feat: Add 7 missing PostgreSQL catalog tables for protocol completeness

.gitignore

@@ -33,4 +33,6 @@ test_*.db*
 # Debug and temporary files
 debug_*
 test_datetime_translation
-benchmark.db
+benchmark.db
+# Worktrees
+.worktrees/

docs/plans/2025-01-25-missing-catalog-tables-design.md

@@ -0,0 +1,217 @@
+# Missing PostgreSQL Catalog Tables Design
+
+## Overview
+
+Add 7 missing PostgreSQL catalog tables to improve protocol completeness:
+- pg_settings
+- pg_sequence
+- pg_trigger
+- pg_collation
+- pg_replication_slots
+- pg_shdepend
+- pg_statistic
+
+## Goals
+
+- **Completeness**: General PostgreSQL protocol completeness
+- **Fidelity**: Dynamic where possible, mapping SQLite state where meaningful
+- **Approach**: Implement all 7 tables together
+
+## Architecture
+
+Follow the existing **CatalogInterceptor pattern**:
+1. Add table names to interception check in `query_interceptor.rs`
+2. Create dedicated handler modules for complex tables
+3. Handle simpler tables inline in `check_table_factor()`
+
+### Table Classification
+
+| Table | Implementation | Rationale |
+|-------|---------------|-----------|
+| pg_settings | Dedicated handler | Many rows, commonly queried, needs SHOW/SET integration |
+| pg_sequence | Dedicated handler | Must query SQLite's sqlite_sequence table dynamically |
+| pg_trigger | Dedicated handler | Must query SQLite's sqlite_master for triggers |
+| pg_collation | Inline static | Small fixed set of collations |
+| pg_replication_slots | Inline stub | Always empty (SQLite has no replication) |
+| pg_shdepend | Inline stub | Always empty (no shared dependencies) |
+| pg_statistic | Inline stub | Complex internal format, stub is appropriate |
+
+### File Structure
+
+```
+src/catalog/
+├── pg_settings.rs    (new)
+├── pg_sequence.rs    (new)
+├── pg_trigger.rs     (new)
+└── mod.rs            (updated)
+```
+
+## Detailed Designs
+
+### pg_settings
+
+Exposes PostgreSQL server configuration. Clients query this during connection setup.
+
+**Column schema:**
+```
+oid, name, setting, unit, category, short_desc, extra_desc,
+context, vartype, source, min_val, max_val, enumvals, boot_val,
+reset_val, sourcefile, sourceline, pending_restart
+```
+
+**Implementation:**
+1. Static configuration map with ~30-40 common settings:
+   - server_version → "16.0"
+   - server_encoding → "UTF8"
+   - client_encoding → "UTF8"
+   - DateStyle → "ISO, MDY"
+   - TimeZone → "UTC"
+   - integer_datetimes → "on"
+   - standard_conforming_strings → "on"
+   - max_connections → "100"
+
+2. Dynamic settings where applicable:
+   - search_path → from session state
+   - transaction_isolation → current transaction level
+
+3. WHERE clause support for `name` filtering (SHOW command compatibility)
+
+**Handler signature:**
+```rust
+pub struct PgSettingsHandler;
+impl PgSettingsHandler {
+    pub async fn handle_query(select: &Select, session: Option<&SessionState>) -> Result<DbResponse, PgSqliteError>;
+}
+```
+
+### pg_sequence
+
+Maps SQLite's autoincrement sequences to PostgreSQL's sequence catalog.
+
+**Column schema:**
+```
+seqrelid, seqtypid, seqstart, seqincrement, seqmax, seqmin, seqcache, seqcycle
+```
+
+**Data source:** SQLite's `sqlite_sequence` table:
+```sql
+SELECT name, seq FROM sqlite_sequence
+```
+
+**Mapping:**
