molt-fetch

A guide for bulk-migrating data from PostgreSQL, MySQL, Oracle, or MSSQL into CockroachDB. It covers storage choices, table handling, resuming failed loads, and checking the result.

In plain words
What is it for?
Use it to configure and run initial database loads with cloud storage, direct transfer, or local storage, then verify the migrated data.
Why use it?
It gives you a defined way to move an existing database and choose how data is transferred. It also makes destructive options, such as dropping and recreating target tables, explicit.

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/cockroachdb/cursor-plugin/molt-fetch
Any agent
npx skills add cockroachdb/cursor-plugin --skill molt-fetch
Clone the repo
git clone --depth 1 https://github.com/cockroachdb/cursor-plugin

Made for: Claude Code, Codex.

Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,287 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.00053 $0.01287
Opus 5 $0.00026 $0.00643
Sonnet 5 $0.00011 $0.00257
Haiku 4.5 $0.00005 $0.00129

Measured 2d ago against content hash d5e3630a1eaa, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

molt-fetch 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 2d ago.

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.

Origin

This is a copy

100% identical to molt-fetch — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/cockroachdb-onboarding-and-migrations/molt-fetch/SKILL.md · 132 lines

How it starts

The opening of the file, as written. The whole thing — 132 lines — stays where its author put it; the contents beside it link to each section on GitHub.

molt fetch

Bulk data migration from source databases (PostgreSQL, MySQL, Oracle, MSSQL) to CockroachDB.

Basic Structure

molt fetch \
  --source "<source-conn>" \
  --target "<crdb-conn>" \
  --bucket-path "s3://bucket/prefix"   # or --direct-copy or --local-path
  [options]

Storage Backends (pick one)

Option When to use
--bucket-path "s3://..." AWS S3 (also gs:// for GCS, azure:// for Azure)
--direct-copy No intermediate storage; fastest for accessible networks
--local-path "/tmp/molt" + --local-path-listen-addr "0.0.0.0:9005" CRDB must reach the listen addr

Cloud auth: pass --use-implicit-auth for IAM/ADC/managed identity, or set AWS_ACCESS_KEY_ID/GOOGLE_APPLICATION_CREDENTIALS env vars.

Table Handling (--table-handling)

Value Behavior
none (default) Append to existing tables
drop-on-target-and-recreate Drop + recreate from source schema; enables auto schema creation. Destroys existing target tables and their data, so use only on fresh or empty targets
truncate-if-exists Truncate before loading; errors if table missing

Import Mode

IMPORT INTO (default): Table goes OFFLINE during load. Highest throughput.

COPY FROM (--use-copy): Table stays ONLINE. Use with --direct-copy. Cannot use compression.

# Zero-downtime load
molt fetch --source "..." --target "..." --direct-copy --use-copy

Key Flags

# Filtering
--table-filter "customers|orders"      # POSIX regex for tables to include
--table-exclusion-filter "temp_.*"     # exclude pattern
--schema-filter "public"               # PostgreSQL only

# Performance
--table-concurrency 4                  # parallel tables (default: 4)
--export-concurrency 4                 # export threads (default: 4)
--row-batch-size 100000                # rows per SELECT (default: 100k)

# Schema
--type-map-file "types.json"           # custom type mappings
--transformations-file "transforms.json"  # column exclusions, table aliases

# Logging
--log-file "migration.log"             # or "stdout"
--logging debug                        # info (default), debug, trace
--metrics-listen-addr "0.0.0.0:3030"  # Prometheus scrape endpoint

Read the full file on GitHub · 132 lines

Files

What ships with it

1 file 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. 2d ago First seen · 132 lines · 53 tokens per session scan A d5e3630a1eaa

Subscribe to this mod's changes

molt-fetch is a skill published in the GitHub repository cockroachdb/cursor-plugin (1 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 53 tokens to every session and 1,287 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to molt-fetch, differing in 0 lines, and is treated as a copy.

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