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• Grafting LINQ onto C# 2 library

  - by P Daddy

  I'm writing a data access layer. It will have C# 2 and C# 3 clients, so I'm compiling against the 2.0 framework. Although encouraging the use of stored procedures, I'm still trying to provide a fairly complete ability to perform ad-hoc queries. I have this working fairly well, already. For the convenience of C# 3 clients, I'm trying to provide as much compatibility with LINQ query syntax as I can. Jon Skeet noticed that LINQ query expressions are duck typed, so I don't have to have an IQueryable and IQueryProvider (or IEnumerable<T>) to use them. I just have to provide methods with the correct signatures. So I got Select, Where, OrderBy, OrderByDescending, ThenBy, and ThenByDescending working. Where I need help are with Join and GroupJoin. I've got them working, but only for one join. A brief compilable example of what I have is this: // .NET 2.0 doesn't define the Func<...> delegates, so let's define some workalikes delegate TResult FakeFunc<T, TResult>(T arg); delegate TResult FakeFunc<T1, T2, TResult>(T1 arg1, T2 arg2); abstract class Projection{ public static Condition operator==(Projection a, Projection b){ return new EqualsCondition(a, b); } public static Condition operator!=(Projection a, Projection b){ throw new NotImplementedException(); } } class ColumnProjection : Projection{ readonly Table table; readonly string columnName; public ColumnProjection(Table table, string columnName){ this.table = table; this.columnName = columnName; } } abstract class Condition{} class EqualsCondition : Condition{ readonly Projection a; readonly Projection b; public EqualsCondition(Projection a, Projection b){ this.a = a; this.b = b; } } class TableView{ readonly Table table; readonly Projection[] projections; public TableView(Table table, Projection[] projections){ this.table = table; this.projections = projections; } } class Table{ public Projection this[string columnName]{ get{return new ColumnProjection(this, columnName);} } public TableView Select(params Projection[] projections){ return new TableView(this, projections); } public TableView Select(FakeFunc<Table, Projection[]> projections){ return new TableView(this, projections(this)); } public Table Join(Table other, Condition condition){ return new JoinedTable(this, other, condition); } public TableView Join(Table inner, FakeFunc<Table, Projection> outerKeySelector, FakeFunc<Table, Projection> innerKeySelector, FakeFunc<Table, Table, Projection[]> resultSelector){ Table join = new JoinedTable(this, inner, new EqualsCondition(outerKeySelector(this), innerKeySelector(inner))); return join.Select(resultSelector(this, inner)); } } class JoinedTable : Table{ readonly Table left; readonly Table right; readonly Condition condition; public JoinedTable(Table left, Table right, Condition condition){ this.left = left; this.right = right; this.condition = condition; } } This allows me to use a fairly decent syntax in C# 2: Table table1 = new Table(); Table table2 = new Table(); TableView result = table1 .Join(table2, table1["ID"] == table2["ID"]) .Select(table1["ID"], table2["Description"]); But an even nicer syntax in C# 3: TableView result = from t1 in table1 join t2 in table2 on t1["ID"] equals t2["ID"] select new[]{t1["ID"], t2["Description"]}; This works well and gives me identical results to the first case. The problem is if I want to join in a third table. TableView result = from t1 in table1 join t2 in table2 on t1["ID"] equals t2["ID"] join t3 in table3 on t1["ID"] equals t3["ID"] select new[]{t1["ID"], t2["Description"], t3["Foo"]}; Now I get an error (Cannot implicitly convert type 'AnonymousType#1' to 'Projection[]'), presumably because the second join is trying to join the third table to an anonymous type containing the first two tables. This anonymous type, of course, doesn't have a Join method. Any hints on how I can do this?

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• How to eliminate NULL fields in TSQL

  - by salvationishere

  I am developing a TSQL query in SSMS 2008 R2. I am trying to develop this query to identify one record / client. Because some of these values are NULL, I am currently doing LEFT JOINS on most of the tables. But the problem with the LEFT JOINs is that now I get 1 record for some clients. But if I change this to INNER JOINs then some clients are excluded entirely because they have NULL values for these columns. How do I limit the query result to just one record / client regardless of NULL values? And if there are non-NULL values then I want it to choose the record with non-NULL values. Here is some of my current output: group_profile_id profile_name license_number is_accepting is_accepting_placement managing_office region vendor_name vendor_id applicant_type Office Address status_description Cert Date2 race ethnicity_desc religion 9CD932F1-6BE1-4F80-AB81-0CE32C565BCF Atreides Foster Home 1 Atreides1 1 Yes Manchester, NH Gulf Atlantic Atreides1 00000007 Treatment Foster Home 4042 Arrakis Avenue, Springfield, VT 05156 Open/Re-opened 2011-06-01 00:00:00.000 NULL NULL NULL DCE354D5-A7CC-409F-B5A3-89BF664B7718 Averitte, Leon and Sandra 00000044 1 Yes Birmingham, AL Gulf Atlantic AL Averitte, Leon and Sandra 00000044 Treatment Foster Home 3816 5th Avenue, Bessemer, AL 35020, (205)482-4307 Open/Re-opened 2011-08-05 00:00:00.000 NULL NULL NULL DCE354D5-A7CC-409F-B5A3-89BF664B7718 Averitte, Leon and Sandra 00000044 1 Yes Birmingham, AL Gulf Atlantic AL Averitte, Leon and Sandra 00000044 Treatment Foster Home 3816 5th Avenue, Bessemer, AL 35020, (205)482-4307 Open/Re-opened 2011-08-05 00:00:00.000 Caucasian/White Non Hispanic NULL AD02A43C-6F38-4F35-8C9E-E12422690BFB Bass, Matthew and Sarah 00000076 1 Yes Jacks on, MS Central Gulf Coast MS Bass, Matthew and Sarah 00000076 Treatment Foster Home 506 Eagelwood Drive, Florence, MS 39073, (601)665-7169 Open/Re-opened 2011-04-01 00:00:00.000 NULL NULL NULL AD02A43C-6F38-4F35-8C9E-E12422690BFB Bass, Matthew and Sarah 00000076 1 Yes Jackson, MS Central Gulf Coast MS Bass, Matthew and Sarah 00000076 Treatment Foster Home 506 Eagelwood Drive, Florence, MS 39073, (601)665-7169 Open/Re-opened 2011-04-01 00:00:00.000 Caucasian/White NULL Baptist You can see that both Averitte and Bass profile names have one record with NULL race, ethnicity, religion. How do I eliminate these rows (rows 2 and 4)? Here is my query currently: select distinct gp.group_profile_id, gp.profile_name, gp.license_number, gp.is_accepting, case when gp.is_accepting = 1 then 'Yes' when gp.is_accepting = 0 then 'No ' end as is_accepting_placement, mo.profile_name as managing_office, regions.[region_description] as region, pv.vendor_name, pv.id as vendor_id, at.description as applicant_type, dbo.GetGroupAddress(gp.group_profile_id, null, 0) as [Office Address], gsv.status_description, ri.[description] as race, ethnicity.description as ethnicity_desc, religion.description as religion from group_profile gp With (NoLock) --Office Information inner join group_profile_type gpt With (NoLock) on gp.group_profile_type_id = gpt.group_profile_type_id and gpt.type_code = 'FOSTERHOME' and gp.agency_id = @agency_id and gp.is_deleted = 0 inner join group_profile mo With (NoLock) on gp.managing_office_id = mo.group_profile_id left outer join payor_vendor pv With (NoLock) on gp.payor_vendor_id = pv.payor_vendor_id left outer join applicant_type at With (NoLock) on gp.applicant_type_id = at.applicant_type_id and at.is_foster_home = 1 inner join group_status_view gsv With (NoLock) on gp.group_profile_id = gsv.group_profile_id and gsv.status_value = 'OPEN' and gsv.effective_date = (Select max(b.effective_date) from group_status_view b With (NoLock) where gp.group_profile_id = b.group_profile_id) left outer join regions With (NoLock) on isnull(mo.regions_id, gp.regions_id) = regions.regions_id left join enrollment en on en.group_profile_id = gp.group_profile_id join event_log el on el.event_log_id = en.event_log_id left join people client on client.people_id = el.people_id left join race With (NoLock) on el.people_id = race.people_id left join group_profile_race gpr with (nolock) on gpr.race_info_id = race.race_info_id left join race_info ri with (nolock) on ri.race_info_id = gpr.race_info_id left join ethnicity With(NoLock) On client.ethnicity = ethnicity.ethnicity_id left join religion on client.religion = religion.religion_id

