ZGETRANGESIZE

Returns the estimated byte size of a key range in the ZMap ordered key-value store.

Syntax

ZGETRANGESIZE <begin> <end>

Parameters

Parameter	Type	Required	Description
begin	bytes	Yes	The start key of the range. Use * for unbounded start (from the beginning of the subspace).
end	bytes	Yes	The end key of the range. Use * for unbounded end (to the end of the subspace).

Return Value

Integer: the estimated size in bytes of the key range.

Behavior

ZGETRANGESIZE returns the estimated byte size of a key range from the ZMap subspace of the session’s current namespace, backed by FoundationDB’s getEstimatedRangeSizeBytes API.

The returned value is an estimate, not an exact count. It is useful for capacity planning and understanding data distribution without materializing the range.

The special value * can be used as a wildcard to represent an unbounded boundary:

• * as begin: starts the range from the very first key in the subspace.
• * as end: extends the range to the very last key in the subspace.

The command supports two transaction modes:

• Auto-commit (one-off): When no explicit transaction is active, Kronotop creates a transaction, performs the read, and commits it immediately. This is the default mode.
• Explicit transaction: When a BEGIN has been issued, the read is performed within the current transaction.

ZGETRANGESIZE also supports snapshot reads. When snapshot mode is enabled on the session, the read does not conflict with concurrent writes, allowing higher throughput for read-heavy workloads.

All data is scoped to the session’s active namespace. The same keys in different namespaces refer to different entries.

Errors

Error Code	Description
ERR	Wrong number of arguments or internal failure.

Examples

Basic range size estimation:

> ZSET key-0 "alpha"
OK
> ZSET key-1 "bravo"
OK
> ZSET key-2 "charlie"
OK

> ZGETRANGESIZE key-0 key-2
(integer) 186

Full subspace size estimation with * *:

> ZGETRANGESIZE * *
(integer) 372

Use within an explicit transaction:

> BEGIN
OK

> ZSET mykey-a "alpha"
OK

> ZSET mykey-b "bravo"
OK

> COMMIT
OK

> BEGIN
OK

> ZGETRANGESIZE mykey-a mykey-b
(integer) 124

> COMMIT
OK