281 lines
12 KiB
Markdown
281 lines
12 KiB
Markdown
# bsdaily
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[bsdaily](https://git.eeqj.de/sneak/bsdaily) is a command-line utility
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written in [Go](https://golang.org) that carves a single day (or a range of
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days) of [Bluesky](https://bsky.app) firehose data out of a large,
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continuously-growing SQLite database and writes it out as a self-contained,
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[zstd](https://facebook.github.io/zstd/)-compressed SQL dump. The dumps are
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named by date (e.g. `2026-06-27.sql.zst`), organized into per-month
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directories, and are designed to be published, archived, mirrored, and later
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re-merged back into a single database.
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The source database is read from a read-only [ZFS](https://openzfs.org)
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snapshot, so extraction never contends with the live firehose ingester that
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is writing to the original database. The tool is operationally
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conservative: it checks free disk space before starting, copies the snapshot
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to fast scratch storage, processes one day at a time to avoid SQLite lock
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contention, verifies every compressed output before publishing it, and
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writes output atomically via a temp-file-and-rename so a partial run never
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leaves a corrupt `.sql.zst` behind.
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This project was written by [@sneak](https://sneak.berlin) to produce a
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daily, mergeable, publicly-mirrorable archive of the Bluesky firehose. It is
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currently a one-person effort. The current version is pre-1.0 and there has
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not yet been a versioned release; [SemVer](https://semver.org) will be used
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for releases.
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# Build Status
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CI runs the standard `make check` (formatting, linting, tests). The `main`
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branch must always be green.
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# Participation
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Primary development happens on a privately-run Gitea instance at
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[https://git.eeqj.de/sneak/bsdaily](https://git.eeqj.de/sneak/bsdaily) and
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issues are [tracked
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there](https://git.eeqj.de/sneak/bsdaily/issues).
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Changes must always be formatted with a standard `go fmt`, syntactically
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valid, and must pass the linting defined in the repository (presently the
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`golangci-lint` defaults), which can be run with a `make lint`. The `main`
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branch is protected and all changes must be made via [pull
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requests](https://git.eeqj.de/sneak/bsdaily/pulls) and pass CI to be merged.
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See [`REPO_POLICIES.md`](REPO_POLICIES.md) for detailed coding standards,
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tooling requirements, and workflow conventions.
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# Entrypoints
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This repository adheres to the
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[Scripts to Rule Them All](https://github.com/github/scripts-to-rule-them-all)
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standard: normalized scripts in `script/` are the entrypoints for the
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development workflow, and the Makefile targets are thin shims that call
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them. We provide:
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- `script/bootstrap` — install all development dependencies (go,
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golangci-lint, Go module download)
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- `script/setup` — make a fresh clone ready for development: runs
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`script/bootstrap`, then `script/install-precommit`
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- `script/projectname` — print the project name (used for the Docker
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image tag)
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- `script/test` — run the test suite (verbose rerun on failure)
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- `script/lint` — run `golangci-lint run ./...`
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- `script/fmt` — format all code (writes)
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- `script/fmt-check` — check formatting (read-only)
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- `script/check` — run `script/test`, `script/lint`, and
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`script/fmt-check`
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- `script/docker` — build the Docker image tagged via
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`script/projectname`
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- `script/cibuild` — CI entrypoint: `docker build .` (the Dockerfile
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runs the checks)
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- `script/precommit` — pre-commit gate: `go mod tidy` + `go fmt` (must
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not change files), then `script/check`
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- `script/install-precommit` — install the git pre-commit hook that
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runs `script/precommit`
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# Problem Statement
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A Bluesky firehose ingester writes every observed post (and associated
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users, hashtags, URLs, and media references) into a single ever-growing
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SQLite database, `firehose.db`. This database has several properties that
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make it awkward to publish or archive directly:
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- It is **large and always growing**, so re-publishing the whole thing every
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day is wasteful.
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- It is **continuously written**, so reading from it directly risks lock
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contention with the live ingester and inconsistent reads.
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- It is **monolithic**, so there is no natural unit at which to mirror,
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share, or distribute "just yesterday's posts".
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What is wanted instead is a stable, immutable, per-day artifact: a small
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file containing exactly one calendar day of firehose data, cheap to publish,
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cheap to mirror, and trivially re-mergeable into a full database by anyone
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who collects a set of them.
