# Fts5

Artifact: [androidx.room3:room3-common](https://developer.android.com/jetpack/androidx/releases/room3) [View Source](https://cs.android.com/search?q=file:androidx/room3/Fts5.kt+class:androidx.room3.Fts5) Added in [3.0.0](https://developer.android.com/jetpack/androidx/releases/room3#3.0.0)

*** ** * ** ***


```
@Target(allowedTargets = [AnnotationTarget.CLASS])
@Retention(value = AnnotationRetention.BINARY)
public annotation Fts5
```

<br />

*** ** * ** ***

Marks an `https://developer.android.com/reference/androidx/room3/Entity` annotated class as a FTS5 entity. This class will have a mapping SQLite FTS5 table in the database.

[FTS5](https://www.sqlite.org/fts5.html) is a SQLite virtual table module that allows full-text searches to be performed on a set of documents.

An FTS entity table always has a column named `rowid` that is the equivalent of an `INTEGER PRIMARY KEY`. Therefore, an FTS entity can only have a single property annotated with `https://developer.android.com/reference/androidx/room3/PrimaryKey`, it must be named `rowid` and must be of `INTEGER` affinity. The property can be optionally omitted in the class but can still be used in queries.

All properties in an FTS entity are of `TEXT` affinity, except the 'rowid' property.

Example:

```
@Entity
@Fts5
data class Mail (
  @PrimaryKey
  @ColumnInfo(name = "rowid")
  val rowId: Long,
  val subject: String,
  val body: String
)
```

**Warning** : The availability of FTS5 is based on the driver used for the database. For Android specifically the `https://developer.android.com/reference/androidx/sqlite/driver/bundled/BundledSQLiteDriver` supports FTS5.

| See also |
|---|---|
| `https://developer.android.com/reference/androidx/room3/Entity` |   |
| `https://developer.android.com/reference/androidx/room3/Dao` |   |
| `https://developer.android.com/reference/androidx/room3/Database` |   |
| `https://developer.android.com/reference/androidx/room3/PrimaryKey` |   |
| `https://developer.android.com/reference/androidx/room3/ColumnInfo` |   |

## Summary

| ### Public methods |
|---|---|
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.reflect/-k-class/index.html<@https://developer.android.com/reference/androidx/annotation/NonNull ?>` | `https://developer.android.com/reference/androidx/room3/Fts5#getContentEntity()()` The external content entity who's mapping table will be used as content for the FTS table. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/String.html` | `https://developer.android.com/reference/androidx/room3/Fts5#getContentRowId()()` The column name to be used as 'content_rowid'. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/room3/FtsOptions.Detail` | `https://developer.android.com/reference/androidx/room3/Fts5#getDetail()()` The 'detail' option affects what is stored in the virtual table. |
| `final boolean` | `https://developer.android.com/reference/androidx/room3/Fts5#getHasColumnSize()()` Enable or disable storing column sizes. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull String[]` | `https://developer.android.com/reference/androidx/room3/Fts5#getNotIndexed()()` The list of column names on the FTS table that won't be indexed. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull int[]` | `https://developer.android.com/reference/androidx/room3/Fts5#getPrefix()()` The list of prefix sizes to index. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/String.html` | `https://developer.android.com/reference/androidx/room3/Fts5#getTokenizer()()` The tokenizer to be used in the FTS table. |
| `final @https://developer.android.com/reference/androidx/annotation/NonNull String[]` | `https://developer.android.com/reference/androidx/room3/Fts5#getTokenizerArgs()()` Optional arguments to configure the defined tokenizer. |

## Public methods

### getContentEntity

```
public final @NonNull KClass<@NonNull ?> getContentEntity()
```

The external content entity who's mapping table will be used as content for the FTS table.

Declaring this value makes the mapping FTS table of this entity operate in "external content" mode. In such mode the FTS table does not store its own content but instead uses the data in the entity mapped table defined in this value. This option allows FTS5 to forego storing the text being indexed which can be used to achieve significant space savings.

In "external mode" the content table and the FTS table need to be synced. Room will create the necessary triggers to keep the tables in sync. Therefore, all write operations should be performed against the content entity table and not the FTS table.

The content sync triggers created by Room will be removed before migrations are executed and are re-created once migrations are complete. This prevents the triggers from interfering with migrations but means that if data needs to be migrated then write operations might need to be done in both the FTS and content tables.

