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• Entity System with C++ templates

  - by tommaisey

  I've been getting interested in the Entity/Component style of game programming, and I've come up with a design in C++ which I'd like a critique of. I decided to go with a fairly pure Entity system, where entities are simply an ID number. Components are stored in a series of vectors - one for each Component type. However, I didn't want to have to add boilerplate code for every new Component type I added to the game. Nor did I want to use macros to do this, which frankly scare me. So I've come up with a system based on templates and type hinting. But there are some potential issues I'd like to check before I spend ages writing this (I'm a slow coder!) All Components derive from a Component base class. This base class has a protected constructor, that takes a string parameter. When you write a new derived Component class, you must initialise the base with the name of your new class in a string. When you first instantiate a new DerivedComponent, it adds the string to a static hashmap inside Component mapped to a unique integer id. When you subsequently instantiate more Components of the same type, no action is taken. The result (I think) should be a static hashmap with the name of each class derived from Component that you instantiate at least once, mapped to a unique id, which can by obtained with the static method Component::getTypeId ("DerivedComponent"). Phew. The next important part is TypedComponentList<typename PropertyType>. This is basically just a wrapper to an std::vector<typename PropertyType> with some useful methods. It also contains a hashmap of entity ID numbers to slots in the array so we can find Components by their entity owner. Crucially TypedComponentList<> is derived from the non-template class ComponentList. This allows me to maintain a list of pointers to ComponentList in my main ComponentManager, which actually point to TypedComponentLists with different template parameters (sneaky). The Component manager has template functions such as: template <typename ComponentType> void addProperty (ComponentType& component, int componentTypeId, int entityId) and: template <typename ComponentType> TypedComponentList<ComponentType>* getComponentList (int componentTypeId) which deal with casting from ComponentList to the correct TypedComponentList for you. So to get a list of a particular type of Component you call: TypedComponentList<MyComponent>* list = componentManager.getComponentList<MyComponent> (Component::getTypeId("MyComponent")); Which I'll admit looks pretty ugly. Bad points of the design: If a user of the code writes a new Component class but supplies the wrong string to the base constructor, the whole system will fail. Each time a new Component is instantiated, we must check a hashed string to see if that component type has bee instantiated before. Will probably generate a lot of assembly because of the extensive use of templates. I don't know how well the compiler will be able to minimise this. You could consider the whole system a bit complex - perhaps premature optimisation? But I want to use this code again and again, so I want it to be performant. Good points of the design: Components are stored in typed vectors but they can also be found by using their entity owner id as a hash. This means we can iterate them fast, and minimise cache misses, but also skip straight to the component we need if necessary. We can freely add Components of different types to the system without having to add and manage new Component vectors by hand. What do you think? Do the good points outweigh the bad?

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• ?12c database ????Adaptive Execution Plans ????????

  - by Liu Maclean(???)

