> **Plain-language companion:** [v0.13.0.md](v0.13.0.md)

## v0.13.0 — Scalability Foundations, Partitioning Enhancements, MERGE Profiling & Multi-Tenant Scheduling

**Status: Released (2026-03-31).**

**Goal:** Deliver the scalability foundations deferred from v0.12.0 —
columnar change tracking and shared change buffers — alongside the
partitioning enhancements that build on v0.11.0's RANGE partitioning spike,
a MERGE deduplication profiling pass, the dbt macro updates, per-database
worker quotas for multi-tenant deployments, the TPC-H-derived benchmarking
harness for data-driven performance validation, and a small SQL coverage
cleanup for PG 16+ expression types.

> Phases: 5 (Scalability), 6 (Partitioning), 7 (MERGE Profiling), 8 (dbt
> Macro Updates), 9 (Multi-Tenant Scheduler Isolation), 10 (TPC-H Benchmark
> Harness), 11 (SQL Coverage Cleanup).

### Scalability Foundations (Phase 5)

> **In plain terms:** These items directly serve the project's primary goal of
> world-class performance and scalability. Columnar change tracking eliminates
> wasted delta processing for wide tables, and shared change buffers reduce
> I/O multiplication in deployments with many stream tables reading from the
> same source.

| Item | Description | Effort | Ref |
|------|-------------|--------|-----|
| A-2 | **Columnar Change Tracking.** Per-column bitmask in CDC triggers; skip rows where no referenced column changed; lightweight UPDATE-only path when only projected columns changed; 50–90% delta-volume reduction for wide-table UPDATE workloads. | 3–4 wk | [PLAN_NEW_STUFF.md §A-2](plans/performance/PLAN_NEW_STUFF.md) | ✅ Done |
| D-4 | **Shared Change Buffers.** Single buffer per source shared across all dependent STs; multi-frontier cleanup coordination; static-superset column mode for initial implementation. | 3–4 wk | [PLAN_NEW_STUFF.md §D-4](plans/performance/PLAN_NEW_STUFF.md) | ✅ Done |
| ~~PERF-2~~ | ~~**Auto-enable `buffer_partitioning` for high-throughput sources.**~~ ✅ Done — throughput-based auto-promotion: buffer exceeding `compact_threshold` in a single refresh cycle is converted to RANGE(lsn) partitioned mode at runtime. | — | [REPORT_OVERALL_STATUS.md §R7](plans/performance/REPORT_OVERALL_STATUS.md) |

> ⚠️ D-4 **multi-frontier cleanup correctness verified.** `MIN(consumer_frontier)`
> used in all cleanup paths. Property-based tests with 5–10 consumers and
> 500 random frontier advancement cases pass.

> **Scalability foundations subtotal: ~6–8 weeks**

### Partitioning Enhancements (Phase 6)

> **In plain terms:** The v0.11.0 spike delivered RANGE partitioning end-to-end.
> These follow-on items extend coverage to the use cases deliberately deferred
> from A1: multi-column keys, retrofitting existing stream tables, LIST-based
> partitions, HASH partitions, and operational quality-of-life improvements.

| Item | Description | Effort | Ref |
|------|-------------|--------|-----|
| ~~A1-1b~~ | ~~**Multi-column partition keys.** Comma-separated `partition_by`; ROW() predicate for composite keys.~~ ✅ Done | — | [src/api.rs](src/api.rs), [src/refresh.rs](src/refresh.rs) |
| ~~A1-1c~~ | ~~**`alter_stream_table(partition_by => …)` support.** Add/change/remove partition key with full storage rebuild.~~ ✅ Done | — | [src/api.rs](src/api.rs), [src/catalog.rs](src/catalog.rs) |
| ~~A1-1d~~ | ~~**LIST partitioning support.** `PARTITION BY LIST` for low-cardinality columns; `IN (…)` predicate style from the delta.~~ ✅ Done | — | [src/api.rs](src/api.rs), [src/refresh.rs](src/refresh.rs) |
| ~~A1-3b~~ | ~~**HASH partitioning via per-partition MERGE loop.** `HASH:col[:N]` with auto-created child partitions; per-partition MERGE through `satisfies_hash_partition()`.~~ ✅ Done | — | [src/api.rs](src/api.rs), [src/refresh.rs](src/refresh.rs) |
| ~~PART-WARN~~ | ~~**Default-partition growth warning.** `warn_default_partition_growth()` after FULL and DIFFERENTIAL refresh.~~ ✅ Done | — | [src/refresh.rs](src/refresh.rs) |

