29b45dd234
- Adds `skills/postgres-best-practices/`: A new skill containing comprehensive Postgres performance optimization rules and guidelines from Supabase. - The skill includes rules for query performance, connection management, security (RLS), and schema design. - Updates `README.md` to include the new skill in the directory.
56 lines
1.7 KiB
Markdown
56 lines
1.7 KiB
Markdown
---
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title: Use Lowercase Identifiers for Compatibility
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impact: MEDIUM
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impactDescription: Avoid case-sensitivity bugs with tools, ORMs, and AI assistants
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tags: naming, identifiers, case-sensitivity, schema, conventions
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---
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## Use Lowercase Identifiers for Compatibility
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PostgreSQL folds unquoted identifiers to lowercase. Quoted mixed-case identifiers require quotes forever and cause issues with tools, ORMs, and AI assistants that may not recognize them.
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**Incorrect (mixed-case identifiers):**
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```sql
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-- Quoted identifiers preserve case but require quotes everywhere
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CREATE TABLE "Users" (
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"userId" bigint PRIMARY KEY,
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"firstName" text,
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"lastName" text
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);
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-- Must always quote or queries fail
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SELECT "firstName" FROM "Users" WHERE "userId" = 1;
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-- This fails - Users becomes users without quotes
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SELECT firstName FROM Users;
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-- ERROR: relation "users" does not exist
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```
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**Correct (lowercase snake_case):**
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```sql
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-- Unquoted lowercase identifiers are portable and tool-friendly
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CREATE TABLE users (
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user_id bigint PRIMARY KEY,
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first_name text,
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last_name text
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);
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-- Works without quotes, recognized by all tools
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SELECT first_name FROM users WHERE user_id = 1;
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```
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Common sources of mixed-case identifiers:
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```sql
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-- ORMs often generate quoted camelCase - configure them to use snake_case
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-- Migrations from other databases may preserve original casing
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-- Some GUI tools quote identifiers by default - disable this
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-- If stuck with mixed-case, create views as a compatibility layer
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CREATE VIEW users AS SELECT "userId" AS user_id, "firstName" AS first_name FROM "Users";
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```
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Reference: [Identifiers and Key Words](https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS)
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