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• JPA : Add and remove operations on lazily initialized collection behaviour ?

  - by Albert Kam

  Hello, im currently trying out JPA 2 and using Hibernate 3.6.x as the engine. I have an entity of ReceivingGood that contains a List of ReceivingGoodDetail, and has a bidirectional relation. Some related codes for each entity follows : ReceivingGood.java @OneToMany(mappedBy="receivingGood", targetEntity=ReceivingGoodDetail.class, fetch=FetchType.LAZY, cascade = CascadeType.ALL) private List<ReceivingGoodDetail> details = new ArrayList<ReceivingGoodDetail>(); public void addReceivingGoodDetail(ReceivingGoodDetail receivingGoodDetail) { receivingGoodDetail.setReceivingGood(this); } void internalAddReceivingGoodDetail(ReceivingGoodDetail receivingGoodDetail) { this.details.add(receivingGoodDetail); } public void removeReceivingGoodDetail(ReceivingGoodDetail receivingGoodDetail) { receivingGoodDetail.setReceivingGood(null); } void internalRemoveReceivingGoodDetail(ReceivingGoodDetail receivingGoodDetail) { this.details.remove(receivingGoodDetail); } @ManyToOne @JoinColumn(name = "receivinggood_id") private ReceivingGood receivingGood; ReceivingGoodDetail.java : public void setReceivingGood(ReceivingGood receivingGood) { if (this.receivingGood != null) { this.receivingGood.internalRemoveReceivingGoodDetail(this); } this.receivingGood = receivingGood; if (receivingGood != null) { receivingGood.internalAddReceivingGoodDetail(this); } } In my experiements with both of these entities, both adding the detail to the receivingGood's collection, and even removing the detail from the receivingGood's collection, will trigger a query to fill the collection before doing the add or remove. This assumption is based on my experiments that i will paste below. My concern is that : is it ok to do changes on only a little bit of records on the collection, and the engine has to query all of the details belonging to the collection ? What if the collection would have to be filled with 1000 records when i just want to edit a single record ? Here are my experiments with the output as the comment above each method : /* Hibernate: select receivingg0_.id as id9_14_, receivingg0_.creationDate as creation2_9_14_, ... too long Hibernate: select receivingg0_.id as id10_20_, receivingg0_.creationDate as creation2_10_20_, ... too long removing existing detail from lazy collection Hibernate: select details0_.receivinggood_id as receivi13_9_8_, details0_.id as id8_, details0_.id as id10_7_, details0_.creationDate as creation2_10_7_, details0_.modificationDate as modifica3_10_7_, details0_.usercreate_id as usercreate10_10_7_, details0_.usermodify_id as usermodify11_10_7_, details0_.version as version10_7_, details0_.buyQuantity as buyQuant5_10_7_, details0_.buyUnit as buyUnit10_7_, details0_.internalQuantity as internal7_10_7_, details0_.internalUnit as internal8_10_7_, details0_.product_id as product12_10_7_, details0_.receivinggood_id as receivi13_10_7_, details0_.supplierLotNumber as supplier9_10_7_, user1_.id as id2_0_, user1_.creationDate as creation2_2_0_, user1_.modificationDate as modifica3_2_0_, user1_.usercreate_id as usercreate6_2_0_, user1_.usermodify_id as usermodify7_2_0_, user1_.version as version2_0_, user1_.name as name2_0_, user2_.id as id2_1_, user2_.creationDate as creation2_2_1_, user2_.modificationDate as modifica3_2_1_, user2_.usercreate_id as usercreate6_2_1_, user2_.usermodify_id as usermodify7_2_1_, user2_.version as version2_1_, user2_.name as name2_1_, user3_.id as id2_2_, user3_.creationDate as creation2_2_2_, user3_.modificationDate as modifica3_2_2_, user3_.usercreate_id as usercreate6_2_2_, user3_.usermodify_id as usermodify7_2_2_, user3_.version as version2_2_, user3_.name as name2_2_, user4_.id as id2_3_, user4_.creationDate as creation2_2_3_, user4_.modificationDate as modifica3_2_3_, user4_.usercreate_id as usercreate6_2_3_, user4_.usermodify_id as usermodify7_2_3_, user4_.version as version2_3_, user4_.name as name2_3_, product5_.id as id0_4_, product5_.creationDate as creation2_0_4_, product5_.modificationDate as modifica3_0_4_, product5_.usercreate_id as usercreate7_0_4_, product5_.usermodify_id as usermodify8_0_4_, product5_.version as version0_4_, product5_.code as code0_4_, product5_.name as name0_4_, user6_.id as id2_5_, user6_.creationDate as creation2_2_5_, user6_.modificationDate as modifica3_2_5_, user6_.usercreate_id as usercreate6_2_5_, user6_.usermodify_id as usermodify7_2_5_, user6_.version as version2_5_, user6_.name as name2_5_, user7_.id as id2_6_, user7_.creationDate as creation2_2_6_, user7_.modificationDate as modifica3_2_6_, user7_.usercreate_id as usercreate6_2_6_, user7_.usermodify_id as usermodify7_2_6_, user7_.version as version2_6_, user7_.name as name2_6_ from ReceivingGoodDetail details0_ left outer join COMMON_USER user1_ on details0_.usercreate_id=user1_.id left outer join COMMON_USER user2_ on user1_.usercreate_id=user2_.id left outer join COMMON_USER user3_ on user2_.usermodify_id=user3_.id left outer join COMMON_USER user4_ on details0_.usermodify_id=user4_.id left outer join Product product5_ on details0_.product_id=product5_.id left outer join COMMON_USER user6_ on product5_.usercreate_id=user6_.id left outer join COMMON_USER user7_ on product5_.usermodify_id=user7_.id where details0_.receivinggood_id=? after removing try selecting the size : 4 after removing, now flushing Hibernate: update ReceivingGood set creationDate=?, modificationDate=?, usercreate_id=?, usermodify_id=?, version=?, purchaseorder_id=?, supplier_id=?, transactionDate=?, transactionNumber=?, transactionType=?, transactionYearMonth=?, warehouse_id=? where id=? and version=? Hibernate: update ReceivingGoodDetail set creationDate=?, modificationDate=?, usercreate_id=?, usermodify_id=?, version=?, buyQuantity=?, buyUnit=?, internalQuantity=?, internalUnit=?, product_id=?, receivinggood_id=?, supplierLotNumber=? where id=? and version=? detail size : 4 */ public void removeFromLazyCollection() { String headerId = "3b373f6a-9cd1-4c9c-9d46-240de37f6b0f"; ReceivingGood receivingGood = em.find(ReceivingGood.class, headerId); // get existing detail ReceivingGoodDetail detail = em.find(ReceivingGoodDetail.class, "323fb0e7-9bb2-48dc-bc07-5ff32f30e131"); detail.setInternalUnit("MCB"); System.out.println("removing existing detail from lazy