Thanks... I meant that the two PK columns are actually primary key of (id, timestamp).. What i don't understand, is why do i need primary keys as timeStamp if not to make an index tree of my table rows ? Does the PK doesn't build an index tree of the rows so i can get a row faster?
Simon Slavin-3 wrote: > > > On 24 Aug 2011, at 12:39pm, LiranR wrote: > >> ID (PK) | TimeStamp (PK) | data | data | and data ... >> ------------------------------------------------------------- >> 1 | 1000001 | float | float | float >> 2 | 1000002 | float | float | float >> 3 | 3 | float | float | float >> 4 | 4 | float | float | float >> ... | ... | float | float | float > > The schema above is a little strange. You can't have two primary keys for > the same table. So either > > A) your ID column is the primary key, the TimeStamp column may or may not > be another key > B) your TimeStamp column is the primary key, the ID column may or may not > be another key > C) you have a primary key of (id,TimeStamp) which would be very unusual > >> As you can see, the table is already has been filled, and its the second >> time entering data. >> the next row to update is row 3, which will be have TimeStamp 1000003. >> Because the face that time stamp is always rising, i can't leave there >> only >> the number 3. > > If you are concerned about the (small amount of) extra work involved in > changing a primary key column, I think you can just have your ID column as > the primary key. > >> Also, I have to use TimeStamp as PK (Primary Key) because of >> the fact that when i want to read data from the table i search the table >> by >> timestamp. > > No, that's not what primary keys are for at all. You can search a SQL > table using any value you like. If you want to make the search fast, make > an INDEX on the column. > > CREATE INDEX myTableTimeStamp ON myTable (TimeStamp) > > Simon. > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > -- View this message in context: http://old.nabble.com/Reindexing-%28if-such-a-thing-exist%29-performance-tp32324832p32326182.html Sent from the SQLite mailing list archive at Nabble.com. _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