> **Partitioning enhancements subtotal: ~5–8 weeks**

### MERGE Profiling (Phase 7)

| Item | Description | Effort | Ref |
|------|-------------|--------|-----|
| G14-MDED | **MERGE deduplication profiling.** Profile how often concurrent-write scenarios produce duplicate key entries requiring pre-MERGE compaction. If ≥10% of refresh cycles need dedup, write an RFC for a two-pass MERGE strategy. | 3–5d | [plans/performance/REPORT_OVERALL_STATUS.md §14](plans/performance/REPORT_OVERALL_STATUS.md) |
| PROF-DLT | **Delta SQL query plan profiling (`explain_delta()` function).** Capture `EXPLAIN (ANALYZE, BUFFERS, FORMAT JSON)` for auto-generated delta SQL queries to identify PostgreSQL execution bottlenecks (join algorithms, scan types, sort spills). Add `pgtrickle.explain_delta(st_name, format DEFAULT 'text')` SQL function; optional `PGS_PROFILE_DELTA=1` environment variable for E2E test auto-capture to `/tmp/delta_plans/<st>.json`. Enables identification of operator-level performance issues (semi-join full scans, deep join chains). Prerequisite for data-driven MERGE optimization. | 1–2w | [PLAN_TPC_H_BENCHMARKING.md §1-5](plans/performance/PLAN_TPC_H_BENCHMARKING.md) |

> **MERGE profiling subtotal: ~1–3 weeks**

### dbt Macro Updates (Phase 8)

> **In plain terms:** Expose the v0.11.0 SQL API additions (`partition_by`, `fuse`,
> `fuse_ceiling`, `fuse_sensitivity`) in the dbt materialization macros so
> dbt users can configure them via `config(...)`. No catalog changes; pure
> Jinja/SQL.

| Item | Description | Effort |
|------|-------------|--------|
| DBT-1 | `partition_by` config option wired through `stream_table.sql`, `create_stream_table.sql`, and `alter_stream_table.sql` | ~1d |
| DBT-2 | `fuse`, `fuse_ceiling`, `fuse_sensitivity` config options wired through the materialization and alter macro with change-detection logic | ~1–2d |
| DBT-3 | dbt docs update: README and SQL_REFERENCE.md dbt section | ~0.5d |

> **dbt macro updates subtotal: ~2–3.5 days**

### Multi-Tenant Scheduler Isolation (Phase 9)

> **In plain terms:** As deployments grow past 10 databases on a single cluster,
> all schedulers compete for the same global background-worker pool. One busy
> database can starve the others. Phase 9 gives operators per-database quotas
> and a priority queue so critical databases always get workers.

| Item | Description | Effort | Ref |
|------|-------------|--------|-----|
| ~~C-3~~ | ~~**Per-database worker quotas.** Add `pg_trickle.per_database_worker_quota` GUC; priority ordering: IMMEDIATE > Hot > Warm > Cold STs; burst capacity up to 150% when other databases are under quota.~~ ✅ Done — GUC registered; `compute_per_db_quota()` with 80% burst; tier-aware `sort_ready_queue_by_priority`; 5 unit tests + 6 E2E tests | — | [src/scheduler.rs](src/scheduler.rs) |

> ⚠️ C-3 depends on C-1 (tiered scheduling) for Hot/Warm/Cold classification. If C-1
> is not ready, fall back to IMMEDIATE > all-other ordering with equal priority within
> each tier; add full tier-aware ordering as a follow-on when C-1 lands in v0.14.0.

