Opening existing DB in read-only mode may throw exception "The database is read only [90097-123]"

[Rafferty]

Hi Thomas -

First I'd like to say how much I admire the engineering and
professionalism of H2. It's inspiring.

I'm testing 1.2 with an app that I've been running with H2 for some
time and seeing a new error that I hadn't seen before.

When it opens an existing DB file with ACCESS_MODE_DATA=R it sometimes
get an exception as below. It looks like PageStore.recover() is
getting called, which in turn is calling PageStore.writePage() , which
bombs out because the conection was opened as read-only.

I'm not sure what recovery is required for this DB. Possibly, the DB
is sometimes not being shutdown correctly, because this problem
doesn't happen all the time. Once it does, however it persists until
I make the connection read-write. Making the connection read-write
makes the problem go away.

I tested setting ACCESS_MODE_LOG=RW while leaving ACCESS_MODE_DATA=R
but this didn't help.

org.h2.jdbc.JdbcSQLException: The database is read only [90097-123]
at org.h2.message.Message.getSQLException(Message.java:111)
at org.h2.message.Message.getSQLException(Message.java:122)
at org.h2.message.Message.getSQLException(Message.java:75)
at org.h2.message.Message.getSQLException(Message.java:157)
at org.h2.engine.Database.checkWritingAllowed(Database.java:1852)
at org.h2.store.FileStore.checkWritingAllowed(FileStore.java:166)
at org.h2.store.FileStore.write(FileStore.java:332)
at org.h2.store.PageStore.writePage(PageStore.java:977)
at org.h2.store.PageLog.recover(PageLog.java:267)
at org.h2.store.PageStore.recover(PageStore.java:1003)
at org.h2.store.PageStore.openExisting(PageStore.java:296)
at org.h2.store.PageStore.open(PageStore.java:254)
at org.h2.engine.Database.getPageStore(Database.java:2299)
at org.h2.engine.Database.open(Database.java:625)
at org.h2.engine.Database.openDatabase(Database.java:228)
at org.h2.engine.Database.<init>(Database.java:222)
at org.h2.engine.Engine.openSession(Engine.java:58)
at org.h2.engine.Engine.openSession(Engine.java:142)
at org.h2.engine.Engine.getSession(Engine.java:122)
at org.h2.engine.SessionFactoryEmbedded.createSession
(SessionFactoryEmbedded.java:17)
at org.h2.engine.SessionRemote.connectEmbeddedOrServer
(SessionRemote.java:245)
at org.h2.engine.SessionRemote.createSession(SessionRemote.java:223)
at org.h2.jdbc.JdbcConnection.<init>(JdbcConnection.java:110)
at org.h2.jdbc.JdbcConnection.<init>(JdbcConnection.java:94)
at org.h2.Driver.connect(Driver.java:58)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)

I'm using H2 1.2.123 on Windows XP with JDK 1.6.0_12

[Thomas Mueller]

Hi,

I think I found the problem. It will be fixed in the next release.

Regards,
Thomas

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[=maximus=]

Thomas,

Is this problem fixed and should one set read-only attributes for
database files and/or it is sufficient to use ACCESS_MODE_DATA=R
parameter? It is not clear whether to use both or not?

Maxim.

[Thomas Mueller]

Hi,

> Is this problem fixed

Yes.

> should one set read-only attributes for
> database files and/or it is sufficient to use ACCESS_MODE_DATA=R
> parameter?

One of both is sufficient.

Regards,
Thomas

[Steve Luo]

Hi Thomas,

I encountered such exception quite often and don't know what's the root cause yet, I'm using h2-1.3.159. The exception looks like below.

org.h2.jdbc.JdbcSQLException: The database is read only [90097-159]
     at org.h2.message.DbException.getJdbcSQLException(DbException.java:329)
     at org.h2.message.DbException.get(DbException.java:169)
     at org.h2.message.DbException.get(DbException.java:146)
     at org.h2.message.DbException.get(DbException.java:135)
     at org.h2.engine.Database.checkWritingAllowed(Database.java:1626)
     at org.h2.store.PageStore.logUndo(PageStore.java:996)
     at org.h2.index.PageDataLeaf.create(PageDataLeaf.java:92)
     at org.h2.index.PageDataIndex.getPage(PageDataIndex.java:227)
     at org.h2.index.PageDataIndex. (PageDataIndex.java:81)
     at org.h2.table.RegularTable. (RegularTable.java:92)
     at org.h2.store.PageStore.openMetaIndex(PageStore.java:1511)
     at org.h2.store.PageStore.recover(PageStore.java:1328)
     at org.h2.store.PageStore.openExisting(PageStore.java:349)
     at org.h2.store.PageStore.open(PageStore.java:273)
     at org.h2.engine.Database.getPageStore(Database.java:2049)
     at org.h2.engine.Database.open(Database.java:553)
     at org.h2.engine.Database.openDatabase(Database.java:220)
     at org.h2.engine.Database. (Database.java:215)
     at org.h2.engine.Engine.openSession(Engine.java:56)
     at org.h2.engine.Engine.openSession(Engine.java:159)
     at org.h2.engine.Engine.createSessionAndValidate(Engine.java:138)
     at org.h2.engine.Engine.createSession(Engine.java:121)
     at org.h2.engine.Engine.createSession(Engine.java:28)
     at org.h2.engine.SessionRemote.connectEmbeddedOrServer(SessionRemote.java:285)
     at org.h2.jdbc.JdbcConnection. (JdbcConnection.java:110)
     at org.h2.jdbc.JdbcConnection. (JdbcConnection.java:94)
     at org.h2.Driver.connect(Driver.java:72)

     at java.sql.DriverManager.getConnection(DriverManager.java:582)
     at java.sql.DriverManager.getConnection(DriverManager.java:185)

     at

My case is just like what this post mentioned. I'm trying open a database with ACCESS_MODE_DATA=R using embedded mode, and then some time this error raised and persisted unless I restart my application.

So, my question is can I safely change to a read write mode when this error occurred? Like:

Connection conn = null;
try {
    conn = DriverManager.getConnection("jdbc:h2:/home/data/test;ACCESS_MODE_DATA=r", "sa", "");
} catch (org.h2.jdbc.JdbcSQLException e) {
   if (e.getMessage().contains("The database is read only"))
       conn = DriverManager.getConnection("jdbc:h2:/home/data/test;ACCESS_MODE_DATA=r", "sa", "");
   else
       throw new RuntimeException(e);
}


Best Regards,
Steve

[Steve Luo]

Sorry, my mistake, the code snippet should be:

Connection conn = null;
try {
    conn = DriverManager.getConnection("jdbc:h2:/home/data/test;ACCESS_MODE_DATA=r", "sa", "");
} catch (org.h2.jdbc.JdbcSQLException e) {
    if (e.getMessage().contains("The database is read only"))

        conn = DriverManager.getConnection("jdbc:h2:/home/data/test", "sa", "")
    else
        throw new RuntimeException(e);

[Christoph Läubrich]

I would asume that the connections/sessions are not closed properly, so the DB tries to revert some uncommited changes.

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[Noel Grandin]

This is what happened

(1) someone opened the DB in rw mode

(2) that program did not shutdown cleanly

(3) you try to open in ro mode

(4) the DB tries to undo the uncommitted changes