  12c R1 ????SQL??????- Adaptive Execution Plans ????????,???????optimizer ??????(runtime)???????????????, ????????????????????? SQL???????? ????????????, ?????????????????????????????????????????????????????????????adaptive plan ????????????????????????????????????,?????subplan???????????????????? ??????, ???????? ???????????????,?????????, ?????? ???????????????”???”????, ???????????????????buffer ???????  ????????????,?????,??????????????????? ???optimizer ?????????????????????????,?????????????????????????????????????????plan???? ??12C?????????????, ???????????????????,?????? ???????????? ????????????2???: Dynamic Plans????: ???????????????????????;??????,???optimizer??????????subplans??????????????, ???????????????????,?????????????? Reoptimization????: ?Dynamic Plans????,Reoptimization??????????????????????Reoptimization??,?????????????????????????,??reoptimization????? OPTIMIZER_ADAPTIVE_REPORTING_ONLY ???? report-only????????????????TRUE,?????????report-only????,???????????????,??????????????? Dynamic Plans ??????????????,????????????????????????, ?????????????,???????????,????????????????????????????????????????? ?????????????final plan??????????????default plan, ??final plan?default plan???????,????????????? subplan ???????????????,???????????????????????? ??????,???????statistics collector ?buffer???????????statistics collector?????????????????,???????????????????????????? ?????????????????????????????????????????,??????????,?????????????? ???????????,???????buffer???? ???????????????,?????????????????????????????,??????buffer,??????final plan? ????????,???????????????????????,????????????????? ?V$SQL??????IS_RESOLVED_DYNAMIC_PLAN??????????final plan???default plan? ??????dynamic plan ???????SQL PLAN directives?????? declare cursor PLAN_DIRECTIVE_IDS is select directive_id from DBA_SQL_PLAN_DIRECTIVES; begin for z in PLAN_DIRECTIVE_IDS loop DBMS_SPD.DROP_SQL_PLAN_DIRECTIVE(z.directive_id); end loop; end; / explain plan for select /*MALCEAN*/ product_name from oe.order_items o, oe.product_information p where o.unit_price=15 and quantity>1 and p.product_id=o.product_id; select * from table(dbms_xplan.display()); Plan hash value: 1255158658 www.askmaclean.com ------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 4 | 128 | 7 (0)| 00:00:01 | | 1 | NESTED LOOPS | | | | | | | 2 | NESTED LOOPS | | 4 | 128 | 7 (0)| 00:00:01 | |* 3 | TABLE ACCESS FULL | ORDER_ITEMS | 4 | 48 | 3 (0)| 00:00:01 | |* 4 | INDEX UNIQUE SCAN | PRODUCT_INFORMATION_PK | 1 | | 0 (0)| 00:00:01 | | 5 | TABLE ACCESS BY INDEX ROWID| PRODUCT_INFORMATION | 1 | 20 | 1 (0)| 00:00:01 | ------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 3 - filter("O"."UNIT_PRICE"=15 AND "QUANTITY">1) 4 - access("P"."PRODUCT_ID"="O"."PRODUCT_ID") alter session set events '10053 trace name context forever,level 1'; OR alter session set events 'trace[SQL_Plan_Directive] disk highest'; select /*MALCEAN*/ product_name from oe.order_items o, oe.product_information p where o.unit_price=15 and quantity>1 and p.product_id=o.product_id; ---------------------------------------------------------------+-----------------------------------+ | Id | Operation | Name | Rows | Bytes | Cost | Time | ---------------------------------------------------------------+-----------------------------------+ | 0 | SELECT STATEMENT | | | | 7 | | | 1 | HASH JOIN | | 4 | 128 | 7 | 00:00:01 | | 2 | NESTED LOOPS | | | | | | | 3 | NESTED LOOPS | | 4 | 128 | 7 | 00:00:01 | | 4 | STATISTICS COLLECTOR | | | | | | | 5 | TABLE ACCESS FULL | ORDER_ITEMS | 4 | 48 | 3 | 00:00:01 | | 6 | INDEX UNIQUE SCAN | PRODUCT_INFORMATION_PK| 1 | | 0 | | | 7 | TABLE ACCESS BY INDEX ROWID | PRODUCT_INFORMATION | 1 | 20 | 1 | 00:00:01 | | 8 | TABLE ACCESS FULL | PRODUCT_INFORMATION | 1 | 20 | 1 | 00:00:01 | ---------------------------------------------------------------+-----------------------------------+ Predicate Information: ---------------------- 1 - access("P"."PRODUCT_ID"="O"."PRODUCT_ID") 5 - filter(("O"."UNIT_PRICE"=15 AND "QUANTITY">1)) 6 - access("P"."PRODUCT_ID"="O"."PRODUCT_ID") ===================================== SPD: BEGIN context at statement level ===================================== Stmt: ******* UNPARSED QUERY IS ******* SELECT /*+ OPT_ESTIMATE (@"SEL$1" JOIN ("P"@"SEL$1" "O"@"SEL$1") ROWS=13.000000 ) OPT_ESTIMATE (@"SEL$1" TABLE "O"@"SEL$1" ROWS=13.000000 ) */ "P"."PRODUCT_NAME" "PRODUCT_NAME" FROM "OE"."ORDER_ITEMS" "O","OE"."PRODUCT_INFORMATION" "P" WHERE "O"."UNIT_PRICE"=15 AND "O"."QUANTITY">1 AND "P"."PRODUCT_ID"="O"."PRODUCT_ID" Objects referenced in the statement PRODUCT_INFORMATION[P] 92194, type = 1 ORDER_ITEMS[O] 92197, type = 1 Objects in the hash table Hash table Object 92197, type = 1, ownerid = 6573730143572393221: No Dynamic Sampling Directives for the object Hash table Object 92194, type = 1, ownerid = 17822962561575639002: No Dynamic Sampling Directives for the object Return code in qosdInitDirCtx: ENBLD =================================== SPD: END context at statement level =================================== ======================================= SPD: BEGIN context at query block level ======================================= Query Block SEL$1 (#0) Return code in qosdSetupDirCtx4QB: NOCTX ===================================== SPD: END context at query block level ===================================== SPD: Return code in qosdDSDirSetup: NOCTX, estType = TABLE SPD: Generating finding id: type = 1, reason = 1, objcnt = 1, obItr = 0, objid = 92197, objtyp = 1, vecsize = 6, colvec = [4, 5, ], fid = 2896834833840853267 SPD: Inserted felem, fid=2896834833840853267, ftype = 1, freason = 1, dtype = 0, dstate = 0, dflag = 0, ver = YES, keep = YES SPD: qosdCreateFindingSingTab retCode = CREATED, fid = 2896834833840853267 SPD: qosdCreateDirCmp retCode = CREATED, fid = 2896834833840853267 SPD: Return code in qosdDSDirSetup: NOCTX, estType = TABLE SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = JOIN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SKIP_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = JOIN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_SCAN SPD: Return code in qosdDSDirSetup: NOCTX, estType = INDEX_FILTER SPD: Generating finding id: type = 1, reason = 1, objcnt = 1, obItr = 0, objid = 92197, objtyp = 1, vecsize = 6, colvec = [4, 5, ], fid = 2896834833840853267 SPD: Modified felem, fid=2896834833840853267, ftype = 1, freason = 1, dtype = 0, dstate = 0, dflag = 0, ver = YES, keep = YES SPD: Generating finding id: type = 1, reason = 1, objcnt = 1, obItr = 0, objid = 92194, objtyp = 1, vecsize = 2, colvec = [1, ], fid = 5618517328604016300 SPD: Modified felem, fid=5618517328604016300, ftype = 1, freason = 1, dtype = 0, dstate = 0, dflag = 0, ver = NO, keep = NO SPD: Generating finding id: type = 1, reason = 1, objcnt = 1, obItr = 0, objid = 92194, objtyp = 1, vecsize = 2, colvec = [1, ], fid = 1142802697078608149 SPD: Modified felem, fid=1142802697078608149, ftype = 1, freason = 1, dtype = 0, dstate = 0, dflag = 0, ver = NO, keep = NO SPD: Generating finding id: type = 1, reason = 2, objcnt = 2, obItr = 0, objid = 92194, objtyp = 1, vecsize = 0, obItr = 1, objid = 92197, objtyp = 1, vecsize = 0, fid = 1437680122701058051 SPD: Modified felem, fid=1437680122701058051, ftype = 1, freason = 2, dtype = 0, dstate = 0, dflag = 0, ver = NO, keep = NO select * from table(dbms_xplan.display_cursor(format=>'report')) ; ????report????adaptive plan Adaptive plan: ------------- This cursor has an adaptive plan, but adaptive plans are enabled for reporting mode only.  The plan that would be executed if adaptive plans were enabled is displayed below. ------------------------------------------------------------------------------------------ | Id  | Operation          | Name                | Rows  | Bytes | Cost (%CPU)| Time     | ------------------------------------------------------------------------------------------ |   0 | SELECT STATEMENT   |                     |       |       |     7 (100)|          | |*  1 |  HASH JOIN         |                     |     4 |   128 |     7   (0)| 00:00:01 | |*  2 |   TABLE ACCESS FULL| ORDER_ITEMS         |     4 |    48 |     3   (0)| 00:00:01 | |   3 |   TABLE ACCESS FULL| PRODUCT_INFORMATION |     1 |    20 |     1   (0)| 00:00:01 | ------------------------------------------------------------------------------------------ SQL> select SQL_ID,IS_RESOLVED_DYNAMIC_PLAN,sql_text from v$SQL WHERE SQL_TEXT like '%MALCEAN%' and sql_text not like '%like%'; SQL_ID IS -------------------------- -- SQL_TEXT -------------------------------------------------------------------------------- 6ydj1bn1bng17 Y select /*MALCEAN*/ product_name from oe.order_items o, oe.product_information p where o.unit_price=15 and quantity>1 and p.product_id=o.product_id ???? explain plan for ????default plan, ??????optimizer???final plan,??V$SQL.IS_RESOLVED_DYNAMIC_PLAN???Y,????????????? DBA_SQL_PLAN_DIRECTIVES?????????????SQL PLAN DIRECTIVES, ???12c? ???MMON?????DML ???column usage??????????,????SMON??? MMON????SGA??PLAN DIRECTIVES??? ?????DBMS_SPD.flush_sql_plan_directive???? select directive_id,type,reason from DBA_SQL_PLAN_DIRECTIVES / DIRECTIVE_ID TYPE REASON ----------------------------------- -------------------------------- ----------------------------- 10321283028317893030 DYNAMIC_SAMPLING JOIN CARDINALITY MISESTIMATE 4757086536465754886 DYNAMIC_SAMPLING JOIN CARDINALITY MISESTIMATE 16085268038103121260 DYNAMIC_SAMPLING JOIN CARDINALITY MISESTIMATE SQL> set pages 9999 SQL> set lines 300 SQL> col state format a5 SQL> col subobject_name format a11 SQL> col col_name format a11 SQL> col object_name format a13 SQL> select d.directive_id, o.object_type, o.object_name, o.subobject_name col_name, d.type, d.state, d.reason 2 from dba_sql_plan_directives d, dba_sql_plan_dir_objects o 3 where d.DIRECTIVE_ID=o.DIRECTIVE_ID 