modify chunk extendable argument: Mark a chunk as extendable (SQL administration API)

Use the modify chunk extendable argument with the admin() or task() function to specify that a particular chunk in an unmirrored dbspace or temporary dbspace can be extended.. 


1  EXECUTE FUNCTION
1 admin
1 task
2  ( " modify chunk extendable "  , " chunk_number " )  ;
Element Description Key Considerations
chunk_number The number of the chunk.

Usage

If a chunk is marked as extendable, either:

  • The server can automatically extend the chunk when the unmirrored dbspace or temporary dbspace containing the chunk runs low or out of free pages.
  • You can use the modify chunk extend argument with the admin() or task() function to extend the size of the chunk.

However, if the extend size for the dbspace or temporary dbspace is set to 0, the server cannot automatically extend an extendable chunk in that space. In this situation, you can still manually extend the chunk.

The server will automatically mark chunks that are allocated from extendable storage pool entries as extendable. Therefore, you do not need to mark these chunks as extendable. For information on extendable storage pool entries, see storagepool add argument: Add a storage pool entry (SQL administration API).

Chunks in mirrored spaces cannot be extended. If you try to make a mirror chunk extendable, you will receive an error.

To identify primary and mirror chunks in a mirrored space, look for the P (primary) or M (mirror) in position 1 of the flags field in onstat -d command output.

Example

The following snippet of onstat -d output shows that chunk number 3 is a mirror chunk: 

Chunks
address      chunk/dbs  offset   size     free    bpages   flags pathname
451191c8     1      1   0        225000   101572           PO-B-- /reg1/rootchunk
451197d0     2      2   0        1250     1149             PO-B-- /reg1/dbs1
451199d0     3      3   0        1250     1149             PO-B-- /reg1/dbs2
46a36638     3      3   0        1250     0                MO-B-- /reg1/chunk2
45119bd0     4      4   0        1250     1149             PO-B-- /reg1/dbs3

Thus, you cannot extend the size of chunk number 3. However, you can specify that chunk number 4 is extendable, as follows:

EXECUTE FUNCTION sysadmin:task("modify chunk extendable", "4");