BlockLobs CLI/ODBC configuration keyword

db2cli.ini keyword syntax:

BlockLobs = 0 | 1

Default setting:

Blocking of result sets returning LOB data types is disabled.

Equivalent statement attribute:

SQL_ATTR_BLOCK_LOBS

Usage notes:

 

Setting BlockLobs to 1 enables all of the LOB data associated with rows that fit completely within a single query block to be returned in a single fetch request, if the server supports LOB blocking. CLI clients which enable BlockLobs = 1 and bind the LOB values directly to buffers can show an increase in memory consumption depending on the amount of data retrieved for one request compared to previous releases. LOB data is described here as being associated with a row, because the LOB data of a result set is itself not contained in the row. Instead, the row contains a reference to the actual LOB data. Therefore, with blocking of result sets returning LOB data types, any rows of the result set that fit completely within the query block (where each row consists of non-LOB data, since LOB data is not stored directly in the row), will have their associated LOB data returned from the server, if the server supports blocking of result sets returning LOB data types.

If the server does not support cursor blocking with LOB columns, then only one row of LOB data will be returned in a single fetch request and the BlockLobs value is ignored. While DB2® does support cursor blocking with LOB columns, other servers may not.

DB2 LUW does not support LOB blocking fetch.

IDS data servers do not support LOB blocking fetch.