> **Multi-tenant scheduler isolation subtotal: ~2–3 weeks**

### TPC-H Benchmark Harness (Phase 10)

> **In plain terms:** The existing TPC-H correctness suite (22/22 queries passing)
> has no timing infrastructure. Phase 10 adds benchmark mode so we can measure
> FULL vs DIFFERENTIAL speedups across all 22 queries — the only way to validate
> that A-2, D-4, and other v0.13.0 changes actually help on realistic analytical
> workloads, and to catch per-query regressions at larger scale factors.

| Item | Description | Effort | Ref |
|------|-------------|--------|-----|
| TPCH-1 | **`TPCH_BENCH=1` benchmark mode for Phase 3.** Instrument `test_tpch_full_vs_differential` with warm-up cycles (`WARMUP_CYCLES=2`), reuse `extract_last_profile()` for `[PGS_PROFILE]` extraction, emit `[TPCH_BENCH]` structured output per cycle (`query=q01 tier=2 cycle=1 mode=DIFF ms=12.7 decision=0.41 merge=11.3 …`). Add `print_tpch_summary()` with per-query FULL/DIFF median, speedup, P95, and MERGE% table. | 4–5h | [PLAN_TPC_H_BENCHMARKING.md §3](plans/performance/PLAN_TPC_H_BENCHMARKING.md) | ✅ Done |
| TPCH-2 | **`just bench-tpch` / `bench-tpch-large` / `bench-tpch-fast` justfile targets.** `bench-tpch`: SF-0.01 with `TPCH_BENCH=1`; `bench-tpch-large`: SF-0.1 with 5 cycles; `bench-tpch-fast`: skip Docker image rebuild. Enables before/after measurement for every v0.13.0 optimization. | 15 min | [PLAN_TPC_H_BENCHMARKING.md §3](plans/performance/PLAN_TPC_H_BENCHMARKING.md) | ✅ Done |
| TPCH-3 | **TPC-H OpTree Criterion micro-benchmarks.** Add composite `OpTree` benchmarks to `benches/diff_operators.rs` representing TPC-H query shapes (`diff_tpch_q01`, `diff_tpch_q05`, `diff_tpch_q08`, `diff_tpch_q18`, `diff_tpch_q21`). Measures pure-Rust delta SQL generation time for complex multi-join/semi-join trees; catches DVM engine regressions without a running database. | 4h | [PLAN_TPC_H_BENCHMARKING.md §4](plans/performance/PLAN_TPC_H_BENCHMARKING.md) | ✅ Done |

> **TPC-H benchmark harness subtotal: ~1 day**

### SQL Coverage Cleanup (Phase 11)

> **In plain terms:** Three small SQL expression gaps that are unscheduled
> anywhere. Two are PG 16+ standard SQL syntax currently rejected with errors;
> one is an audit-gated correctness check for recursive CTEs with non-monotone
> operators. All are low-effort items that round out DVM coverage without
> adding scope risk.