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# Proposed Solution
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A tool, `bsdaily`, that:
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- locates the most recent read-only **ZFS daily snapshot** of the firehose
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filesystem, so it reads from a consistent point-in-time copy that the live
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ingester cannot be writing to;
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- copies the snapshot's database files to fast scratch storage;
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- **extracts** a single day's `posts` (and all rows reachable from them) into
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a fresh, minimal per-day SQLite database;
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- **dumps** that per-day database to SQL and pipes it through multithreaded
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zstd compression;
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- **verifies** the compressed output (zstd integrity check plus a sanity
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check that the decompressed stream actually looks like SQL);
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- **publishes** the result atomically as
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`DailiesBase/YYYY-MM/YYYY-MM-DD.sql.zst`.
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Each daily dump is emitted with `INSERT` statements over the full schema
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(including the deduplicated `users`, `hashtags`, and `urls` lookup tables),
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so any collection of daily dumps can be merged into a single database by
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rewriting `INSERT INTO` to `INSERT OR IGNORE INTO` and replaying them in
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sequence. Two helper scripts ([`merge_daily_dumps.sh`](merge_daily_dumps.sh)
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and [`regenerate_auxiliary_tables.sql`](regenerate_auxiliary_tables.sql)) are
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included to do exactly this and to rebuild the aggregate statistics
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(`use_count`, `first_seen`, user `resolved_at`/`updated_at`) afterward.
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# Design Goals
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- **Never disturb the live ingester.** All reads come from a ZFS snapshot,
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never the live database.
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- **Crash-safe, idempotent runs.** Output is written to a temp file and
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atomically renamed; a day whose final output already exists is skipped, so
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re-running a range is safe and resumable.
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- **Mergeable output.** Daily dumps re-combine losslessly into a full
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database via `INSERT OR IGNORE`.
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- **Operationally cautious.** Free-space preflight checks on both scratch and
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output filesystems; explicit verification of every artifact before it is
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published.
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- **Fast where it's free.** Large snapshot copies use a 256MiB buffer,
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pre-allocate the destination, and (on Linux) issue `posix_fadvise`
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sequential/willneed hints; extraction uses aggressive,
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crash-unsafe-by-design SQLite pragmas because the working data lives only
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in disposable scratch space.
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# Non-Goals
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- **Real-time export.** `bsdaily` operates on daily snapshots; the freshest
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day it can produce is the snapshot date minus one.
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- **Schema ownership.** The schema is defined by the upstream firehose
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ingester; [`schema.sql`](schema.sql) is included for reference only.
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`bsdaily` copies whatever table and index DDL it finds in the source.
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- **Cross-platform deployment.** It is built and run on Linux (the
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free-space check and fadvise hints use `golang.org/x/sys/unix`; a non-Linux
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build compiles but is a no-op for the fadvise hints). The hard-coded paths
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assume the production host's ZFS layout.
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# How It Works
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A single run proceeds as follows:
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1. **Find the snapshot.** Scan `SnapshotBase` for directories matching
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`zfs-auto-snap_daily-YYYY-MM-DD-NNNN`, pick the most recent, and confirm
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it contains `firehose.db`.
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2. **Determine target days.** Default to the snapshot date minus one day;
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or use `--date`, or every day in the inclusive `--from`/`--to` range.
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3. **Preflight disk space.** Require at least 500GiB free on the scratch
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filesystem and 20GiB free on the output filesystem.
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4. **Copy the database to scratch.** Copy `firehose.db`, its `-wal`, and (if
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present) its `-shm` from the snapshot into a fresh temp directory under
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`TmpBase`.
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5. **Per day**, processed strictly one at a time to avoid SQLite contention:
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- skip the day if its final output file already exists;
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- `ATTACH` the copied source DB to a new empty per-day DB, recreate the
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table DDL, and `INSERT ... SELECT` the target day's `posts` plus all
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rows reachable from them (`posts_hashtags`, `posts_urls`, `hashtags`,
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`urls`, `users`, and `media` if that table exists);
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- abort the day cleanly if there are zero posts (`ErrNoPosts`), rather
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than emitting an empty dump;
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- recreate indexes, detach the source, and verify the inserted row count;
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- `sqlite3 .dump | zstdmt` into a hidden temp file;
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- run a zstd integrity check and confirm the decompressed head looks like
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SQL;
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- atomically rename into place and delete the per-day scratch DB.
