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flexsearch/doc/persistent.md
2025-05-23 18:03:10 +02:00

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# Persistent Indexes
FlexSearch provides a new Storage Adapter where indexes are delegated through persistent storages.
Supported:
- [IndexedDB (Browser)](persistent-indexeddb.md)
- [Redis](persistent-redis.md)
- [SQLite](persistent-sqlite.md)
- [Postgres](persistent-postgres.md)
- [MongoDB](persistent-mongodb.md)
- [Clickhouse](persistent-clickhouse.md)
The `.export()` and `.import()` methods are still available for non-persistent In-Memory indexes.
All search capabilities are available on persistent indexes like:
- Context-Search
- Suggestions
- Cursor-based Queries (Limit/Offset)
- Scoring (supports a resolution of up to 32767 slots)
- Document-Search
- Partial Search
- Multi-Tag-Search
- Boost Fields
- Custom Encoder
- Resolver
- Tokenizer
- Document Store (incl. enrich results)
- Worker Threads to run in parallel
- Auto-Balanced Cache (top queries + last queries)
All persistent variants are optimized for larger sized indexes under heavy workload. Almost every task will be streamlined to run in batch/parallel, getting the most out of the selected database engine. Whereas the InMemory index can't share their data between different nodes when running in a cluster, every persistent storage can handle this by default.
Examples Node.js:
- [nodejs-commonjs](../example/nodejs-commonjs):
- [basic-persistent](../example/nodejs-commonjs/basic-persistent)
- [document-persistent](../example/nodejs-commonjs/document-persistent)
- [nodejs-esm](../example/nodejs-esm):
- [basic-persistent](../example/nodejs-esm/basic-persistent)
- [document-persistent](../example/nodejs-esm/document-persistent)
Examples Browser:
- [browser-legacy](../example/browser-legacy):
- [basic-persistent](../example/browser-legacy/basic-persistent)
- [document-persistent](../example/browser-legacy/document-persistent)
- [browser-module](../example/browser-module):
- [basic-persistent](../example/browser-module/basic-persistent)
- [document-persistent](../example/browser-module/document-persistent)
## Browser (IndexedDB)
```js
import { Index, IndexedDB } from "../dist/flexsearch.bundle.module.min.js";
// create an index
const index = new Index();
// create db instance with optional prefix
const db = new IndexedDB("my-store");
// mount and await before transfering data
await index.mount(db);
// update the index as usual
index.add(1, "content...");
index.update(2, "content...");
index.remove(3);
// changes are automatically committed by default
// when you need to wait for the task completion, then you
// can use the commit method explicitely:
await index.commit();
```
Alternatively mount a store by index creation:
```js
const index = new Index({
db: new IndexedDB("my-store")
});
// await for the db response before access the first time
await index.db;
// apply changes to the index
// ...
```
Query against a persistent storage just as usual:
```js
const result = await index.search("gulliver");
```
Auto-Commit is enabled by default and will process changes asynchronously in batch.
You can fully disable the auto-commit feature and perform them manually:
```js
const index = new Index({
db: new Storage("my-store"),
commit: false
});
// update the index
index.add(1, "content...");
index.update(2, "content...");
index.remove(3);
// transfer all changes to the db
await index.commit();
```
You can call the commit method manually also when `commit: true` option was set.
## Node.js
```js
import { Index } from "flexsearch";
import Database from "flexsearch/db/postgres";
// create an index
const index = new Index();
// create db instance with optional prefix
const db = new Database("my-store");
// mount and await before transfering data
await index.mount(db);
// update the index as usual
index.add(1, "content...");
index.update(2, "content...");
index.remove(3);
// changes are automatically committed by default
// when you need to wait for the task completion, then you
// can use the commit method explicitely:
await index.commit();
```
## Benchmark
The benchmark was measured in "terms per second".
<table>
<tr>
<th align="left">Store</th>
<th>Add</th>
<th>Search 1</th>
<th>Search N</th>
<th>Replace</th>
<th>Remove</th>
<th>Not Found</th>
<th>Scaling</th>
</tr>
<tr>
<td></td>
<td align="right"><sub>terms per sec</sub></td>
<td align="right"><sub>terms per sec</sub></td>
<td align="right"><sub>terms per sec</sub></td>
<td align="right"><sub>terms per sec</sub></td>
<td align="right"><sub>terms per sec</sub></td>
<td align="right"><sub>terms per sec</sub></td>
<td></td>
</tr>
<!--
<tr>
<td align="left">Memory</td>
<td align="right">28,345,405</td>
<td align="right">65,180,102</td>
<td align="right">12,098,298</td>
<td align="right">19,099,981</td>
<td align="right">36,164,827</td>
<td align="right">143,369,175</td>
<td align="right">No</td>
</tr>
-->
<tr>
<td align="left">IndexedDB</td>
<td align="right">123,298</td>
<td align="right">83,823</td>
<td align="right">62,370</td>
<td align="right">57,410</td>
<td align="right">171,053</td>
<td align="right">425,744</td>
<td align="right">No</td>
</tr>
<tr>
<td align="left">Redis</td>
<td align="right">1,566,091</td>
<td align="right">201,534</td>
<td align="right">859,463</td>
<td align="right">117,013</td>
<td align="right">129,595</td>
<td align="right">875,526</td>
<td align="right">Yes</td>
</tr>
<tr>
<td align="left">Sqlite</td>
<td align="right">269,812</td>
<td align="right">29,627</td>
<td align="right">129,735</td>
<td align="right">174,445</td>
<td align="right">1,406,553</td>
<td align="right">122,566</td>
<td align="right">No</td>
</tr>
<tr>
<td align="left">Postgres</td>
<td align="right">354,894</td>
<td align="right">24,329</td>
<td align="right">76,189</td>
<td align="right">324,546</td>
<td align="right">3,702,647</td>
<td align="right">50,305</td>
<td align="right">Yes</td>
</tr>
<tr>
<td align="left">MongoDB</td>
<td align="right">515,938</td>
<td align="right">19,684</td>
<td align="right">81,558</td>
<td align="right">243,353</td>
<td align="right">485,192</td>
<td align="right">67,751</td>
<td align="right">Yes</td>
</tr>
<tr>
<td align="left">Clickhouse</td>
<td align="right">1,436,992</td>
<td align="right">11,507</td>
<td align="right">22,196</td>
<td align="right">931,026</td>
<td align="right">3,276,847</td>
<td align="right">16,644</td>
<td align="right">Yes</td>
</tr>
</table>
__Search 1:__ Single term query<br>
__Search N:__ Multi term query (Context-Search)
The benchmark was executed against a single client.
## Delete Store + Migration
Actually there exist no migration tool. You will probably need some kind of migration on future updates or when you need to re-create the index on the database.
> [!CAUTION]
> Please use the methods `index.destroy()` and `index.clear()` carefully. This methods will delete contents (truncate, drop) from the database accordingly to the passed `name` on initialization.
Just clear all contents (truncate equivalent) from a store which connected to an index:
```js
// always define a unique name when assigning a storage
const db = new Database("my-store", config);
await index.mount(db);
// truncate all contents
await index.clear();
```
Drop all tables (and its schema):
```js
// always define a unique name when assigning a storage
const db = new Database("my-store", config);
await index.mount(db);
// drop all associated tables
await index.destroy();
```
A full migration cycle could be combined by:
```js
// always define a unique name when assigning a storage
const db = new Database("my-store", config);
await index.mount(db);
// drop all associated tables
await index.destroy();
// when destroyed you'll need to mount again
// to run table creation
await index.mount(db);
// access index ...
```