ISAM limits

The following are the capacities and minimum/maximum limits of Synergy ISAM.

Synergy ISAM capacities and limits

Capacity

Maximum

Minimum

Keys defined per file

255

1

Segments defined per key

8

1

Length of key

254 on Windows and UNIX (or, 251 if the key allows duplicates or 250 if the key allows duplicates and this is a terabyte file)

255 on OpenVMS

1

Length of key segment

Same as defined key length

Number of records per file

Approximately 250,000,000 for nonterabyte files

The actual value varies depending on key size, index density, and available disk space.

0

Record length a

On Windows and UNIX, use this formula:

65,534 – (3 * number of keys allowing duplicates), – 2 if variable or compressed, – 6 if static RFA, – 2 if static RFA and variable or compressed

32,234 on OpenVMS

4
(or 5 for terabyte files)

Size per disk file (.ism and .is1)

231 (or 248 for terabyte files)

Combined null key size per file

1K

0

Keys per duplicate key value

16,777,216 (or 4 billion for terabyte files)

Index depth per key

16

Static RFA reuse

127

a. In Synergy .NET and 64-bit traditional Synergy, a file created with a variable record type and a maximum record size of 0 can contain larger records that are limited only by the amount of memory you have available or 2 GB.