Support for Partial Indexes (Filtered Indexes) #5749

jay-l-e-e · 2026-01-23T14:46:37Z

Summary

This PR implements support for partial indexes (also known as filtered indexes) in Prisma Schema Language. Partial indexes allow creating indexes that only include rows matching a specific condition, reducing index size and improving query performance.

There was an issue related to this PR that was 5 years old. 😱

New Syntax

Raw SQL Syntax (all supported databases)

model User {
  id       Int     @id
  email    String
  status   String
  
  @@unique([email], where: raw("status = 'active'"))
  @@index([email], where: raw("deletedAt IS NULL"))
}

Object Literal Syntax (type-safe alternative)

model Post {
  id        Int      @id
  title     String
  published Boolean
  
  @@index([title], where: { published: true })
  @@unique([title], where: { published: { not: false } })
}

Preview Feature

This feature is gated behind the partialIndexes preview feature:

generator client {
  provider        = "prisma-client-js"
  previewFeatures = ["partialIndexes"]
}

Supported Databases

Database	Support	Migrations	Introspection	Notes
PostgreSQL	✅ Full	✅	✅	Full predicate support
SQLite	✅ Full	✅	✅	Full predicate support
SQL Server	✅ Full	✅	✅	Filtered indexes via `CREATE INDEX`
CockroachDB	⚠️ Partial	✅ Create only	❌	Cannot introspect predicate text
MySQL	❌	-	-	Not supported by the database

CockroachDB Limitation

CockroachDB supports creating partial indexes but cannot introspect predicate text. This means:

✅ Initial index creation works
❌ Predicate modifications are not detected
❌ add/modify/remove predicate migrations don't work

The differ skips predicate comparison for CockroachDB to prevent false-positive migrations.

Changes

PSL Parser (`psl/`)

Grammar: Extended Pest grammar with object_expression and object_member rules
AST: Added Expression::Object variant and ObjectMember struct
Types: Added WhereClause, WhereCondition, WhereFieldCondition, WhereValue enums
Validation: Added partial_index_is_supported validation requiring preview feature
Capabilities: Added PartialIndex connector capability for PostgreSQL, SQLite, CockroachDB, SQL Server

Schema Engine (`schema-engine/`)

DDL Generation: Implemented CREATE INDEX ... WHERE for all supported databases
Migrations:
- Added predicates_match() trait method to SqlSchemaDifferFlavour
- Delegate predicate comparison to flavour-specific implementations
- CockroachDB skips predicate comparison (DB limitation)
Introspection:
- Modified PostgreSQL/SQLite/MSSQL describers to fetch index predicates
- Auto-injects partialIndexes preview feature when partial indexes detected
Normalization:
- PostgreSQL predicates wrapped in parentheses to match DB format
- SQL Server predicates wrapped in parentheses for consistency

SQL Server Specifics

Filtered unique indexes must be created via CREATE INDEX (not as table constraints)
Modified render_create_table_as to exclude filtered unique indexes from constraints
Added filter_definition column to index introspection query

SQL DDL (`libs/sql-ddl/`)

Added WhereClause support to CreateIndex for PostgreSQL
Implemented CreatePartialIndex for SQLite

Test Coverage

PSL Unit Tests (`psl/psl/tests/attributes/partial_index.rs`)

33 test cases covering:
- Raw SQL syntax for @@unique and @@index
- Object literal syntax (boolean, string, number, null conditions)
- Multiple field conditions
- { not: true/false/null } syntax
- Error cases (unsupported databases, invalid syntax)
- CockroachDB support

Migration Tests (`schema-engine/sql-migration-tests/`)

Database	unique	normal	compound	add	modify	remove	Total
PostgreSQL	✅	✅	✅	✅	✅	✅	6
SQLite	✅	✅	✅	✅	✅	✅	6
SQL Server	✅	✅	✅	✅	✅	✅	6
CockroachDB	✅	✅	✅	-	-	-	3

Total: 21 migration tests

Introspection Tests (`schema-engine/sql-introspection-tests/`)

PostgreSQL partial unique index introspection
SQLite partial unique index introspection
SQL Server partial unique index introspection
Automatic preview feature injection
Field-level @unique with where clause

Generated SQL Examples

PostgreSQL

CREATE UNIQUE INDEX "User_email_key" ON "User" ("email") WHERE (status = 'active'::text);

