Space required for segmented table spaces
The following table lists the notations in the calculations for segmented tables.
Notations used to calculate space for table spaces
Notation | Description |
|---|---|
n | Number of rows in the table |
k | Average row length for the table |
p | PCTFREE |
f | FREEPAGE |
m | Page size in KB (4, 8, 16, or 32) |
j | Maximum rows per page (255 or MAXROWS) |
s | (100 - p) / 100 |
ps | Pages per space map |
FLOOR | The operation of discarding the decimal portion of the real number |
CEILING | The operation of rounding a real number to the next highest integer |
MIN | The operation of selecting the lowest integer value |
Total data pages and free pages for a table in a segmented table space
The formulas in the following table are approximations.
Total data pages and free pages for a table
Value | Formula |
|---|---|
Usable space per page | FLOOR (s * ((m * 1024) - 22)) |
Rows per page | MIN (j, FLOOR (usable space per page / (k + 8))) |
Data pages | CEILING (n / rows per page) |
Free pages | FLOOR (data pages / MIN(f, (segsize - 1))), or 0 if f = 0 |
Total data and free pages for table | FLOOR ((data pages + free pages + segsize - 1) / segsize) * segsize |
Total data pages and free pages for a table space
The formula in the following table is an approximation.
Total data pages and free pages for a table space
Value | Formula |
|---|---|
Total data pages and free pages | table 1 pages + table 2 pages + ..... (for all tables) |
Total number of pages in a table space
The formulas in the following table are approximations.
Total number of pages in a table space
Value | Formula |
|---|---|
Dictionary pages | |
Space map pages | CEILING ((total data and free pages + dictionary pages) / ps) |
Total table space pages | 1 + total data and free pages + dictionary pages + space map pages |
Total table space space in KB | Total table space pages * m (rounded to allocation unit) |
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