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.