4 and o.object_name in ('ORDER_ITEMS') 5 order by d.directive_id; DIRECTIVE_ID OBJECT_TYPE OBJECT_NAME COL_NAME TYPE STATE REASON ------------ ------------ ------------- ----------- -------------------------------- ----- ------------------------------------- --- 1.8156E+19 COLUMN ORDER_ITEMS UNIT_PRICE DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE 1.8156E+19 TABLE ORDER_ITEMS DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE 1.8156E+19 COLUMN ORDER_ITEMS QUANTITY DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE DBA_SQL_PLAN_DIRECTIVES????? _BASE_OPT_DIRECTIVE ? _BASE_OPT_FINDING SELECT d.dir_own#, d.dir_id, d.f_id, decode(type, 1, 'DYNAMIC_SAMPLING', 'UNKNOWN'), decode(state, 1, 'NEW', 2, 'MISSING_STATS', 3, 'HAS_STATS', 4, 'CANDIDATE', 5, 'PERMANENT', 6, 'DISABLED', 'UNKNOWN'), decode(bitand(flags, 1), 1, 'YES', 'NO'), cast(d.created as timestamp), cast(d.last_modified as timestamp), -- Please see QOSD_DAYS_TO_UPDATE and QOSD_PLUS_SECONDS for more details -- about 6.5 cast(d.last_used as timestamp) - NUMTODSINTERVAL(6.5, 'day') FROM sys.opt_directive$ d ??dbms_spd??? SQL PLAN DIRECTIVES, SQL PLAN DIRECTIVES???retention ???53?: Package: DBMS_SPD This package provides subprograms for managing Sql Plan Directives(SPD). SPD are objects generated automatically by Oracle server. For example, if server detects that the single table cardinality estimated by optimizer is off from the actual number of rows returned when accessing the table, it will automatically create a directive to do dynamic sampling for the table. When any Sql statement referencing the table is compiled, optimizer will perform dynamic sampling for the table to get more accurate estimate. Notes: DBMSL_SPD is a invoker-rights package. The invoker requires ADMINISTER SQL MANAGEMENT OBJECT privilege for executing most of the subprograms of this package. Also the subprograms commit the current transaction (if any), perform the operation and commit it again. DBA view dba_sql_plan_directives shows all the directives created in the system and the view dba_sql_plan_dir_objects displays the objects that are included in the directives. -- Default value for SPD_RETENTION_WEEKS SPD_RETENTION_WEEKS_DEFAULT CONSTANT varchar2(4) := '53'; | STATE : NEW : Newly created directive. | : MISSING_STATS : The directive objects do not | have relevant stats. | : HAS_STATS : The objects have stats. | : PERMANENT : A permanent directive. Server | evaluated effectiveness and these | directives are useful. | | AUTO_DROP : YES : Directive will be dropped | automatically if not | used for SPD_RETENTION_WEEKS. | This is the default behavior. | NO : Directive will not be dropped | automatically. Procedure: flush_sql_plan_directive This procedure allows manually flushing the Sql Plan directives that are automatically recorded in SGA memory while executing sql statements. The information recorded in SGA are periodically flushed by oracle background processes. This procedure just provides a way to flush the information manually. ????”_optimizer_dynamic_plans”(enable dynamic plans)????????,???TRUE??DYNAMIC PLAN? ???FALSE???????????? ????,Dynamic Plan????????????Nested Loop?Hash Join???case ,????????Nested loop???????????HASH JOIN,?HASH JOIN????????????????? ????????subplan?????,???? pass?? ?join method???,?????STATISTICS COLLECTOR???cardinality?,???????HASH JOIN?????Nested Loop,????????????subplan?????access path; ???????Sales??????????????????,????HASH JOIN,??SUBPLAN??customers?????????;?????Nested Loop,???????cust_id?????Range Scan+Access by Rowid? Cardinality feedback Cardinality feedback????????11.2????,????????re-optimization???;  ???????????,Cardinality feedback?????????????????????????? ???????????????????,?????????????????,??????????Cardinality feedback????????????? ????????????????????????? ??????????????Cardinality feedback ??: ????????,???????????,??????????,????????????????selectivity ??? ????????????: ??????,?????????????????????????????????,??????????????????? ????????????????????????????????????????,?????????????????????????? ?????????,???????????????,?????????? ??????????Cardinality ????,??????join Cardinality ????????? Cardinality feedback???????cursor?,?Cursor???aged out????? SELECT /*+ gather_plan_statistics */ product_name FROM order_items o, product_information p WHERE o.unit_price = 15 AND quantity > 1 AND p.product_id = o.product_id Plan hash value: 1553478007 ---------------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | OMem | 1Mem | Used-Mem | ---------------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 13 |00:00:00.01 | 24 | 20 | | | | |* 1 | HASH JOIN | | 1 | 4 | 13 |00:00:00.01 | 24 | 20 | 2061K| 2061K| 429K (0)| |* 2 | TABLE ACCESS FULL| ORDER_ITEMS | 1 | 4 | 13 |00:00:00.01 | 7 | 6 | | | | | 3 | TABLE ACCESS FULL| PRODUCT_INFORMATION | 1 | 1 | 288 |00:00:00.01 | 17 | 14 | | | | ---------------------------------------------------------------------------------------------------------------------------------------- SELECT /*+ gather_plan_statistics */ product_name FROM order_items o, product_information p WHERE o.unit_price = 15 AND quantity > 1 AND p.product_id = o.product_id Plan hash value: 1553478007 ------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem | ------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 13 |00:00:00.01 | 24 | | | | |* 1 | HASH JOIN | | 1 | 13 | 13 |00:00:00.01 | 24 | 2061K| 2061K| 413K (0)| |* 2 | TABLE ACCESS FULL| ORDER_ITEMS | 1 | 13 | 13 |00:00:00.01 | 7 | | | | | 3 | TABLE ACCESS FULL| PRODUCT_INFORMATION | 1 | 288 | 288 |00:00:00.01 | 17 | | | | ------------------------------------------------------------------------------------------------------------------------------- Note ----- - statistics feedback used for this statement SQL> select count(*) from v$SQL where SQL_ID='cz0hg2zkvd10y'; COUNT(*) ---------- 2 SQL>select sql_ID,USE_FEEDBACK_STATS FROM V$SQL_SHARED_CURSOR where USE_FEEDBACK_STATS ='Y'; SQL_ID U ------------- - cz0hg2zkvd10y Y ????????Cardinality feedback????,???????????????????????????,????????????order_items???????? ????2??????plan hash value??(??????????),?????2????child cursor??????gather_plan_statistics???actual : A-ROWS  estimate :E-ROWS????????? Automatic Re-optimization ???dynamic plan, Re-optimization???????????????  ?  ??????????????? ????????????????????????????????  ???????????,??????????????, ???????????????????? ???????????  Re-optimization??, ????????????????????? Re-optimization????dynamic plan??????????  dynamic plan????????????????????, ???????????????????? ????,??????????join order ??????????????,?????????????join order????? ??????,????????Re-optimization, ??Re-optimization ??????????????????? ?Oracle database 12c?,join statistics?????????????????????,??????????????????????Re-optimization???????????adaptive cursor sharing????? ????????????????,???????????? ????? ???????statistics collectors ????????????????????Re-optimization??????2?????????????,???????????????? ??????????????Re-optimization?????,?????????????????????? ???v$SQL??????IS_REOPTIMIZABLE?????????????????????Re-optimization,??????????Re-optimization???,?????Re-optimization ,???????reporting????? IS_REOPTIMIZABLE VARCHAR2(1) This columns shows whether the next execution matching this child cursor will trigger a reoptimization. The values are:   Y: If the next execution will trigger a reoptimization R: If the child cursor contains reoptimization information, but will not trigger reoptimization because the cursor was compiled in reporting mode N: If the child cursor has no reoptimization information ??1: select plan_table_output from table (dbms_xplan.display_cursor('gwf99gfnm0t7g',NULL,'ALLSTATS LAST')); SQL_ID  gwf99gfnm0t7g, child number 0 ------------------------------------- SELECT /*+ SFTEST gather_plan_statistics */ o.order_id, v.product_name FROM  orders o,   ( SELECT order_id, product_name FROM order_items o, product_information p     WHERE  p.product_id = o.product_id AND list_price < 50 AND min_price < 40  ) v WHERE o.order_id = v.order_id Plan hash value: 1906736282 ------------------------------------------------------------------------------------------------------------------------------------------- | Id  | Operation             | Name                | Starts | E-Rows | A-Rows |   A-Time   | Buffers | Reads  |  OMem |  1Mem | Used-Mem | ------------------------------------------------------------------------------------------------------------------------------------------- |   0 | SELECT STATEMENT      |                     |      1 |        |    269 |00:00:00.02 |    1336 |     18 |       |       |          | |   1 |  NESTED LOOPS         |                     |      1 |      1 |    269 |00:00:00.02 |    1336 |     18 |       |       |          | |   2 |   MERGE JOIN CARTESIAN|                     |      1 |      4 |   9135 |00:00:00.02 |      34 |     15 |       |       |          | |*  3 |    TABLE ACCESS FULL  | PRODUCT_INFORMATION |      1 |      1 |     87 |00:00:00.01 |      33 |     14 |       |       |          | |   4 |    BUFFER SORT        |                     |     87 |    105 |   9135 |00:00:00.01 |       1 |      1 |  4096 |  4096 | 4096  (0)| |   5 |     INDEX FULL SCAN   | ORDER_PK            |      1 |    105 |    105 |00:00:00.01 |       1 |      1 |       |       |          | |*  6 |   INDEX UNIQUE SCAN   | ORDER_ITEMS_UK      |   9135 |      1 |    269 |00:00:00.01 |    1302 |      3 |       |       |          | ------------------------------------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): ---------------------------------------------------    3 - filter(("MIN_PRICE"<40 AND "LIST_PRICE"<50))    6 - access("O"."ORDER_ID"="ORDER_ID" AND "P"."PRODUCT_ID"="O"."PRODUCT_ID") SQL_ID  gwf99gfnm0t7g, child number 1 ------------------------------------- SELECT /*+ SFTEST gather_plan_statistics */ o.order_id, v.product_name