sqlite/README.md

# SQLite — steady-state query execution SimPoint traces

DynamoRIO (drmemtrace) SimPoint traces of **SQLite 3.53.4** executing queries
against an already-populated on-disk database. Database creation, schema
initialization and dataset loading are deliberately **not** in these traces.

| | |
|---|---|
| Traces | 4 SimPoints |
| Instructions per trace | 120,000,000 fetched (60M warmup chunk + 60M SimPoint chunk) |
| Format | drmemtrace offline trace (encoded), one `.zip` per SimPoint |
| Threads | 1 |
| System calls in traced region | 0 |
| Total size | 870 MB |
| Recommended Scarab `--inst_limit` | 120000000 |

```
sqlite/
├── README.md                   this file
├── README_RELEASE.md           release notes, layout, PC->source instructions
├── RELEASE_MANIFEST.json       per-SimPoint segment / cluster / weight / sha256
├── SHA256SUMS                  checksums for every file
├── trace_clustering_info.json  segment size, warmup chunks, flow, excluded phases
├── fingerprint/                BBV fingerprint (bbfp, inscount, pcmap, pieces/)
├── simpoints/                  SimPoint 3.2 output + selection/substitution record
├── traces_simp/
│   ├── trace/{12,22,27,54}.zip the traces
│   └── bin/                    modules.log + the module images it references
├── validation/                 counts, zip/invariant checks, steady-state evidence
└── workload/                   workload description, driver sources, scripts
```

## The application

SQLite is an embedded relational database — the query engine runs in-process,
so a trace of the client is a trace of the database. Nothing is CPU-idle
waiting on a server.

- Source: official amalgamation `sqlite-amalgamation-3530400.zip`
  from <https://www.sqlite.org/2026/>
- Version 3.53.4, source id
  `2026-07-24 19:02:57 bf7c7f30031888f4e796e429ab3978879485813aaca6f641c7b33e4e09459bcc`
- `sqlite3.c` sha256 `b1dd5d74ec7f29055a6684fa06fb3c2f6821c87dd38f9a458dfd2e8a1db28189`
- Built with
  `gcc -O2 -g -no-pie -DSQLITE_THREADSAFE=0 -DSQLITE_OMIT_LOAD_EXTENSION -DSQLITE_DEFAULT_MEMSTATUS=0 -DSQLITE_MAX_MMAP_SIZE=4294967296`

`-no-pie` is deliberate: it makes runtime PCs in the trace equal link-time
addresses, so they map straight back to source.

## The dataset

Synthetic, generated by the untraced setup binary (`workload/src/sqlite_setup.c`)
with a fixed LCG seed, so it is reproducible bit-for-bit:

```sql
CREATE TABLE records(
  id      INTEGER PRIMARY KEY,   -- 1 .. 3,000,000, dense
  k       INTEGER NOT NULL,      -- scattered over [0, 6,000,000), ~1.27 rows/key
  v0      INTEGER NOT NULL,
  v1      INTEGER NOT NULL,
  payload TEXT NOT NULL);        -- 64 bytes
CREATE INDEX idx_k ON records(k);
ANALYZE;
```

3,000,000 rows, 4 KiB pages, **302 MB** database file. `k` is scattered so the
secondary index imposes a different B-tree order than the rowid table, making
index lookups a genuine second descent plus a rowid seek rather than a
sequential walk.

Connection settings for the traced process: `SQLITE_OPEN_READONLY`,
`PRAGMA query_only=ON`, `PRAGMA locking_mode=EXCLUSIVE`,
`PRAGMA mmap_size=2GiB`, `PRAGMA cache_size=-524288`.
`locking_mode=EXCLUSIVE` takes the shared file lock once instead of `fcntl()`-ing
on every implicit read transaction — without it two syscalls per query dominate
the profile and bury the B-tree work. `mmap_size` covers the whole database, so
page reads are served from the mapping and there is no long page-cache warm-up
phase to pollute clustering.

## Query mix

Three rounds of four read-only query phases, all issued from statements
prepared once and `sqlite3_reset()` per iteration:

| phase | query | per round | exercises |
|---|---|---|---|
| 1 | `SELECT v0,v1,payload FROM records WHERE id = ?` | 60,000 | rowid B-tree descent, record lookup |
| 2 | `SELECT id,v0 FROM records INDEXED BY idx_k WHERE k = ?` | 50,000 | index B-tree descent + rowid table seek, key comparison |
| 3 | `SELECT id,v0,v1 FROM records WHERE id BETWEEN ? AND ?` (64 rows) | 4,900 | cursor movement across leaf pages, cell parsing |
| 4 | `SELECT id,k FROM records INDEXED BY idx_k WHERE k BETWEEN ? AND ?` | 5,000 | covering-index cursor movement, record compare |

Whole traced run: **3,383,340,000 fetched instructions**.

