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https://issues.apache.org/jira/browse/DERBY-48?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12619742#action_12619742
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Daniel John Debrunner commented on DERBY-48:
--------------------------------------------
I can't tell from the release note exactly what the incompatible change is so
it's hard to comment on if it should be backported.
E.g.:
- The summary "This is no longer the case", it doesn't seem clear what
'This' refers to, should it be part of the previous sentence, e.g. "as well,
this is ..."?
Maybe the summary could be re-written to describe what does happen, rather
than focusing on the previous behaviour?
- In "Symptoms Seen ..." section it says the schema will be created earlier
than it would have before, is this true, from the summary it seems it is
created at the same time as previously? I.e. the only change is if the
transaction is rolled back, not when the schema is created?
- The "Rationale for change" is more describing what is implemented, rather
than the justification for changing it. Maybe it could be more along the lines
of:
"Implicit schema creation is now performed in its own transaction to
avoid deadlocks with other connections accessing the same schema"
Is this change in behaviour for all implicit schema creations or just for the
default schema, it was hard to tell from the comments in this entry? That might
change the release note as well.
> A connection request that has a default schema that is being created by
> another transaction will fail to connect
> -----------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-48
> URL: https://issues.apache.org/jira/browse/DERBY-48
> Project: Derby
> Issue Type: Bug
> Components: JDBC
> Affects Versions: 10.0.2.0, 10.0.2.1, 10.0.2.2, 10.1.1.0
> Reporter: Kathey Marsden
> Assignee: Dag H. Wanvik
> Fix For: 10.5.0.0
>
> Attachments: derby-48-1.diff, derby-48-1.stat, derby-48-2.diff,
> derby-48-2.stat, derby-48-3.diff, derby-48-3.stat, derby-48-4.diff,
> derby-48-4.stat, derby-48-5.diff, derby-48-5.stat, derby-48-6.diff,
> derby-48-6.stat, derby-48-7.diff, derby-48-7.stat,
> LazyDefaultSchemaCreationTest.java, releaseNote.html
>
>
> A connection request that has a default schema that is being
> created by another transaction will block until that transaction
> completes (or time out). Probably in this situation the connection
> request should be succeed as if the schema does not exist.
> This is a problem in particular for a prepared XA transaction, where even
> after restarting the system, the user cannot reconnect and recover the
> transaction.
> Here is the reproduction in ij.
> java -Dij.exceptionTrace=true -Dij.protocol=jdbc:derby: -Dij.user=me
> -Dij.password=pw org.apache.derby.tools.ij
> ij version 10.0 (C) Copyright IBM Corp. 1997, 2004.
> ij> connect 'testdb;create=true';
> ij> autocommit off;
> ij> create table mytabi(i int);
> 0 rows inserted/updated/deleted
> ij> connect 'testdb';
> ERROR 40XL1: A lock could not be obtained within the time requestedERROR
> 40XL1: A lock could not be obtained within the time requested
> at
> org.apache.derby.iapi.error.StandardException.newException(StandardException.java:295)
> at
> org.apache.derby.impl.services.locks.LockSet.lockObject(LockSet.java:408)
> at
> org.apache.derby.impl.services.locks.SinglePool.lockAnObject(SinglePool.java:168)
> at
> org.apache.derby.impl.services.locks.SinglePool.lockObject(SinglePool.java:220)
> at
> org.apache.derby.impl.store.raw.xact.RowLocking3.lockRecordForRead(RowLocking3.java:181)
> at
> org.apache.derby.impl.store.access.heap.HeapController.lockRow(HeapController.java:425)
> at
> org.apache.derby.impl.store.access.heap.HeapController.lockRow(HeapController.java:543)
> at
> org.apache.derby.impl.store.access.btree.index.B2IRowLocking3.lockRowOnPage(B2IRowLocking3.java:329)
> at
> org.apache.derby.impl.store.access.btree.index.B2IRowLocking3._lockScanRow(B2IRowLocking3.java:571)
> at
> org.apache.derby.impl.store.access.btree.index.B2IRowLockingRR.lockScanRow(B2IRowLockingRR.java:115)
> at
> org.apache.derby.impl.store.access.btree.BTreeForwardScan.fetchRows(BTreeForwardScan.java:374)
> at
> org.apache.derby.impl.store.access.btree.BTreeScan.next(BTreeScan.java:1691)
> at
> org.apache.derby.impl.sql.catalog.DataDictionaryImpl.getDescriptorViaIndex(DataDictionaryImpl.java:7118)
> at
> org.apache.derby.impl.sql.catalog.DataDictionaryImpl.locateSchemaRow(DataDictionaryImpl.java:1381)
> at
> org.apache.derby.impl.sql.catalog.DataDictionaryImpl.getSchemaDescriptor(DataDictionaryImpl.java:1291)
> at
> org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.initDefaultSchemaDescriptor(GenericLanguageCon
> at
> org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.initialize(GenericLanguageConnectionContext.ja
> at
> org.apache.derby.impl.db.BasicDatabase.setupConnection(BasicDatabase.java:267)
> at
> org.apache.derby.impl.jdbc.TransactionResourceImpl.startTransaction(TransactionResourceImpl.java:182)
> at
> org.apache.derby.impl.jdbc.EmbedConnection.<init>(EmbedConnection.java:237)
> at
> org.apache.derby.impl.jdbc.EmbedConnection20.<init>(EmbedConnection20.java:49)
> at
> org.apache.derby.impl.jdbc.EmbedConnection30.<init>(EmbedConnection30.java:56)
> at
> org.apache.derby.jdbc.Driver30.getNewEmbedConnection(Driver30.java:68)
> at org.apache.derby.jdbc.Driver169.connect(Driver169.java:172)
> at java.sql.DriverManager.getConnection(DriverManager.java:512)
> at java.sql.DriverManager.getConnection(DriverManager.java:140)
> at org.apache.derby.impl.tools.ij.ij.dynamicConnection(ij.java:843)
> at org.apache.derby.impl.tools.ij.ij.ConnectStatement(ij.java:700)
> at org.apache.derby.impl.tools.ij.ij.ijStatement(ij.java:528)
> at org.apache.derby.impl.tools.ij.utilMain.go(utilMain.java:283)
> at org.apache.derby.impl.tools.ij.Main.go(Main.java:204)
> at org.apache.derby.impl.tools.ij.Main.mainCore(Main.java:170)
> at org.apache.derby.impl.tools.ij.Main14.main(Main14.java:50)
> at org.apache.derby.tools.ij.main(ij.java:54)
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