FROM  orders o,   ( SELECT order_id, product_name FROM order_items o, product_information p     WHERE  p.product_id = o.product_id AND list_price < 50 AND min_price < 40  ) v WHERE o.order_id = v.order_id Plan hash value: 35479787 -------------------------------------------------------------------------------------------------------------------------------------------- | Id  | Operation              | Name                | Starts | E-Rows | A-Rows |   A-Time   | Buffers | Reads  |  OMem |  1Mem | Used-Mem | -------------------------------------------------------------------------------------------------------------------------------------------- |   0 | SELECT STATEMENT       |                     |      1 |        |    269 |00:00:00.01 |      63 |      3 |       |       |          | |   1 |  NESTED LOOPS          |                     |      1 |    269 |    269 |00:00:00.01 |      63 |      3 |       |       |          | |*  2 |   HASH JOIN            |                     |      1 |    313 |    269 |00:00:00.01 |      42 |      3 |  1321K|  1321K| 1234K (0)| |*  3 |    TABLE ACCESS FULL   | PRODUCT_INFORMATION |      1 |     87 |     87 |00:00:00.01 |      16 |      0 |       |       |          | |   4 |    INDEX FAST FULL SCAN| ORDER_ITEMS_UK      |      1 |    665 |    665 |00:00:00.01 |      26 |      3 |       |       |          | |*  5 |   INDEX UNIQUE SCAN    | ORDER_PK            |    269 |      1 |    269 |00:00:00.01 |      21 |      0 |       |       |          | -------------------------------------------------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): ---------------------------------------------------    2 - access("P"."PRODUCT_ID"="O"."PRODUCT_ID")    3 - filter(("MIN_PRICE"<40 AND "LIST_PRICE"<50))    5 - access("O"."ORDER_ID"="ORDER_ID") Note -----    - statistics feedback used for this statement    SQL> select IS_REOPTIMIZABLE,child_number FROM V$SQL  A where A.SQL_ID='gwf99gfnm0t7g'; IS CHILD_NUMBER -- ------------ Y             0 N             1    1* select child_number,other_xml From v$SQL_PLAN  where SQL_ID='gwf99gfnm0t7g' and other_xml is not nul SQL> / CHILD_NUMBER OTHER_XML ------------ --------------------------------------------------------------------------------            1 <other_xml><info type="cardinality_feedback">yes</info><info type="db_version">1              2.1.0.1</info><info type="parse_schema"><![CDATA["OE"]]></info><info type="plan_              hash">35479787</info><info type="plan_hash_2">3382491761</info><outline_data><hi              nt><![CDATA[IGNORE_OPTIM_EMBEDDED_HINTS]]></hint><hint><![CDATA[OPTIMIZER_FEATUR              ES_ENABLE('12.1.0.1')]]></hint><hint><![CDATA[DB_VERSION('12.1.0.1')]]></hint><h              int><![CDATA[ALL_ROWS]]></hint><hint><![CDATA[OUTLINE_LEAF(@"SEL$F5BB74E1")]]></              hint><hint><![CDATA[MERGE(@"SEL$2")]]></hint><hint><![CDATA[OUTLINE(@"SEL$1")]]>              </hint><hint><![CDATA[OUTLINE(@"SEL$2")]]></hint><hint><![CDATA[FULL(@"SEL$F5BB7              4E1" "P"@"SEL$2")]]></hint><hint><![CDATA[INDEX_FFS(@"SEL$F5BB74E1" "O"@"SEL$2"              ("ORDER_ITEMS"."ORDER_ID" "ORDER_ITEMS"."PRODUCT_ID"))]]></hint><hint><![CDATA[I              NDEX(@"SEL$F5BB74E1" "O"@"SEL$1" ("ORDERS"."ORDER_ID"))]]></hint><hint><![CDATA[              LEADING(@"SEL$F5BB74E1" "P"@"SEL$2" "O"@"SEL$2" "O"@"SEL$1")]]></hint><hint><![C              DATA[USE_HASH(@"SEL$F5BB74E1" "O"@"SEL$2")]]></hint><hint><![CDATA[USE_NL(@"SEL$              F5BB74E1" "O"@"SEL$1")]]></hint></outline_data></other_xml>            0 <other_xml><info type="db_version">12.1.0.1</info><info type="parse_schema"><![C              DATA["OE"]]></info><info type="plan_hash">1906736282</info><info type="plan_hash              _2">2579473118</info><outline_data><hint><![CDATA[IGNORE_OPTIM_EMBEDDED_HINTS]]>              </hint><hint><![CDATA[OPTIMIZER_FEATURES_ENABLE('12.1.0.1')]]></hint><hint><![CD              ATA[DB_VERSION('12.1.0.1')]]></hint><hint><![CDATA[ALL_ROWS]]></hint><hint><![CD              ATA[OUTLINE_LEAF(@"SEL$F5BB74E1")]]></hint><hint><![CDATA[MERGE(@"SEL$2")]]></hi              nt><hint><![CDATA[OUTLINE(@"SEL$1")]]></hint><hint><![CDATA[OUTLINE(@"SEL$2")]]>              </hint><hint><![CDATA[FULL(@"SEL$F5BB74E1" "P"@"SEL$2")]]></hint><hint><![CDATA[              INDEX(@"SEL$F5BB74E1" "O"@"SEL$1" ("ORDERS"."ORDER_ID"))]]></hint><hint><![CDATA              [INDEX(@"SEL$F5BB74E1" "O"@"SEL$2" ("ORDER_ITEMS"."ORDER_ID" "ORDER_ITEMS"."PROD              UCT_ID"))]]></hint><hint><![CDATA[LEADING(@"SEL$F5BB74E1" "P"@"SEL$2" "O"@"SEL$1              " "O"@"SEL$2")]]></hint><hint><![CDATA[USE_MERGE_CARTESIAN(@"SEL$F5BB74E1" "O"@"              SEL$1")]]></hint><hint><![CDATA[USE_NL(@"SEL$F5BB74E1" "O"@"SEL$2")]]></hint></o              utline_data></other_xml> ??2: SELECT /*+gather_plan_statistics*/ * FROM customers WHERE cust_state_province='CA' AND country_id='US'; SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY_CURSOR(FORMAT=>'ALLSTATS LAST')); PLAN_TABLE_OUTPUT ------------------------------------- SQL_ID b74nw722wjvy3, child number 0 ------------------------------------- select /*+gather_plan_statistics*/ * from customers where CUST_STATE_PROVINCE='CA' and country_id='US' Plan hash value: 1683234692 -------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | -------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 29 |00:00:00.01 | 17 | 14 | |* 1 | TABLE ACCESS FULL| CUSTOMERS | 1 | 8 | 29 |00:00:00.01 | 17 | 14 | -------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter(("CUST_STATE_PROVINCE"='CA' AND "COUNTRY_ID"='US')) SELECT SQL_ID, CHILD_NUMBER, SQL_TEXT, IS_REOPTIMIZABLE FROM V$SQL WHERE SQL_TEXT LIKE 'SELECT /*+gather_plan_statistics*/%'; SQL_ID CHILD_NUMBER SQL_TEXT I ------------- ------------ ----------- - b74nw722wjvy3 0 select /*+g Y ather_plan_ statistics* / * from cu stomers whe re CUST_STA TE_PROVINCE ='CA' and c ountry_id=' US' EXEC DBMS_SPD.FLUSH_SQL_PLAN_DIRECTIVE; SELECT TO_CHAR(d.DIRECTIVE_ID) dir_id, o.OWNER, o.OBJECT_NAME, o.SUBOBJECT_NAME col_name, o.OBJECT_TYPE, d.TYPE, d.STATE, d.REASON FROM DBA_SQL_PLAN_DIRECTIVES d, DBA_SQL_PLAN_DIR_OBJECTS o WHERE d.DIRECTIVE_ID=o.DIRECTIVE_ID AND o.OWNER IN ('SH') ORDER BY 1,2,3,4,5; DIR_ID OWNER OBJECT_NAME COL_NAME OBJECT TYPE STATE REASON ----------------------- ----- ------------- ----------- ------ ---------------- ----- ------------------------ 1484026771529551585 SH CUSTOMERS COUNTRY_ID COLUMN DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE 1484026771529551585 SH CUSTOMERS CUST_STATE_ COLUMN DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY PROVINCE MISESTIMATE 1484026771529551585 SH CUSTOMERS TABLE DYNAMIC_SAMPLING NEW SINGLE TABLE CARDINALITY MISESTIMATE SELECT /*+gather_plan_statistics*/ * FROM customers WHERE cust_state_province='CA' AND country_id='US'; ELECT * FROM TABLE(DBMS_XPLAN.DISPLAY_CURSOR(FORMAT=>'ALLSTATS LAST')); PLAN_TABLE_OUTPUT ------------------------------------- SQL_ID b74nw722wjvy3, child number 1 ------------------------------------- select /*+gather_plan_statistics*/ * from customers where CUST_STATE_PROVINCE='CA' and country_id='US' Plan hash value: 1683234692 ----------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | ----------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 29 |00:00:00.01 | 17 | |* 1 | TABLE ACCESS FULL| CUSTOMERS | 1 | 29 | 29 |00:00:00.01 | 17 | ----------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter(("CUST_STATE_PROVINCE"='CA' AND "COUNTRY_ID"='US')) Note ----- - cardinality feedback used for this statement SELECT SQL_ID, CHILD_NUMBER, SQL_TEXT, IS_REOPTIMIZABLE FROM V$SQL WHERE SQL_TEXT LIKE 'SELECT /*+gather_plan_statistics*/%'; SQL_ID CHILD_NUMBER SQL_TEXT I ------------- ------------ ----------- - b74nw722wjvy3 0 select /*+g Y ather_plan_ statistics* / * from cu stomers whe re CUST_STA TE_PROVINCE ='CA' and c ountry_id=' US' b74nw722wjvy3 1 select /*+g N ather_plan_ statistics* / * from cu stomers whe re CUST_STA TE_PROVINCE ='CA' and c ountry_id=' US' SELECT /*+gather_plan_statistics*/ CUST_EMAIL FROM CUSTOMERS WHERE CUST_STATE_PROVINCE='MA' AND COUNTRY_ID='US'; SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY_CURSOR(FORMAT=>'ALLSTATS LAST')); PLAN_TABLE_OUTPUT ------------------------------------- SQL_ID 3tk6hj3nkcs2u, child number 0 ------------------------------------- Select /*+gather_plan_statistics*/ cust_email From customers Where cust_state_province='MA' And country_id='US' Plan hash value: 1683234692 ------------------------------------------------------------------------------- |Id | Operation | Name | Starts|E-Rows|A-Rows| A-Time |Buffers| ------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 2 |00:00:00.01| 16 | |*1 | TABLE ACCESS FULL| CUSTOMERS | 1 | 2| 2 |00:00:00.01| 16 | ----------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter(("CUST_STATE_PROVINCE"='MA' AND "COUNTRY_ID"='US')) Note ----- - dynamic sampling used for this statement (level=2) - 1 Sql Plan Directive used for this statement EXEC DBMS_SPD.FLUSH_SQL_PLAN_DIRECTIVE; SELECT TO_CHAR(d.DIRECTIVE_ID) dir_id, o.OWNER, o.OBJECT_NAME, o.SUBOBJECT_NAME col_name, o.OBJECT_TYPE, d.TYPE, d.STATE, d.REASON FROM DBA_SQL_PLAN_DIRECTIVES d, DBA_SQL_PLAN_DIR_OBJECTS o WHERE d.DIRECTIVE_ID=o.DIRECTIVE_ID AND o.OWNER IN ('SH') ORDER BY 1,2,3,4,5; DIR_ID OW OBJECT_NA COL_NAME OBJECT TYPE STATE REASON ------------------- -- --------- ---------- ------- --------------- ------------- ------------------------ 1484026771529551585 SH CUSTOMERS COUNTRY_ID COLUMN DYNAMIC_SAMPLING MISSING_STATS SINGLE TABLE CARDINALITY MISESTIMATE 1484026771529551585 SH CUSTOMERS CUST_STATE_ COLUMN DYNAMIC_SAMPLING MISSING_STATS SINGLE TABLE CARDINALITY PROVINCE MISESTIMATE 1484026771529551585 SH CUSTOMERS TABLE DYNAMIC_SAMPLING MISSING_STATS SINGLE TABLE CARDINALITY MISESTIMATE