collection"); receivingGood.removeReceivingGoodDetail(detail); System.out.println("after removing try selecting the size : " + receivingGood.getDetails().size()); System.out.println("after removing, now flushing"); em.flush(); System.out.println("detail size : " + receivingGood.getDetails().size()); } /* Hibernate: select receivingg0_.id as id9_14_, receivingg0_.creationDate as creation2_9_14_, ... too long Hibernate: select receivingg0_.id as id10_20_, receivingg0_.creationDate as creation2_10_20_, ... too long adding existing detail into lazy collection Hibernate: select details0_.receivinggood_id as receivi13_9_8_, details0_.id as id8_, details0_.id as id10_7_, details0_.creationDate as creation2_10_7_, details0_.modificationDate as modifica3_10_7_, details0_.usercreate_id as usercreate10_10_7_, details0_.usermodify_id as usermodify11_10_7_, details0_.version as version10_7_, details0_.buyQuantity as buyQuant5_10_7_, details0_.buyUnit as buyUnit10_7_, details0_.internalQuantity as internal7_10_7_, details0_.internalUnit as internal8_10_7_, details0_.product_id as product12_10_7_, details0_.receivinggood_id as receivi13_10_7_, details0_.supplierLotNumber as supplier9_10_7_, user1_.id as id2_0_, user1_.creationDate as creation2_2_0_, user1_.modificationDate as modifica3_2_0_, user1_.usercreate_id as usercreate6_2_0_, user1_.usermodify_id as usermodify7_2_0_, user1_.version as version2_0_, user1_.name as name2_0_, user2_.id as id2_1_, user2_.creationDate as creation2_2_1_, user2_.modificationDate as modifica3_2_1_, user2_.usercreate_id as usercreate6_2_1_, user2_.usermodify_id as usermodify7_2_1_, user2_.version as version2_1_, user2_.name as name2_1_, user3_.id as id2_2_, user3_.creationDate as creation2_2_2_, user3_.modificationDate as modifica3_2_2_, user3_.usercreate_id as usercreate6_2_2_, user3_.usermodify_id as usermodify7_2_2_, user3_.version as version2_2_, user3_.name as name2_2_, user4_.id as id2_3_, user4_.creationDate as creation2_2_3_, user4_.modificationDate as modifica3_2_3_, user4_.usercreate_id as usercreate6_2_3_, user4_.usermodify_id as usermodify7_2_3_, user4_.version as version2_3_, user4_.name as name2_3_, product5_.id as id0_4_, product5_.creationDate as creation2_0_4_, product5_.modificationDate as modifica3_0_4_, product5_.usercreate_id as usercreate7_0_4_, product5_.usermodify_id as usermodify8_0_4_, product5_.version as version0_4_, product5_.code as code0_4_, product5_.name as name0_4_, user6_.id as id2_5_, user6_.creationDate as creation2_2_5_, user6_.modificationDate as modifica3_2_5_, user6_.usercreate_id as usercreate6_2_5_, user6_.usermodify_id as usermodify7_2_5_, user6_.version as version2_5_, user6_.name as name2_5_, user7_.id as id2_6_, user7_.creationDate as creation2_2_6_, user7_.modificationDate as modifica3_2_6_, user7_.usercreate_id as usercreate6_2_6_, user7_.usermodify_id as usermodify7_2_6_, user7_.version as version2_6_, user7_.name as name2_6_ from ReceivingGoodDetail details0_ left outer join COMMON_USER user1_ on details0_.usercreate_id=user1_.id left outer join COMMON_USER user2_ on user1_.usercreate_id=user2_.id left outer join COMMON_USER user3_ on user2_.usermodify_id=user3_.id left outer join COMMON_USER user4_ on details0_.usermodify_id=user4_.id left outer join Product product5_ on details0_.product_id=product5_.id left outer join COMMON_USER user6_ on product5_.usercreate_id=user6_.id left outer join COMMON_USER user7_ on product5_.usermodify_id=user7_.id where details0_.receivinggood_id=? after adding try selecting the size : 5 after adding, now flushing Hibernate: update ReceivingGood set creationDate=?, modificationDate=?, usercreate_id=?, usermodify_id=?, version=?, purchaseorder_id=?, supplier_id=?, transactionDate=?, transactionNumber=?, transactionType=?, transactionYearMonth=?, warehouse_id=? where id=? and version=? detail size : 5 */ public void editLazyCollection() { String headerId = "3b373f6a-9cd1-4c9c-9d46-240de37f6b0f"; ReceivingGood receivingGood = em.find(ReceivingGood.class, headerId); // get existing detail ReceivingGoodDetail detail = em.find(ReceivingGoodDetail.class, "323fb0e7-9bb2-48dc-bc07-5ff32f30e131"); detail.setInternalUnit("MCB"); System.out.println("adding existing detail into lazy collection"); receivingGood.addReceivingGoodDetail(detail); System.out.println("after adding try selecting the size : " + receivingGood.getDetails().size()); System.out.println("after adding, now flushing"); em.flush(); System.out.println("detail size : " + receivingGood.getDetails().size()); } Please share your experience on this matter ! Thank you !

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• How to preserve order of temp table rows when inner joined with another table?

  - by Triynko

  Does an SQL Server "join" preserve any kind of row order consistently (i.e. that of the left table or that of the right table)? Psuedocode: create table #p (personid bigint); foreach (id in personid_list) insert into #p (personid) values (id) select id from users inner join #p on users.personid = #p.id Suppose I have a list of IDs that correspond to person entries. Each of those IDs may correspond to zero or more user accounts (since each person can have multiple accounts). To quickly select columns from the users table, I populate a temp table with person ids, then inner join it with the users table. I'm looking for an efficient way to ensure that the order of the results in the join matches the order of the ids as they were inserted into the temp table, so that the user list that's returned is in the same order as the person list as it was entered. I've considered the following alternatives: using "#p inner join users", in case the left table's order is preserved using "#p left join users where id is not null", in case a left join preserves order and the inner join doesn't using "create table (rownum int, personid bigint)", inserting an incrementing row number as the temp table is populated, so the results can be ordered by rownum in the join using an SQL Server equivalent of the "order by order of [tablename]" clause available in DB2 I'm currently using option 3, and it works... but I hate the idea of using an order by clause for something that's already ordered. I just don't know if the temp table preserves the order in which the rows were inserted or how the join operates and what order the results come out in.