| Item | Description | Effort | Ref |
|------|-------------|--------|-----|
| SQL-RECUR | **Recursive CTE non-monotone divergence audit.** Write an E2E test for a recursive CTE with `EXCEPT` or aggregation in the recursive term (`WITH RECURSIVE … SELECT … EXCEPT SELECT …`). If the test passes → downgrade G1.3 to P4 (verified correct, no code change). If it fails → add a guard in `diff_recursive_cte` that detects non-monotone recursive terms and rejects them with `ERROR: non-monotone recursive CTEs are not supported in DIFFERENTIAL mode — use FULL`. | 6–8h | [GAP_SQL_PHASE_7.md §G1.3](plans/sql/GAP_SQL_PHASE_7.md) |
| SQL-PG16-1 | **`IS JSON` predicate support (PG 16+).** `expr IS JSON`, `expr IS JSON OBJECT`, `expr IS JSON ARRAY`, `expr IS JSON SCALAR`, `expr IS JSON WITH UNIQUE KEYS` — standard SQL/JSON predicates rejected today. Add a `T_JsonIsPredicate` arm in `parser.rs`; the predicate is treated opaquely (no delta decomposition); it passes through to the delta SQL unchanged where the PG executor evaluates it natively. | 2–3h | [GAP_SQL_PHASE_6.md §G1.4](plans/sql/GAP_SQL_PHASE_6.md) |
| SQL-PG16-2 | **SQL/JSON constructor support (PG 16+).** `JSON_OBJECT(…)`, `JSON_ARRAY(…)`, `JSON_OBJECTAGG(…)`, `JSON_ARRAYAGG(…)` — standard SQL/JSON constructors (`T_JsonConstructorExpr`) currently rejected. Add opaque pass-through in `parser.rs`; treat as scalar expressions (no incremental maintenance of the JSON value itself); handle the aggregate variants the same way as other custom aggregates (full group rescan). | 4–6h | [GAP_SQL_PHASE_6.md §G1.5](plans/sql/GAP_SQL_PHASE_6.md) |

> **SQL coverage cleanup subtotal: ~1–2 days**

### DVM Engine Improvements (Phase 10)

> **In plain terms:** The delta SQL generated for deep multi-table joins
> (e.g., TPC-H Q05/Q09 with 6 joined tables) computes identical pre-change
> snapshots redundantly at every reference site, spilling multi-GB temporary
> files that exceed `temp_file_limit`. Nested semi-joins (Q20) exhibit an
> O(n²) blowup from fully materializing the right-side pre-change state.
> These improvements target the intermediate data volume directly in the
> delta SQL generator, with TPC-H 22/22 DIFFERENTIAL correctness as the
> measurable gate.

