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Limitations

Limitations

Number of parts in an index

For TREE or HASH indexes, the maximum is 255 (box.schema.INDEX_PART_MAX). For RTREE indexes, the maximum is 1 but the field is an ARRAY of up to 20 dimensions. For BITSET indexes, the maximum is 1.

Number of indexes in a space

128 (box.schema.INDEX_MAX).

Number of fields in a tuple

The theoretical maximum is 2,147,483,647 (box.schema.FIELD_MAX). The practical maximum is whatever is specified by the space’s field_count member, or the maximal tuple length.

Number of bytes in a tuple

The maximal number of bytes in a tuple is roughly equal to memtx_max_tuple_size (with a metadata overhead of about 20 bytes per tuple, which is added on top of useful bytes). By default, the value of memtx_max_tuple_size is 1,048,576. To increase it, specify a larger value when starting the Tarantool instance. For example, box.cfg{memtx_max_tuple_size=2*1048576}.

Slab size

The maximal size of an allocatable memory unit (slab) is equal to one quarter of memtx_max_tuple_size (by default, approximately 262,000 bytes). To see memory usage statistics broken down by slab size, use box.slab.stats().

Number of bytes in an index key

If a field in a tuple can contain a million bytes, then the index key can contain a million bytes, so the maximum is determined by factors such as Number of bytes in a tuple, not by the index support.

Number of spaces

The theoretical maximum is 65,000 (box.schema.SPACE_MAX).

Number of connections

The practical limit is the number of file descriptors that one can set with the operating system.

Space size

The total maximum size for all spaces is in effect set by memtx_memory, which in turn is limited by the total available memory.

Update operations count

The maximum number of operations that can be in a single update is 4000 (BOX_UPDATE_OP_CNT_MAX).

Number of users and roles

32 (BOX_USER_MAX).

Length of an index name or space name or user name

32 (box.schema.NAME_MAX).

Number of replicas in a replica set

32 (box.schema.REPLICA_MAX).