Snowflake Inc.

Zhaohui Zhang

William H Waddington

Dimitrios Tsirogiannis

Alexander Miller

Chen Luo

Nikolaos Romanos Katsipoulakis

Cristian Diaconu

The subject technology generates a nested object based on a set of metadata, the set of metadata including information linking the nested object to a table object associated with a base table. The subject technology generates a second table object associated with the nested object, the second table object representing a secondary index of the base table, the second table object including information linking the second table object to the nested object. The subject technology generates a second nested object based on a particular set of metadata, the particular set of metadata including information linking the second nested object to the table object. The subject technology generates a third table object associated with the second nested object, the third table object representing a particular secondary index of the base table, the third table object including information linking the third table object to the second nested object.

Hybrid table secondary index for lookups, unique checks, and referential integrity constraints

The subject technology receives a query, the query including a statement for performing a join operation on a first table and a second table. The subject technology executes, by an execution node using a generated query plan, the query. The subject technology performs, during execution of the query by the execution node, a runtime range pruning process. The subject technology determines a set of range sets for pruning, each range set including a set of columns from the first table, the set of columns being removed from undergoing a read operation as part of executing the query. The subject technology determines, based on a range bloom vector, a set of rows in a particular range set of the first table to avoid scanning in connection with the read operation. The subject technology performs the read operation based a remaining set of rows.

Runtime join pruning to improve join performance for tables

The subject technology receives, by a distributed database, transactional queries against a key-value database comprising data managed by key-value pairs. The subject technology performs, using asynchronous threads of execution nodes of the distributed database, asynchronous transformation and compaction of key-value pairs of data that corresponds to the plurality of transactional queries. The subject technology performs, using asynchronous threads of execution nodes of the distributed database, asynchronous transformation and compaction of a set of secondary indexes that corresponds to the plurality of transactional queries. The subject technology processes, using transactional threads in the execution nodes, the plurality of transactional queries to generate results data, the asynchronous threads performing the asynchronous transformation and compaction while the transactional threads generate the results data.

Distributed database that uses hybrid table secondary indexes

The subject technology performs, using asynchronous threads of execution nodes of a distributed database, asynchronous transformation and compaction of key-value pairs of data that correspond to a plurality of transactional queries, the asynchronous threads transforming the key-value pairs from an initial format to a commit format that includes a commit time of data committed to the distributed database, the asynchronous threads compacting the key-value pairs by deleting the key-value pairs in the initial format. The subject technology processes, using transactional threads in the execution nodes, the plurality of transactional queries to generate results data, the asynchronous threads performing the asynchronous transformation and compaction while the transactional threads generate the results data. The subject technology stores the results data.

Scalable compaction for a distributed database

The subject technology receives a statement to initiate an online index building process of an index. The subject technology determines that the index can be generated. The subject technology performs a write operation to store an index record indicating an initial status of the online index building process. The subject technology performs a statement fencing process. The subject technology performs a back-filling process of the index. The subject technology validates the index.

Online index creation for multi-version database without table locks

The subject technology obtains a read timestamp of a first transaction. The subject technology performs a first read operation on a parent table associated with the first transaction to determine a set of committed versions of the parent table. The subject technology determines whether a key exists in the parent table based on the first transaction. The subject technology, in response to the key existing in the parent table, performs a first write operation on a child table. The subject technology determines whether a duplicate key exists in the child table. The subject technology, in response to determining that there is no duplicate key in the child table, determines whether there is a conflict with the key. The subject technology, in response to determining that there is no conflict with the key, performs a second write operation on a secondary index table of the child table.

Query processing using hybrid table secondary indexes

The subject technology determines that a first visible version of a key is not one of a N number of newest versions of the key based on searching for the key in a regular space to locate the first visible version of the key. The subject technology performs a search of an undo space to locate a second visible version of the key. The subject technology determines whether the first visible version or the second visible version of the key is newer. The subject technology provides a newer version of the key between the first visible version and the second visible version of the key.

Long-lived statements optimizations in a database system

The subject technology receives a query, the query including a set of statements, the set of statements including a first statement comprising a first data manipulation language operation. The subject technology determines that the set of statements includes at least one statement defining a first constraint, and a second statement indicating that the first constraint is statement deferrable for performing validation of the first constraint. The subject technology generates a key value constraint check operator as a node in a query plan. The subject technology generates a key value DML operator as a second node in the query plan, the key value DML operator corresponding to the first DML operation. The subject technology performs, using the key value constraint check operator, a validation process of the first constraint based at least in part on a set of violating keys of each DML operation from the set of statements.

Deferred constraints support in distributed database systems

Runtime join pruning to improve join performance for database tables

The subject technology inserts, by a first transaction, a new version of an object, the first transaction including a first statement to perform an update operation to a row in a first table, the object corresponding to data in the row to be updated, the first statement including information comprising an object key associated with the object. The subject technology performs, by a second transaction, a range read, the range read including information indicating the object key. The subject technology receives a set of conflicting transactions from the range read. The subject technology determines that a conflict occurred between the first transaction and a third transaction from the set of conflicting transactions. The subject technology performs a restart of the first transaction in response to determining that the conflict occurred.

Concurrency control for transactions in database systems

The subject technology receives, from a metadata database, information related to a base table. The subject technology determines a table object associated with the base table, the table object including a first set of metadata. The subject technology generates a nested object based on a second set of metadata, the second set of metadata including information linking the nested object to the table object. The subject technology generates a second table object associated with the nested object, the second table object representing a secondary index of the base table, the second table object including information linking the second table object to the nested object. The subject technology establishes a link between the second table object to the base table based on the nested object. The subject technology stores, in the metadata database, the nested object and the second table object.

A distributed database compaction system can perform compaction for transactional queries in an asynchronous matter without affecting completion of the queries. The compaction system can implement asynchronous transformation of key pairs in the database, and older keys can be periodically purged using a scheduled compactor. Subsequent queries use the compacted stored keys to perform efficient queries with direct reads of committed transactions and more efficient access to key values stores of the distributed database.

Scalable compaction in a concurrent transaction processing distributed database

The subject technology performs a search for a key in a regular space to locate a first visible version of the key. The subject technology determines that the first visible version of the key is not one of a N number of newest versions of the key. The subject technology performs a search of an undo space to locate a second visible version of the key. The subject technology determines whether the first visible version or the second visible version of the key is newer. The subject technology provides a newer version of the key between the first visible version and the second visible version of the key.

Optimizations for long-lived statements in a database system

The subject technology inserts, by a first transaction, a new version of an object, the inserting corresponding to a first statement from the first transaction, the first statement including information indicating a first key, a first transaction identifier, a first statement number, and a first restart count. The subject technology performs, by a second transaction, a range read, the range read including information indicating the first key. The subject technology receives, after performing the range read, a set of conflicting transactions. The subject technology determines that a conflict occurred between the first transaction and a third transaction from the set of conflicting transactions.

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Redwood City, CA, United States of America

Zhaohui Zhang