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• Mysql - help me optimize this query (improved question)

  - by sandeepan-nath

  About the system: - There are tutors who create classes and packs - A tags based search approach is being followed.Tag relations are created when new tutors register and when tutors create packs (this makes tutors and packs searcheable). For details please check the section How tags work in this system? below. Following is the concerned query SELECT SUM(DISTINCT( t.tag LIKE "%Dictatorship%" )) AS key_1_total_matches, SUM(DISTINCT( t.tag LIKE "%democracy%" )) AS key_2_total_matches, COUNT(DISTINCT( od.id_od )) AS tutor_popularity, CASE WHEN ( IF(( wc.id_wc > 0 ), ( wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date > '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'classes_published', CASE WHEN ( IF(( lp.id_lp > 0 ), ( lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'packs_published', td . *, u . * FROM tutor_details AS td JOIN users AS u ON u.id_user = td.id_user LEFT JOIN learning_packs_tag_relations AS lptagrels ON td.id_tutor = lptagrels.id_tutor LEFT JOIN learning_packs AS lp ON lptagrels.id_lp = lp.id_lp LEFT JOIN learning_packs_categories AS lpc ON lpc.id_lp_cat = lp.id_lp_cat LEFT JOIN learning_packs_categories AS lpcp ON lpcp.id_lp_cat = lpc.id_parent LEFT JOIN learning_pack_content AS lpct ON ( lp.id_lp = lpct.id_lp ) LEFT JOIN webclasses_tag_relations AS wtagrels ON td.id_tutor = wtagrels.id_tutor LEFT JOIN webclasses AS wc ON wtagrels.id_wc = wc.id_wc LEFT JOIN learning_packs_categories AS wcc ON wcc.id_lp_cat = wc.id_wp_cat LEFT JOIN learning_packs_categories AS wccp ON wccp.id_lp_cat = wcc.id_parent LEFT JOIN order_details AS od ON td.id_tutor = od.id_author LEFT JOIN orders AS o ON od.id_order = o.id_order LEFT JOIN tutors_tag_relations AS ttagrels ON td.id_tutor = ttagrels.id_tutor JOIN tags AS t ON ( t.id_tag = ttagrels.id_tag ) OR ( t.id_tag = lptagrels.id_tag ) OR ( t.id_tag = wtagrels.id_tag ) WHERE ( u.country = 'IE' OR u.country IN ( 'INT' ) ) AND CASE WHEN ( ( t.id_tag = lptagrels.id_tag ) AND ( lp.id_lp 0 ) ) THEN lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( ( t.id_tag = wtagrels.id_tag ) AND ( wc.id_wc 0 ) ) THEN wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( od.id_od 0 ) THEN od.id_author = td.id_tutor AND o.order_status = 'paid' AND CASE WHEN ( od.id_wc 0 ) THEN od.can_attend_class = 1 ELSE 1 END ELSE 1 END GROUP BY td.id_tutor HAVING key_1_total_matches = 1 AND key_2_total_matches = 1 ORDER BY tutor_popularity DESC, u.surname ASC, u.name ASC LIMIT 0, 20 The problem The results returned by the above query are correct (AND logic working as per expectation), but the time taken by the query rises alarmingly for heavier data and for the current data I have it is like 25 seconds as against normal query timings of the order of 0.005 - 0.0002 seconds, which makes it totally unusable. It is possible that some of the delay is being caused because all the possible fields have not yet been indexed. The tag field of tags table is indexed. Is there something faulty with the query? What can be the reason behind 20+ seconds of execution time? How tags work in this system? When a tutor registers, tags are entered and tag relations are created with respect to tutor's details like name, surname etc. When a Tutors create packs, again tags are entered and tag relations are created with respect to pack's details like pack name, description etc. tag relations for tutors stored in tutors_tag_relations and those for packs stored in learning_packs_tag_relations. All individual tags are stored in tags table. The explain query output:- Please see this screenshot - http://www.test.examvillage.com/Explain_query.jpg

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• Speed up this query joining to a table multiple times

  - by Mongus Pong

  Hi, I have this query that (stripped right down) goes something like this : SELECT [Person_PrimaryContact].[LegalName], [Person_Manager].[LegalName], [Person_Owner].[LegalName], [Person_ProspectOwner].[LegalName], [Person_ProspectBDM].[LegalName], [Person_ProspectFE].[LegalName], [Person_Signatory].[LegalName] FROM [Cache] LEFT JOIN [dbo].[Person] AS [Person_Owner] WITH (NOLOCK) ON [Person_Owner].[PersonID] = [Cache].[ClientOwnerID] LEFT JOIN [dbo].[Person] AS [Person_Manager] WITH (NOLOCK) ON [Person_Manager].[PersonID] = [Cache].[ClientManagerID] LEFT JOIN [dbo].[Person] AS [Person_Signatory] WITH (NOLOCK) ON [Person_Signatory].[PersonID] = [Cache].[ClientSignatoryID] LEFT JOIN [dbo].[Person] AS [Person_PrimaryContact] WITH (NOLOCK) ON [Person_PrimaryContact].[PersonID] = [Cache].[PrimaryContactID] LEFT JOIN [dbo].[Person] AS [Person_ProspectOwner] WITH (NOLOCK) ON [Person_ProspectOwner].[PersonID] = [Cache].[ProspectOwnerID] LEFT JOIN [dbo].[Person] AS [Person_ProspectBDM] WITH (NOLOCK) ON [Person_ProspectBDM].[PersonID] = [Cache].[ProspectBDMID] LEFT JOIN [dbo].[Person] AS [Person_ProspectFE] WITH (NOLOCK) ON [Person_ProspectFE].[PersonID] = [Cache].[ProspectFEID] Person is a huge table and each join to it has a pretty significant hit in the execution plan. Is there anyway I can adjust this query so that I am only linking to it once, or at least get SQL Server to scan through it only once?

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• For text-align:right; in TD, why does "style" work and "class" not?

  - by Will Fastie

  If I include this in a table cell: <td style="text-align: right; font-style: italic; color: maroon;">... the contents of the cell are aligned as I expect. If I include the following CSS: .right-notice { text-align: right; font-style: italic; color: maroon; } and this cell: <td class=".right-notice">... the contents of the cell are not right aligned. Why is this? What don't I know? If I change the CSS to replace text-align with float, that works. Thanks.

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• How to get rid of devices in the right panel of Nautilus ?

