---
title: Index Build
---

### Maintenance Working Memory

The default Postgres `maintenance_work_mem` value of `64MB` is quite conservative and can slow down parallel index builds. We recommend at least `64MB` per
[parallel worker](/documentation/configuration/index#parallel-indexing-workers).

```bash postgresql.conf
maintenance_work_mem = 16GB
```

Each worker is required to have at least `15MB` memory. If `maintenance_work_mem` is set too low, an error will be returned.

### Parallel Indexing Workers

ParadeDB uses Postgres' `max_parallel_maintenance_workers` setting to determine the degree of parallelism during `CREATE INDEX`/`REINDEX`. Postgres' default is `2`, which may be too low for large tables.

```sql
SET max_parallel_maintenance_workers = 8;
```

In order for `max_parallel_maintenance_workers` to take effect, it must be less than or equal to both `max_parallel_workers` and `max_worker_processes`.

### Target Segment Count

By default, `CREATE INDEX`/`REINDEX` will create as many segments as there are CPUs on the host machine. This can be changed with
`paradedb.target_segment_count`.

For optimal performance, the segment count should equal the number of parallel workers that a query can receive, which is controlled by
[`max_parallel_workers_per_gather`](/documentation/configuration/parallel#parallel-workers). If `max_parallel_workers_per_gather` is greater than the number of CPUs on the host machine, then increasing the target segment count to match `max_parallel_workers_per_gather` can improve query
performance.

```sql
SET paradedb.target_segment_count = 32;
```