## How the excluded phases were excluded

The workload is split into **two separate binaries**, so no excluded-phase code
path is even reachable from the traced process:

| binary | phase | traced |
|---|---|---|
| `sqlite_setup` | database file allocation, `CREATE TABLE`, `CREATE INDEX`, schema initialization, bulk `INSERT` of 3M rows, `ANALYZE` | no |
| `sqlite_query` | steady-state query execution against the existing database | **yes** |

`sqlite_query` contains no DDL and no DML. Its only non-query work is
`sqlite3_open_v2()` plus four `sqlite3_prepare_v2()` calls: **480,604
instructions**, measured on a query-free run. That is 0.014% of the traced run
and under 1% of a single fingerprint segment. The earliest released SimPoint
region starts 660,000,000 instructions in, so none of it appears in any trace.

## Collection method

Flow: `cluster_then_trace` — fingerprint natively, cluster, then capture one
DynamoRIO trace per selected SimPoint. This matches
`scarab-infra/common/scripts/run_simpoint_trace.py` and avoids materializing a
~16 GB whole-run trace.

1. **Fingerprint.** `drrun -disable_traces -max_bb_instrs 256 -opt_cleancall 2
   -c libfpg.so -no_use_bb_pc -segment_size 60000000` over the whole
   `sqlite_query` run → 57 segments of 60,000,000 instructions.
2. **Cluster.** SimPoint 3.2, `-maxK 5 -dim 100 -fixedLength off -numInitSeeds 10
   -coveragePct .99`. BIC chose **k = 4**, and the clusters recovered exactly the
   four query phases and their three repetitions:

   | cluster | segments | query phase | representative |
   |---|---|---|---|
   | 2 | 0-4, 19-22, 38-41 | rowid point lookups | 22 |
   | 3 | 5-8, 23-27, 42-46 | index lookups | 27 |
   | 1 | 9-13, 28-32, 47-51 | rowid range scans | 12 |
   | 0 | 14-18, 33-37, 52-56 | index range scans | 54 |

   SimPoint's own representative for cluster 0 was segment 56, the partial
   trailing segment (16,512,018 instructions). It was replaced by segment 54,
   the next-closest full segment to the centroid (0.0371956 vs 0.0366442);
   recorded in `simpoints/substitutions.txt`. Every representative's preceding
   segment is in the same cluster, so each archive's warmup chunk is in the same
   query phase as its measured chunk.
3. **Trace.** Per SimPoint,
   `drrun -t drcachesim -offline -count_fetched_instrs -trace_after_instrs <seg-1>*60M
   -trace_for_instrs 120000000`.
4. **Convert.** `portabilize_trace.py`, then
   `drraw2trace -chunk_instr_count 60000000`.
5. **Minimize.** Keep `chunk.0000` (warmup) + `chunk.0001` (SimPoint region) →
   120,000,000 instructions per released archive.

Tooling: DynamoRIO 10.0.0, SimPoint 3.2, fingerprint client `libfpg.so`, all
inside container image `allbench_traces:00022fc`. Capture host
`clnode130.clemson.cloudlab.us`.

## The traces

| file | segment | cluster | weight | query phase | size |
|---|---|---|---|---|---|
| `traces_simp/trace/22.zip` | 22 | 2 | 0.231008 | rowid point lookups | 387 MB |
| `traces_simp/trace/27.zip` | 27 | 3 | 0.248778 | index lookups | 367 MB |
| `traces_simp/trace/12.zip` | 12 | 1 | 0.266548 | rowid range scans | 75 MB |
| `traces_simp/trace/54.zip` | 54 | 0 | 0.253666 | index range scans | 69 MB |

Weights sum to 1.0. All four archives contain exactly 120,000,000 fetched
instructions, pass `unzip -t`, pass `drcachesim -simulator_type
invariant_checker`, and have distinct sha256 values.

## Verification that this is the steady state

Two independent methods, both under `validation/steady_state/`.