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• ASP.NET MVC2 Radio Button generates duplicate HTML id-s

  - by Dmitriy Nagirnyak

  Hi, It seems that the default ASP.NET MVC2 Html helper generates duplicate HTML IDs when using code like this (EditorTemplates/UserType.ascx): <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<UserType>" %> <%: Html.RadioButton("", UserType.Primary, Model == UserType.Primary) %> <%: Html.RadioButton("", UserType.Standard, Model == UserType.Standard) %> <%: Html.RadioButton("", UserType.ReadOnly, Model == UserType.ReadOnly) %> The HTML it produces is: <input checked="checked" id="UserType" name="UserType" type="radio" value="Primary" /> <input id="UserType" name="UserType" type="radio" value="Standard" /> <input id="UserType" name="UserType" type="radio" value="ReadOnly" /> That clearly shows a problem. So I must be misusing the Helper or something. I can manually specify the id as html attribute but then I cannot guarantee it will be unique. So the question is how to make sure that the IDs generated by RadioButton helper are unique for each value and still preserve the conventions for generating those IDs (so nested models are respected? (Preferably not generating IDs manually.) Thanks, Dmitriy,

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• How can I create a generaic ValidationAttribute in C#?

  - by sabbour

  I'm trying to create a UniqueAttribute using the System.ComponentModel.DataAnnotations.ValidationAttribute I want this to be generic as in I could pass the Linq DataContext, the table name, the field and validate if the incoming value is unique or not. Here is a non-compilable code fragment that I'm stuck at right now: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.ComponentModel.DataAnnotations; using System.Data.Linq; using System.ComponentModel; namespace LinkDev.Innovation.Miscellaneous.Validation.Attributes { public class UniqueAttribute : ValidationAttribute { public string Field { get; set; } public override bool IsValid(object value) { string str = (string)value; if (String.IsNullOrEmpty(str)) return true; // this is where I'm stuck return (!Table.Where(entity => entity.Field.Equals(str)).Any()); } } } I should be using this in my model as follows: [Required] [StringLength(10)] [Unique(new DataContext(),"Groups","name")] public string name { get; set; }

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• 'click' observer in Prototype

  - by Tom

  I have a page which contains several divs (each with a unique ID and the same class, 'parent'). Underneath each "parent" div, is a div with class "child" and unique ID name -child. This DIV is upon page load empty. Whenever you click on a parent DIV, the following code is executed. $$('div.parent').each(function(s){ $(s).observe('click', function(event){ event.stop(); var filer = $(s).readAttribute('filer'); var currentElement = $(s).id; var childElement = currentElement + '-children'; new Ajax.Updater ({success: childElement}, root + '/filers/interfacechildren', { parameters: {parentId: currentElement, filer: filer} }); }); }); Of course, it's possible that a child node is again a parent ont its own. The response looks like this (Smarty with Zend Framework): {foreach from=$ifaces item=interface} <div id="{$interface->name}" filer="{$interface->system_id}" class="parent">{$interface->name}</div> <div id="{$interface->name}-children" class="child"></div> {/foreach} Whenever I click on a "parent" div that is loaded inside a child, nothing happens :( Any suggestions / fixes how to fix this?

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• Django: Validation error in Admin

  - by tomwolber

  NEWBIE ALERT! background: For the first time, I am writing a model that needs to be validated. I cannot have two Items that have overlapping "date ranges". I have everything working, except when I raise forms.ValidationError, I get the yellow screen of death (debug=true) or a 500 page (debug=false). My question: How can I have an error message show up in the Admin (like when you leave a required filed blank)? Sorry for my inexperience, please let me know if I can clarify the question better. Models.py from django.db import models from django import forms from django.forms import ModelForm from django.db.models import Q class Item(models.Model): name = models.CharField(max_length=500) slug = models.SlugField(unique=True) startDate = models.DateField("Start Date", unique="true") endDate = models.DateField("End Date") def save(self, *args, **kwargs): try: Item.objects.get(Q(startDate__range=(self.startDate,self.endDate))|Q(endDate__range=(self.startDate,self.endDate))|Q(startDate__lt=self.startDate,endDate__gt=self.endDate)) #check for validation, which may raise an Item.DoesNotExist error, excepted below #if the validation fails, raise this error: raise forms.ValidationError('Someone has already got that date, or somesuch error message') except Item.DoesNotExist: super(Item,self).save(*args,**kwargs) def __unicode__(self): return self.name def get_absolute_url(self): return "/adtest/%s/" % self.slug

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• Cannot rollback ransaction with Entity Framework

  - by Luca

  I have to do queries on uncommitted changes and I tried to use transactions, but I found that it do not work if there are exceptions. I made a simple example to reproduce the problem. I have a database with only one table called "Tabella" and the table has two fields: "ID" is a autogenerated integer, and "Valore" is an integer with a Unique constraint. Then I try to run this code: using (TransactionScope scope = new TransactionScope()) { Db1Container db1 = new Db1Container(); try { db1.AddToTabella(new Tabella() { Valore = 1 }); db1.SaveChanges(); } catch { } try { db1.AddToTabella(new Tabella() { Valore = 1 }); db1.SaveChanges(); //Unique constraint is violated here and an exception is thrown } catch { } try { db1.AddToTabella(new Tabella() { Valore = 2 }); db1.SaveChanges(); } catch { } //scope.Complete(); //NEVER called } //here everything should be rolled back Now if I look into the database it should contain no records because the transaction should rollback, instead I find two records!!!! One with Valore=1 and one with Valore=2. I am missing something? It looks like the second call to SaveChanges method rollback its own changes and "deletes" the transaction, then the third call to SaveChanges commits the changes of the first and the third insert (at this point it is like the transaction not exists). I also tried to use SaveChanges(false) method (even without calling AcceptAllChanges method), but with no success: I have the same behaviour. I do not want the transaction to be rolled back automatically by SaveChanges, because I want to correct the errors (for example by user interaction in the catch statement) and make a retry. Can someone help me with this? It seems like a "bug", and it is giving me a really big headache...

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• Writing an efficient cron job script utilizing Zend_Mail_Storage_Imap.

  - by fireeyedboy

  I'm new to the IMAP protocol and Zend_Mail_Storage and I'm writing a small php script for a cron job that should regularly poll an IMAP account and check for new messages, and send an e-mail if new messages have arrived. As you can imagine, I want to only poll the IMAP account for relevant messages, and I only want to send a new e-mail if new messages have arrived since the last polled new message. So I thought of keeping track of the last message I polled with some unique identifier for a message. But I'm a bit uncertain about whether the methods I want to utilize for this do what I expect them to do though. So my questions are: Does the iterator position of Zend_Mail_Storage_Imap actually resemble some IMAP unique identifier for messages, or is it simply only and internal position of Zend_Mail_Storage_Abstract? For instance, if I tell it to seek() to message 5 (which I stored from an earlier session) will it indeed seek to the appropriate message on the IMAP server, even if for instance messages have been deleted since last session? Would keeping track of this latest polled message id in a file suffice for a cron job that, say, polls the account every 5 or 10 minutes? Or is this too naive, and should I be using a database for instance. Or is there maybe a much easier way to keep track of such state with Zend_Mail_Storage_Abstract? Also, do I need to poll every IMAP folder? Or is everything accumulated when I poll INBOX? If you could shed some light on any of these matters, I'ld appreciate it. Thanks in advance.

