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docs: adding context to timeuuid using v1 feature #980

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May 13, 2024
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docs: adding context to timeuuid using v1 feature #980

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docs: adding context to timeuuid using v1 feature
danielhe4rt Apr 23, 2024
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docs: adding context to timeuuid creation
danielhe4rt May 2, 2024
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docs: adding context to timeuuid using v1 feature
danielhe4rt May 12, 2024
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7 changes: 7 additions & 0 deletions Cargo.lock.msrv
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51 changes: 47 additions & 4 deletions docs/source/data-types/timeuuid.md
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Original file line number Diff line number Diff line change
@@ -1,8 +1,8 @@
# Timeuuid

`Timeuuid` is represented as `value::CqlTimeuuid`.
`value::CqlTimeuuid` is a wrapper for `uuid::Uuid` with custom ordering logic
which follows Scylla/Cassandra semantics.
The `Timeuuid` type is represented as `value::CqlTimeuuid`.

Also, `value::CqlTimeuuid` is a wrapper for `uuid::Uuid` with custom ordering logic which follows Scylla/Cassandra semantics.
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```rust
# extern crate scylla;
Expand All @@ -27,4 +27,47 @@ if let Some(rows) = session.query("SELECT a FROM keyspace.table", &[]).await?.ro
}
# Ok(())
# }
```
```

## Creating your own Timeuuid

To create your own `Timeuuid` objects from timestamp-based `uuid` v1, you need to enable the feature `v1` of `uuid` crate using:

```shell
cargo add uuid -F v1
```

and now you're gonna be able to use the `uuid::v1` features:

```rust
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# extern crate uuid;
# extern crate scylla;
# use scylla::Session;
# use std::error::Error;
# use std::str::FromStr;
use scylla::IntoTypedRows;
use scylla::frame::value::CqlTimeuuid;
use uuid::Uuid;
# async fn check_only_compiles(session: &Session) -> Result<(), Box<dyn Error>> {

// Tip: you can use random stable numbers or your MAC Address
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let node_id = [0x12, 0x34, 0x56, 0x78, 0x9A, 0xBC];

// Build your Timeuuid with the current timestamp
let to_insert = CqlTimeuuid::from(Uuid::now_v1(&node_id));

session
.query("INSERT INTO keyspace.table (a) VALUES(?)", (to_insert,))
.await?;

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// Read timeuuid from the table
if let Some(rows) = session.query("SELECT a FROM keyspace.table", &[]).await?.rows {
for row in rows.into_typed::<(CqlTimeuuid,)>() {
let (timeuuid_value,): (CqlTimeuuid,) = row?;
}
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Don't use raw rows field on QueryResult; prefer rows_typed::<(CqlTimeuuid,)>() method:

Suggested change
if let Some(rows) = session.query("SELECT a FROM keyspace.table", &[]).await?.rows {
for row in rows.into_typed::<(CqlTimeuuid,)>() {
let (timeuuid_value,): (CqlTimeuuid,) = row?;
}
}
let mut iter = session.query("SELECT a FROM keyspace.table", &[]).await?.rows_typed::<(CqlTimeuuid,)>();
while let Some((timeuuid_value,)) = iter.next().transpose()? {
// do something with timeuuid_value
}

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I'll update, but can you explain in details why I shouldn't use it?

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Fixed! Ready to merge.

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rows make you interact with an untyped, materialised vec of columns. At the present state of the driver, the main drawback is reduced type safety; as you call into_typed anyway, this negative aspect is mitigated.
Another reason for avoiding using rows ATM, which is relevant here, is the ongoing deserialization refactor. We ditch the materialized vec of CqlValue at all to reduce unnecessary allocations. The new deserialization framework is lazy, which means that the values are going to be deserialized on-the-fly straight to the end type, based on the type provided in the iterator (rows_typed::<T>).
With the new framework having landed in the driver, rows will be removed at all (although their capabilities can be emulated for the users that really need them).

See #955

}
# Ok(())
# }
```

Learn more about UUID::v1 [here](https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_1_(date-time_and_MAC_address)).
2 changes: 1 addition & 1 deletion examples/Cargo.toml
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Expand Up @@ -16,7 +16,7 @@ tracing = "0.1.25"
tracing-subscriber = { version = "0.3.14", features = ["env-filter"] }
chrono = { version = "0.4", default-features = false }
time = { version = "0.3.22" }
uuid = "1.0"
uuid = { version = "1.0", features = ["v1"]}
tower = "0.4"
stats_alloc = "0.1"
clap = { version = "3.2.4", features = ["derive"] }
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