Memory Subheaps Dumps

Each heap may have one or more subheaps. These can be dumped using the command

    ALTER SESSION SET EVENTS
    'immediate trace name heapdump_addr level level';

where the level is the address of the subheap.

The syntax for this command changed in Oracle 9.2

Oracle 9.0.1 and below

Oracle 9.2.0 and above

Oracle 9.0.1 and below

For Oracle 9.0.1 and below a summary dump is obtained by setting the level to the decimal value of the address. A detailed dump is obtained by adding 1 to the decimal value of the address.

For example to dump the subheap at address 0x8057eb78, first convert the address to decimal (2153245560)

The subheap address can be found in the heapdump, for example

    ds=0x8057eb78

For a summary dump use

    ALTER SESSION SET EVENTS
    'immediate trace name heapdump_addr level 2153245560';

For a detailed dump, add 1 to the address e.g.

    ALTER SESSION SET EVENTS
    'immediate trace name heapdump_addr level 2153245561';

Oracle 9.2.0 and above

In Oracle 9.2 and above, for a summary dump

    ALTER SESSION SET EVENTS
    'immediate trace name heapdump_addr level 1, addr 2153245560';

The following ORADEBUG command has the same effect

    ORADEBUG DUMP HEAPDUMP_ADDR 1 2153245560

In Oracle 9.2 and above, for a detailed dump

    ALTER SESSION SET EVENTS
    'immediate trace name heapdump_addr level 2, addr 2153245560';

Note that in Oracle 9.2 it is no longer necessary to add 1 to the address

The following ORADEBUG command has the same effect

    ORADEBUG DUMP HEAPDUMP_ADDR 2 2153245560

A SQL statement child cursor contains two subheaps, heap 0 and heap 6. The addresses for the subheaps is reported by the X$KGLOB object for the child cursor (not the parent cursor). Among other places the child cursor address is externalized in the CHILD_ADDRESS column in V$SQL.

For example if the child cursor is 0x20F07A88 then the addresses of subheaps 0 and 6 can be determined using

    SELECT kglobhd0, kglobhd6 
    FROM x$kglob
    WHERE kglhdadr = '20F07A88';

    KGLOBHD0 KGLOBHD6
    -------- --------
    24F675A0 20FB94E4

 

In Oracle 11.2 (and possibly lower versions) it is possible to specify the address in hexadecimal

    ALTER SESSION SET EVENTS
    'immediate trace name heapdump_addr level 2, addr 0x24F675A0';

http://www.juliandyke.com/Diagnostics/Dumps/HEAPDUMP_ADDR.html