---
title: Type-specific table access
sidebar_label: Type-specific table access
---

[`db.liveTable`](./basics.md#live-tables) and [`db.historicalTable`](./basics.md#historical-tables) cover the common case of retrieving a table by namespace and table
name. Some data sources support additional, source-specific options that don't fit those two methods — for example,
pinning an Iceberg table to a specific snapshot, or replaying historical data as if it were ticking live.

`db.as` lets you "mix in" a type-specific accessor for these cases, while still applying the same access controls and
audit logging as `db.liveTable` and `db.historicalTable`.

> [!NOTE]
> `db.as` and the table access types described here are part of the Core+ (`io.deephaven.enterprise.database.Database`) API and are available from Groovy and Java only. Python's `db.live_table` and `db.historical_table` work as usual and automatically pick up type-specific sources such as Iceberg (see [Iceberg's live and historical access](../data-guide/batch-data/iceberg.md#live-and-historical-access)), but the `db.as(...)` entry point itself does not yet have a Python wrapper.

## Overview

`db.as(factory)` takes a `TableAccessFactory` and returns a `DatabaseTableAccess`, an accessor with a `table(options)`method that takes source-specific options instead of a bare namespace/table name pair:

```groovy
myTypeSpecificAccessor = db.as(MyTypeSpecificAccessor.factory())
myTable = myTypeSpecificAccessor.table(myOptions)
```

Deephaven Enterprise ships two built-in accessors:

- [`IcebergTableAccess`](../data-guide/batch-data/iceberg.md#type-specific-access-icebergtableaccess) — Iceberg-specific options such as a pinned snapshot or manual refresh control.
- [`ReplayAccess`](./replay-access.md) — replay a single table (or another `db.as(...)` source) as historical data ticking in on a simulated clock, without a dedicated Replay Query.

## Building a custom table access

Customers may implement their own `TableAccess` for a data source not covered by the built-in accessors, in support of
one or both of:

- Explicit, type-specific access via `db.as(MyAccess.factory())`.
- Transparent access through the existing `db.liveTable` and `db.historicalTable` (and Python `live_table`/`historical_table`) calls, the same way Iceberg tables work today.

Extend `DatabaseTableAccessAclBase`, which applies Deephaven's access controls and audit logging around your
table-fetching logic so you don't have to reimplement either:

```java
public final class MyTableAccess
        extends DatabaseTableAccessAclBase<MyTableAccess.Options, MyPreAclTable, Table> {

    public static Database.TableAccessFactory<MyTableAccess> factory() {
        return MyTableAccess::new;
    }

    private MyTableAccess(final Database db) {
        super(db);
    }

    // extract namespace/tableName/isRefreshing/event from your own Options type
    @Override protected String namespace(Options options) { /*...*/ }
    @Override protected String tableName(Options options) { /*...*/ }
    @Override public boolean isRefreshing(Options options) { /*...*/ }
    @Override protected String event(Options options) { /*...*/ }

    // fetch the table before ACLs are applied
    @Override protected MyPreAclTable tableImpl(Options options) { /*...*/ }

    // return the table after ACLs have been applied (usually just intermediate.aclOrPre())
    @Override protected Table postAclTableApply(IntermediateResults<Options, MyPreAclTable> intermediate) { /*...*/ }
}
```

To make your accessor available transparently through `db.liveTable`/`db.historicalTable`, additionally implement
`Database.TableAccessAdapter.Provider` and register it for discovery via [`ServiceLoader`](../sys-admin/optional-settings/service-loader.md). Your provider's
`supports(Schema)` method determines which schemas it applies to, and `liveTableOptions`/`historicalTableOptions`
adapt a `namespace`, `tableName`, and `TableOptions` into your accessor's own options type.

## Related documentation

- [Deephaven database basics](./basics.md)
- [Iceberg](../data-guide/batch-data/iceberg.md)
- [Replay a table programmatically](./replay-access.md)
- [Create a replay query](./replayer.md)
- [Registering implementations with ServiceLoader](../sys-admin/optional-settings/service-loader.md)
- [`Database` Javadoc](https://docs.deephaven.io/javadoc/coreplus/2026.01/io/deephaven/enterprise/database/Database.html)
- [`DatabaseTableAccessAclBase` Javadoc](https://docs.deephaven.io/javadoc/coreplus/2026.01/io/deephaven/enterprise/database/DatabaseTableAccessAclBase.html)