  - by Patryk

  I would like to rid of not mounted ntfs partition from Nautilus' right panel ( I just want 352 GB Filesystem - d drive to be there. First of all 352 GB Filesystem is in fact d so I do not know why it is duplicated. Secondly I have put Acer and SYSTEM RESERVED to be nouser mounts on purpose, so that I (or sombody else) will not format it (or else) by accident. So my /etc/fstab looks like this : #comments....... # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 UUID=1384cee0-6a71-4b83-b0d3-1338db925168 / ext4 noatime,errors=remount-ro 0 1 UUID=e3729117-b936-4c1d-9883-aee73dab6729 none swap sw 0 0 #------ MY WINDOWS D DRIVE---------- UUID=98E8B14DE8B12A80 /media/d ntfs defaults,errors=remount-ro,user 0 0 # #-------ACER---------------- UUID=01CBEA9D4476C2F0 /media/acer ntfs defaults,noauto,noexec,ro,nouser 0 0 # #-------SYSTEM RESERVED----- UUID=01CBEA95760F9330 /media/systemreserved ntfs defaults,noauto,noexec,ro,nouser 0 0 #UUID=58F9-C17E /boot/efi vfat defaults 0 1 blkid and fdisk -l root@XXX:/home/YYY# fdisk -l ... Device Boot Start End Blocks Id System /dev/sda1 4096 27262975 13629440 27 Hidden NTFS WinRE /dev/sda2 27262992 27467791 102400 7 HPFS/NTFS/exFAT /dev/sda3 27467792 232267775 102399992 7 HPFS/NTFS/exFAT /dev/sda4 232267793 976771071 372251639+ f W95 Ext'd (LBA) /dev/sda5 232267795 918867967 343300086+ 7 HPFS/NTFS/exFAT /dev/sda6 * 918870016 968044543 24587264 83 Linux /dev/sda7 968046592 976771071 4362240 82 Linux swap / Solaris root@XXX:/home/YYY# blkid /dev/sda1: LABEL="PQSERVICE" UUID="01CBEA95730D28A0" TYPE="ntfs" /dev/sda2: LABEL="SYSTEM RESERVED" UUID="01CBEA95760F9330" TYPE="ntfs" /dev/sda3: LABEL="Acer" UUID="01CBEA9D4476C2F0" TYPE="ntfs" /dev/sda5: UUID="98E8B14DE8B12A80" TYPE="ntfs" /dev/sda6: UUID="1384cee0-6a71-4b83-b0d3-1338db925168" TYPE="ext4" /dev/sda7: UUID="e3729117-b936-4c1d-9883-aee73dab6729" TYPE="swap"

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• How do I have to take into account the direction in which the camera is facing when creating a first person strafe (left/right) movement

  - by Chris

  This is the code I am currently using, and it works great, except for the strafe always causes the camera to move along the X axis which is not relative to the direction in which the camera is actually facing. As you can see currently only the x location is updated: [delta * -1, 0, 0] How should I take into account the direction in which the camera is facing (I have the camera's target x,y,z) when creating a first person strafe (left/right) movement? case 'a': var eyeOriginal = g_eye; var targetOriginal = g_target; var viewEye = g_math.subVector(g_eye, g_target); var viewTarget = g_math.subVector(g_target, g_eye); viewEye = g_math.addVector([delta * -1, 0, 0], viewEye); viewTarget = g_math.addVector([delta * -1, 0, 0], viewTarget); g_eye = g_math.addVector(viewEye, targetOriginal); g_target = g_math.addVector(viewTarget, eyeOriginal); break; case 'd': var eyeOriginal = g_eye; var targetOriginal = g_target; var viewEye = g_math.subVector(g_eye, g_target); var viewTarget = g_math.subVector(g_target, g_eye); viewEye = g_math.addVector([delta, 0, 0], viewEye); viewTarget = g_math.addVector([delta, 0, 0], viewTarget); g_eye = g_math.addVector(viewEye, targetOriginal); g_target = g_math.addVector(viewTarget, eyeOriginal); break;

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• What is the right way to Windows 7/Ubuntu 10.10 Dual-Triple Boot Partitioning for Laptop OEM?

  - by Denja

  Hi Linux Community, I find my self struggling with the ever slow and buggy windoze OS once again. It's Time to change with the Ubuntu 10.10 64bit as a really faster Operating System. My Hard Disk laptop as a RECOVERY and HP_TOOLS partition they are both Primary. I Have the System Recovery DVD for Windows 64bit should anything happen. Here's the layout I used with windows before: * (C:) Windows 7 system partition NTFS - 284,89GB (Primary,Boot,Pagefile,Dump) * HP_TOOLS system partition FAT32 - 99MB (Primary) * (D:) RECOVERY partition NTFS - 12,90GB (Primary) * SYSTEM partition NTFS 199MB (Primary) Here's the layout I want to make based on your answers * (C:) Windows 7 system partition NTFS - 60GB (Primary) (sda1) * (D:) Windows DATA partition (user files) NTFS - 120GB(Primary)(sda2);wanna share with Linux * Linux root Ext4 - 100GB (Primary)(sda3) (Ubuntu 10.10 64bit) * Linux swap swap- RAM size, 3GB (sda4) * Linux root Ext3- 15,9GB (Extended)(sda5) (OpenSuse or Puppy) Here is my New Ubuntu 10.10 64bit layout in use now: * SYSTEM partition NTFS 199MB (Primary) (sda1) **Partition 1 does not end on cylinder boundary.(?)** * (C:) Windows 7 system partition NTFS - 90GB (Primary) (sda2) * (D:) Windows 7 RECOVERY partition NTFS - 12,90GB (Primary) (sda3) * Linux system partition EXTENDED - 195GB (Logical) * Linux root Ext4- 10GB (Extended) (sda5) * Linux home Ext3- 185GB (Extended) (sda6) I didn't know if I could wipe all previous partitions when i installed Ubuntu because of the RECOVERY partition so I just made the space for my extended partition by deleting the HP_TOOLS (Fat32). By doing this I managed to make and successfully install Ubuntu 64 but I couldn't actually make the partition for the swap or a third Linux OS. Question 1: What is the right way to Windows 7/Ubuntu 10.10 Dual-Triple Boot Partitioning for Laptop OEM?? Thank you in advance for your advises and suggestions and Happy New Year to All!!

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• Nested entities in Google App Engine. Do I do it right?

  - by Aleksandr Makov

  Trying to make most of the GAE Datastore entities concept, but some doubts drill my head. Say I have the model: class User(ndb.Model): email = ndb.StringProperty(indexed=True) password = ndb.StringProperty(indexed=False) first_name = ndb.StringProperty(indexed=False) last_name = ndb.StringProperty(indexed=False) created_at = ndb.DateTimeProperty(auto_now_add=True) @classmethod def key(cls, email): return ndb.Key(User, email) @classmethod def Add(cls, email, password, first_name, last_name): user = User(parent=cls.key(email), email=email, password=password, first_name=first_name, last_name=last_name) user.put() UserLogin.Record(email) class UserLogin(ndb.Model): time = ndb.DateTimeProperty(auto_now_add=True) @classmethod def Record(cls, user_email): login = UserLogin(parent=User.key(user_email)) login.put() And I need to keep track of times of successful login operations. Each time user logs in, an UserLogin.Record() method will be executed. Now the question — do I make it right? Thanks. EDIT 2 Ok, used the typed arguments, but then it raised this: Expected Key instance, got User(key=Key('User', 5418393301680128), created_at=datetime.datetime(2013, 6, 27, 10, 12, 25, 479928), email=u'[email protected]', first_name=u'First', last_name=u'Last', password=u'password'). It's clear to understand, but I don't get why the docs are misleading? They implicitly propose to use: # Set Employee as Address entity's parent directly... address = Address(parent=employee) But Model expects key. And what's worse the parent=user.key() swears that key() isn't callable. And I found out the user.key works. EDIT 1 After reading the example form the docs and trying to replicate it — I got type error: TypeError('Model constructor takes no positional arguments.'). This is the exacto code used: user = User('[email protected]', 'password', 'First', 'Last') user.put() stamp = UserLogin(parent=user) stamp.put() I understand that Model was given the wrong argument, BUT why it's in the docs?

