Skip to content

Add API ref for create_chunk and drop_chunk #4596

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: latest
Choose a base branch
from
Open

Add API ref for create_chunk and drop_chunk #4596

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
92 changes: 92 additions & 0 deletions api/hypertable/create_chunk.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,92 @@
---
api_name: create_chunk()
excerpt: Create a chunk with specified dimensional constraints
topics: [hypertables]
keywords: [chunks, hypertables, create]
api:
license: apache
type: function
products: [cloud, mst, self_hosted]
---

# create_chunk()

Manually create a chunk with specific time ranges and space partition boundaries in a [$HYPERTABLE][hypertable-docs].

You can either create a new chunk, or attach an existing table as a chunk. When you add an existing table, it is attached to the $HYPERTABLE and used as the data table for
the new chunk. If necessary, $TIMESCALE_DB renames the table, and/or moves the table to the specified schema.

Creating a chunk requires `INSERT` privileges on the $HYPERTABLE. If `chunk_table` is provided, the table must
have the same columns and compatible constraints as the $HYPERTABLE. CHECK constraints must have the same names
as the parent table.

## Samples

- **Create a new chunk for a $HYPERTABLE with specific time and space constraints**:

```sql
SELECT * FROM _timescaledb_functions.create_chunk(
'conditions',
'{"time": [1514419200000000, 1515024000000000], "device": [-9223372036854775808, 1073741823]}'
);
```

- **Create a chunk with a custom schema and table name**:

```sql
SELECT * FROM _timescaledb_functions.create_chunk(
'conditions',
'{"time": [1515024000000000, 1519024000000000], "device": [-9223372036854775808, 1073741823]}',
'custom_schema',
'custom_chunk_name'
);
```

- **Create a chunk from an existing table**:

```sql
-- Create a table with the same structure as your hypertable
CREATE TABLE my_chunk_table (time timestamptz NOT NULL, device int, temp float);

-- Attach it as a chunk
SELECT * FROM _timescaledb_functions.create_chunk(
'conditions',
'{"time": [1519024000000000, 1519628800000000]}',
schema_name => 'public',
table_name => 'my_chunk',
chunk_table => 'my_chunk_table'
);
```

- **For timestamp dimensions, you can also use string values**:

```sql
SELECT * FROM _timescaledb_functions.create_chunk(
'conditions',
'{"time": ["2018-01-01 00:00:00", "2018-01-08 00:00:00"]}'
);
```

## Arguments

|Name|Type|Default|Required| Description |
|-|-|-|-|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|`hypertable`|REGCLASS||✔| The $HYPERTABLE_CAP to create the chunk for |
|`slices`|JSONB||✔| A JSONB object specifying the dimensional constraints for the chunk. Each dimension must be specified with a two-element array `[range_start, range_end]`. <br/><br/>Each key is a dimension column name as defined in `hypertable`, and each value is a two-element array `[range_start, range_end]`. <br/><br/>For timestamp dimensions, use numeric values representing microseconds from Unix epoch or ISO 8601 timestamp strings. For example, `"2018-01-01 00:00:00"`). For integer or space dimensions, use numeric values matching the dimension's data type. <br/><br/>All dimensions defined in the $HYPERTABLE must be specified. For example: `{"time": [1514419200000000, 1515024000000000], "device": [-9223372036854775808, 1073741823]}` |
|`schema_name`|NAME|`NULL`|✖| Schema name for the chunk. If not specified, $TIMESCALE_DB uses the default chunk schema |
|`table_name`|NAME|`NULL`|✖| Table name for the chunk. If not specified, $TIMESCALE_DB generates a default chunk name |
|`chunk_table`|REGCLASS|`NULL`|✖| Attach an existing table as the chunk. The table is renamed and/or moved as necessary to match `schema_name` and `table_name` |

## Returns

|Column|Type| Description |
|-|-|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|`chunk_id`|INTEGER| The internal ID of the chunk |
|`hypertable_id`|INTEGER| The internal ID of the $HYPERTABLE |
|`schema_name`|NAME| Schema name of the new chunk |
|`table_name`|NAME| Table name of the new chunk |
|`relkind`|CHAR| The relation kind (usually 'r' for regular table) |
|`slices`|JSONB| The dimensional constraints that define the chunk |
|`created`|BOOLEAN| `true` if a new chunk was new. If a chunk with the same dimensional constraints already exists, the function returns information about the existing chunk with `created` set to `false` |

[hypertable-docs]: /use-timescale/:currentVersion:/hypertables/
55 changes: 55 additions & 0 deletions api/hypertable/drop_chunk.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,55 @@
---
api_name: drop_chunk()
excerpt: Drop a single chunk
topics: [hypertables, data retention]
keywords: [chunks, hypertables, drop, delete]
api:
license: apache
type: function
products: [cloud, mst, self_hosted]
---

# drop_chunk()

Drop a single chunk from a [$HYPERTABLE][hypertable-docs].

`drop_chunk()` first validates the chunk status, if it is safe to remove, it removes both the chunk
table and its entry from the chunk catalog.

You cannot drop compressed chunks directly.

## Samples

- **Drop a specific chunk by name**:

```sql
SELECT _timescaledb_functions.drop_chunk('_timescaledb_internal._hyper_1_2_chunk');
```

- **Drop a chunk using a variable**:

```sql
DO $$
DECLARE
chunk_name regclass;
BEGIN
SELECT show_chunks('conditions', older_than => INTERVAL '6 months')
INTO chunk_name
LIMIT 1;

PERFORM _timescaledb_functions.drop_chunk(chunk_name);
END $$;
```

## Arguments

|Name|Type|Default|Required| Description |
|-|-|-|-|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|`chunk`|REGCLASS||✔| The name of the chunk to drop. You can use a schema-qualified name, such as `_timescaledb_internal._hyper_1_2_chunk`. If the chunk is in the search path, you can use the unqualified name. |

## Returns

Returns `true` when `chunk` is successfully dropped.

[hypertable-docs]: /use-timescale/:currentVersion:/hypertables/
[drop_chunks]: /api/:currentVersion:/hypertable/drop_chunks/
8 changes: 8 additions & 0 deletions api/page-index/page-index.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,14 @@ module.exports = [
title: "drop_chunks",
href: "drop_chunks",
},
{
title: "create_chunk",
href: "create_chunk",
},
{
title: "drop_chunk",
href: "drop_chunk",
},
{
title: "reorder_chunk",
href: "reorder_chunk",
Expand Down