dsfb_database/adapters/
ceb.rs

1//! CEB adapter (Cardinality Estimation Benchmark, Negi et al.).
2//!
3//! Real subset CSV columns (after `scripts/fetch_ceb.sh` exports the
4//! pickle to CSV):
5//!   * `query_id`, `subplan_id`
6//!   * `true_rows` (ground truth from PostgreSQL `EXPLAIN ANALYZE`)
7//!   * `est_rows` (PostgreSQL optimiser estimate)
8//!   * optional: `query_class`, `template_id`
9//!
10//! What we extract:
11//!   * `Cardinality` — `log10(true_rows / est_rows)` per `(query_id, subplan_id)`.
12//!     This is the only public dataset in our stack with **ground-truth
13//!     cardinalities**, which is why we treat its results as the
14//!     cardinality-mismatch motif's primary empirical evidence.
15//!
16//! What we cannot extract:
17//!   * Latency, plan changes over time, contention, cache I/O — CEB is a
18//!     batch benchmark, not a temporal trace; we synthesise time as
19//!     `t = subplan_index_within_query + query_index * 1.0` so the trace is
20//!     well-defined.
21
22use super::DatasetAdapter;
23use crate::residual::{cardinality, ResidualStream};
24use anyhow::{Context, Result};
25use rand::{Rng, SeedableRng};
26use std::collections::HashMap;
27use std::path::Path;
28
29/// Upper bound on the number of CEB rows loaded from a CSV. The
30/// published CEB release is ~13k rows; this ~7000× headroom catches
31/// runaway input without silently truncating realistic datasets.
32const MAX_CEB_ROWS: usize = 100_000_000;
33
34pub struct Ceb;
35
36#[derive(Debug, serde::Deserialize)]
37struct Row {
38    query_id: String,
39    subplan_id: String,
40    true_rows: f64,
41    est_rows: f64,
42}
43
44impl DatasetAdapter for Ceb {
45    fn name(&self) -> &'static str {
46        "ceb"
47    }
48
49    fn load(&self, path: &Path) -> Result<ResidualStream> {
50        let mut rdr = csv::Reader::from_path(path)
51            .with_context(|| format!("opening ceb csv at {}", path.display()))?;
52        let mut rows: Vec<Row> = rdr
53            .deserialize()
54            .filter_map(Result::ok)
55            .take(MAX_CEB_ROWS)
56            .collect();
57        debug_assert!(rows.len() <= MAX_CEB_ROWS, "iterator bound enforced");
58        rows.sort_by(|a, b| a.query_id.cmp(&b.query_id));
59        let mut stream = ResidualStream::new(format!(
60            "ceb@{}",
61            path.file_name().and_then(|n| n.to_str()).unwrap_or("?")
62        ));
63        // Synthesise a time index: each query gets one second; subplans
64        // within a query are spaced 0.01 s apart.
65        let mut q_index: HashMap<String, usize> = HashMap::new();
66        let mut sp_index: HashMap<String, usize> = HashMap::new();
67        for r in &rows {
68            let next_q = q_index.len();
69            let qi = *q_index.entry(r.query_id.clone()).or_insert(next_q);
70            let next_sp = sp_index.len();
71            let sp = *sp_index
72                .entry(format!("{}#{}", r.query_id, r.subplan_id))
73                .or_insert(next_sp);
74            let t = qi as f64 + (sp % 100) as f64 * 0.01;
75            cardinality::push(
76                &mut stream,
77                t,
78                &format!("{}#{}", r.query_id, r.subplan_id),
79                r.est_rows,
80                r.true_rows,
81            );
82        }
83        stream.sort();
84        Ok(stream)
85    }
86
87    fn exemplar(&self, seed: u64) -> ResidualStream {
88        let mut rng = rand_pcg::Pcg64::seed_from_u64(seed);
89        let mut stream = ResidualStream::new(format!("ceb-exemplar-seed{seed}"));
90        // 200 queries; subplans 1..=10. The first 100 queries have
91        // well-calibrated estimates; queries 100..200 develop a 30x
92        // under-estimate on subplan 7 (a join with stale stats).
93        //
94        // Channels in the exemplar are *per-subplan-template* (`sp{n}`),
95        // not per-(query, subplan), because the operator-meaningful
96        // grouping for cardinality drift is "the same logical join
97        // across queries" — and a per-(query, subplan) channel would
98        // contain a single sample, which the EMA cannot smooth.
99        // Real-data CEB load (`load(path)`) keeps the
100        // per-(query, subplan) channel because each subplan in CEB is a
101        // distinct statement; the exemplar collapses for demo clarity.
102        for q in 0..200 {
103            for sp in 1..=10 {
104                let t = q as f64 + (sp as f64) * 0.01;
105                let true_rows: f64 = 1000.0_f64 * (1.0 + rng.gen_range(0.0..2.0));
106                let est_rows: f64 = if q >= 100 && sp == 7 {
107                    true_rows / 30.0
108                } else {
109                    true_rows * (1.0 + rng.gen_range(-0.1..0.1))
110                };
111                cardinality::push(&mut stream, t, &format!("sp{sp}"), est_rows, true_rows);
112            }
113        }
114        stream.sort();
115        stream
116    }
117}
dsfb_database/adapters/ceb.rs

dsfb_database/adapters/
ceb.rs
