It seems that this scheme would suffer under a race condition. On Wed, Mar 24, 2010 at 11:00 AM, Jesus Ibanez <jesusiba...@gmail.com>wrote:
> You can generate UUIDs based on time with http://jug.safehaus.org/ if you > use Java. And its easy to use, just have to insert one line: > UUID uuid = UUIDGenerator.getInstance().generateTimeBasedUUID(); > > Maybe a solution to your cuestion: > > To "replace" the autoincrement of MySQL, you can create a column family of > type Super ordering super columns by decreasing order and naming the super > columns with a numeric value. So then, if you want to insert a new value, > first read the last inserted column name and add 1 to the returned value. > Then insert a new super column wich it name will be the new value. > > Be careful with super columns, becouse I think that if you want to read > just a column of a super column, all columns will be deserialized. > > So you will have this: > > > Super_Columns_Family_Name = { // this is a ColumnFamily name of type Super > one_key: { // this is the key to this row inside the Super CF > > n: {column1: "value 1", column2: "value 2", ... , columnN: "value n"}, > > n-1: {column1: "value 1", column2: "value 2", ... , columnN: "value > n"}, > > ... > > 2: {column1: "value 1", column2: "value 2", ... , columnN: "value n"}, > 1: {column1: "value 1", column2: "value 2", ... , columnN: "value n"}, > }, > > another_key: { // this is the key to this row inside the Super CF > > > > n: {column1: "value 1", column2: "value 2", ... , columnN: "value n"}, > > n-1: {column1: "value 1", column2: "value 2", ... , columnN: "value > n"}, > > ... > > 2: {column1: "value 1", column2: "value 2", ... , columnN: "value n"}, > 1: {column1: "value 1", column2: "value 2", ... , columnN: "value n"}, > }, > > } > > The super columns that represent the autoincrement value are the ones named > as: n, n-1, ... , 2, 1. > > Hope it helps! > > Jesus. > > > > 2010/3/24 Sylvain Lebresne <sylv...@yakaz.com> > > > How can I replace the "auto increament" attribute in MySQL >> > with Cassandra? >> >> You can't. Not easily at least. >> >> > If I can't, how can I generate an ID which is globally >> > unique for each of columns? >> >> Check UUIDs: >> http://en.wikipedia.org/wiki/Universally_Unique_Identifier >> >> > >> > Thanks, >> > >> > Sent from my iPhone >> > >> > >