SQLite

CREATE UNIQUE INDEX "User_email_key" ON "User" ("email") WHERE status = 'active';

SQL Server

CREATE UNIQUE NONCLUSTERED INDEX [User_email_key] ON [dbo].[User]([email]) WHERE ([status]='active');

CockroachDB

CREATE UNIQUE INDEX "User_email_key" ON "User" ("email") WHERE (status = 'active');

Key Files

File	Changes
`psl/schema-ast/src/parser/datamodel.pest`	Grammar rules for object expressions
`psl/schema-ast/src/ast/expression.rs`	`Expression::Object` AST type
`psl/parser-database/src/attributes.rs`	`where` clause parsing logic
`psl/parser-database/src/walkers/index.rs`	SQL predicate generation
`psl/psl-core/src/common/preview_features.rs`	`PartialIndexes` feature flag
`psl/psl-core/src/builtin_connectors/mssql_datamodel_connector.rs`	MSSQL `PartialIndex` capability
`schema-engine/.../sql_schema_calculator.rs`	DDL generation with predicates
`schema-engine/.../sql_schema_differ/table.rs`	Predicate comparison for migrations
`schema-engine/.../sql_schema_differ_flavour.rs`	`predicates_match()` trait method
`schema-engine/.../flavour/postgres/schema_differ.rs`	CockroachDB predicate handling
`schema-engine/.../flavour/mssql/renderer.rs`	SQL Server filtered index rendering
`schema-engine/.../flavour/mssql/schema_differ.rs`	SQL Server index matching
`schema-engine/sql-schema-describer/src/mssql.rs`	SQL Server predicate introspection
`schema-engine/.../introspection/`	Partial index introspection

Checklist

jay-l-e-e · 2026-01-23T20:36:13Z

@jacek-prisma Could you please review this PR?

jay-l-e-e · 2026-01-26T18:26:50Z

@jkomyno Hi, Could you please review this PR?

mikiyasET · 2026-01-27T08:28:14Z

@aqrln @tomhoule This needs to be reviewed.

jay-l-e-e · 2026-01-27T09:11:14Z

This PR has passed all tests that can be run locally, including tests against the real database and the shadow database. Clippy and fmt have both been applied. I’d like to run the GitHub Actions workflow.

daunJung-dev · 2026-02-03T07:31:26Z

@aqrln could you review this PR? I hope it pass review

codspeed-hq · 2026-02-05T16:28:59Z

Merging this PR will not alter performance

✅ 11 untouched benchmarks
⏩ 11 skipped benchmarks¹

_{Comparing jay-l-e-e:feat/partial-index-support (9af3b26) with main (57b675f)}

11 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

jay-l-e-e · 2026-02-06T04:45:05Z

Okay, I can see that some tests have failed. I’ll fix the problem!

jay-l-e-e · 2026-02-06T06:50:19Z

@jacek-prisma Added missing predicate: None to sql-schema-describer test snapshots. The Index struct gained a new field in the partial index commit, which required snapshot updates.

Please re-run the tests! Thank you 👍

jay-l-e-e · 2026-02-06T08:44:50Z

I have also added tests to verify partial indexes (filtered indexes) are correctly described for PostgreSQL, SQLite, MSSQL, and CockroachDB.

libs/sql-ddl/src/sqlite.rs

psl/parser-database/src/walkers/index.rs

psl/schema-ast/src/ast/expression.rs

psl/parser-database/src/types.rs

psl/psl-core/src/configuration/generator.rs

schema-engine/connectors/sql-schema-connector/src/flavour/mssql/schema_calculator.rs

schema-engine/connectors/sql-schema-connector/src/introspection/introspection_pair/index.rs

psl/parser-database/src/walkers/index.rs

jay-l-e-e · 2026-02-07T04:30:17Z

@jacek-prisma The tests I previously added to sql-schema-describer were failing in CI, so I updated the SQL schemas to be deterministic and fixed the snapshots accordingly. I've also addressed all of the review feedback. Could you re-run the CI workflow?

Thanks!

jay-l-e-e · 2026-02-07T05:05:15Z

@jacek-prisma The tests I previously added to sql-schema-describer were failing in CI, so I updated the SQL schemas to be deterministic and fixed the snapshots accordingly. I've also addressed all of the review feedback. Could you re-run the CI workflow?

