.. (לתיקייה המכילה) | ||
According to what should we sort the hops in topKLoadedHops? | |
their actual load |
what I cannot do in java? | |
this answer will updated according to the questions you'll send. The main idea is that if you can write a query that do something that you want, write an SQL query, and don't use java. you can't: 1. verify that your query has returned a path without cycles - this is what unit tests are for and the additional functions in some objects are implement for, for you to test yourselves. 2. sort your query results 3. return the answers yourselves by maintaining local data structures in your program, without sending a query to the SQL server. you can: 1. use for/while loops 2. verify a ResultSet is empty 3. verify function input although it is highly recommended to use SQL. 4. write auxiliary functions |
whats is a cycle in path? | |
given a source = 1 and destination = 2 and 2 hops (1,2) and (2,1) the path [(1,2)] is legal while the path [(1,2),(2,1),(1,2)] is not since it contains a cycle |
I'm having trouble setting up the environment or run the example program. | |
1. come to office hours or schedule a meeting with Dvir (if possible) if you really can't make it 2. read the manuals all the way till the end. 3. read the manuals all the way till the end. 4. really, read the manuals all the way till the end. We wrote them while setting up the environment from scratch, and we tried to be as detailed as possible so you won't need to encounter difficulties. |
IMPORTANT! | |
the actual load of the hop |
UPDATED!!: when should I return BAD_PARAMS and when should I return NOT_EXISTS ? | |
on object creation: Always return BAD_PARAMS since NOT_EXISTS is not an option unless you create a user with a non existing hop, only in this case you should return NOT_EXISTS on hop update: 1. when given illegal source or destination - NOT_EXISTS 2. when given illegal load factor - BAD_PARAMS on user update: 1. when given illegal id - NOT EXISTS 2. when given a legal id but illegal hop values (e.g. less then 1 in source or destination) - BAD_PARAMS 3. when given a legal id, and legal hop values, but the hop does not exists - NOT_EXISTS |
In getAllPaths, can I make K queries, run the independently, and merge the results in Java? | |
no, for 2 reasons: 1. you are not allowed to do any data manipulations in Java, on the returned data, other then transform the data in the ResultSet to the business objects. 2. since you need to sort the paths according to their actual load, you will have to sort your merged list in Java, which is forbidden. |
Cam I use loops in Java to make a nested query? | |
yes |
can we have some information about error codes & exceptions? | |
sure https://www.postgresql.org/docs/9.6/static/errcodes-appendix.html https://docs.oracle.com/javase/7/docs/api/java/sql/SQLException.html |
how do I work with ResultSet? | |
a basic tutorial which prints the results held in the ResultSet http://www.postgresqltutorial.com/postgresql-jdbc/query/ you are smart & great students, and have enough skills and knowledge to adapt this tutorial to HW requirement |
can I use arithmetic operators in datalog? | |
yes |
my machine broke \ I cannot set up environment, etc..What should I do? | |
a pool of virtual machine has been assigned to us with all the programs installed (PostgresSQL, Intelij, Eclipse, Maven). the initial password for the superuser "Postgres" is "cs236363". in order the have access to a virtual machine you should follow the instructions in the link: http://cswp.cs.technion.ac.il/vdi-services/ if you don't have a CS account yet you should follow: שלום רב, כל מי שרשום לקורס, ומשנה את הסיסמא בשרת t2, נפתח לו חשבון ב – CS, בשרת csl2 וב- DOMAIN td-csf. להלן הפרטים. אם זה לא הסתדר, יש לשלוח לאילנה עדות uedutatcs.technion.ac.il מספר זהות, שם מלא, שם משתמש בשרתי הטכניון, ומספר טלפון כדי שאבדוק אם יש בעיה. כדי שיפתח לך חשבון ב- CS, עליך לשנות את סיסמת חשבונך בשרת t2. על מנת שיפתח לך חשבון ב- CS, אנא: החלף סיסמא בשרת t2 והמתן כ-30 דקות עד להיווצרות החשבון החדש. שינוי סיסמא בעזרת מספר הזיהוי והקוד הסודי: באתר: הקוד מאפשר לך לפתוח ולנהל חשבון במחשב tx/t2 באמצעות אתר האינטרנט : http://techwww.technion.ac.il/new-account שינוי סיסמא במידה וידועה הסיסמא הנוכחית באתר: http://cis-account.technion.ac.il אילנה |