Re: Online Extent Sizing

I found the following method for extent sizing in the Informix DBA training course. I still dont't have the skills to know well if the algorithm is completely correct, but if there is an error I hope some of the gurus can help. Action Calculation -------------------------------- ------------------------------------ 1. Determine each index length. Add 8 bytes to the length of the key. 2. Determine total index length. Sum up all index entries from step 1. 3. Account for index overhead. Add 25% to the sum of step 2. 4. Estimate initial table size. Guess the number of initial rows. 5. Size index space needed. Multiply the result from step 3 by the number of rows from step 4. 6. Convert index space to Kb. Divide index space by 1024 7. Determine page length in bytes Check PAGESIZE in tbconfig file; and subtract 32 to obtain subtract 32 (page overhead) usable page space 8. Determine row length. Sum up all column lengths in the row; add 4 (slot table entry) 9. Determine how many whole rows Divide page size from step 7 by row can fit on a page. length in step 8 and round down to the greatest whole number. 10. Determine the number of data Divide the number of rows from step pages for the initial table 4 by the number of rows per page in step 9; round up. 11. Size the space needed for data Multiply the number of pages of step pages in the initial extent 10 by the size of a full page. 12. Convert data size to Kb. Divide step 11 by 1024 13. Determine size of the initial Add results of step 12 and step 6 extent in Kb. 14. Estimate table growth. Guess the number of subsequent rows 15. Size subsequent extents Repeat steps 5-6 for index space and steps 10-13 for data space. Use the estimate in step 14 as the number of rows in step 5 and 10. Divide the final result by 7. ------------------- Juan M. de Villeros ejda142@delta.eafit.edu.co