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• consistency of Trigger Procedure (before row trigger) Postgresql

  - by elgcom

  Using Postgresql. I try to use TRIGGER procedure to make some consistency check on INSERT. The question is ...... whether "BEFORE INSERT FOR EACH ROW" can make sure each row to insert "checked" and "inserted" one after another? do I need extra lock on table to survive from concurrent insert? check for new row1 - insert row1 - check for new row2 - insert row2 -- -- -- unexpired product name is unique. CREATE TABLE product ( "name" VARCHAR(100) NOT NULL, "expired" BOOLEAN NOT NULL ); CREATE OR REPLACE FUNCTION check_consistency() RETURNS TRIGGER AS $$ BEGIN IF EXISTS (SELECT * FROM product WHERE name=NEW.name AND expired='false') THEN RAISE EXCEPTION 'duplicated!!!'; END IF; RETURN NEW; END; $$ LANGUAGE plpgsql; CREATE TRIGGER trigger_check_consistency BEFORE INSERT ON product FOR EACH ROW EXECUTE PROCEDURE check_consistency(); -- INSERT INTO product VALUES("prod1", true); INSERT INTO product VALUES("prod1", false); INSERT INTO product VALUES("prod1", false); // exception! this is OK name | expired ============== p1 | true p1 | true p1 | false This is not OK name | expired ============== p1 | true p1 | false p1 | false or maybe I should ask, how can I use Trigger to implement "Primary" or "Unique" constraint-like SQL.

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• Oracle command hangs when using view for "WHERE x IN..." subquery

  - by Calvin Fisher

  I'm working on a web service that fetches data from an oracle data source in chunks and passes it back to an indexing/search tool in XML format. I'm the C#/.NET guy, and am kind of fuzzy on parts of Oracle. Our Oracle team gave us the following script to run, and it works well: SELECT ROWID, [columns] FROM [table] WHERE ROWID IN ( SELECT ROWID FROM ( SELECT ROWID FROM [table] WHERE ROWID > '[previous_batch_last_rowid]' ORDER BY ROWID ) WHERE ROWNUM <= 10000 ) ORDER BY ROWID 10,000 rows is an arbitrary but reasonable chunk size and ROWID is sufficiently unique for our purposes to use as a UID since each indexing run hits only one table at a time. Bracketed values are filled in programmatically by the web service. Now we're going to start adding views to the indexing, each of which will union a few separate tables. Since ROWID would no longer function as a unique identifier, they added a column to the views (VIEW_UNIQUE_ID) that concatenates the ROWIDs from the component tables to construct a UID for each union. But this script does not work, even though it follows the same form as the previous one: SELECT VIEW_UNIQUE_ID, [columns] FROM [view] WHERE VIEW_UNIQUE_ID IN ( SELECT VIEW_UNIQUE_ID FROM ( SELECT VIEW_UNIQUE_ID FROM [view] WHERE ROWID > '[previous_batch_last_view_unique_id]' ORDER BY VIEW_UNIQUE_ID ) WHERE ROWNUM <= 10000 ) ORDER BY VIEW_UNIQUE_ID It hangs indefinitely with no response from the Oracle server. I've waited 20+ minutes and the SQLTools dialog box indicating a running query remains the same, with no progress or updates. I've tested each subquery independently and each works fine and takes a very short amount of time (<= 1 second), so the view itself is sound. But as soon as the inner two SELECT queries are added with "WHERE VIEW_UNIQUE_ID IN...", it hangs. Why doesn't this query work for views? In what important way are they not interchangeable here?

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• DDD principlers and ASP.NET MVC project design

  - by kaivalya

  Two part questions I have a product aggregate that has; Prices PackagingOptions ProductDescriptions ProductImages etc I have modeled one product repository and did not create individual repositories for any of the child classes. All db operations are handled through product repository. Am I understanding the DDD concept correctly so far? Sometimes the question comes to my mind that having a repository for lets say packaging options could make my life easier by directly fetching a the packaging option from the DB by using its ID instead of asking the product repository to find it in its PackagingOptions collection and give it to me.. Second part is managing the edit create operations using ASP.MVC frame work I am currently trying to manage all add edit remove of these child collections of product through product controller(sound right?). One challenge I am now facing is; If I edit a specific packaging option of product through mydomain/product/editpackagingoption/10 I have access to the id of the packaging option But I don't have the ID of the product it self and this forces me to write a query to first find the product that has this specific packaging option then edit that product and the revelant packaging option. I can do this as all packaging option have their unique ID but this would fail if I have collections that don't have unique ID. That feels very wrong.. The next option I thought of is sending both the product and packaging option IDs on the url like; mydomain/product/editpackagingoption/3/10 But I am not sure if that is a good design either. So I am at a point that I am a bit confused. might be having fundamental misunderstandings around all of this... I would appreciate if you bear with the long question and help me put this together. thanks!

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• Limiting choices from an intermediary ManyToMany junction table in Django

  - by Matthew Rankin

  Background I've created three Django models—Inventory, SalesOrder, and Invoice—to model items in inventory, sales orders for those items, and invoices for a particular sales order. Each sales order can have multiple items, so I've used an intermediary junction table—SalesOrderItems—using the through argument for the ManyToManyField. Also, partial billing of a sales orders is allowed, so I've created a ForeignKey in the Invoice model related to the SalesOrder model, so that a particular sales order can have multiple invoices. Here's where I deviate from what I've normally seen. Instead of relating the Invoice model to the Item model via a ManyToManyField, I've related the Invoice model to the SalesOrderItem intermediary junction table through the intermediary junction table InvoiceItem. I've done this because it better models reality—our invoices are tied to sales orders and can only include items that are tied to that sales order as opposed to any item in inventory. I will admit that it does seem strange having the intermediary junction table of a ManyToManyField related to the intermediary junction table of another ManyToManyField. Question How can I limit the choices available for the invoice_items in the Invoice model to just the sales_order_items of the SalesOrder model for that particular Invoice? (I tried using limit_choices_to= {'sales_order': self.invoice.sales_order}) as part of the item = models.ForeignKey(SalesOrderItem) in the InvoiceItem model, but that didn't work. Am I correct in thinking that limiting the choices for the invoice_items should be handled in the model instead of in a form? Code class Item(models.Model): item_num = models.SlugField(unique=True) default_price = models.DecimalField(max_digits=10, decimal_places=2, blank=True, null=True) class SalesOrderItem(models.Model): item = models.ForeignKey(Item) sales_order = models.ForeignKey('SalesOrder') unit_price = models.DecimalField(max_digits=10, decimal_places=2) quantity = models.DecimalField(max_digits=10, decimal_places=4) class SalesOrder(models.Model): customer = models.ForeignKey(Party) so_num = models.SlugField(max_length=40, unique=True) sales_order_items = models.ManyToManyField(Item, through=SalesOrderItem) class InvoiceItem(models.Model): item = models.ForeignKey(SalesOrderItem) invoice = models.ForeignKey('Invoice') unit_price = models.DecimalField(max_digits=10, decimal_places=2) quantity = models.DecimalField(max_digits=10, decimal_places=4) class Invoice(models.Model): invoice_num = models.SlugField(max_length=25) sales_order = models.ForeignKey(SalesOrder) invoice_items = models.ManyToManyField(SalesOrderItem, through='InvoiceItem')

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• RESTful idempotence

  - by DutrowLLC

  I'm designing a RESTful web service utilizing ROA(Resource oriented architecture). I'm trying to work out an efficient way to guarantee idempotence for PUT requests that create new resources in cases that the server designates the resource key. From my understanding, the traditional approach is to create a type of transaction resource such as /CREATE_PERSON. The the client-server interaction for creating a new person resource would be in two parts: Step 1: Get unique transaction id for creating the new PERSON resource::: **Client request:** GET /CREATE_PERSON **Server response:** 200 OK transaction-id:"as8yfasiob" Step 2: Create the new person resource in a request guaranteed to be unique by using the transaction id::: **Client request** PUT /CREATE_PERSON/{transaction_id} first_name="Big bubba" **Server response** 201 Created // (If the request is a duplicate, it would send this PersonKey="398u4nsdf" // same response without creating a new resource. It // would perhaps send an error response if the was used // on a transaction id non-duplicate request, but I have // control over the client, so I can guarantee that this // won't happen) The problem that I see with this approach is that it requires sending two requests to the server in order to do to single operation of creating a new PERSON resource. This creates a performance issues increasing the chance that the user will be waiting around for the client to complete their request. I've been trying to hash out ideas for eliminating the first step such as pre-sending transaction-id's with each request, but most of my ideas have other issues or involve sacrificing the statelessness of the application. Is there a way to do this?

