Enum fdb::transaction::MutationType

#[non_exhaustive]
pub enum MutationType {
    Add,
    And,
    BitAnd,
    Or,
    BitOr,
    Xor,
    BitXor,
    AppendIfFits,
    Max,
    Min,
    SetVersionstampedKey,
    SetVersionstampedValue,
    ByteMin,
    ByteMax,
    CompareAndClear,
}

A set of operations that can be performed atomically on a database.

These options can be passed to mutate method.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Add

addend

Performs an addition of little-endian integers. If the existing value in the database is not present or shorter than param, it is first extended to the length of param with zero bytes. If param is shorter than the existing value in the database, the existing value is truncated to match the length of param. The integers to be added must be stored in a little-endian representation. They can be signed in two’s complement representation or unsigned. You can add to an integer at a known offset in the value by prepending the appropriate number of zero bytes to param and padding with zero bytes to match the length of the value. However, this offset technique requires that you know the addition will not cause the integer field within the value to overflow.

And

value with which to perform bitwise and

Deprecated

BitAnd

value with which to perform bitwise and

Performs a bitwise and operation. If the existing value in the database is not present, then param is stored in the database. If the existing value in the database is shorter than param, it is first extended to the length of param with zero bytes. If param is shorter than the existing value in the database, the existing value is truncated to match the length of param.

Or

value with which to perform bitwise or

Deprecated

BitOr

value with which to perform bitwise or

Performs a bitwise or operation. If the existing value in the database is not present or shorter than param, it is first extended to the length of param with zero bytes. If param is shorter than the existing value in the database, the existing value is truncated to match the length of param.

Xor

value with which to perform bitwise xor

Deprecated

BitXor

value with which to perform bitwise xor

Performs a bitwise xor operation. If the existing value in the database is not present or shorter than param, it is first extended to the length of param with zero bytes. If param is shorter than the existing value in the database, the existing value is truncated to match the length of param.

AppendIfFits

value to append to the database value

Appends param to the end of the existing value already in the database at the given key (or creates the key and sets the value to param if the key is empty). This will only append the value if the final concatenated value size is less than or equal to the maximum value size (i.e., if it fits). WARNING: No error is surfaced back to the user if the final value is too large because the mutation will not be applied until after the transaction has been committed. Therefore, it is only safe to use this mutation type if one can guarantee that one will keep the total value size under the maximum size.

Max

value to check against database value

Performs a little-endian comparison of byte strings. If the existing value in the database is not present or shorter than param, it is first extended to the length of param with zero bytes. If param is shorter than the existing value in the database, the existing value is truncated to match the length of param. The larger of the two values is then stored in the database.

Min

value to check against database value

Performs a little-endian comparison of byte strings. If the existing value in the database is not present, then param is stored in the database. If the existing value in the database is shorter than param, it is first extended to the length of param with zero bytes. If param is shorter than the existing value in the database, the existing value is truncated to match the length of param. The smaller of the two values is then stored in the database.

SetVersionstampedKey

value to which to set the transformed key

Transforms key using a versionstamp for the transaction. Sets the transformed key in the database to param. The key is transformed by removing the final four bytes from the key and reading those as a little-Endian 32-bit integer to get a position pos. The 10 bytes of the key from pos to pos + 10 are replaced with the versionstamp of the transaction used. The first byte of the key is position 0. A versionstamp is a 10 byte, unique, monotonically (but not sequentially) increasing value for each committed transaction. The first 8 bytes are the committed version of the database (serialized in big-Endian order). The last 2 bytes are monotonic in the serialization order for transactions. WARNING: At this time, versionstamps are compatible with the Tuple layer only in the Java, Python, and Go bindings. Also, note that prior to API version 520, the offset was computed from only the final two bytes rather than the final four bytes.

SetVersionstampedValue

value to versionstamp and set

Transforms param using a versionstamp for the transaction. Sets the key given to the transformed param. The parameter is transformed by removing the final four bytes from param and reading those as a little-Endian 32-bit integer to get a position pos. The 10 bytes of the parameter from pos to pos + 10 are replaced with the versionstamp of the transaction used. The first byte of the parameter is position 0. A versionstamp is a 10 byte, unique, monotonically (but not sequentially) increasing value for each committed transaction. The first 8 bytes are the committed version of the database (serialized in big-Endian order). The last 2 bytes are monotonic in the serialization order for transactions. WARNING: At this time, versionstamps are compatible with the Tuple layer only in the Java, Python, and Go bindings. Also, note that prior to API version 520, the versionstamp was always placed at the beginning of the parameter rather than computing an offset.

ByteMin

value to check against database value

Performs lexicographic comparison of byte strings. If the existing value in the database is not present, then param is stored. Otherwise the smaller of the two values is then stored in the database.

ByteMax

value to check against database value

Performs lexicographic comparison of byte strings. If the existing value in the database is not present, then param is stored. Otherwise the larger of the two values is then stored in the database.

CompareAndClear

Value to compare with

Performs an atomic compare and clear operation. If the existing value in the database is equal to the given value, then given key is cleared.

Trait Implementations

impl Clone for MutationType

fn clone(&self) -> MutationType

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MutationType

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Copy for MutationType