Tabulator

NOTE: This feature requires Quilt stack version 1.55.0 or higher

Tabulator aggregates tabular data objects across multiple packages using AWS Athena. Admins define schemas and data sources for CSV, TSV, or Parquet files, enabling users to run SQL queries directly on the contents of Quilt packages. You can even use named capture groups to extract additional columns from the logical key and package name.

The configuration is written in YAML and managed using the quilt3.admin.tabulator APIs or via the Quilt Admin UI:

Admin UI for setting Tabulator configuration

Configuration

Each Tabulator configuration is written in YAML, following the structure outlined below.

Example

schema:
  - name: name  # must match ^[a-z_][a-z0-9_]*$
    type: STRING  # usually BOOLEAN, INT, FLOAT, DOUBLE, STRING, DATE, TIMESTAMP
  - name: length
    type: INT
  - name: effective_length
    type: FLOAT
  - name: tpm
    type: FLOAT
  - name: num_reads
    type: FLOAT
source:
  type: quilt-packages  # currently the only supported type
  package_name: "^ccle/(?<date>[^_]+)_(?<study_id>[^_]+)_nfcore_rnaseq$"
  logical_key: "salmon/(?<sample_id>[^/]+)/quant*\\.genes\\.sf$"
parser:
  format: csv  # or `parquet`
  delimiter: "\t"
  header: true

1. Schema: The schema defines the columns in the table. Each column must have a name and a type. The name must match the regular expression ^[a-z_][a-z0-9_]*$. For CSV/TSVs, these names do not need to match the column names in the document. For Parquet, they must match except for case. However, if column names are present in a CSV/TSV, you must set header to true in the parser configuration.

2. Types: Must be uppercase and match the Apache Arrow Data Types used by Amazon Athena. Valid types are BOOLEAN, TINYINT, SMALLINT, INT, BIGINT, FLOAT, DOUBLE, STRING, BINARY, DATE, TIMESTAMP.

3. Source: The source defines the packages and objects to query. The type must be quilt-packages. The package_name is a regular expression that matches the package names to include. The logical_key is a regular expression that matches the keys of the objects to include. The regular expression may include named capture groups that will be added as columns to the table.

4. Parser: The parser defines how to read the files. The format must be one of csv or parquet. The optional delimiter (defaults to ',') is the character used to separate fields in the CSV file. The optional header field (defaults to 'false') is a boolean that indicates whether the first row of the CSV file contains column names.

Added columns

In addition to the columns defined in the schema, Tabulator will add:

• any named capture groups from the logical key regular expression

• $pkg_name for the package name

• $logical_key for the object as referenced by the package

• $physical_key for the underlying S3 URI

• $top_hash for the revision of the package containing the object (currently we query only the latest package revision)

Caveats

1. Schema Consistency: All files in the package that match the logical key must have the same schema as defined in the configuration.

2. Memory Usage: Tabulator may fail on large files (> 10 GB), files with large rows (> 100 KB), and large numbers of files (> 10000). Additionally, Athena has a 16 MB limit per row.

3. Cost Management: Querying very large datasets can be expensive (approximately dollars per terabyte). Be sure to set up appropriate cost controls and monitoring.

4. Access Restrictions: Due to the way permissions are configured, Tabulator cannot be accessed from the AWS Console or views. You must access Tabulator via the Quilt Catalog in order to query the tables.

5. Concurrency: Tabulator will attempt to process each file concurrently, but may be limited by the concurrency of Athena or the federation lambda in the region where the query is running. If you are experiencing slow performance, it may be because the concurrency is too low. You can increase the concurrency in that region's AWS Service Quotas console.

6. Athena VPC: If you are using a VPC endpoint for Athena, you must ensure it is accessible from the Quilt stack and Tabulator lambda.

Usage

Once the configuration is set, users can query the tables using the Athena tab from the Quilt Catalog. Note that because Tabulator runs with elevated permissions, it cannot be accessed from the AWS Console.

For example, to query the ccle-tsv table from the appropriate workgroup in the quilt-tf-dev-federator stack, where the database (bucket name) is udp-spec:

SELECT * FROM "quilt-tf-dev-federator-tabulator"."udp-spec"."ccle-tsv"

You can join this with any other Athena table, including the package and object tables automatically created by Quilt. For example, this is the package table:

SELECT * FROM "userathenadatabase-1qstaay0czbf"."udp-spec_packages-view"
LIMIT 10

We can then join on PKG_NAME to add the user_meta field from the package metadata to the tabulated results:

SELECT
  "ccle-tsv".*,
  "udp-spec_packages-view".user_meta
FROM "quilt-tf-dev-federator-tabulator"."udp-spec"."ccle-tsv"
JOIN "userathenadatabase-1qstaay0czbf"."udp-spec_packages-view"
ON "ccle-tsv".pkg_name = "udp-spec_packages-view".pkg_name