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• noSQL/SQL/RoR: Trying to build scalable ratings table for the game

  - by alexeypro

  I am trying to solve complex thing (as it looks to me). I have next entities: PLAYER (few of them, with names like "John", "Peter", etc.). Each has unique ID. For simplicity let's think it's their name. GAME (few of them, say named "Hide and Seek", "Jump and Run", etc.). Same - each has unique ID. For simplicity of the case let it be it's name for now. SCORE (it's numeric). So, how it works. Each PLAYER can play in multiple GAMES. He gets some SCORE in every GAME. I need to build rating table -- and not one! Table #1: most played GAMES Table #2: best PLAYERS in all games (say the total SCORE in every GAME). Table #3: best PLAYERS per GAME (by SCORE in particularly that GAME). I could be build something straight right away, but that will not work. I will have more than 10,000 players; and 15 games, which will grow for sure. Score can be as low as 0, and as high as 1,000,000 (not sure if higher is possible at this moment) for player in the game. So I really need some relative data. Any suggestions? I am planning to do it with SQL, but may be just using it for key-value storage; anything -- any ideas are welcome. Thank you!

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• MySQL stuck on "using filesort" when doing an "order by"

  - by noko

  I can't seem to get my query to stop using filesort. This is my query: SELECT s.`pilot`, p.`name`, s.`sector`, s.`hull` FROM `pilots` p LEFT JOIN `ships` s ON ( (s.`game` = p.`game`) AND (s.`pilot` = p.`id`) ) WHERE p.`game` = 1 AND p.`id` <> 2 AND s.`sector` = 43 AND s.`hull` > 0 ORDER BY p.`last_move` DESC Table structures: CREATE TABLE IF NOT EXISTS `pilots` ( `id` mediumint(5) unsigned NOT NULL AUTO_INCREMENT, `game` tinyint(3) unsigned NOT NULL DEFAULT '0', `last_move` int(10) NOT NULL DEFAULT '0', UNIQUE KEY `id` (`id`), KEY `last_move` (`last_move`), KEY `game_id_lastmove` (`game`,`id`,`last_move`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ; CREATE TABLE IF NOT EXISTS `ships` ( `id` mediumint(5) unsigned NOT NULL AUTO_INCREMENT, `game` tinyint(3) unsigned NOT NULL DEFAULT '0', `pilot` mediumint(5) unsigned NOT NULL DEFAULT '0', `sector` smallint(5) unsigned NOT NULL DEFAULT '0', `hull` smallint(4) unsigned NOT NULL DEFAULT '50', UNIQUE KEY `id` (`id`), KEY `game` (`game`), KEY `pilot` (`pilot`), KEY `sector` (`sector`), KEY `hull` (`hull`), KEY `game_2` (`game`,`pilot`,`sector`,`hull`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ; The explain: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE p ref id,game_id_lastmove game_id_lastmove 1 const 7 Using where; Using filesort 1 SIMPLE s ref game,pilot,sector... game_2 6 const,fightclub_alpha.p.id,const 1 Using where; Using index edit: I cut some of the unnecessary pieces out of my queries/table structure. Anybody have any ideas?

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• SQLiteDataAdapter Fill exception C# ADO.NET

  - by Lirik

  I'm trying to use the OleDb CSV parser to load some data from a CSV file and insert it into a SQLite database, but I get an exception with the OleDbAdapter.Fill method and it's frustrating: An unhandled exception of type 'System.Data.ConstraintException' occurred in System.Data.dll Additional information: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. Here is the source code: public void InsertData(String csvFileName, String tableName) { String dir = Path.GetDirectoryName(csvFileName); String name = Path.GetFileName(csvFileName); using (OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + dir + @";Extended Properties=""Text;HDR=No;FMT=Delimited""")) { conn.Open(); using (OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * FROM " + name, conn)) { QuoteDataSet ds = new QuoteDataSet(); adapter.Fill(ds, tableName); // <-- Exception here InsertData(ds, tableName); // <-- Inserts the data into the my SQLite db } } } class Program { static void Main(string[] args) { SQLiteDatabase target = new SQLiteDatabase(); string csvFileName = "D:\\Innovations\\Finch\\dev\\DataFeed\\YahooTagsInfo.csv"; string tableName = "Tags"; target.InsertData(csvFileName, tableName); Console.ReadKey(); } } The "YahooTagsInfo.csv" file looks like this: tagId,tagName,description,colName,dataType,realTime 1,s,Symbol,symbol,VARCHAR,FALSE 2,c8,After Hours Change,afterhours,DOUBLE,TRUE 3,g3,Annualized Gain,annualizedGain,DOUBLE,FALSE 4,a,Ask,ask,DOUBLE,FALSE 5,a5,Ask Size,askSize,DOUBLE,FALSE 6,a2,Average Daily Volume,avgDailyVolume,DOUBLE,FALSE 7,b,Bid,bid,DOUBLE,FALSE 8,b6,Bid Size,bidSize,DOUBLE,FALSE 9,b4,Book Value,bookValue,DOUBLE,FALSE I've tried the following: Removing the first line in the CSV file so it doesn't confuse it for real data. Changing the TRUE/FALSE realTime flag to 1/0. I've tried 1 and 2 together (i.e. removed the first line and changed the flag). None of these things helped... One constraint is that the tagId is supposed to be unique. Here is what the table look like in design view: Can anybody help me figure out what is the problem here?

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• what is called KEY

  - by Bharanikumar

  CREATE TABLE `ost_staff` ( `staff_id` int(11) unsigned NOT NULL auto_increment, `group_id` int(10) unsigned NOT NULL default '0', `dept_id` int(10) unsigned NOT NULL default '0', `username` varchar(32) collate latin1_german2_ci NOT NULL default '', `firstname` varchar(32) collate latin1_german2_ci default NULL, `lastname` varchar(32) collate latin1_german2_ci default NULL, `passwd` varchar(128) collate latin1_german2_ci default NULL, `email` varchar(128) collate latin1_german2_ci default NULL, `phone` varchar(24) collate latin1_german2_ci NOT NULL default '', `phone_ext` varchar(6) collate latin1_german2_ci default NULL, `mobile` varchar(24) collate latin1_german2_ci NOT NULL default '', `signature` varchar(255) collate latin1_german2_ci NOT NULL default '', `isactive` tinyint(1) NOT NULL default '1', `isadmin` tinyint(1) NOT NULL default '0', `isvisible` tinyint(1) unsigned NOT NULL default '1', `onvacation` tinyint(1) unsigned NOT NULL default '0', `daylight_saving` tinyint(1) unsigned NOT NULL default '0', `append_signature` tinyint(1) unsigned NOT NULL default '0', `change_passwd` tinyint(1) unsigned NOT NULL default '0', `timezone_offset` float(3,1) NOT NULL default '0.0', `max_page_size` int(11) NOT NULL default '0', `created` datetime NOT NULL default '0000-00-00 00:00:00', `lastlogin` datetime default NULL, `updated` datetime NOT NULL default '0000-00-00 00:00:00', PRIMARY KEY (`staff_id`), UNIQUE KEY `username` (`username`), KEY `dept_id` (`dept_id`), **KEY `issuperuser` (`isadmin`),** **KEY `group_id` (`group_id`,`staff_id`)** ) ENGINE=MyISAM AUTO_INCREMENT=35 DEFAULT CHARSET=latin1 COLLATE=latin1_german2_ci; Hi the above query is the osticket open source one, i know primary key , foreign key , unique but AM NOT SURE WHAT IS THIS KEY group_id (group_id,staff_id) Please tell me, this constraints name....

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• Database design for invoices, invoice lines & revisions

  - by FreshCode

  I'm designing the 2nd major iteration of a relational database for a franchise's CRM (with lots of refactoring) and I need help on the best database design practices for storing job invoices and invoice lines with a strong audit trail of any changes made to each invoice. Current schema Invoices Table InvoiceId (int) // Primary key JobId (int) StatusId (tinyint) // Pending, Paid or Deleted UserId (int) // auditing user Reference (nvarchar(256)) // unique natural string key with invoice number Date (datetime) Comments (nvarchar(MAX)) InvoiceLines Table LineId (int) // Primary key InvoiceId (int) // related to Invoices above Quantity (decimal(9,4)) Title (nvarchar(512)) Comment (nvarchar(512)) UnitPrice (smallmoney) Revision schema InvoiceRevisions Table RevisionId (int) // Primary key InvoiceId (int) JobId (int) StatusId (tinyint) // Pending, Paid or Deleted UserId (int) // auditing user Reference (nvarchar(256)) // unique natural string key with invoice number Date (datetime) Total (smallmoney) Schema design considerations 1. Is it sensible to store an invoice's Paid or Pending status? All payments received for an invoice are stored in a Payments table (eg. Cash, Credit Card, Cheque, Bank Deposit). Is it meaningful to store a "Paid" status in the Invoices table if all the income related to a given job's invoices can be inferred from the Payments table? 2. How to keep track of invoice line item revisions? I can track revisions to an invoice by storing status changes along with the invoice total and the auditing user in an invoice revision table (see InvoiceRevisions above), but keeping track of an invoice line revision table feels hard to maintain. Thoughts? 3. Tax How should I incorporate sales tax (or 14% VAT in SA) when storing invoice data?