+- seqrelid → Generate OID from table name hash
+- seqtypid → 20 (int8 OID)
+- seqstart → 1
+- seqincrement → 1
+- seqmax → current seq value from sqlite_sequence
+- seqmin → 1
+- seqcache → 1
+- seqcycle → false
+
+### pg_trigger
+
+Maps SQLite triggers to PostgreSQL's trigger catalog.
+
+**Column schema:**
+```
+oid, tgrelid, tgparentid, tgname, tgfoid, tgtype, tgenabled,
+tgisinternal, tgconstrrelid, tgconstrindid, tgconstraint,
+tgdeferrable, tginitdeferred, tgnargs, tgattr, tgargs, tgqual,
+tgoldtable, tgnewtable
+```
+
+**Data source:** SQLite's `sqlite_master`:
+```sql
+SELECT name, tbl_name, sql FROM sqlite_master WHERE type = 'trigger'
+```
+
+**Note:** Reuse existing `parse_trigger_sql()` logic from information_schema.triggers implementation.
+
+### pg_collation (Static)
+
+**Column schema:**
+```
+oid, collname, collnamespace, collowner, collprovider, collisdeterministic,
+collencoding, collcollate, collctype, colliculocale, collicurules, collversion
+```
+
+**Implementation:** Return 3 standard collations:
+- default (oid 100)
+- C (oid 950)
+- POSIX (oid 951)
+
+### pg_replication_slots (Empty stub)
+
+**Column schema:**
+```
+slot_name, plugin, slot_type, datoid, database, temporary, active,
+active_pid, xmin, catalog_xmin, restart_lsn, confirmed_flush_lsn, ...
+```
+
+**Implementation:** Always return empty result set. SQLite has no replication.
+
+### pg_shdepend (Empty stub)
+
+**Column schema:**
+```
+dbid, classid, objid, objsubid, refclassid, refobjid, deptype
+```
+
+**Implementation:** Always return empty result set. Not applicable to SQLite's single-file model.
+
+### pg_statistic (Empty stub)
+
+**Column schema:**
+```
+starelid, staattnum, stainherit, stanullfrac, stawidth, stadistinct,
+stakind1-5, staop1-5, stacoll1-5, stanumbers1-5, stavalues1-5
+```
+
+**Implementation:** Always return empty result set. pg_stats (already implemented) is the user-facing view.
+
+## Integration Points
+
+### query_interceptor.rs changes
+
+**1. Update table detection (lines 50-61):**
+```rust
+let has_catalog_tables = lower_query.contains("pg_catalog") ||
+   // ... existing tables ...
+   lower_query.contains("pg_settings") ||
+   lower_query.contains("pg_sequence") ||
+   lower_query.contains("pg_trigger") ||
+   lower_query.contains("pg_collation") ||
+   lower_query.contains("pg_replication_slots") ||
+   lower_query.contains("pg_shdepend") ||
+   lower_query.contains("pg_statistic");
+```
+
+**2. Add routing in check_table_factor():**
+- Route pg_settings, pg_sequence, pg_trigger to dedicated handlers
+- Handle pg_collation, pg_replication_slots, pg_shdepend, pg_statistic inline
+
+### mod.rs changes
+
+```rust
+pub mod pg_settings;
+pub mod pg_sequence;
+pub mod pg_trigger;
+```
+
+## Migration Consideration
+
+No SQLite migrations needed - these are all virtual tables handled by the interceptor, not backed by SQLite tables.
+
+## Estimates
+
+| Table | Type | Lines of code |
+|-------|------|---------------|
+| pg_settings | Dedicated handler | ~200 |
+| pg_sequence | Dedicated handler | ~100 |
+| pg_trigger | Dedicated handler | ~120 |
+| pg_collation | Inline static | ~40 |
+| pg_replication_slots | Inline stub | ~20 |
+| pg_shdepend | Inline stub | ~20 |
+| pg_statistic | Inline stub | ~30 |
+
+**Total:** ~530 lines of new code