# Is it possible (or useful) to fetch the last key?

**URL:** <https://forums.foundationdb.org/t/is-it-possible-or-useful-to-fetch-the-last-key/400>\
**Category:** Using FoundationDB\
**Tags:** bindings\
**Created:** [May 11, 2018, 5:25pm UTC](https://forums.foundationdb.org/t/is-it-possible-or-useful-to-fetch-the-last-key/400 "2018-05-11T17:25:32Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![amirouche](https://sea1.discourse-cdn.com/foundationdb/user_avatar/forums.foundationdb.org/amirouche/32/2096_2.png) [@amirouche](https://forums.foundationdb.org/u/amirouche)\
**Post date:** [May 11, 2018, 5:25pm UTC](https://forums.foundationdb.org/t/is-it-possible-or-useful-to-fetch-the-last-key/400/1 "2018-05-11T17:25:32Z")

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The default upper bound of ranges in Python bindings is `b'\xFF'`. If there is another key that is bigger, like `b'\xFFFF'` it will be not be returned by `transaction.get_range(begin=None, begin=None)` basically, using the current high level API there is no way to retrieve the whole database in a reliable way. Is that correct?

One way to work around is to prefix all keys with `\x00` or use the tuple module.

Also, what is the purpose of the `strinc` function in the python bindings. Here is its definition:

```python
def strinc(key):
    key = key.rstrip(b'\xff')
    if len(key) == 0:
        raise ValueError('Key must contain at least one byte not equal to 0xFF.')
    return key[:-1] + six.int2byte(ord(key[-1:]) + 1)

```

TIA

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**Author:** ![ajbeamon](https://sea1.discourse-cdn.com/foundationdb/user_avatar/forums.foundationdb.org/ajbeamon/32/13_2.png) [@ajbeamon](https://forums.foundationdb.org/u/ajbeamon)\
**Post date:** [May 11, 2018, 5:34pm UTC](https://forums.foundationdb.org/t/is-it-possible-or-useful-to-fetch-the-last-key/400/2 "2018-05-11T17:34:27Z")

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The `\xff` key-space is reserved for system use, and therefore shouldn’t be used by a client under normal circumstances. However, there are transaction options which grant read-only and full access to the system keys, should you need them. See `set_read_system_keys` and `set_access_system_keys` in our [documentation](https://apple.github.io/foundationdb/api-python.html#transaction-options).

The `strinc` function is designed to produce the key that serves as the exclusive upper-bound for all keys prefixed by the argument. In other words, it is the first key for which the argument is not a prefix. For example, if you call `strinc(banana)`, the result will be `bananb`. There is no such key for any argument that contains only 0 or more `\xff` bytes, which is the reason for the error condition.

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<div class="post-metadata">

**Author:** ![ajbeamon](https://sea1.discourse-cdn.com/foundationdb/user_avatar/forums.foundationdb.org/ajbeamon/32/13_2.png) [@ajbeamon](https://forums.foundationdb.org/u/ajbeamon)\
**Post date:** [May 11, 2018, 5:41pm UTC](https://forums.foundationdb.org/t/is-it-possible-or-useful-to-fetch-the-last-key/400/3 "2018-05-11T17:41:25Z")

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I’ll also add that the system key-space ends at `\xff\xff`, so there are no keys in the database beyond that. However, there are some special “magic” keys that begin with `\xff\xff` which can be read on the client to yield various information, and don’t require any special options to access. For example, the key `\xff\xff/connection_string` returns the contents of the cluster file on the client. Another useful one is `\xff\xff/status/json` to get status information from a client. Sadly, I don’t think there’s one place that documents all of these, but that’s probably something we should try to do. You can see [here](https://apple.github.io/foundationdb/administration.html?#accessing-cluster-file-information-from-a-client) and [here](https://apple.github.io/foundationdb/mr-status.html?#accessing-machine-readable-status) for the documentation of the ones listed above.