I've been using JPA to instert entities into a database but I've run up
against a problem where I need to do an insert and get the primary key of the
record last inserted. Using PostgreSQL I would use an INSERT RETURNING
statement which would return the record id, but with an entity manager doing
all this, the only way I know is to use SELECT CURRVAL. So the problem
becomes, I have several data sources sending data into a message driven bean
(usually 10-100 messages at once from each source) via OpenMQ and inside this
MDB I persists this to PostgreSQL via the entity manager. It's at this point
*I think* there will be a "race condition like" effect of having so many
inserts that I won't necessarily get the last record id using SELECT CURRVAL.
My MDB persists 3 entity beans via an entity manager like below. Any help on
how to better do this much appreciated. [code] public void onMessage(Message
msg) { Integer agPK = 0; Integer scanPK = 0; Integer lookPK = 0; Iterator
iter = null; List agKeys = null; List scanKeys = null; try { iag = (IAgBean)
(new InitialContext()).lookup( "java:comp/env/ejb/AgBean"); TextMessage tmsg
= (TextMessage) msg; // insert this into table only if doesn't exists Ag ag =
new Ag(msg.getStringProperty("name")); agKeys = (List) (iag.getPKs(ag)); iter
= agKeys.iterator(); if (iter.hasNext()) { agPK = ((Ag) iter.next()).getId();
} else { // no PK found so not in dbase, insert new iag.addAg(ag); agKeys =
(List) (iag.getPKs(ag)); iter = agKeys.iterator(); if (iter.hasNext()) { agPK
= ((Ag) iter.next()).getId(); } } // insert this into table always iscan =
(IScanBean) (new InitialContext()).lookup( "java:comp/env/ejb/ScanBean");
Scan scan = new Scan(); scan.setName(msg.getStringProperty("name"));
scan.setCode(msg.getIntProperty("code")); iscan.addScan(scan); scanKeys =
(List) iscan.getPKs(scan); iter = scanKeys.iterator(); if (iter.hasNext()) {
scanPK = ((Scan) iter.next()).getId(); } // insert into this table the two
primary keys above ilook = (ILookBean) (new InitialContext()).lookup(
"java:comp/env/ejb/LookBean"); Look look = new Look(); if (agPK.intValue() !=
0 && scanPK.intValue() != 0) { look.setAgId(agPK); look.setScanId(scanPK);
ilook.addLook(look); } // ... [/code]
--
[Message sent by forum member 'rrlangly']
View Post: http://forums.java.net/node/891146