| Item | Description | Effort | Ref |
|------|-------------|--------|-----|
| DI-1 | **Named CTE L₀ snapshots.** Emit per-leaf pre-change snapshots as named CTEs (`NOT MATERIALIZED` default; `MATERIALIZED` when reference count ≥ 3); deduplicate 3–10× redundant `EXCEPT ALL` evaluations per leaf. Targets Q05/Q09 temp spill root cause. | 2–3d | [PLAN_DVM_IMPROVEMENTS.md §DI-1](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-2 | **Pre-image read from change buffer + aggregate UPDATE-split.** Replace per-leaf `EXCEPT ALL` with a `NOT EXISTS` anti-join on `pk_hash` + direct `old_*` read. Per-leaf conditional fallback to `EXCEPT ALL` when delta exceeds `max_delta_fraction` for that leaf. Includes aggregate UPDATE-split: the 'D' side of `SUM(CASE WHEN …)` evaluates using `old_*` column values, superseding DI-8’s band-aid. | 3.5–5.5d | [PLAN_DVM_IMPROVEMENTS.md §DI-2](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-3 | **Group-key filtered aggregate old rescan.** Restrict non-algebraic aggregate `EXCEPT ALL` rescans to affected groups via `EXISTS (… IS NOT DISTINCT FROM …)` filter. NULL-safe. Independent quick win. | 0.5–1d | [PLAN_DVM_IMPROVEMENTS.md §DI-3](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-6 | **Lazy semi-join R_old materialization.** Skip `EXCEPT ALL` for unchanged semi-join right children; push down equi-join key as a filter when R_old is needed. Eliminates Q20-type O(n²) blowup. | 1–2d | [PLAN_DVM_IMPROVEMENTS.md §DI-6](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-4 | **Shared R₀ CTE cache.** Cache pre-change snapshot SQL by OpTree node identity to avoid regenerating duplicate inline subqueries for shared subtrees. Depends on DI-1. | 1–2d | [PLAN_DVM_IMPROVEMENTS.md §DI-4](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-5 | **Part 3 correction consolidation.** Consolidate per-node Part 3 correction CTEs for linear inner-join chains into a single term. | 2–3d | [PLAN_DVM_IMPROVEMENTS.md §DI-5](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-7 | **Scan-count-aware strategy selector.** `max_differential_joins` and `max_delta_fraction` per-stream-table options; auto-fallback to FULL refresh when join count or delta-rate threshold is exceeded. Complements DI-2's per-leaf fallback with a coarser per-ST guard at scheduler decision time. | 1–2d | [PLAN_DVM_IMPROVEMENTS.md §DI-7](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-8 | **SUM(CASE WHEN …) algebraic drift fix.** Detect `Expr::Raw("CASE …")` in `is_algebraically_invertible()` and fall back to GROUP_RESCAN. Q14 is unaffected (parsed as `ComplexExpression`, already GROUP_RESCAN). Correctness band-aid superseded by DI-2’s aggregate UPDATE-split. | ~0.5d | [PLAN_DVM_IMPROVEMENTS.md §DI-8](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-9 | **Scheduler skips IMMEDIATE-mode tables.** Raise `scheduler_interval_ms` GUC cap to 600,000 ms; return early from refresh-due check for `refresh_mode = IMMEDIATE` (verified safe: IMMEDIATE drains TABLE-source buffers synchronously; downstream CALCULATED tables detected via `has_stream_table_source_changes()` independently). | 0.5d | [PLAN_DVM_IMPROVEMENTS.md §DI-9](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-10 | **SF=1 benchmark validation gate.** Add `bench-tpch-sf1` justfile target (`TPCH_SF=1 TPCH_BENCH=1`). Gate v0.13.0 release on 22/22 queries at SF=1. CI: manual dispatch only (60–180 min runtime, 4h timeout). | ~0.5d | [PLAN_DVM_IMPROVEMENTS.md §DI-10](plans/performance/PLAN_DVM_IMPROVEMENTS.md) |
| DI-11 | **Predicate pushdown + deep-join L₀ threshold + planner hints.** (a) Enable `push_filter_into_cross_joins()` with scalar-subquery guard. (b) Deep-join L₀ threshold (4+ scans): skip L₀ reconstruction, use L₁ + Part 3 correction. (c) Deep-join planner hints (5+ scans): disable nestloop, raise work_mem, override temp_file_limit. Result: 22/22 TPC-H DIFFERENTIAL. | ~1d | — |

> **DI-2 promoted from v1.x:** CDC `old_*` column capture was completed as
> part of the typed-column CDC rewrite (already in production). DI-2 scope
> includes both the join-level pre-image capture (`NOT EXISTS` anti-join) and
> an aggregate UPDATE-split that uses `old_*` values for the 'D' side of
> SUM(CASE WHEN …), superseding DI-8's GROUP_RESCAN band-aid.

> **Implementation order:** DI-8 → DI-9 → DI-1 → DI-3 → DI-2 → DI-6 → DI-4 → DI-5 → DI-7 → DI-10 → DI-11

> **DVM improvements subtotal: ~2–3 weeks** (DI-8/DI-9 are small independent fixes; DI-1–DI-7 are the core engine work; DI-10 is a validation run; DI-11 is predicate pushdown + deep-join optimization)

### Regression-Free Testing Initiative (Q2 2026)

> Tracking: [TESTING_GAPS_2_IMPLEMENTATION_PROPOSAL.md](plans/testing/TESTING_GAPS_2_IMPLEMENTATION_PROPOSAL.md)

Addresses 9 structural weaknesses identified in the regression risk analysis.
Target: reduce regression escape rate from ~15% to <5%.

