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// Copyright Materialize, Inc. and contributors. All rights reserved.
//
// Use of this software is governed by the Business Source License
// included in the LICENSE file.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0.
use std::collections::BTreeMap;
use std::iter;
use std::sync::LazyLock;
use differential_dataflow::lattice::Lattice;
use differential_dataflow::operators::arrange::Arranged;
use differential_dataflow::trace::cursor::IntoOwned;
use differential_dataflow::trace::{Batch, BatchReader, Cursor, TraceReader};
use differential_dataflow::{AsCollection, Collection};
use itertools::{EitherOrBoth, Itertools};
use maplit::btreemap;
use mz_ore::cast::CastFrom;
use mz_repr::{ColumnName, ColumnType, Datum, Diff, GlobalId, Row, RowPacker, ScalarType};
use timely::dataflow::channels::pact::Pipeline;
use timely::dataflow::operators::Operator;
use timely::dataflow::{Scope, Stream};
use crate::avro::DiffPair;
/// Given a stream of batches, produce a stream of groups of DiffPairs, grouped
/// by key, at each timestamp.
///
// This is useful for some sink envelopes (e.g., Debezium and Upsert), which
// need to do specific logic based on the _entire_ set of before/after diffs for
// a given key at each timestamp.
pub fn combine_at_timestamp<G: Scope, Tr>(
arranged: Arranged<G, Tr>,
) -> Collection<G, (Option<Row>, Vec<DiffPair<Row>>), Diff>
where
G::Timestamp: Lattice + Copy,
Tr: Clone
+ for<'a> TraceReader<
Key<'a> = &'a Option<Row>,
Val<'a> = &'a Row,
Time = G::Timestamp,
Diff = Diff,
>,
Tr::Batch: Batch,
for<'a> Tr::TimeGat<'a>: Ord,
{
let mut rows_buf = vec![];
let x: Stream<G, ((Option<Row>, Vec<DiffPair<Row>>), G::Timestamp, Diff)> = arranged
.stream
.unary(Pipeline, "combine_at_timestamp", move |_, _| {
move |input, output| {
while let Some((cap, batches)) = input.next() {
let mut session = output.session(&cap);
batches.swap(&mut rows_buf);
for batch in rows_buf.drain(..) {
let mut befores = vec![];
let mut afters = vec![];
let mut cursor = batch.cursor();
while cursor.key_valid(&batch) {
let k = cursor.key(&batch);
// Partition updates into retractions (befores)
// and insertions (afters).
while cursor.val_valid(&batch) {
let v = cursor.val(&batch);
cursor.map_times(&batch, |t, diff| {
let diff = diff.into_owned();
let update = (
t.into_owned(),
v.clone(),
usize::cast_from(diff.unsigned_abs()),
);
if diff < 0 {
befores.push(update);
} else {
afters.push(update);
}
});
cursor.step_val(&batch);
}
// Sort by timestamp.
befores.sort_by_key(|(t, _v, _diff)| *t);
afters.sort_by_key(|(t, _v, _diff)| *t);
// Convert diff into unary representation.
let befores = befores
.drain(..)
.flat_map(|(t, v, cnt)| iter::repeat((t, v)).take(cnt));
let afters = afters
.drain(..)
.flat_map(|(t, v, cnt)| iter::repeat((t, v)).take(cnt));
// At each timestamp, zip together the insertions
// and retractions into diff pairs.
let groups = itertools::merge_join_by(
befores,
afters,
|(t1, _v1), (t2, _v2)| t1.cmp(t2),
)
.map(|pair| match pair {
EitherOrBoth::Both((t, before), (_t, after)) => {
(t, Some(before.clone()), Some(after.clone()))
}
EitherOrBoth::Left((t, before)) => (t, Some(before.clone()), None),
EitherOrBoth::Right((t, after)) => (t, None, Some(after.clone())),
})
.group_by(|(t, _before, _after)| *t);
// For each timestamp, emit the group of
// `DiffPair`s.
for (t, group) in &groups {
let group = group
.map(|(_t, before, after)| DiffPair { before, after })
.collect();
session.give(((k.clone(), group), t, 1));
}
cursor.step_key(&batch);
}
}
}
}
});
x.as_collection()
}
// NOTE(benesch): statically allocating transient IDs for the
// transaction and row types is a bit of a hack to allow us to attach
// custom names to these types in the generated Avro schema. In the
// future, these types should be real types that get created in the
// catalog with userspace IDs when the user creates the sink, and their
// names and IDs should be plumbed in from the catalog at the moment
// the sink is created.
pub(crate) const TRANSACTION_TYPE_ID: GlobalId = GlobalId::Transient(1);
pub(crate) const DBZ_ROW_TYPE_ID: GlobalId = GlobalId::Transient(2);
pub static ENVELOPE_CUSTOM_NAMES: LazyLock<BTreeMap<GlobalId, String>> = LazyLock::new(|| {
btreemap! {
TRANSACTION_TYPE_ID => "transaction".into(),
DBZ_ROW_TYPE_ID => "row".into(),
}
});
pub(crate) fn dbz_envelope(
names_and_types: Vec<(ColumnName, ColumnType)>,
) -> Vec<(ColumnName, ColumnType)> {
let row = ColumnType {
nullable: true,
scalar_type: ScalarType::Record {
fields: names_and_types,
custom_id: Some(DBZ_ROW_TYPE_ID),
},
};
vec![("before".into(), row.clone()), ("after".into(), row)]
}
pub fn dbz_format(rp: &mut RowPacker, dp: DiffPair<Row>) {
if let Some(before) = dp.before {
rp.push_list_with(|rp| rp.extend_by_row(&before));
} else {
rp.push(Datum::Null);
}
if let Some(after) = dp.after {
rp.push_list_with(|rp| rp.extend_by_row(&after));
} else {
rp.push(Datum::Null);
}
}