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Step 05 of 8 Hours to days (volume-dependent)· advanced

Step 5: Backfill Historical Data

Bulk-copy all historical data into target. The sync from Phase 4 keeps it current after this point.

What you're doing in this step

Do an initial bulk copy of all data from source to target. SQL Server → Azure SQL: Azure DMS handles this. SQL Server → Postgres: pgloader / AWS DMS / custom ETL. For very large data: parallel chunked copy by date range or PK range.

Recommended prompts

Use one of these to do the work in your IDE

Open the template to read it in full. Click Copy prompt to grab it (with your stack values pre-filled where they apply) — then paste into Claude Code, Cursor, or wherever you build.

Primary recommendation 1-2 days

Data Migration Plan

Plan a safe data migration: schema mapping, ETL strategy, dual-write or one-shot, validation, and cutover with rollback.

View template

Template· Template 1 day

SQL Server to Modern Schema Translator

Translate SQL Server schemas to modernized SQL Server (Azure SQL) or Postgres, handling type differences, constraints, and stored procedure migration.

Use this when: Need the type-mapping reference open during backfill troubleshooting

postgressql

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Recommended skills

Drop these into Claude Code for this phase

Skills auto-trigger on the right kind of request. Install once; they apply to every prompt that fits.

Skill· Skill 5 min setup

Data Validation Skill

Claude Code skill that compares old and new system outputs for parity — running validation queries on both DBs and reporting drift.

claude-codesql

View skill

Skill· Skill 5 min setup

Database Migration Skill

Claude Code skill that generates safe forward and reverse migrations with transaction-wrapping, idempotency, and zero-downtime patterns.

claude-code

View skill

Recommended MCP configs

Wire these tools into Claude Code first

MCP servers give Claude Code direct access to external systems (Jira, browsers, databases). Configure once.

MCP config· MCP config 10 min setup

Postgres MCP for Evoke

Pre-configured Postgres MCP server for Claude Code — schema inspection and read-only queries to make database work safer and faster.

claude-codemcppostgres

View config

MCP config· MCP config 5 min setup

Filesystem MCP for Evoke

Pre-configured filesystem MCP server for Claude Code — safe, scoped read/write access to project files.

claude-codemcp

View config

When you're done

Verify these in your own work before moving on

This is a checklist for you to mentally tick off in your repo and IDE — the site doesn't track it, you do.

Backfill complete
Row counts match source (within tolerance)
Aggregate sums match
Sample row spot-checks passed (50+ random rows per table compared field-by-field)
FK integrity preserved (no orphans introduced)
Indexes in place on target
Statistics updated on target
Performance validated (top 20 hot queries tested)

Common pitfalls

What goes wrong at this step

Sequential single-threaded copy of large tables — chunk and parallelize
Loading data before creating indexes — usually right (faster), but means queries are slow during the load window
Statistics not updated — query planner makes bad decisions until ANALYZE runs
Forgetting to reset sequences — auto-increment columns must continue past the max source value

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