| Phase | Item | Status |
|-------|------|--------|
| P1 | Test infrastructure hardening: `#[must_use]` on poll helpers; `wait_for_condition` with exponential backoff; `assert_column_types_match` | ✅ Done (2026-03-28) |
| P2 | Join multi-cycle correctness: 7 tests — LEFT/RIGHT/FULL join, join-key update, both-sides DML, 4-table chain, NULL key | ✅ Done (2026-03-28) |
| P3 | Differential ≡ Full equivalence: 11 tests covering every major DVM operator class; `effective_refresh_mode` guard | ✅ Done (2026-03-28) |
| P4 | DVM operator execution: LATERAL MAX subquery multi-cycle (5 cycles) + recursive CTE org hierarchy multi-cycle (5 cycles) | ✅ Done (2026-03-28) |
| P5 | Failure recovery & schema evolution: 6 failure recovery tests (FR-1..6 in `e2e_failure_recovery_tests.rs`) + 5 schema evolution tests (SE-1..5 in `e2e_ddl_event_tests.rs`) | ✅ Done (2026-03-28) |
| P6 | MERGE template unit tests: 8 pure-Rust tests — `determine_refresh_action` (×5) + `build_is_distinct_clause` boundary (×3) in `src/refresh.rs` | ✅ Done (2026-03-28) |

> **v0.13.0 total: ~15–23 weeks** (Scalability: 6–8w, Partitioning: 5–8w, MERGE Profiling: 1–3w, dbt: 2–3.5d, Multi-tenant: 2–3w, TPC-H harness: ~1d, SQL cleanup: ~1–2d, DVM improvements: ~2–3w)

