakeRange(2, [fieldType length]-3)]; if ([className isEqualToString:@"NSString"]) { fieldValue = [rs stringForColumn:fieldName]; } else if ([className isEqualToString:@"NSDate"]) { NSDateFormatter* dateFormatter = [[NSDateFormatter alloc] init]; [dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss"]; NSString *theDate = [rs stringForColumn:fieldName]; if (theDate) { fieldValue = [dateFormatter dateFromString: theDate]; } else { fieldValue = nil; } [dateFormatter release]; } else if ([className isEqualToString:@"NSInteger"]) { fieldValue = [NSNumber numberWithInt: [rs intForColumn :fieldName]]; } else if ([className isEqualToString:@"NSDecimalNumber"]) { fieldValue = [rs stringForColumn :fieldName]; if (fieldValue) { fieldValue = [NSDecimalNumber decimalNumberWithString:[rs stringForColumn :fieldName]]; } } else if ([className isEqualToString:@"NSNumber"]) { fieldValue = [NSNumber numberWithDouble: [rs doubleForColumn:fieldName]]; } else { //Is a relationship one-to-one? if (![fieldType hasPrefix:@"NS"]) { id rel = class_createInstance(NSClassFromString(className), sizeof(unsigned)); Class theClass = [rel class]; if ([rel isKindOfClass:[DbObject class]]) { fieldValue = [rel init]; //Load the record... NSInteger Id = [rs intForColumn:[theClass relationName]]; if (Id>0) { [fieldValue release]; Db *db = [Db currentDb]; fieldValue = [db loadById: theClass theId:Id]; } } } else { NSString *error = [NSString stringWithFormat:@"Err Can't get value for field %@ of type %@", fieldName, fieldType]; NSLog(error); NSException *e = [NSException exceptionWithName:@"DBError" reason:error userInfo:nil]; @throw e; } } } return fieldValue; }

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• Using UUIDs for cheap equals() and hashCode()

  - by Tom McIntyre

  I have an immutable class, TokenList, which consists of a list of Token objects, which are also immutable: @Immutable public final class TokenList { private final List<Token> tokens; public TokenList(List<Token> tokens) { this.tokens = Collections.unmodifiableList(new ArrayList(tokens)); } public List<Token> getTokens() { return tokens; } } I do several operations on these TokenLists that take multiple TokenLists as inputs and return a single TokenList as the output. There can be arbitrarily many TokenLists going in, and each can have arbitrarily many Tokens. These operations are expensive, and there is a good chance that the same operation (ie the same inputs) will be performed multiple times, so I would like to cache the outputs. However, performance is critical, and I am worried about the expense of performing hashCode() and equals() on these objects that may contain arbitrarily many elements (as they are immutable then hashCode could be cached, but equals will still be expensive). This led me to wondering whether I could use a UUID to provide equals() and hashCode() simply and cheaply by making the following updates to TokenList: @Immutable public final class TokenList { private final List<Token> tokens; private final UUID uuid; public TokenList(List<Token> tokens) { this.tokens = Collections.unmodifiableList(new ArrayList(tokens)); this.uuid = UUID.randomUUID(); } public List<Token> getTokens() { return tokens; } public UUID getUuid() { return uuid; } } And something like this to act as a cache key: @Immutable public final class TopicListCacheKey { private final UUID[] uuids; public TopicListCacheKey(TopicList... topicLists) { uuids = new UUID[topicLists.length]; for (int i = 0; i < uuids.length; i++) { uuids[i] = topicLists[i].getUuid(); } } @Override public int hashCode() { return Arrays.hashCode(uuids); } @Override public boolean equals(Object other) { if (other == this) return true; if (other instanceof TopicListCacheKey) return Arrays.equals(uuids, ((TopicListCacheKey) other).uuids); return false; } } I figure that there are 2^128 different UUIDs and I will probably have at most around 1,000,000 TokenList objects active in the application at any time. Given this, and the fact that the UUIDs are used combinatorially in cache keys, it seems that the chances of this producing the wrong result are vanishingly small. Nevertheless, I feel uneasy about going ahead with it as it just feels 'dirty'. Are there any reasons I should not use this system? Will the performance costs of the SecureRandom used by UUID.randomUUID() outweigh the gains (especially since I expect multiple threads to be doing this at the same time)? Are collisions going to be more likely than I think? Basically, is there anything wrong with doing it this way?? Thanks.

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• Make c# matrix code faster

  - by Wam

  Hi all, Working on some matrix code, I'm concerned of performance issues. here's how it works : I've a IMatrix abstract class (with all matrices operations etc), implemented by a ColumnMatrix class. abstract class IMatrix { public int Rows {get;set;} public int Columns {get;set;} public abstract float At(int row, int column); } class ColumnMatrix : IMatrix { private data[]; public override float At(int row, int column) { return data[row + columns * this.Rows]; } } This class is used a lot across my application, but I'm concerned with performance issues. Testing only read for a 2000000x15 matrix against a jagged array of the same size, I get 1359ms for array access agains 9234ms for matrix access : public void TestAccess() { int iterations = 10; int rows = 2000000; int columns = 15; ColumnMatrix matrix = new ColumnMatrix(rows, columns); for (int i = 0; i < rows; i++) for (int j = 0; j < columns; j++) matrix[i, j] = i + j; float[][] equivalentArray = matrix.ToRowsArray(); TimeSpan totalMatrix = new TimeSpan(0); TimeSpan totalArray = new TimeSpan(0); float total = 0f; for (int iteration = 0; iteration < iterations; iteration++) { total = 0f; DateTime start = DateTime.Now; for (int i = 0; i < rows; i++) for (int j = 0; j < columns; j++) total = matrix.At(i, j); totalMatrix += (DateTime.Now - start); total += 1f; //Ensure total is read at least once. total = total > 0 ? 0f : 0f; start = DateTime.Now; for (int i = 0; i < rows; i++) for (int j = 0; j < columns; j++) total = equivalentArray[i][j]; totalArray += (DateTime.Now - start); } if (total < 0f) logger.Info("Nothing here, just make sure we read total at least once."); logger.InfoFormat("Average time for a {0}x{1} access, matrix : {2}ms", rows, columns, totalMatrix.TotalMilliseconds); logger.InfoFormat("Average time for a {0}x{1} access, array : {2}ms", rows, columns, totalArray.TotalMilliseconds); Assert.IsTrue(true); } So my question : how can I make this thing faster ? Is there any way I can make my ColumnMatrix.At faster ? Cheers !