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• How to Create Deterministic Guids

  - by desigeek

  In our application we are creating Xml files with an attribute that has a Guid value. This value needed to be consistent between file upgrades. So even if everything else in the file changes, the guid value for the attribute should remain the same. One obvious solution was to create a static dictionary with the filename and the Guids to be used for them. Then whenever we generate the file, we look up the dictionary for the filename and use the corresponding guid. But this is not feasible coz we might scale to 100's of files and didnt want to maintain big list of guids. So another approach was to make the Guid the same based on the path of the file. Since our file paths and application directory structure are unique, the Guid should be unique for that path. So each time we run an upgrade, the file gets the same guid based on its path. I found one cool way to generate such 'Deterministic Guids' (Thanks Elton Stoneman). It basically does this: private Guid GetDeterministicGuid(string input) { //use MD5 hash to get a 16-byte hash of the string: MD5CryptoServiceProvider provider = new MD5CryptoServiceProvider(); byte[] inputBytes = Encoding.Default.GetBytes(input); byte[] hashBytes = provider.ComputeHash(inputBytes); //generate a guid from the hash: Guid hashGuid = new Guid(hashBytes); return hashGuid; } So given a string, the Guid will always be the same. Are there any other approaches or recommended ways to doing this? What are the pros or cons of that method?

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• Generic Dictionary and generating a hashcode for multi-part key

  - by Andrew

  I have an object that has a multi-part key and I am struggling to find a suitable way override GetHashCode. An example of what the class looks like is. public class wibble{ public int keypart1 {get; set;} public int keypart2 {get; set;} public int keypart3 {get; set;} public int keypart4 {get; set;} public int keypart5 {get; set;} public int keypart6 {get; set;} public int keypart7 {get; set;} public single value {get; set;} } Note in just about every instance of the class no more than 2 or 3 of the keyparts would have a value greater than 0. Any ideas on how best to generate a unique hashcode in this situation? I have also been playing around with creating a key that is not unique, but spreads the objects evenly between the dictionaries buckets and then storing objects with matched hashes in a List< or LinkedList< or SortedList<. Any thoughts on this?

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• How to select form input based on label inner HTML?

  - by Shane

  I have multiple forms that are dynamically created with different input names and id's. The only thing unique they will have is the inner HTML of the label. Is it possible to select the input via the label inner HTML with jQuery? Here is an example of one of my patient date of birth blocks, there are many and all unique except for innerHTML. <div class="iphorm-element-spacer iphorm-element-spacer-text iphorm_1_8-element-spacer"> <label for="iphorm_081a9e2e6b9c83d70496906bb4671904150cf4b43c0cb1_8">events=Object { mouseover=[1], mouseout=[1]}handle=function()data=Object { InFieldLabels={...}} Patient DOB <span class="iphorm-required">*</span> </label> <div class="iphorm-input-wrap iphorm-input-wrap-text iphorm_1_8-input-wrap"> <input id="iphorm_081a9e2e6b9c83d70496906bb4671904150cf4b43c0cb1_8" class="iphorm-element-text iphorm_1_8" type="text" value="" name="iphorm_1_8">events=Object { focus=[1], blur=[1], keydown=[1], more...}handle=function() </div> <div class="iphorm-errors-wrap iphorm-hidden"> </div> This is in a Wordpress Plugin and because we are building to allow employees to edit their sites (this is actually a Wordpress Network), we do not want to alter the plugin if possible. Note that the label "for" and the input "id" share the same dynamic key, so this might be a way to maybe get the id, but wanted to see if there is a shorter way of doing this.

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• Secure Password Storage and Transfer

  - by Andras Zoltan

  I'm developing a new user store for my organisation and am now tackling password storage. The concepts of salting, HMAC etc are all fine with me - and want to store the users' passwords either salted and hashed, HMAC hashed, or HMAC salted and hashed - not sure what the best way will be - but in theory it won't matter as it will be able to change over time if required. I want to have an XML & JSON service that can act as a Security Token Service for client-side apps. I've already developed one for another system, which requires that the client double-encrypts a clear-text password using SHA1 first and then HMACSHA1 using a 128 unique key (or nonce) supplied by the server for that session only. I'd like to repeat this technique for the new system - upgrading the algo to SHA256 (chosen since implementations are readily available for all aforementioned platforms - and it's much stronger than SHA1) - but there is a problem. If I'm storing the password as a salted hash in the user-store, the client will need to be sent that salt in order to construct the correct hash before being HMACd with the unique session key. This would completely go against the point of using a salt in the first place. Equally, if I don't use salt for password storage, but instead use HMAC, it's still the same problem. At the moment, the only solution I can see is to use naked SHA256 hashing for the password in the user store, so that I can then use this as a starting point on both the server and the client for a more secure salted/hmacd password transfer for the web service. This still leaves the user store vulnerable to a dictionary attack were it ever to be accessed; and however unlikely that might be - assuming it will never happen simply doesn't sit well with me. Greatly appreciate any input.

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• mysql database normalization question

  - by Chocho

  here is my 3 tables: table 1 -- stores user information and it has unique data table 2 -- stores place category such as, toronto, ny, london, etc hence this is is also unique table 3 -- has duplicate information. it stores all the places a user have been. the 3 tables are linked or joined by these ids: table 1 has an "table1_id" table 2 has an "table2_id" and "place_name" table 3 has an "table3_id", "table1_id", "place_name" i have an interface where an admin sees all users. beside a user is "edit" button. clicking on that edit button allows you to edit a specific user in a form fields which has a multiple drop down box for "places". if an admin edits a user and add 1 "places" for the user, i insert that information using php. if the admin decides to deselect that 1 "places" do i delete it or mark it as on and off? how about if the admin decides to select 2 "places" for the user; change the first "places" and add an additional "places". will my table just keep growing and will i have just redundant information? thanks.

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• HTML onmouseover doesn't work to show up text

  - by REALFREE

  I'm trying to show some information on a picture when onmouseover/onmouseout event occurs. What I want to achieve is something like this website does on top selling. My code is like this: <div class="container" onmouseover="$('#info').css('display','block');" onmouseout="$('#info').css('display','none');"> <img src=..."> <div id="info" style="display:none"> ... some text ... </div> </div> So div info block is initially hidden, but when mouse is on a picture I want the information to appear on corresponding picture (with tint background on the image to see text well). But somewhat it doesn't work. I appreciate any suggestion how to approach this problem. Edit: more precisely, the reason why I choose to use inline because I need to show/hide text corresponding to the image(contain unique div id)that user put their mouse on/out. That means I have many div container and each container has unique div id.

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• MySQL & PHP - select/option lists and showing data to users that still allows me to generate queries

  - by Andrew Heath

  Sorry for the unclear title, an example will clear things up: TABLE: Scenario_victories ID scenid timestamp userid side playdate 1 RtBr001 2010-03-15 17:13:36 7 1 2010-03-10 2 RtBr001 2010-03-15 17:13:36 7 1 2010-03-10 3 RtBr001 2010-03-15 17:13:51 7 2 2010-03-10 ID and timestamp are auto-insertions by the database when the other 4 fields are added. The first thing to note is that a user can record multiple playings of the same scenario (scenid) on the same date (playdate) possibly with the same outcome (side = winner). Hence the need for the unique ID and timestamps for good measure. Now, on their user page, I'm displaying their recorded play history in a <select><option>... list form with 2 buttons at the end - Delete Record and Go to Scenario My script takes the scenid and after hitting a few other tables returns with something more user-friendly like: (playdate) (from scenid) (from side) ######################################################### # 2010-03-10 Road to Berlin #1 -- Germany, Hungary won # # 2010-03-10 Road to Berlin #1 -- Germany, Hungary won # # 2010-03-10 Road to Berlin #1 -- Soviet Union won # ######################################################### [Delete Record] [Go To Scenario] in HTML: <select name="history" size=3> <option>2010-03-10 Road to Berlin #1 -- Germany, Hungary won</option> <option>2010-03-10 Road to Berlin #1 -- Germany, Hungary won</option> <option>2010-03-10 Road to Berlin #1 -- Soviet Union won</option> </select> Now, if you were to highlight the first record and click Go to Scenario there is enough information there for me to parse it and produce the exact scenario you want to see. However, if you were to select Delete Record there is not - I have the playdate and I can parse the scenid and side from what's listed, but in this example all three records would have the same result. I appear to have painted myself into a corner. Does anyone have a suggestion as to how I can get some unique identifying data (ID and/or timestamp) to ride along on this form without showing it to the user? PHP-only please, I must be NoScript compliant!

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