**Exhaustive, instruction-exact.** `function_profile-segment-<N>.txt` attributes
100% of each archive's 120,000,000 instructions to functions, computed from the
BBV fingerprint of the identical deterministic run. Query execution accounts for
85.2-96.3% of every window:

| segment | query phase | query-execution share | dominant functions |
|---|---|---|---|
| 22 | rowid point lookups | 85.24% | `sqlite3VdbeExec` 18.4%, `sqlite3BtreeTableMoveto` 12.1%, `sqlite3GetVarint` 10.7%, `getPageMMap` 5.3% |
| 27 | index lookups | 86.36% | `sqlite3BtreeIndexMoveto` 13.6%, `sqlite3VdbeExec` 12.9%, `vdbeRecordCompareInt` 7.9%, `getPageMMap` 6.2% |
| 12 | rowid range scans | 96.31% | `sqlite3VdbeExec` 59.7%, `btreeParseCellPtr` 5.2%, `sqlite3VdbeSerialGet` 3.8%, `sqlite3BtreeNext` 1.7% |
| 54 | index range scans | 96.34% | `sqlite3VdbeExec` 49.2%, `sqlite3VdbeRecordCompareWithSkip` 8.9%, `sqlite3VdbeMemFromBtreeZeroOffset` 4.8% |

The remainder is SQLite support code (memory management, `sqlite3VdbeMemRelease`,
value conversion) plus a fraction of a percent of libc.

**Independent, from the trace files themselves.**
`trace_hot_functions-segment-<N>.txt` runs `drcachesim -simulator_type histogram`
on each `.zip` and maps the hot instruction-fetch lines through `nm` and
`modules.log`. Same functions, same ordering.

**Negative check.** `excluded_phase_check.tsv` reports the instruction count of
every database-creation, schema-initialization, dataset-population and
SQL-compilation function in each archive — `sqlite3BtreeInsert`,
`balance_nonroot`, `allocateBtreePage`, `sqlite3PagerWrite`, `insertCell`,
`sqlite3CreateIndex`, `sqlite3StartTable`, `sqlite3InitOne`, `sqlite3AnalysisLoad`,
`sqlite3RunParser`, `sqlite3Prepare`, `sqlite3WhereBegin`, and others:

> **0 instructions, in all four archives, in all four categories.**

Note on classification: `sqlite3BtreeBeginTrans` / `sqlite3BtreeCommitPhaseTwo`
do appear. On a read-only, `query_only=ON` connection these are the per-query
*read*-transaction begin and teardown — query execution state management, not
writes — so they are counted as query execution. No write path is reachable.

`validation/basic_counts/` additionally shows 1 thread and **0 system-call
markers** per archive: the traced regions are pure userspace B-tree work.

## Mapping runtime PCs back to source

`traces_simp/bin/modules.log` is the DynamoRIO module table recorded at capture
time (load base, extent, path for every module). The module images it references
are shipped alongside it, so PCs resolve all the way to source. The main binary
is at `0x400000` (`-no-pie`) and carries `-g` debug info, so a trace PC in that
range is already a link-time address:

```bash
addr2line -f -C -e traces_simp/bin/sqlite_query 0x497d40
```

For other modules subtract the module `start` from `modules.log`, or pass
`-alt_module_dir traces_simp/bin` to drcachesim tools.
`workload/bin/sqlite_query.nm` holds the symbol table.

## Reproducing

`workload/src/` contains everything: `sqlite_setup.c`, `sqlite_query.c`,
`build.sh`, `trace_simpoints.sh`, `validate.sh`, `verify_steady_state.py`,
`fp_funcs.py`, `trace_pc_funcs.py`.

```bash
bash build.sh                                                      # build both binaries
./sqlite_setup /path/records.db 3000000                            # untraced: create + load
./sqlite_query /path/records.db 3 60000 50000 4900 5000 3000000    # the traced phase
```

## Layout note

`fingerprint/` holds `bbfp`, `bbfp.inscount`, `pcmap`, `pieces/segment.N` and
`segment_size`. It does not have the `fingerprint/0..N/PARAMS.in` directories or
`footprint_pieces/` seen in the `leveldb` / `duckdb` / `rocksdb` folders of this
dataset — those are artifacts of the `trace_then_cluster` flow, which
fingerprints a materialized whole-run trace with Scarab. Everything else matches
that layout exactly. The flow used here is recorded in
`trace_clustering_info.json`.