See the [External Content FTS5 Tables](https://www.sqlite.org/fts5.html#external_content_tables) documentation for details.

| Returns |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.reflect/-k-class/index.html<@https://developer.android.com/reference/androidx/annotation/NonNull ?>` | The external content entity. |

### getContentRowId

```
public final @NonNull String getContentRowId()
```

The column name to be used as 'content_rowid'.

Declaring this value without setting `https://developer.android.com/reference/androidx/room3/Fts5#(kotlin.String,kotlin.Array,kotlin.reflect.KClass,kotlin.String,kotlin.IntArray,kotlin.Boolean,androidx.room3.FtsOptions.Detail,kotlin.Array)` is an error.

For details, see the [content_rowid= option documentation](https://www.sqlite.org/fts5.html#external_content_tables).

| Returns |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/String.html` | The column name to be used as 'content_rowid'. |

### getDetail

```
public final @NonNull FtsOptions.Detail getDetail()
```

The 'detail' option affects what is stored in the virtual table.

Using values other than `https://developer.android.com/reference/androidx/room3/FtsOptions.Detail#FULL` will reduce the space consumed but will also affect the FTS capabilities and efficiency. The default value is `https://developer.android.com/reference/androidx/room3/FtsOptions.Detail#FULL`.

For details, see the [detail= option documentation](https://www.sqlite.org/fts5.html#the_detail_option).

| Returns |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/room3/FtsOptions.Detail` | The 'detail' option. |

### getHasColumnSize

```
public final boolean getHasColumnSize()
```

Enable or disable storing column sizes. Defaults to `true`.

For details, see the [columnsize= option documentation](https://www.sqlite.org/fts5.html#the_columnsize_option).

| Returns |
|---|---|
| `boolean` | The 'columnsize' option. |

### getNotIndexed

```
public final @NonNull String[] getNotIndexed()
```

The list of column names on the FTS table that won't be indexed.

For details, see the [UNINDEXED column option documentation](https://www.sqlite.org/fts5.html#the_unindexed_column_option).

| Returns |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull String[]` | A list of column names that will not be indexed by the FTS extension. |

### getPrefix

```
public final @NonNull int[] getPrefix()
```

The list of prefix sizes to index.

For details, [the prefix= option documentation](https://www.sqlite.org/fts5.html#prefix_indexes).

| Returns |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull int[]` | A list of non-zero positive prefix sizes to index. |

### getTokenizer

```
public final @NonNull String getTokenizer()
```

The tokenizer to be used in the FTS table.

The default value is `https://developer.android.com/reference/androidx/room3/FtsOptions#TOKENIZER_UNICODE61()`. Tokenizer arguments can be defined with `https://developer.android.com/reference/androidx/room3/Fts5#(kotlin.String,kotlin.Array,kotlin.reflect.KClass,kotlin.String,kotlin.IntArray,kotlin.Boolean,androidx.room3.FtsOptions.Detail,kotlin.Array)`.

If a custom tokenizer is used, the tokenizer and its arguments are not verified at compile time.

For details, see [SQLite tokenizers documentation](https://www.sqlite.org/fts5.html#tokenizers)

| Returns |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/lang/String.html` | The tokenizer to use on the FTS table. Built-in available tokenizers are `https://developer.android.com/reference/androidx/room3/FtsOptions#TOKENIZER_UNICODE61()`, `https://developer.android.com/reference/androidx/room3/FtsOptions#TOKENIZER_PORTER()`, `https://developer.android.com/reference/androidx/room3/FtsOptions#TOKENIZER_ASCII()` and `https://developer.android.com/reference/androidx/room3/FtsOptions#TOKENIZER_TRIGRAM()`. |

| See also |
|---|---|
| `https://developer.android.com/reference/androidx/room3/Fts5#(kotlin.String,kotlin.Array,kotlin.reflect.KClass,kotlin.String,kotlin.IntArray,kotlin.Boolean,androidx.room3.FtsOptions.Detail,kotlin.Array)` |   |

### getTokenizerArgs

```
public final @NonNull String[] getTokenizerArgs()
```

Optional arguments to configure the defined tokenizer.

Tokenizer arguments are a white-space series of values represented on this annotation value list. For example, `tokenizerArgs = ["separators", "'.'"]` defines the dot character as an additional separator when using the `https://developer.android.com/reference/androidx/room3/FtsOptions#TOKENIZER_UNICODE61()` tokenizer.

The available arguments that can be defined depend on the tokenizer defined, see the [SQLite tokenizers documentation](https://www.sqlite.org/fts5.html#tokenizers) for details.

| Returns |
|---|---|
| `@https://developer.android.com/reference/androidx/annotation/NonNull String[]` | A list of tokenizer arguments strings. |