Getting Error : Cannot attach data store shared-memory segment,

Question

HI Team,
I am trying to integrate Timesten IMDB in my application.
Machine details
Windows 2003, 32 bit, 4GB RAM.
IMDB DB details
Permanent size 500MB, temp size 40MB.
If I try to connect to database using ttisql it get connected. But If I try to connect in my Java application I get following exception.
java.sql.SQLException: [TimesTen][TimesTen 11.2.1.3.0 ODBC Driver][TimesTen]TT0837: Cannot attach data store shared-memory segment, error 8 -- file "db.c", lineno 7966, procedure "sbDbCreate"
at com.timesten.jdbc.JdbcOdbc.createSQLException(JdbcOdbc.java:3269)
at com.timesten.jdbc.JdbcOdbc.standardError(JdbcOdbc.java:3418)
at com.timesten.jdbc.JdbcOdbc.standardError(JdbcOdbc.java:3383)
at com.timesten.jdbc.JdbcOdbc.SQLDriverConnect(JdbcOdbc.java:787)
at com.timesten.jdbc.JdbcOdbcConnection.connect(JdbcOdbcConnection.java:1800)
at com.timesten.jdbc.TimesTenDriver.connect(TimesTenDriver.java:303)
at com.timesten.jdbc.TimesTenDriver.connect(TimesTenDriver.java:159)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:207)
Maximum permanent size that works with Java application is 100MB. But it would not be enough for our use.
Could anybody let me know the way to resolve/reason for getting this error? Any response would be appreciated.
Thanks in Advance,
Regards,
atul

Answer 1

This is a very common problem on 32-bit Windows. A TimesTen datastore is a single region of 'shared memory' allocated as a shared mapping from the paging file. In 'direct mode', when the application process(in your case either ttIsql or the JVM) 'connects' to the datastore the datastore memory region is mapped into the process address space. In order for this to happen it is necessary for there to be a free region in the process adddress space that is at least the size of the datastore. This region must be contiguous (i.e. a single region). Unfortunately, the process memory map in 32-bit Windows is typically highly fragmented and the more DLLs that a process uses the worse this is. Also, JVMs typically use a lot of memory, depending on configuration.
Your options to solve this are really limited to:
1. Significantly reduce the memory used by the JVM (may not be possible).
2. Use a local client/server connection from Java instead of a direct mode connection. To minismise the performance overhead make sure you use the optimised ShmIpc connectivity rather than TCP/IP. Even with this there is likely to be a >50% reduction in performance compared to direct mode.
3. Switch to 64-bit Windows, 64-bit TimesTen and 64-bit Java. Even without adding any extra memory to your machine thsi will very likely fix the problem.
Option (3) is by far the best one.
Regards,
Chris