Snowflake Inc.

Nileema Shingte

Saurin Shah

Benoit Dageville

Thierry Cruanes

Subramanian Muralidhar

Istvan Cseri

Torsten Walther Grabs

Marianne Shaw

Vasile Paraschiv

Jiaqi Yan

Polita Paulus

Xinglian Liu

Selcuk Aya

Muthunagappan Muthuraman

Wai Sing Wong

Steven P Herbert

Marcia Feitel

James Malone

Nithin Mahesh

Dennis Huo

Ronald Lee Ortloff

System and method for efficiently querying external tables are described herein. In an embodiment, a database platform receives a query that is directed at least in part to external data in an external table stored on a data storage platform that is external to the database platform. The external table includes a plurality of partitions. The database platform identifies, from external-table metadata, a subset of the plurality of partitions of the external table as including data that potentially satisfies the query. The external-table metadata is stored by the database platform. The database platform identifies data that satisfies the query by scanning the identified subset of the partitions, and responds to the query at least in part with the identified data that satisfies the query.

Systems and methods for efficiently querying external tables

The subject technology provides embodiments for supporting a unified table which may be a managed table or an unmanaged table. Managed tables are those where the subject technology manages the metastore/catalog for the table, whereas unmanaged tables are tables where an external catalog controls the table and the subject technology integrates with that catalog to work with the table, but does not assume control of the table.

Unified table data access in user-specified formats on internal storage and user-managed storage

A database export system exports data using a plurality of nodes that process the data to generate structured result files that are partitioned by an export parameter in an export request. The database export system distributes the data and merges the files to avoid small file creation and increase processing speed via parallelism. The database export system generates the result files of a specified maximum size in a final format, where the files are processed merged in a temporary file format. The parallel processing is optimized and constrained per the amount of processing nodes, available memory, requested final file sizes, and operation based ordering to complete data exports in a scalable multi-stage approach.

Export data from tables into partitioned folders on an external data lake

The subject technology receives a command to commit a table in a different table format on an external volume. The subject technology generates a first snapshot of the table on internal storage. The subject technology generates a first list of metadata files on the internal storage. The subject technology generates, based on the first list of metadata files, a first set of metadata files on the internal storage. The subject technology generates a second snapshot of the table on the external volume. The subject technology generates a second list of metadata files on the external volume. The subject technology generates, based on the second list of metadata files, a second set of metadata files on the external volume. The subject technology generates a first set of data files in a different file format on the external volume.

Providing table data access in user-specified formats on user-managed storage

In an embodiment, a database platform receives a query that is directed at least in part to external data in an external table stored on a data storage platform that is external to the database platform. The external table includes a plurality of partitions. The database platform identifies, from external-table metadata, a subset of the plurality of partitions of the external table as including data that potentially satisfies the query. The external-table metadata is stored by the database platform. The database platform identifies data that satisfies the query by scanning the identified subset of the partitions, and responds to the query at least in part with the identified data that satisfies the query.

Disclosed herein are embodiments of systems and methods for partition-based scanning of external tables for query processing. In an example embodiment, a database platform receives a query that includes one or more predicates, where the query is directed at least to data in an external table that is stored in an external storage platform that is external to the database platform. The database platform identifies, based on metadata that summarizes the data in the external table, one or more partitions of the external table that potentially include data that satisfies the one or more predicates. The database platform also identifies, from the one or more identified partitions, data that satisfies the one or more predicates. The database platform sends a response to the query to the client, the response comprising the data satisfying the one or more predicates.

Partition-based scanning of external tables for query processing

Systems, methods, and devices for generating a materialized view over an external table. A method includes connecting a database platform to an external table such that the database platform has read access for the external table and does not have write access for the external table. The method includes generating, by the database platform, a materialized view over the external table. The method includes receiving a notification that a modification has been made to the external table, the modification comprising one or more of an addition of a file, a deletion of a file, or an update to a file in a source location for the external table. The method includes, in response to the external table being modified, refreshing the materialized view such that the materialized view comprises an accurate representation of the external table.

Materialized views over external tables in database systems

Disclosed herein are systems and methods for pruning external data. In an embodiment, a database platform receives a query directed at least in part to external data in an external table on an external data storage platform. The external table includes partitions that correspond to storage locations in a source directory of the external data storage platform. The storage locations contain files that contain the external data. The database platform identifies, from external-table metadata that is stored by the database platform and that maps the partitions of the external table to the storage locations in the source directory, a subset of the partitions as including data that potentially satisfies the query. The database platform identifies data that satisfies the query by scanning the identified subset of the partitions, and responds to the query at least in part with the identified data that satisfies the query.

Systems and methods for pruning external data

Disclosed herein are systems and methods for selective scanning of external partitions. In an embodiment, a database platform receives a query directed at least in part to an external table stored on an external data storage platform. The external table is partitioned into partitions corresponding to storage locations in the external data storage platform. The database platform prunes, using external-table metadata that is stored by the database platform and that maps the partitions of the external table to the storage locations in the external data storage platform, those partitions that do not potentially contain data that satisfies the query. The database platform identifies data that satisfies the query by scanning any one or more of the partitions of the external table that were not pruned, and responds to the query at least in part with the identified data that satisfies the query.

Systems and methods for selective scanning of external partitions

The subject technology receives a notification that a modification has been made to an external table, the modification comprising inserting at least one row of new data to the external table, the at least one row corresponding to a first micro-partition that includes a first portion of data from the external table prior to the inserting. The subject technology, in response to the notification indicating the modification to the external table, generates a new micro-partition different from the first micro-partition, the new micro-partition including the inserted at least one row of new data and the first portion of data from the external table. The subject technology generates a refreshed materialized view based at least in part on the generated new micro-partition such that the refreshed materialized view comprises a representation of the external table after the modification has been made.

Notifying modifications to external tables in database systems

Systems, methods, and devices for automated maintenance of external tables in database systems are disclosed. A method includes receiving, by a database platform, read access to content in an external data storage platform that is separate from the database platform. The method includes defining an external table based on the content in the external data storage platform. The method includes connecting the database platform to the external table such that the database platform has read access for the external table and does not have write access for the external table. The method includes generating metadata for the external table, the metadata comprising information about data stored in the external table. The method includes receiving a notification that a modification has been made to the content in the external data storage platform, the modification comprising one or more of an addition of a file, a deletion of a file, or an update to a file in a source location for the external table. The method includes refreshing the metadata for the external table in response to the modification being made to the content in the external data storage platform.

Automated maintenance of external tables in database systems

Disclosed herein are systems and methods for processing queries over external tables. In an embodiment, a database platform receives a query directed at least to data in an external table stored in a storage platform that is external to the database platform. The database platform uses metadata that summarizes the data in the external table to identify one or more partitions of the external table as potentially including data satisfying the query, and generates a query plan that includes a plurality of discrete subtasks that collectively include instructions to scan the identified one or more partitions of the external table for data satisfying the query. The database platform assigns, based on the metadata, the plurality of discrete subtasks to one or more nodes in an execution platform, and refreshes the metadata in response to a threshold number of modifications being made to the external table.

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San Mateo, CA, United States of America

Nileema Shingte