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Message Posted: Mon, 11 Aug 2003 @ 10:49:55 GMT

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Hi All

We also experienced a few cases of table growth. This apparently had to do not only with table headers, but with byte / word alignment. Squeezing a column down to a byte didn't help as the record still allocated a second byte for the even byte alignment.

That is, the table

create table t (
  pi  integer
  val  smallint
)
unique primary index (pi)
;

has a record consisting of

header info: 14 bytes
pi:           4 bytes
val:          2 bytes
thus totaling 20 bytes.

Compressing Val to one of 63 distinct values led to

header info: 15 bytes
pi:           4 bytes
val:          0 bytes

totaling 19 bytes. This being odd, an extra byte of padding is added for alignment, so no actual space saved.

Teradata did suggest that this was a kind of worst cae scenario though.

Regards.

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