Thanks!

I've pushed to my branch and all CI tests are passing now, including the Schema Engine tests.

schema-engine/sql-schema-describer/src/sqlite.rs

schema-engine/connectors/sql-schema-connector/src/flavour/mssql/schema_calculator.rs

jacek-prisma · 2026-02-09T14:35:21Z

Thanks for addressing my comments @jay-l-e-e , I left 2 additional comments about 2 edge cases that I think still need to be handled

jay-l-e-e · 2026-02-10T04:33:33Z

@jacek-prisma Hi, I've addressed all the review comments you left. I also added unit tests for the changes and verified they pass. Would you mind running the CI workflow when you get a chance? Thanks.

Add support for partial indexes with WHERE clauses in Prisma Schema Language. Features: - New raw() syntax for WHERE clauses: @@unique([email], where: raw("status = 'active'")) - Object literal syntax for conditions: @@unique([email], where: { active: true }) - Supports: boolean (true/false), null, string, and number values - Conditions: equals, not equals (!=), IS NULL, IS NOT NULL - Support for PostgreSQL, SQLite, SQL Server (filtered indexes), and CockroachDB - Preview feature flag: partialIndexes - Auto-injection of preview feature during introspection Schema Engine: - SQL generation for partial indexes across all supported databases - Migration diffing with predicate comparison - Introspection of existing partial indexes - CockroachDB limitation handling (cannot introspect predicate text) SQL Server specifics: - Filtered unique indexes created via CREATE INDEX (not table constraints) - Predicate normalization for consistent diffing Tests: - Comprehensive migration tests for all supported databases - Introspection tests for PostgreSQL, SQLite, SQL Server, and CockroachDB

Add missing 'predicate: None' field to Index struct expectations in sql-schema-describer tests. This field was added in the partial index support commit but the test snapshots were not updated.

… databases Added tests to verify partial indexes (filtered indexes) are correctly described for PostgreSQL, SQLite, MSSQL, and CockroachDB.

…se extraction

…QL identifier replacement & fmt

…scape handling

…d name in where_clause_as_sql

…al index where clauses

… and move SQL rendering to walker_ext_traits

…d use structural assertions in PSL tests

…s test

jacek-prisma · 2026-02-11T11:45:09Z

Hi @jay-l-e-e
This PR will be merged soon.
Also can you avoid force pushing after approval please, becauses it forces us to re-review the changes.

jay-l-e-e · 2026-02-11T12:06:39Z

Hi @jacek-prisma, I’m really glad to hear that the PR may be merged soon. Thank you very much.
The reason I did a force push was to rebase onto the latest commit of the main branch. Although there were no code changes, I realize that I pushed it carelessly as you mentioned. I’ll be more careful going forward.
Have a great day!

[TML-1865](https://linear.app/prisma-company/issue/TML-1865/enterprise-support-lightfield-create-index-concurrently)

jay-l-e-e · 2026-02-11T12:25:25Z

@jacek-prisma Hmm, a new PR was just merged and it caused a conflict. It seems to be because the version of sqlparser in the PR you recently merged was bumped to 0.60.

While I was working, I had considered upgrading sqlparser to 0.60 as well (since version 0.60 includes support for predicates), but I ended up not proceeding with it. Would you like me to update my changes to align with version 0.60?

jay-l-e-e · 2026-02-11T12:25:56Z

Oh, I see you’re already working on resolving it. I’ll step back and leave it to you.

…support Add comprehensive documentation for the new `partialIndexes` preview feature, which enables `where` argument on `@@index`, `@@unique`, and `@unique` attributes for PostgreSQL, SQLite, SQL Server, and CockroachDB. Ref: prisma/prisma-engines#5749, prisma/prisma#6974

jay-l-e-e mentioned this pull request Jan 23, 2026

Conditional uniqueness constraints; Partial/Filtered (Unique) Indexes prisma/prisma#6974

Open

jay-l-e-e force-pushed the feat/partial-index-support branch from af7a275 to f59ae96 Compare January 23, 2026 20:29

jay-l-e-e force-pushed the feat/partial-index-support branch 2 times, most recently from 6f861f6 to f4647c7 Compare January 26, 2026 18:07

jay-l-e-e force-pushed the feat/partial-index-support branch 2 times, most recently from 2ce8b62 to 9c97582 Compare February 6, 2026 08:26