> For the complete documentation index, see [llms.txt](https://docs.slingdata.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.slingdata.io/connections/database-connections/dynamodb.md). # DynamoDB Connect & Ingest data from / to AWS DynamoDB DynamoDB is AWS's managed key-value and document database: a table is a set of items, each addressed by a primary key (a partition key, optionally plus a sort key). See for more details. Sling connects through the AWS SDK for Go v2 and talks to the DynamoDB API directly. There is no SQL engine behind the connection: Sling renders each read into a **scan descriptor** (table, filter expression, projected fields and limit) and applies writes item by item, where a `PutItem` batch upserts by primary key. ## Setup The following credentials keys are accepted: * `region` **(required)** -> AWS region of the tables, e.g. `us-east-1`. * `access_key_id` (optional) -> AWS access key ID. When omitted, the AWS credential chain is used (environment variables, shared config/credentials, instance metadata). * `secret_access_key` (optional) -> AWS secret access key. * `session_token` (optional) -> AWS session token, for temporary credentials. * `profile` (optional) -> AWS profile name from `~/.aws/credentials`. * `endpoint` (optional) -> Custom endpoint, for example DynamoDB Local (`http://localhost:8000`) or another compatible service. {% hint style="info" %} For **DynamoDB Local**, set `endpoint` and `region` only. It accepts any credentials, so Sling signs with placeholder keys and no AWS account is needed: ```bash $ docker run -p 8000:8000 amazon/dynamodb-local $ sling conns set DYNAMODB type=dynamodb endpoint=http://localhost:8000 region=us-east-1 ``` {% endhint %} ### Using `sling conns` Here are examples of setting a connection named `DYNAMODB`. We must provide the `type=dynamodb` property: {% code overflow="wrap" %} ```bash # using the AWS credential chain (env vars, ~/.aws/credentials, instance role) $ sling conns set DYNAMODB type=dynamodb region=us-east-1 # explicit keys $ sling conns set DYNAMODB type=dynamodb region=us-east-1 \ access_key_id=AKIAIOSFODNN7EXAMPLE \ secret_access_key=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY # a named profile, or temporary credentials with a session token $ sling conns set DYNAMODB type=dynamodb region=us-east-1 profile=prod $ sling conns set DYNAMODB type=dynamodb region=us-east-1 \ access_key_id= \ secret_access_key= \ session_token= # DynamoDB Local $ sling conns set DYNAMODB type=dynamodb endpoint=http://localhost:8000 region=us-east-1 $ sling conns test DYNAMODB ``` {% endcode %} ### Environment Variable See [here](https://docs.slingdata.io/connections/database-connections/pages/eAdVs2BHCgdr6RS8GoJC#dot-env-file-.env.sling) to learn more about the `.env.sling` file. {% code overflow="wrap" %} ```bash export DYNAMODB='{ type: dynamodb, region: "us-east-1" }' export DYNAMODB='{ type: dynamodb, region: "us-east-1", access_key_id: "AKIAIOSFODNN7EXAMPLE", secret_access_key: "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY" }' ``` {% endcode %} ### Sling Env File YAML See [here](https://docs.slingdata.io/connections/database-connections/pages/eAdVs2BHCgdr6RS8GoJC#sling-env-file-env.yaml) to learn more about the sling `env.yaml` file. ```yaml connections: DYNAMODB: type: dynamodb region: us-east-1 # use explicit keys, or omit them to use the AWS credential chain access_key_id: secret_access_key: session_token: # for temporary credentials profile: default # AWS profile from ~/.aws/credentials # DynamoDB Local DYNAMODB_LOCAL: type: dynamodb endpoint: http://localhost:8000 region: us-east-1 ``` ## Primary Keys A DynamoDB table cannot exist without a primary key, and Sling upserts by that key. Sling takes it from the stream's `primary_key` (or unique key), then from the source's primary key, and when the stream declares none it adds a `_sling_id` column and keys the table on it — keying on a data column instead would collapse rows whose values repeat. Set the key explicitly whenever the data has a natural one: ```yaml source: POSTGRES target: DYNAMODB defaults: mode: incremental primary_key: [id] update_key: updated_at streams: public.orders: object: default.orders ``` DynamoDB has no schemas, so Sling always uses the `default` schema in object names. A composite key is declared as multiple columns (`primary_key: [id, code]`), which maps to a partition key plus a sort key. ## Reading Data * A stream is read with `Scan`, so a bare table name returns every item. * `select` with explicit fields and a `limit` are pushed down to the scan (`select id, code from orders limit 100`). * Filtered reads use the `where` stream option with a JSON filter expression: ```yaml streams: default.orders: object: public.orders_pg where: '{"code": {"$gt": 15}}' ``` Supported filter operators are `$eq`, `$ne`, `$lt`, `$lte`, `$gt`, `$gte`, `$in`, `$between`, `$begins_with` and `$exists`. Values are stored with the type of their column (numbers as `N`, booleans as `BOOL`, timestamps as ISO strings). * `incremental` and `backfill` translate `update_key` (and `range`) into the same filter, so no SQL is rendered for the source. * `order by` is **not** pushed down, since a scan returns items unordered. Sort downstream, or in the target. * A `select ... where ...` written by hand is rejected with an error rather than silently dropping the condition. Use the `where` option above. ## Writing Data * `full-refresh` recreates and reloads the table, `truncate` empties it while keeping the key schema, and `incremental` upserts by primary key. * Writes go straight to the table (no temp tables on the target), and the merge strategies `insert`, `update`, `update_insert` and `delete_insert` are applied by Sling as it streams. * `delete_missing` is supported, both `soft` (the row stays, flagged with `_sling_deleted_at`) and `hard` (the row is deleted). See [Capture Deletes](/examples/database-to-database/capture_deletes.md). Sling also records `_sling_loaded_at` on every item it writes. ## Type Mapping | DynamoDB attribute | Sling type | | ------------------ | ------------------------------------------- | | `N` | decimal / number | | `S` | text (ISO strings for dates and timestamps) | | `BOOL` | bool | | `M`, `L` | json | | `B`, `BS` | binary | | `NS`, `SS`, `NULL` | json / text | Numbers are written as `N` (never as `S`), JSON is written as a native map rather than a string, and nulls are omitted from the item. ## Limitations * **No SQL engine.** Views are not supported (Sling renders view statements away instead of failing), and neither are joins, expressions or `order by`. Reads are scans: a filter expression is applied by the scan, so the table is still read in full to match items. * **No secondary indexes.** DynamoDB keys are declared when the table is created, so Sling does not create indexes (including unique indexes) on DynamoDB targets. * **Key columns only carry real typing.** Attribute values keep their DynamoDB type, but only the key attributes are strongly typed by the table definition; Sling infers the rest from the data. * **Item size limit.** DynamoDB caps an item at 400 KB, so wide or large rows can be rejected by the service. If you are facing issues connecting, give [`sling assist`](/sling-cli/ai/assist.md) a try, or reach out to us at , on [discord](https://discord.gg/q5xtaSNDvp) or open a Github Issue [here](https://github.com/slingdata-io/sling-cli/issues). --- # Agent Instructions This documentation is published with GitBook. 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