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• Image 1 becomes image 2 with sliding effect from left to right?

  - by Paul

  I would like to show a second image appearing while a "door" is closing on my character. I've got my character in the middle of the screen and a door coming from the left. When the door passes my character, I would like to have this second image appearing little by little. So far, I've gotten by with fadingOut the character and then fadingIn my second image of the character at the same position when the door is completely closed, but I would like to have both of them at the same time. (the effect that image 1 becomes image 2 when the door is sliding from left to right). Would you know how to do this with Cocos2d? Here are the images : at first, the character is blue, and the door is coming from the left : Then, behind the black door, the character becomes red, but only behind this door, so it stays blue when the door is not on him, and will become completely red when the door passes the character : EDIT : with this code, the black door hides the red and blue rectangles : (And if i add each of my layers at a different depth, and only use GL_LESS, same thing) blue.position = ccp( size.width*0.5 , size.height/2 ); red.position = ccp( size.width*0.46 , size.height/2 ); black.position = ccp( size.width*0.1 , size.height/2 ); glEnable(GL_DEPTH_TEST); [batch addChild:red z:0]; [batch addChild:black z:2]; glDepthFunc(GL_GREATER); [batch addChild:blue z:1]; glDepthFunc(GL_LESS); id action1 = [CCMoveTo actionWithDuration:3 position:ccp(size.width,size.height/2)]; [black runAction: [CCSequence actions:action1, nil]];

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• Is chroot the right choice for my use case?

  - by Anthony

  Backstory: I am working on setting up a MineCraft server and want to allow admins to have ssh access to the MineCraft server console and appropriate mc server files, but not the whole system. The console provided by the minecraft server is only available to the user that launched the process. In addition, the admins will need terminal access to some basic cli tools such as wget, cp, mv, rm, and a text editor. Plan: I have already setup the ssh aspect of things, requiring pre-shared keys and whatnot. Setup a jailed environment in which all user activity will be contained. Setup user accounts. - The first user account will be the minecraft user. The minecraft user will start the MC server in a multiuser screen session and allow the other admins to attach to it. - Subsequent users should have their own /home directory for normal usage. Setup acl for the appropriate files to allow each user to edit the mc server files. No one will be doing system updates, nor will anyone be installing any programs, so I'll be the only user with sudo. The Issues: I don't want the ssh users to have access to the whole system. Users will still need to use wget or curl to update the mc server files. Is chroot the right tool for this use case, or is there something more appropriate for the job? I have no experience setting up a chroot environment and have found several tools to aid in this process. Jailkit seems to be the most robust, but it's not in the standard repos.

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• Interface (contract), Generics (universality), and extension methods (ease of use). Is it a right design?

  - by Saeed Neamati

  I'm trying to design a simple conversion framework based on these requirements: All developers should follow a predefined set of rules to convert from the source entity to the target entity Some overall policies should be able to be applied in a central place, without interference with developers' code Both the creation of converters and usage of converter classes should be easy To solve these problems in C# language, A thought came to my mind. I'm writing it here, though it doesn't compile at all. But let's assume that C# compiles this code: I'll create a generic interface called IConverter public interface IConverter<TSource, TTarget> where TSource : class, new() where TTarget : class, new() { TTarget Convert(TSource source); List<TTarget> Convert(List<TSource> sourceItems); } Developers would implement this interface to create converters. For example: public class PhoneToCommunicationChannelConverter : IConverter<Phone, CommunicationChannle> { public CommunicationChannel Convert(Phone phone) { // conversion logic } public List<CommunicationChannel> Convert(List<Phone> phones) { // conversion logic } } And to make the usage of this conversion class easier, imagine that we add static and this keywords to methods to turn them into Extension Methods, and use them this way: List<Phone> phones = GetPhones(); List<CommunicationChannel> channels = phones.Convert(); However, this doesn't even compile. With those requirements, I can think of some other designs, but they each lack an aspect. Either the implementation would become more difficult or chaotic and out of control, or the usage would become truly hard. Is this design right at all? What alternatives I might have to achieve those requirements?

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• nautilus will not start, no right click menu, apps will not run due to 64bit libicui18n.so.48 overwritten with 32bit, ubuntu 12.04

  - by Dewb

  yeah so i broke my system trying to install support for 32bit apps. Somehow the 32bit set of libicu*.so.48 files replaced my 64bit files and now nothing works. I know what the problem is and how to fix it , what i need is some help. I need some kind soul running a 64bit install of Ubuntu 12.04 to simply go into their /usr/lib dir and copy the files that have the form libicu*.so.48* (8 of them i think, maybe 16 i dunno how many there is supposed to be since they were overwritten). Anyway if you could put those files in an archive, zip or tar preferred and then email/share the link. I was able to get these files installed but they're from the latest edition of fedora and while i can now use my computer , it's not that stable things don't start right smoothly every time like they used to .... and well its a simple ordeal to put things back the way they were if someone wouldn't mind helping out. also any help setting up the libraries related to 32bit apps would be great as well as i apparently screwed that up royally. Thanks for any help or advice

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• Monday at Oracle OpenWorld 2012 - Must See Session: “Using the Right Tools, Techniques, and Technologies for Integration Projects”

  - by Lionel Dubreuil

  Don’t miss this “CON8669 - Using the Right Tools, Techniques, and Technologies for Integration Projects“ session with Timothy Hall - Sr. Director, Oracle: Date: Monday, Oct 1, Time: 3:15 PM - 4:15 PM Location: Moscone South - 308 Every integration project brings its own unique set of challenges. There are many tools and techniques to choose from. How do you ensure that you have a means of consistently and repeatedly making decisions about which tools, techniques, and technologies are used? In working with many customers around the globe, Oracle has developed a set of criteria to help evaluate a variety of common integration questions. This session explores these criteria and how they have been further organized into decision trees that offer a repeatable means for ensuring that project teams are given the same guidance from project to project. Using these techniques, the presentation shows how you can reduce risk and speed productivity for your projects Objectives for this session are to: Discuss common questions that arise at the start of integration projects Review various decision criteria and approaches for getting to a consistent set of answers Explore how these techniques can be used to reduce risk and speed productivity Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";}

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• How to move a selcection of files into a new folder via the right click menu?

