sqlite-optimization

A guide to improving SQLite applications. SQLite is a database stored in a file; the guide covers read/write settings, relationships, indexes, query inspection, and safe concurrent writes.

In plain words
What is it for?
Use it to configure SQLite, add useful indexes, inspect query plans, and coordinate writes from multiple threads.
Why use it?
It helps address slow queries and database-lock errors when an application has several readers or writes at the same time.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/vikasudasi/skill-vault/sqlite-optimization
Any agent
npx skills add vikasudasi/skill-vault --skill sqlite-optimization
Clone the repo
git clone --depth 1 https://github.com/vikasudasi/skill-vault

Made for: Claude Code, Codex.

Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 445 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00026 $0.00445
Opus 5 $0.00013 $0.00222
Sonnet 5 $0.00005 $0.00089
Haiku 4.5 $0.00003 $0.00044

Measured yesterday against content hash d87afb70a02f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

sqlite-optimization scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/sqlite_bench.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skill_vault/data/skills/sqlite-optimization/SKILL.md · 57 lines

What it actually says

SQLite Optimization for Application Use

Use when your SQLite-backed app is slow, hitting lock errors, or you're scaling a single-file database for concurrent readers.

Connection setup (do this every time)

PRAGMA journal_mode=WAL;
PRAGMA foreign_keys=ON;
PRAGMA synchronous=NORMAL;

WAL lets readers run concurrently with a single writer; synchronous=NORMAL is safe with WAL and much faster than FULL.

Indexes

  • Index foreign keys and columns used in WHERE/JOIN/ORDER BY.
  • A composite index (a, b) serves WHERE a=? AND WHERE a=? AND b=?, not WHERE b=?.
  • Confirm with EXPLAIN QUERY PLAN.

Concurrency-safe writes

One shared connection with check_same_thread=False needs a single lock around any multi-statement transaction — serialize writes through one threading.RLock (see Skill Vault's db_lock). Interleaved statements on one connection raise cannot start a transaction within a transaction.

Profiling

EXPLAIN QUERY PLAN SELECT ...
.timer on

Read the plan left-to-right; a SCAN on a big table usually means a missing index.

Pitfalls

  • PRAGMA journal_mode=WAL survives per connection, but must be set on the connection that does the work — set it once at connect.
  • Don't open a new connection per query in a loop; reuse one and lock writes.
  • Back up with sqlite3 .backup or conn.backup() (WAL safe), never by copying the file alone.
Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 57 lines · 26 tokens per session scan A d87afb70a02f

Subscribe to this mod's changes

sqlite-optimization is a skill published in the GitHub repository vikasudasi/skill-vault (0 stars, last pushed 16d ago), licensed Apache-2.0. It adds 26 tokens to every session and 445 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.