gaussdb-adaptation

name: gaussdb-adaptation description: Use this skill when porting SQL Server or vanilla PostgreSQL code to Huawei GaussDB (Kernel 505.x / openGauss-based). TRIGGER when source code or SQL contains any of — Microsoft.Data.SqlClient, SqlBulkCopy, NEXT VALUE FOR, ON COMMIT DROP, CREATE TEMPORARY SEQUENCE, dbo., NVARCHAR, ISNULL(, GETDATE(), OPTION (MAXDOP, TOP N, @@IDENTITY, WITH (NOLOCK), [bracketed] identifiers, #tempTable; OR csproj references DotNetCore.GaussDB, DotNetCore.EntityFrameworkCore.GaussDB, HuaweiCloud.Driver.GaussDB, HuaweiCloud.EntityFrameworkCore.GaussDB, Npgsql.EntityFrameworkCore.PostgreSQL alongside a GaussDB target; OR appsettings has Persistence.Provider=GaussDb; OR user mentions GaussDB / openGauss / 高斯数据库 / SHA256 SASL / password_encryption_type / apuração GaussDB migration.

GaussDB Adaptation

Overview

GaussDB (Huawei, kernel 505.x / openGauss-based) speaks a PG-compatible but not identical dialect. Code that compiles and runs against SQL Server — or even vanilla PostgreSQL — often fails on GaussDB in three categories:

1. SQL dialect — e.g. CREATE TEMPORARY SEQUENCE and ON COMMIT DROP are rejected at runtime
2. Driver / authentication — DotNetCore.GaussDB fails SHA256-only servers with a cryptic protocol error; Huawei's own HuaweiCloud.Driver.GaussDB works but uses a different namespace
3. Bulk loading — SqlBulkCopy has no drop-in replacement; the correct pattern is BeginBinaryImport + COPY ... FROM STDIN BINARY

The skill encodes landmines discovered on a real production port, with concrete before/after pairs.

Quick Start

For any adaptation task, run this 4-step flow:

1. Audit — run scripts/sql_dialect_audit.py <project-root> to locate all anti-patterns, or grep for them manually (trigger list above)
2. Map SQL dialect — rewrite hits using references/sql-dialect-map.md
3. Verify driver + auth — confirm csproj packages + using match the server's password_encryption_type per references/connectivity-and-auth.md
4. Validate end-to-end — run scripts/gaussdb_connect_probe.cs against the target GaussDB to confirm connection + BINARY COPY + nextval all work; then build the real project

Workflow Decision Tree

Core Rules

• Never use in a GaussDB target: ON COMMIT DROP, CREATE TEMPORARY SEQUENCE, TOP N, OPTION (...), WITH (NOLOCK), dbo. schema prefix, IDENTITY(…) column type, @@IDENTITY, #tempTable, [bracketed] identifiers, NVARCHAR, ISNULL(, GETDATE(), DATEADD(, NEWID(), LEN(, SET XACT_ABORT, SET NOCOUNT, BEGIN TRY … END CATCH, EXEC proc @p=v, DECLARE @var, MERGE ... OUTPUT, INSERT ... OUTPUT
• Always check SHOW password_encryption_type on the target server before choosing a driver:
  • 0 or 1 → DotNetCore.GaussDB 9.0.0 (MD5 path works, net9.0 OK)
  • 2 (SHA256-only, GaussDB 505+ default) → HuaweiCloud.Driver.GaussDB 0.1.0 (only one with working SHA256 SASL for this server family)
• Replace SqlBulkCopy.WriteToServerAsync(tbl) with using var w = conn.BeginBinaryImport($"""COPY "{t}" FROM STDIN BINARY"""); foreach row → w.StartRow(); w.Write(v, GaussDBDbType.X); await w.CompleteAsync(ct);
• Reserve id blocks via SELECT nextval('seq') - N + 1 in a single roundtrip; never IDENTITY columns in new tables
• Temp tables: CREATE TEMP TABLE x (...) ON COMMIT DELETE ROWS; — preceded by DROP TABLE IF EXISTS x; for reentrant batches
• Temp sequences: don't create them. Use a permanent sequence with DROP SEQUENCE IF EXISTS x; CREATE SEQUENCE x ...; bracket, and a final DROP SEQUENCE IF EXISTS x; at script end

Default Deliverables

When invoked, produce:

• A hit list from the dialect audit (file:line → category → suggested replacement)
• Rewritten code for each hit, preserving business semantics
• A driver/auth verdict (is current csproj compatible with target server?) with upgrade steps if not
• An e2e verification command the user can run (usually the bundled probe script, parameterized with their DSN)

Sanitization Rules

• Never emit real connection strings, passwords, hostnames, or customer identifiers into checked-in files. Use placeholders: <host>, <port>, <user>, <pwd>, <database>
• When demonstrating a connection in a generated file, read DSN from environment (GAUSSDB_DSN) rather than hard-coding
• Treat private NuGet package names, internal namespaces, and business domain terms in examples as illustrative; genericize when documenting

Script Use

• scripts/sql_dialect_audit.py <dir> — stdlib-only Python, walks a tree and reports every anti-pattern by file:line → category. Use to quickly inventory an unfamiliar codebase before planning a port.
• scripts/gaussdb_connect_probe.cs — single-file .NET 9 probe. GAUSSDB_DSN=... dotnet run to verify a driver + server combo. Exercises connect, encryption check, BINARY COPY, nextval, commit. Use to confirm the environment before touching business code.

Reference Use

Pull in only when the task demands:

• references/sql-dialect-map.md — the authoritative side-by-side rewrite table
• references/connectivity-and-auth.md — driver decision tree, server encryption modes, connection-string keys
• references/bulk-load-patterns.md — BINARY COPY template, id block allocation, reentrant temp tables
• references/common-pitfalls.md — real-world traps: raw-string CS8998, namespace copy-paste leaks, DI that compiles-but-fails-at-runtime, private package namespace moves