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6. **Clean up** the temp directory and log a processed/skipped/total summary.
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# Usage
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```
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bsdaily # extract the snapshot date minus one day
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bsdaily --date 2026-06-27 # extract a single specific day
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bsdaily --from 2026-06-01 --to 2026-06-27 # extract an inclusive range
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```
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Flags:
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- `-d`, `--date YYYY-MM-DD` — extract a single day. Mutually exclusive with
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`--from`/`--to`.
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- `--from YYYY-MM-DD` — start of an inclusive range (requires `--to`).
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- `--to YYYY-MM-DD` — end of an inclusive range (requires `--from`).
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With no flags, the tool extracts the day before the latest snapshot. All
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progress is logged as structured `slog` text to stderr.
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## Merging dumps back into a database
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```
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# Using the helper script:
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./merge_daily_dumps.sh merged.db daily_dumps/*.sql.zst
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# Or by hand:
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zstdcat *.sql.zst | sed 's/INSERT INTO/INSERT OR IGNORE INTO/g' | sqlite3 merged.db
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sqlite3 merged.db < regenerate_auxiliary_tables.sql
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```
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# Requirements
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- **Go** (see [`go.mod`](go.mod) for the toolchain version) to build.
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- **Linux** for production use (ZFS snapshots, `statfs` free-space checks,
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`posix_fadvise` hints).
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- The **`sqlite3`** and **`zstdmt`** (multithreaded zstd) binaries on
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`PATH`; `zstdcat` is used for verification. SQLite reads/writes during
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extraction use the pure-Go [`modernc.org/sqlite`](https://pkg.go.dev/modernc.org/sqlite)
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driver, so no cgo is required for that part.
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# Configuration
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Operational parameters are compile-time constants in
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[`internal/bsdaily/config.go`](internal/bsdaily/config.go):
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- `SnapshotBase` — `/srv/berlin.sneak.fs.blueskyarchive/.zfs/snapshot`
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- `TmpBase` — `/srv/storage/tmp` (fast scratch space for copies + per-day DBs)
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- `DailiesBase` — `/srv/berlin.sneak.fs.bluesky-dailies` (output root)
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- `MinTmpFreeGB` / `MinDailiesFreeGB` — `500` / `20`
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- `zstdCompressionLevel` — `15`
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- `sqliteCacheSizeKB` — `200000` (≈200MB)
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These are tuned for one specific production host; adjust and rebuild to run
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elsewhere.
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# Data Model
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The firehose schema (reference copy in [`schema.sql`](schema.sql)) centers
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on a `posts` table, with `users` keyed by DID and many-to-many junction
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tables linking posts to deduplicated `hashtags` and `urls`. An optional
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`media` table tracks downloaded blobs by content hash. `bsdaily` does not
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own this schema; it reflects whatever DDL exists in the source snapshot and
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selects forward from `posts` along the foreign-key relationships to produce a
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referentially-complete per-day slice.
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# Use Cases
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## Daily public archive
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Publish one small, immutable file per day to static HTTP (or IPFS, or a
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mirror network) so that anyone can fetch exactly the day(s) they want and
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re-merge them locally.
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## Backfilling a range
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Run `--from`/`--to` over a span of dates to (re)generate any missing daily
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dumps; already-published days are skipped, so the operation is resumable and
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safe to re-run.
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## Reconstituting a full database
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Collect any set of daily dumps and merge them with `INSERT OR IGNORE` to
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rebuild a complete, queryable SQLite database, then regenerate the aggregate
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statistics tables.
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# See Also
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## Links
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- Repo: [https://git.eeqj.de/sneak/bsdaily](https://git.eeqj.de/sneak/bsdaily)
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- Issues: [https://git.eeqj.de/sneak/bsdaily/issues](https://git.eeqj.de/sneak/bsdaily/issues)
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- Bluesky: [https://bsky.app](https://bsky.app)
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- zstd: [https://facebook.github.io/zstd/](https://facebook.github.io/zstd/)
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# Authors
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- [@sneak <sneak@sneak.berlin>](mailto:sneak@sneak.berlin)
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# License
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- [WTFPL](https://wtfpl.net)
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