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Physical attributes clause

pctfree   10 
pctused   40 
initrans   1 
maxtrans 255
storage-clause
The physical attributes clause appears as part of a segment attribute clause or create cluaster statement.
The pctused and pctfree storage parameters can be used in create table, create index and create cluster statements.

pctfree

pctfree controls if a block is considered a free block. A block is considered free as long as there is at least pctfree% space free in the block. The free space is then available for update statements that grow the data within the rows.
The default for pctfree is 10%.

pctused

When a block is not free, it only becomes free again when it is filled less than pctused. This might be the case after update or delete statements.
The default for pctused is 40%.
The sum of pctfree and pctused must be less than 100%.

initrans

maxtrans