Sizing Indexes - URGENT

From: <JayK_at_ibsplc.com>
Date: Sun, 16 Mar 2003 20:08:44 -0800
Message-ID: <F001.0056B5DE.20030316200844@fatcity.com>

Dear All,

I have a task on hand to size a database for our application. I have used the Oracle rule to find out the rowsize of rows in a table.

1. Space available for the data (SAD) = data block size ? block header size = db_block_size ? kcbh ? ub4 ? ktbbh ? (initrans -1)* ktbit ? kdbh
2. Available Data Space (ADS) = ceil(SAD * (1-pctfree/100)) ? kdbt
3. Space used per row (SPR) = (Total size of the columns data length) + (1 byte per column with length < 250 )+ (3 * 1 byte per column with length >= 250)
4. Row Size (ROWSZ) = 3 * ub1 + SPR
5. Space used per row(SPROW) = max(ub1 * 3 + ub4 + sb2, ROWSZ) + sb2
6. Total Size of the table = Expected Number of records * SPROW

I hope this formula is correct.

How can I do the sizing of indexes. Shouldn't I take into account the 10 bytes consumed by the ROWID pseudocolumn apart from the column(s) that are indexed ?

TIA for all your help.

Best Regards
Jai
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  INET: JayK_at_ibsplc.com

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