  - by LinuxDudester

  I recently switch from OSX to Xubuntu 14.04 and I'm loving my new found freedom. For the most part I've managed to customize my Linux operating system to my needs and likes. But theres one feature I'm missing the most. I need to toss a bunch of items in a folder really fast, since I am working with lots of images and text files. In OS X there was a nifty shortcut that manages the operation in one fell swoop so you don't have to make a folder and then take further action to populate it. All I needed to is to select the items I want in the Finder (file manager), right-click on them to bring up OS X's contextual menu, and choose the first option: New Folder with Selection. The Finder will then create a new folder with those items stored safely inside, removing at least one step from the process for you automatically. Super easy! Now I was wondering how can I do this in Linux? Or most importantly in Xubuntu? Any help would be greatly appreciated!

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• "Do it right, against customer's wishes" - how is it called?

  - by SF.

  We know the optimal situation of negotiating corrections of specifications with the customer, getting the specs to do what the client wanted, not what they said or thought they wanted. That's negotiating, explaining. Sometimes, we're unable to convince the client. We're forced to produce broken as designed. This, called "demonology" by merit of mages summoning demons and demons fulfilling their wishes very literally, causing the mage's demise as result, is another approach that will leave the customer very dissatisfied once they realize their error, and of course try to pin the blame on the developer. Now I just faced a very different approach: the customer created simple specs that fail to account for some critical caveat, and is completely unwilling to fix them, admit the obvious errors and accept suggested corrections. The product made to these specs will be critically broken, and possibly might cost human lives. Still, it's too late to drop the contract entirely. The contract has punitive clauses for that, ones we can't really accept. The boss' decision? We do the work right and lie to the customer that we did it according to the specs. The algorithms in question are hidden deep enough under the surface, the product will do the work just fine, won't fail in the caveat situation, and unless someone digs too deep, they will never discover we didn't break it as requested. Is there some common name for this tactics of execution of specs?

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• SQL SERVER – Example of Performance Tuning for Advanced Users with DB Optimizer

  - by Pinal Dave

  Performance tuning is such a subject that everyone wants to master it. In beginning everybody is at a novice level and spend lots of time learning how to master the art of performance tuning. However, as we progress further the tuning of the system keeps on getting very difficult. I have understood in my early career there should be no need of ego in the technology field. There are always better solutions and better ideas out there and we should not resist them. Instead of resisting the change and new wave I personally adopt it. Here is a similar example, as I personally progress to the master level of performance tuning, I face that it is getting harder to come up with optimal solutions. In such scenarios I rely on various tools to teach me how I can do things better. Once I learn about tools, I am often able to come up with better solutions when I face the similar situation next time. A few days ago I had received a query where the user wanted to tune it further to get the maximum out of the performance. I have re-written the similar query with the help of AdventureWorks sample database. SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID; User had similar query to above query was used in very critical report and wanted to get best out of the query. When I looked at the query – here were my initial thoughts Use only column in the select statements as much as you want in the application Let us look at the query pattern and data workload and find out the optimal index for it Before I give further solutions I was told by the user that they need all the columns from all the tables and creating index was not allowed in their system. He can only re-write queries or use hints to further tune this query. Now I was in the constraint box – I believe * was not a great idea but if they wanted all the columns, I believe we can’t do much besides using *. Additionally, if I cannot create a further index, I must come up with some creative way to write this query. I personally do not like to use hints in my application but there are cases when hints work out magically and gives optimal solutions. Finally, I decided to use Embarcadero’s DB Optimizer. It is a fantastic tool and very helpful when it is about performance tuning. I have previously explained how it works over here. First open DBOptimizer and open Tuning Job from File >> New >> Tuning Job. Once you open DBOptimizer Tuning Job follow the various steps indicates in the following diagram. Essentially we will take our original script and will paste that into Step 1: New SQL Text and right after that we will enable Step 2 for Generating Various cases, Step 3 for Detailed Analysis and Step 4 for Executing each generated case. Finally we will click on Analysis in Step 5 which will generate the report detailed analysis in the result pan. The detailed pan looks like. It generates various cases of T-SQL based on the original query. It applies various hints and available hints to the query and generate various execution plans of the query and displays them in the resultant. You can clearly notice that original query had a cost of 0.0841 and logical reads about 607 pages. Whereas various options which are just following it has different execution cost as well logical read. There are few cases where we have higher logical read and there are few cases where as we have very low logical read. If we pay attention the very next row to original query have Merge_Join_Query in description and have lowest execution cost value of 0.044 and have lowest Logical Reads of 29. This row contains the query which is the most optimal re-write of the original query. Let us double click over it. Here is the query: SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID OPTION (MERGE JOIN) If you notice above query have additional hint of Merge Join. With the help of this Merge Join query hint this query is now performing much better than before. The entire process takes less than 60 seconds. Please note that it the join hint Merge Join was optimal for this query but it is not necessary that the same hint will be helpful in all the queries. Additionally, if the workload or data pattern changes the query hint of merge join may be no more optimal join. In that case, we will have to redo the entire exercise once again. This is the reason I do not like to use hints in my queries and I discourage all of my users to use the same. However, if you look at this example, this is a great case where hints are optimizing the performance of the query. It is humanly not possible to test out various query hints and index options with the query to figure out which is the most optimal solution. Sometimes, we need to depend on the efficiency tools like DB Optimizer to guide us the way and select the best option from the suggestion provided. Let me know what you think of this article as well your experience with DB Optimizer. Please leave a comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Partition Wise Joins

  - by jean-pierre.dijcks

  Some say they are the holy grail of parallel computing and PWJ is the basis for a shared nothing system and the only join method that is available on a shared nothing system (yes this is oversimplified!). The magic in Oracle is of course that is one of many ways to join data. And yes, this is the old flexibility vs. simplicity discussion all over, so I won't go there... the point is that what you must do in a shared nothing system, you can do in Oracle with the same speed and methods. The Theory A partition wise join is a join between (for simplicity) two tables that are partitioned on the same column with the same partitioning scheme. In shared nothing this is effectively hard partitioning locating data on a specific node / storage combo. In Oracle is is logical partitioning. If you now join the two tables on that partitioned column you can break up the join in smaller joins exactly along the partitions in the data. Since they are partitioned (grouped) into the same buckets, all values required to do the join live in the equivalent bucket on either sides. No need to talk to anyone else, no need to redistribute data to anyone else... in short, the optimal join method for parallel processing of two large data sets. PWJ's in Oracle Since we do not hard partition the data across nodes in Oracle we use the Partitioning option to the database to create the buckets, then set the Degree of Parallelism (or run Auto DOP - see here) and get our PWJs. The main questions always asked are: How many partitions should I create? What should my DOP be? In a shared nothing system the answer is of course, as many partitions as there are nodes which will be your DOP. In Oracle we do want you to look at the workload and concurrency, and once you know that to understand the following rules of thumb. Within Oracle we have more ways of joining of data, so it is important to understand some of the PWJ ideas and what it means if you have an uneven distribution across processes. Assume we have a simple scenario where we partition the data on a hash key resulting in 4 hash partitions (H1 -H4). We have 2 parallel processes that have been tasked with reading these partitions (P1 - P2). The work is evenly divided assuming the partitions are the same size and we can scan this in time t1 as shown below. Now assume that we have changed the system and have a 5th partition but still have our 2 workers P1 and P2. The time it takes is actually 50% more assuming the 5th partition has the same size as the original H1 - H4 partitions. In other words to scan these 5 partitions, the time t2 it takes is not 1/5th more expensive, it is a lot more expensive and some other join plans may now start to look exciting to the optimizer. Just to post the disclaimer, it is not as simple as I state it here, but you get the idea on how much more expensive this plan may now look... Based on this little example there are a few rules of thumb to follow to get the partition wise joins. First, choose a DOP that is a factor of two (2). So always choose something like 2, 4, 8, 16, 32 and so on... Second, choose a number of partitions that is larger or equal to 2* DOP. Third, make sure the number of partitions is divisible through 2 without orphans. This is also known as an even number... Fourth, choose a stable partition count strategy, which is typically hash, which can be a sub partitioning strategy rather than the main strategy (range - hash is a popular one). Fifth, make sure you do this on the join key between the two large tables you want to join (and this should be the obvious one...). Translating this into an example: DOP = 8 (determined based on concurrency or by using Auto DOP with a cap due to concurrency) says that the number of partitions >= 16. Number of hash (sub) partitions = 32, which gives each process four partitions to work on. This number is somewhat arbitrary and depends on your data and system. In this case my main reasoning is that if you get more room on the box you can easily move the DOP for the query to 16 without repartitioning... and of course it makes for no leftovers on the table... And yes, we recommend up-to-date statistics. And before you start complaining, do read this post on a cool way to do stats in 11.