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• C++ Optimize if/else condition

  - by Heye

  I have a single line of code, that consumes 25% - 30% of the runtime of my application. It is a less-than comparator for an std::set (the set is implemented with a Red-Black-Tree). It is called about 180 Million times within 52 seconds. struct Entry { const float _cost; const long _id; // some other vars Entry(float cost, float id) : _cost(cost), _id(id) { } }; template<class T> struct lt_entry: public binary_function <T, T, bool> { bool operator()(const T &l, const T &r) const { // Most readable shape if(l._cost != r._cost) { return r._cost < l._cost; } else { return l._id < r._id; } } }; The entries should be sorted by cost and if the cost is the same by their id. I have many insertions for each extraction of the minimum. I thought about using Fibonacci-Heaps, but I have been told that they are theoretically nice, but suffer from high constants and are pretty complicated to implement. And since insert is in O(log(n)) the runtime increase is nearly constant with large n. So I think its okay to stick to the set. To improve performance I tried to express it in different shapes: return l._cost < r._cost || r._cost > l._cost || l._id < r._id; return l._cost < r._cost || (l._cost == r._cost && l._id < r._id); Even this: typedef union { float _f; int _i; } flint; //... flint diff; diff._f = (l._cost - r._cost); return (diff._i && diff._i >> 31) || l._id < r._id; But the compiler seems to be smart enough already, because I haven't been able to improve the runtime. I also thought about SSE but this problem is really not very applicable for SSE... The assembly looks somewhat like this: movss (%rbx),%xmm1 mov $0x1,%r8d movss 0x20(%rdx),%xmm0 ucomiss %xmm1,%xmm0 ja 0x410600 <_ZNSt8_Rb_tree[..]+96> ucomiss %xmm0,%xmm1 jp 0x4105fd <_ZNSt8_Rb_[..]_+93> jne 0x4105fd <_ZNSt8_Rb_[..]_+93> mov 0x28(%rdx),%rax cmp %rax,0x8(%rbx) jb 0x410600 <_ZNSt8_Rb_[..]_+96> xor %r8d,%r8d I have a very tiny bit experience with assembly language, but not really much. I thought it would be the best (only?) point to squeeze out some performance, but is it really worth the effort? Can you see any shortcuts that could save some cycles? The platform the code will run on is an ubuntu 12 with gcc 4.6 (-stl=c++0x) on a many-core intel machine. Only libraries available are boost, openmp and tbb. I am really stuck on this one, it seems so simple, but takes that much time. I have been crunching my head since days thinking how I could improve this line... Can you give me a suggestion how to improve this part, or is it already at its best?

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• What's the fastest lookup algorithm for a pair data structure (i.e, a map)?

  - by truncheon

  In the following example a std::map structure is filled with 26 values from A - Z (for key) and 0 – 26 for value. The time taken (on my system) to lookup the last entry (10000000 times) is roughly 250 ms for the vector, and 125 ms for the map. (I compiled using release mode, with O3 option turned on for g++ 4.4) But if for some odd reason I wanted better performance than the std::map, what data structures and functions would I need to consider using? I apologize if the answer seems obvious to you, but I haven't had much experience in the performance critical aspects of C++ programming. UPDATE: This example is rather trivial and hides the true complexity of what I'm trying to achieve. My real world project is a simple scripting language that uses a parser, data tree, and interpreter (instead of a VM stack system). I need to use some kind of data structure (perhaps map) to store the variables names created by script programmers. These are likely to be pretty randomly named, so I need a lookup method that can quickly find a particular key within a (probably) fairly large list of names. #include <ctime> #include <map> #include <vector> #include <iostream> struct mystruct { char key; int value; mystruct(char k = 0, int v = 0) : key(k), value(v) { } }; int find(const std::vector<mystruct>& ref, char key) { for (std::vector<mystruct>::const_iterator i = ref.begin(); i != ref.end(); ++i) if (i->key == key) return i->value; return -1; } int main() { std::map<char, int> mymap; std::vector<mystruct> myvec; for (int i = 'a'; i < 'a' + 26; ++i) { mymap[i] = i - 'a'; myvec.push_back(mystruct(i, i - 'a')); } int pre = clock(); for (int i = 0; i < 10000000; ++i) { find(myvec, 'z'); } std::cout << "linear scan: milli " << clock() - pre << "\n"; pre = clock(); for (int i = 0; i < 10000000; ++i) { mymap['z']; } std::cout << "map scan: milli " << clock() - pre << "\n"; return 0; }

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