Member MDBX_cmp_func (const MDBX_val *a, const MDBX_val *b) noexcept

It is recommend not using custom comparison functions, but instead converting the keys to one of the forms that are suitable for built-in comparators (for instance take look to the Value-to-Key functions). The reasons to not using custom comparators are:

The order of records could not be validated without your code. So mdbx_chk utility will reports "wrong order" errors and the -i option is required to suppress ones.
A records could not be ordered or sorted without your code. So mdbx_load utility should be used with -a option to preserve input data order.
However, the custom comparators feature will never be removed. You have been warned but still can use custom comparators knowing about the issues noted above. In this case you should ignore deprecated warnings or define MDBX_DEPRECATED macro to empty to avoid ones.

Member MDBX_COALESCE

Always enabled since v0.12 and deprecated since v0.13.

Member mdbx_dbi_open_ex (MDBX_txn *txn, const char *name, MDBX_db_flags_t flags, MDBX_dbi *dbi, MDBX_cmp_func *keycmp, MDBX_cmp_func *datacmp)

Please avoid using custom comparators and use mdbx_dbi_open() instead.

Member mdbx_env_get_maxkeysize (const MDBX_env *env)

Please use mdbx_env_get_maxkeysize_ex() and/or mdbx_env_get_maxvalsize_ex()

Member mdbx_env_info (const MDBX_env *env, MDBX_envinfo *info, size_t bytes)

Please use mdbx_env_info_ex() instead.

Member mdbx_env_set_mapsize (MDBX_env *env, size_t size)

Please use mdbx_env_set_geometry() instead.

Member mdbx_env_stat (const MDBX_env *env, MDBX_stat *stat, size_t bytes)

Please use mdbx_env_stat_ex() instead.

Member MDBX_MAPASYNC

Please use MDBX_SAFE_NOSYNC instead of MDBX_MAPASYNC.

Member MDBX_NOTLS

Please use MDBX_NOSTICKYTHREADS instead.

Member mdbx_txn_straggler (const MDBX_txn *txn, int *percent)

Please use mdbx_txn_info() instead.