**Exit criteria:**
- [x] A-2: Columnar change tracking bitmask skips irrelevant rows; key column classification ✅, `__pgt_key_changed` annotation ✅, P5 value-only fast path ✅, `DiffResult.has_key_changed` signal propagation ✅, MERGE value-only UPDATE optimization ✅, upgrade script ✅ ✅ Done
- [x] D-4: Shared buffer serves multiple STs via per-source `changes_{oid}` naming; `pgt_change_tracking.tracked_by_pgt_ids` reference counting; `shared_buffer_stats()` observability; property-based test with 5–10 consumers (3 properties, 500 cases) ✅ Done; 5 E2E fan-out tests
- [x] PERF-2: `buffer_partitioning = 'auto'` activates RANGE(lsn) partitioned mode for high-throughput sources — throughput-based `should_promote_inner()` heuristic, `convert_buffer_to_partitioned()` runtime migration, 10 unit tests + 3 E2E tests, `docs/CONFIGURATION.md` updated ✅ Done
- [x] A1-1b: Multi-column RANGE partition keys work end-to-end; composite ROW() predicate triggers partition pruning; 3 E2E tests + 5 unit tests ✅ Done
- [x] A1-1c: `alter_stream_table(partition_by => …)` repartitions existing storage table without data loss; add/change/remove tested
- [x] A1-1d: LIST partitioning creates `PARTITION BY LIST` storage; IN-list predicate injected; single-column-only validated; 4 E2E tests pass
- [x] A1-3b: HASH partitioning uses per-partition MERGE loop; auto-creates N child partitions; `satisfies_hash_partition()` filter; 22 unit tests + 6 E2E tests ✅ Done
- [x] PART-WARN: `WARNING` emitted when default partition has rows after refresh; `warn_default_partition_growth()` on both FULL and DIFFERENTIAL paths ✅ Done
- [x] G14-MDED: Deduplication frequency profiling complete; `TOTAL_DIFF_REFRESHES` + `DEDUP_NEEDED_REFRESHES` shared-memory atomic counters; `pgtrickle.dedup_stats()` reports ratio; RFC threshold documented at ≥10% ✅ Done
- [x] PROF-DLT: `pgtrickle.explain_delta(st_name, format)` function captures delta query plans in text/json/xml/yaml; `PGS_PROFILE_DELTA=1` auto-capture to `/tmp/delta_plans/`; documented in SQL_REFERENCE.md ✅ Done
- [x] C-3: Per-database worker quota enforced; tier-aware priority sort (IMMEDIATE > Hot > Warm > Cold) implemented; GUC + E2E quota tests added; `compute_per_db_quota()` with burst at 80% cluster load ✅ Done
- [x] TPCH-1/2: `TPCH_BENCH=1` mode emits `[TPCH_BENCH]` lines + summary table; `just bench-tpch` and `bench-tpch-large` targets functional ✅ Done
- [x] TPCH-3: Five TPC-H OpTree Criterion benchmarks pass and run without a PostgreSQL backend ✅ Done
- [x] DBT-1/2/3: `partition_by`, `fuse`, `fuse_ceiling`, `fuse_sensitivity` exposed in dbt macros; change detection wired; integration tests added; README and SQL_REFERENCE.md updated ✅ Done
- [x] SQL-RECUR: Recursive CTE non-monotone audit complete; G1.3 downgraded to P4 — two Tier 3h E2E tests verify recomputation fallback is correct ✅ Done
- [x] SQL-PG16-1: `IS JSON` predicate accepted in DIFFERENTIAL defining queries; E2E tests in `e2e_expression_tests.rs` confirm correct delta behaviour ✅ Done
- [x] SQL-PG16-2: `JSON_OBJECT`, `JSON_ARRAY`, `JSON_OBJECTAGG`, `JSON_ARRAYAGG` accepted in DIFFERENTIAL defining queries; E2E tests in `e2e_expression_tests.rs` confirm correct delta behaviour ✅ Done
- [x] `scripts/check_upgrade_completeness.sh` passes (all catalog changes in `sql/pg_trickle--0.12.0--0.13.0.sql`) ✅ Done — 58 functions, 8 new columns, all covered
- [x] DI-8: `is_algebraically_invertible()` detects `Expr::Raw("CASE …")` and returns `false` for `SUM(CASE WHEN …)` (Q14 unaffected — `ComplexExpression`); Q12 removed from `DIFFERENTIAL_SKIP_ALLOWLIST`; 4 unit tests ✅ Done
- [x] DI-9: `scheduler_interval_ms` cap raised to 600,000 ms; scheduler skips IMMEDIATE-mode tables in `check_schedule()`; verified safe for CALCULATED dependants ✅ Done
- [x] DI-1: Named CTE L₀ snapshots implemented (`NOT MATERIALIZED` default, `MATERIALIZED` when ref ≥ 3); Q05/Q09 pass DIFFERENTIAL correctness ✅ Done
- [x] DI-2: `NOT EXISTS` anti-join replaces `EXCEPT ALL` in `build_pre_change_snapshot_sql()`; per-leaf conditional `EXCEPT ALL` fallback when delta > `max_delta_fraction`; aggregate UPDATE-split blocked on Q12 drift root cause (DI-8 band-aid retained) ✅ Done
- [x] DI-3: Already implemented — non-algebraic aggregate old rescan filtered via `EXISTS (… IS NOT DISTINCT FROM …)` to affected groups; NULL-safe ✅ Done
- [x] DI-6: Semi-join R_old lazy materialization with key push-down; Q20 DIFF passes at SF=0.01 ✅ Done
- [x] DI-4/5/7: R₀ cache (subset of DI-1), Part 3 threshold raised from 3→5, strategy selector + max_delta_fraction complete ✅ Done
- [x] DI-10: `bench-tpch-sf1` target added; 22/22 queries pass at SF=0.01 (3 cycles, zero drift) ✅ Done
- [x] DI-11: Predicate pushdown enabled with scalar-subquery guard; deep-join L₀ threshold (4 scans); deep-join planner hints (5+ total scans); 22/22 TPC-H DIFFERENTIAL ✅ Done
- [x] Extension upgrade path tested (`0.12.0 → 0.13.0`) ✅ Done


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