Yes, it is possible. You can override the default generator name with the @SequenceGenerator annotation. Base class @MappedSuperclass public abstract class PersistentEntity implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = “default_gen”) protected Long id = 0L; public Long getId() { return id; } public void setId(Long id) … Read more
Sequences have gaps to permit concurrent inserts. Attempting to avoid gaps or to re-use deleted IDs creates horrible performance problems. See the PostgreSQL wiki FAQ. PostgreSQL SEQUENCEs are used to allocate IDs. These only ever increase, and they’re exempt from the usual transaction rollback rules to permit multiple transactions to grab new IDs at the … Read more
You’re mixing very different things in your question, so I’ll just answer a different question You are now asking about one of the most important interface in Python: iterable – it’s basically anything you can use like for elem in iterable. iterable has three descendants: sequence, generator and mapping. A sequence is a iterable with … Read more
Use the TRUNCATE SQL command. For a single table the syntax is the following: TRUNCATE TABLE table_name RESTART IDENTITY; For multiple tables: TRUNCATE TABLE table_foo, table_bar RESTART IDENTITY; What it does: Automatically restart sequences owned by columns of the truncated table(s). Details here: TRUNCATE @ postgresql.org
This problem can be solved in O(n*m + r) time, where r is the total length of the results, using the classic longest common subsequence algorithm. Once the table is made, as in Wikipedia’s example, replace it with a list of the cells with a diagonal arrow that also have a value corresponding with their … Read more
This is a solution suggested by the MySQl manual: If expr is given as an argument to LAST_INSERT_ID(), the value of the argument is returned by the function and is remembered as the next value to be returned by LAST_INSERT_ID(). This can be used to simulate sequences: Create a table to hold the sequence counter … Read more
Assuming that you want to group the data before you generate the key with the sequence, it sounds like you want something like INSERT INTO HISTORICAL_CAR_STATS ( HISTORICAL_CAR_STATS_ID, YEAR, MONTH, MAKE, MODEL, REGION, AVG_MSRP, CNT) SELECT MY_SEQ.nextval, year, month, make, model, region, avg_msrp, cnt FROM (SELECT ‘2010’ year, ’12’ month, ‘ALL’ make, ‘ALL’ model, REGION, … Read more
Mutability for sequences only guarantees that you’ll be able to swap out the items for different ones (via the update method), as you can with e.g. primitive arrays. It does not guarantee that you’ll be able to make the sequence larger (that’s what the Growable trait is for) or smaller (Shrinkable). Buffer is the abstract … Read more