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• AI for a mixed Turn Based + Real Time battle system - Something "Gambit like" the right approach?

  - by Jason L.

  This is maybe a question that's been asked 100 times 1,000 different ways. I apologize for that :) I'm in the process of building the AI for a game I'm working on. The game is a turn based one, in the vein of Final Fantasy but also has a set of things that happen in real time (reactions). I've experimented with FSM, HFSMs, and Behavior Trees. None of them felt "right" to me and all felt either too limiting or too generic / big. The idea I'm toying with now is something like a "Rules engine" that could be likened to the Gambit system from Final Fantasy 12. I would have a set of predefined personalities. Each of these personalities would have a set of conditions it would check on each event (Turn start, time to react, etc). These conditions would be priority ordered, and the first one that returns true would be the action I take. These conditions can also point to a "choice" action, which is just an action that will make a choice based on some Utility function. Sort of a mix of FSM/HFSM and a Utility Function approach. So, a "gambit" with the personality of "Healer" may look something like this: (ON) Ally HP = 0% - Choose "Relife" spell (ON) Ally HP < 50% - Choose Heal spell (ON) Self HP < 65% - Choose Heal spell (ON) Ally Debuff - Choose Debuff Removal spell (ON) Ally Lost Buff - Choose Buff spell Likewise, a "gambit" with the personality of "Agressor" may look like this: (ON) Foe HP < 10% - Choose Attack skill (ON) Foe any - Choose target - Choose Attack skill (ON) Self Lost Buff - Choose Buff spell (ON) Foe HP = 0% - Taunt the player What I like about this approach is it makes sense in my head. It also would be extremely easy to build an "AI Editor" with an approach like this. What I'm worried about is.. would it be too limiting? Would it maybe get too complicated? Does anyone have any experience with AIs in Turn Based games that could maybe provide me some insight into this approach.. or suggest a different approach? Many thanks in advance!!!

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• How can I be prepared to join a company?

  - by Aerovistae

  There's more to it than that, but this title was the best way I could think of to sum it up. I'm a senior in a good computer science program, and I'm graduating early. About to start interviews and all whatnot. I'm not a super-experienced programmer, not one of those people who started in middle school. I'm decent at this, but I'm not among the best, not nearly. I have to do an awful lot of googling. So today I'm meeting some fellow for lunch at a campus cafe to discuss some front-end details when this tall, good-looking guy begs pardon, says he's new to campus, says he's wondering if we know where he can go to sign up for recruiting developers. Quickly evolves into long conversation: he's the CEO of a seems-to-be-doing-well start-up. Hiring passionate interns and full-times. Sounds great! I take one look at his site on my own computer later, immediately spot a major bug. No idea how to fix it, but I see it. I go over to the page code, and good god. It's the standard amount of code you would expect from a full-scale web application, a couple dozen pages of HTML and scripts. I don't even know where to start reading it. I've built sites from scratch, but obviously never on that scale, nor have I ever worked on one of that scale. I have no idea which bit might generate the bug. But that sets me thinking: How could someone like me possibly settle into an environment like that? A start-up is a very high-pressure working environment. I don't know if I can work at that pace under those constraints-- I would hate to let people down. And with only 10 employees, it's not like anyone has much time to help you get your bearings. Somewhere in there is a question. Can you see it? I'm asking for general advice here. Maybe even anecdotal advice. Is joining a start-up right out of college a scary process? Am I overestimating what it would take to figure out the mass of code behind this site? What's the likelihood a decent but only moderately-experienced coder could earn his pay at such a place? For instance, I know nothing of server-side/back-end programming. Never touched it. That scares me.

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• How to add the Windows defender into Windows Explorer's right click menu to scan a particular drive/folder/file on demand?

  - by avirk

  There is no option in Windows Explorer to scan a particular drive (or file) on demand by right clicking on it in Windows Explorer as we had in Windows 7 with Microsoft Security Essentials or like other antivirus solutions. I know we can run a custom scan for the particular drive or specific folder but that process is too lengthy and time consuming. The guide How to Add a "Windows Defender" Cascading Desktop Context Menu in Windows 8 explains how we can add Windows Defender in the desktop right click menu, so I'm curious, is there a way to add it in the Windows Explorer right click menu to launch a search whenever I need to?

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• Two-page view in Word, shouldn't the first page be on the right?

  - by Cylindric

  Greetings Superusers, I'm putting together a lengthy document in Word, and it's going to be printed and bound duplex. I've put page-numbers "outside" etc, and all is pretty. The problem is, in the "Two Pages" view, it puts p1 on the left, then p2 on the right, then p3 below on the left, and p4 on the right. p1 p2 p3 p4 p5 p6 Shouldn't this be slightly different though? When I get to print it, p1 is on the right, not the left, so the preview should go p1 p2 p3 p4 p5 p6 Because when I "open" the book, it's pages 2 and 3 that are side-by-side. This makes layout tweaking confusing, because it's not instantly obvious which pages will be "visible" to the reader at the same time together. Have I missed something? I can't just put a blank page first, because that would bugger up the printing, as the printer automatically duplexes and binds etc. (Office 2008, by the way)

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• Why can't I extend the C: drive on Vista? Because I have Free Space to its right instead of Unalloca

  - by tzup

  Okay this is annoying! I have a C: drive that is the primary partition (bootable) that I would like to extend. In order to do that it seems like I need to have Unallocated Space to the right of the partition. Right now, I have "Free Space" to the right. How in the world do I make it Unallocated (not formatted)? There must be some command line utility to be able to do this. Please help!

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